SARS-CoV-2 と COVID-19 に関する備忘録 Vol.22――腫瘍細胞・内皮細胞・およびマクロファージでコロナウイルスのスパイクプロテインが検出された…etc.

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SARS-CoV-2 と COVID-19 に関するメモ・備忘録

◆High Risk of Heart Tumors after COVID-19【MDPI Journals　2023年10月20日】

Abstract

An emergence of evidence suggests that severe COVID-19 is associated with an increased risk of developing breast and gastrointestinal cancers. The aim of this research was to assess the risk of heart tumors development in patients who have had COVID-19. Methods: A comparative analysis of 173 heart tumors was conducted between 2016 and 2023. Immunohistochemical examination with antibodies against spike SARS-CoV-2 was performed on 21 heart tumors: 10 myxomas operated before 2020 (the control group), four cardiac myxomas, one proliferating myxoma, three papillary fibroelastomas, two myxofibrosarcomas, one chondrosarcoma resected in 2022–2023. Immunohistochemical analysis with antibodies against CD34 and CD68 was also conducted on the same 11 Post-COVID period heart tumors. Immunofluorescent examination with a cocktail of antibodies against spike SARS-CoV-2/CD34 and spike SARS-CoV-2/CD68 was performed in 2 cases out of 11 (proliferating myxoma and classic myxoma). Results: A 1.5-fold increase in the number of heart tumors by 2023 was observed, with a statistically significant increase in the number of myxomas. There was no correlation with vaccination, and no significant differences were found between patients from 2016–2019 and 2021–2023 in terms of gender, age, and cardiac rhythm dis-orders. Morphological examination revealed the expression of spike SARS-CoV-2 in tumor cells, endothelial cells, and macrophages in 10 out of 11 heart tumors. Conclusion: The detection of SARS-CoV-2 persistence in endothelium and macrophages as well as in tumor cells of benign and malignant cardiac neoplasms, the increase in the number of these tumors, especially cardiac myxomas, after the pandemic by 2023 may indicate a trend toward an increased risk of cardiac neoplasms in COVID-19 patients, which re-quires further research on this issue and a search for new evidence.

1. Introduction

Our knowledge of the coronavirus is constantly being updated. Data analysis from nearly 154,000 people with SARS-CoV-2 gives a dismal projection for long-term cardiovascular outcomes of COVID-19. After recovery from the acute phase of the disease, many studies within last few years have presented a high risk of different cardiovascular problems, including heart rhythm disturbances, myocarditis, pericarditis, blood clots, strokes, myocardial infarction and heart failure. Furthermore, there was evidence of risks in people who had mild and latent COVID-19 infection.

There is an opinion in the literature that SARS-CoV-2 infection also leads to the development of cardiovascular diseases “de novo”. One of mechanisms of pathogenesis is endotheliitis. It is now known that SARS-CoV-2 is able to suppress the immune response to virus entry into the body. Lymphopenia has been described in many patients which is most often characterized by decreased levels in CD4+ and CD8+ T-lymphocytes, which is also a characteristic feature of a number of coronavirus infections. CD4+ T cells specific for SARS-CoV-2 express IFNγ, TNF-ά, IL-2, which indicate the development of a Th1-type cellular response. In addition, direct, long-term damage by cardiomyocyte virus persistence due to the failure of the T-cells immune response are not excluded. A decrease in the number of T lymphocytes has been shown in mouse models to be accompanied by the development of intense inflammation in the lungs. At the moment, the pathogenetic mechanisms of myocardial damage are still at the stage of hypotheses.

The current literature pays attention to the potential link between of COVID-19 and long-term cancer risk. Viruses damage host DNA, disrupt apoptosis as well as suppress host immune responses. SARS-CoV-2 contains safe proteins that play important roles in cell cycle progression, metabolism, epigenetics, translation and RNA processing. Some authors believe that long-term COVID-19 can contribute to the development of cancer in recovered patients and accelerate a tumor progression. This theory stems from the increasing body of evidence regarding SARS-CoV-2’s capacity to influence cancer-related pathways, encourage persistent low-grade inflammation and induce tissue damage. Mendelian randomization to investigate the causal relationship between COVID-19 and 33 different types of carcinomas in the European population revealed an increased risk of HER2-positive breast cancer, esophageal, gastric and colon cancer with a genetic predisposition to severe coronavirus infection. Aim of the study: To assess the risk of developing heart tumors in patients who have had COVID-19.

 

◆Repeated Omicron exposures override ancestral SARS-CoV-2 immune imprinting【nature　2023年11月22日】

Abstract

The continuing emergence of SARS-CoV-2 variants highlights the need to update COVID-19 vaccine compositions. However, immune imprinting induced by vaccination based on the ancestral (hereafter referred to as WT) strain would compromise the antibody response to Omicron-based boosters. Vaccination strategies to counter immune imprinting are critically needed. Here we investigated the degree and dynamics of immune imprinting in mouse models and human cohorts, especially focusing on the role of repeated Omicron stimulation. In mice, the efficacy of single Omicron boosting is heavily limited when using variants that are antigenically distinct from WT—such as the XBB variant—and this concerning situation could be mitigated by a second Omicron booster. Similarly, in humans, repeated Omicron infections could alleviate WT vaccination-induced immune imprinting and generate broad neutralization responses in both plasma and nasal mucosa. Notably, deep mutational scanning-based epitope characterization of 781 receptor-binding domain (RBD)-targeting monoclonal antibodies isolated from repeated Omicron infection revealed that double Omicron exposure could induce a large proportion of matured Omicron-specific antibodies that have distinct RBD epitopes to WT-induced antibodies. Consequently, immune imprinting was largely mitigated, and the bias towards non-neutralizing epitopes observed in single Omicron exposures was restored. On the basis of the deep mutational scanning profiles, we identified evolution hotspots of XBB.1.5 RBD and demonstrated that these mutations could further boost the immune-evasion capability of XBB.1.5 while maintaining high ACE2-binding affinity. Our findings suggest that the WT component should be abandoned when updating COVID-19 vaccines, and individuals without prior Omicron exposure should receive two updated vaccine boosters.

Main

SARS-CoV-2 continues to evolve, and new mutants emerge under continuous humoral immune pressure. New variants, such as the XBB lineages, are capable of evading antibodies induced by vaccination or infection, resulting in repeated infections among populations. Therefore, it is critical to develop updated vaccines that can elicit strong immune responses against the latest variants.

mRNA vaccine platforms can quickly adapt to new SARS-CoV-2 variants. However, as the majority of the population was vaccinated with the ancestral SARS-CoV-2 strain (WT), immune imprinting induced by WT vaccination presents a major challenge to the performance of updated boosters. This is because boosting with a variant that is antigenically distinct from WT would mostly recall memory B cells induced by WT vaccination and mask the de novo generation of variant-specific B cells, which would hinder the generation of appropriate humoral immunity against new and emerging variants.

It is crucial to explore vaccination strategies that can counter immune imprinting. In this paper, we investigated the dynamics of immune imprinting in both mouse models and human cohorts, with a particular focus on whether repeated exposure to Omicron variants could alleviate immune imprinting.

 

◆Sequential activation of DNA viruses by the RNA virus SARS-CoV-2 in patients with long COVID syndrome【European Heart Journal　2023年11月9日】

Abstract

Background

Reactivation of Epstein-Barr virus (EBV) has been suggested to play role in long lasting multiorgan symptoms several months after the initial COVID-19 illness.

Purpose

The aim of our prospective study was to 1) to evaluate the reactivation of DNA viruses of EBV, Cytomegalovirus, Herpes simplex, Varicella zoster and Parvovirus-B19 by SARS-CoV-2 in patients with the diagnosis of long-COVID syndrome, 2) to investigate the effect of supposed virus reactivation on clinical conditions and long COVID syndromes.

Methods

Patients with long COVID syndrome were prospectively included into the Vienna PostCoV Registry between March 15th 2021 and September 30th 2021. – The time between COVID-19 infection and first clinical visit was 219±98 days (7±3 months). Clinical symptoms were documented and patients were divided into symptoms-oriented subgroups with dominantly respiratory, cardiovascular or neuropsychologic complaints. Qualitative and quantitative viral IgG and IgM titer of the selected DNA viruses of n=105 patients were compared with age and sex-matched healthy (non-infected, non-vaccinated, n=105) controls, who had neither spike- nor nucleocapsid antibodies, nor clinical history of COVID-19 disease.

Results

Long Covid patients had significantly higher cumulative number of IgM positivity of the DNA viruses (18.1% vs 6.7%, p=0.02), and significantly elevated quantitative EBV IgG (420±296 vs 339±282 mg/dL, p=0.033) and Parvo-B19 IgM (0.28±0.29 vs 0.03±0.12 mg/dL, p<0.001) titer as compared to healthy controls. Significantly more patients with long COVID symptoms had an EBV IgG titer above the detection limit as compared with healthy controls (40% vs 28%, p=0.018), suggesting EBV virus reactivation and chronic EBV infection. EBV IgG titer was significantly higher in patients with dominant respiratory symptoms, while elevated Parvo-B19 IgM titer was observed in patients with dominant cardiovascular complaints. In patients with long-COVID syndrome the quantitative EBV IgG titer increased with the time between infection and blood sampling (logarithmic correlation, p=0.011), suggesting the subclinical continuous EBV activation by the SARS-CoV2 RNA virus, while the quantitative Parvo-B19 IgM titer decreased linearly during the observation period. Conclusions

In this study of patients with long-COVID syndrome, SARS-CoV-2 infection apparently activated certain types of DNA viruses (EBV, and Parvo-B19), as demonstrated by the significantly higher incidence of cumulative IgM positivity, and elevated EBV IgG and parvovirus-B19 IgM titers, in long-COVID patients compared to healthy controls.

 

◆Distinguishing features of long COVID identified through immune profiling【nature　2023年9月25日】

Abstract

Post-acute infection syndromes may develop after acute viral disease. Infection with SARS-CoV-2 can result in the development of a post-acute infection syndrome known as long COVID. Individuals with long COVID frequently report unremitting fatigue, post-exertional malaise, and a variety of cognitive and autonomic dysfunctions. However, the biological processes that are associated with the development and persistence of these symptoms are unclear. Here 275 individuals with or without long COVID were enrolled in a cross-sectional study that included multidimensional immune phenotyping and unbiased machine learning methods to identify biological features associated with long COVID. Marked differences were noted in circulating myeloid and lymphocyte populations relative to the matched controls, as well as evidence of exaggerated humoral responses directed against SARS-CoV-2 among participants with long COVID. Furthermore, higher antibody responses directed against non-SARS-CoV-2 viral pathogens were observed among individuals with long COVID, particularly Epstein–Barr virus. Levels of soluble immune mediators and hormones varied among groups, with cortisol levels being lower among participants with long COVID. Integration of immune phenotyping data into unbiased machine learning models identified the key features that are most strongly associated with long COVID status. Collectively, these findings may help to guide future studies into the pathobiology of long COVID and help with developing relevant biomarkers.

Main

Recovery from acute viral infections is heterogeneous and chronic symptoms may linger for months to years in some individuals. Moreover, persistent sequelae may develop after acute infection by a number of viruses from a diverse range of viral families. Post-acute infection syndromes (PAIS) following microbial infections have also been described for over a century. Yet despite their ubiquity, the basic biology underlying PAIS development, even for extensively studied PAIS such as myalgic encephalomyelitis/chronic fatigue syndrome, remains unclear.

SARS-CoV-2 is a Betacoronavirus that is responsible for almost 7 million deaths worldwide. Infection causes COVID-19, which can manifest as a severe respiratory disease marked by extensive immunological and multiorgan system dysfunction. Recovery from COVID-19 is often complete; however, individuals (even those with initially mild disease courses) may have increased risks for adverse clinical events and abnormal clinical findings.

In addition to developing isolated dysfunctions, some patients recovering from COVID-19 may develop a group of new onset or aggravated sequelae known as long COVID (LC). Clinically, LC presents as a constellation of debilitating symptoms including unremitting fatigue, post-exertional malaise, cognitive impairment and autonomic dysfunction, alongside other less common manifestations. These persistent sequelae markedly impair physical and cognitive function and reduce quality of life. Estimates of LC prevalence vary substantially, but prospective studies suggest that about one in eight individuals with COVID-19 experience persistent somatic symptoms that are attributable to past SARS-CoV-2 infection. Although the underlying pathogenesis of LC remains unclear, current hypotheses include the persistence of virus or viral remnants in tissues; development or aggravation of autoimmunity; microbial dysbiosis; reactivation of non-SARS-CoV-2 latent viral infections; and tissue damage caused by chronic inflammation.

To investigate the biological underpinnings of LC, a cross-sectional study was designed (Mount Sinai–Yale long COVID; hereafter, MY-LC) involving 275 participants comprising five study groups: (1) healthcare workers infected with SARS-CoV-2 before vaccination (HCW); (2) healthy, uninfected, vaccinated controls (healthy control (HC) group); (3) previously infected, vaccinated controls without persistent symptoms (convalescent control (CCs) group); (4) individuals with persistent symptoms after acute infection (LC); and (5) a second group of individuals with persistent symptoms after acute infection from an independent study (external LC, hereafter EXT-LC). Among the CC and LC groups, enrolled participants had primarily mild (non-hospitalized) acute COVID-19 and samples for this study were acquired, on average, more than a year after their acute infection. The HC, CC and LC groups underwent systematic, multidimensional immunophenotyping and unbiased machine learning of aggregated data to identify potential LC biomarkers.

◆Divergent adaptive immune responses define two types of long COVID【Frontiers in Immunology　2023年7月20日】

Background: The role of adaptive immune responses in long COVID remains poorly understood, with contrasting hypotheses suggesting either an insufficient antiviral response or an excessive immune response associated with inflammatory damage. To address this issue, we set to characterize humoral and CD4+ T cell responses in long COVID patients prior to SARS-CoV-2 vaccination.

Methods: Long COVID patients who were seropositive (LC+, n=28) or seronegative (LC-, n=23) by spike ELISA assay were recruited based on (i) an initial SARS-CoV-2 infection documented by PCR or the conjunction of three major signs of COVID-19 and (ii) the persistence or resurgence of at least 3 symptoms for over 3 months. They were compared to COVID patients with resolved symptoms (RE, n=29) and uninfected control individuals (HD, n=29).

Results: The spectrum of persistent symptoms proved similar in both long COVID groups, with a trend for a higher number of symptoms in the seronegative group (median=6 vs 4.5; P=0.01). The use a highly sensitive S-flow assay enabled the detection of low levels of SARS-CoV-2 spike-specific IgG in 22.7% of ELISA-seronegative long COVID (LC-) patients. In contrast, spike-specific IgG levels were uniformly high in the LC+ and RE groups. Multiplexed antibody analyses to 30 different viral antigens showed that LC- patients had defective antibody responses to all SARS-CoV-2 proteins tested but had in most cases preserved responses to other viruses. A sensitive primary T cell line assay revealed low but detectable SARS-CoV-2-specific CD4 responses in 39.1% of LC- patients, while response frequencies were high in the LC+ and RE groups. Correlation analyses showed overall strong associations between humoral and cellular responses, with exceptions in the LC- group.

Conclusions: These findings provide evidence for two major types of antiviral immune responses in long COVID. Seropositive patients showed coordinated cellular and humoral responses at least as high as those of recovered patients. In contrast, ELISA-seronegative long COVID patients showed overall low antiviral responses, with detectable specific CD4+ T cells and/or antibodies in close to half of patients (52.2%). These divergent findings in patients sharing a comparable spectrum of persistent symptoms raise the possibility of multiple etiologies in long COVID.

Introduction

A significant proportion of patients with COVID-19 experience persisting symptoms more than two months after an initial infection with SARS-CoV-2. This post-viral syndrome is termed long COVID, post-acute sequelae of SARS-CoV-2 infection (PASC), or post-COVID-19 condition, as defined by the WHO. Long COVID is characterized by a diverse array of symptoms, with a predominance of debilitating fatigue, difficulties in memory and concentration, and dyspnea. Additional symptoms include signs of autonomic dysfunction, such as tachycardia and poor regulation of blood pressure, and may also include digestive, renal, reproductive, vascular, and immunological manifestations. Early studies suggested a high frequency (above 30%) of persisting symptoms in patients who had been hospitalized for severe COVID-19. It is now clear, however, that patients with an initially moderate or mild form of COVID-19 can also experience prolonged or resurgent symptoms that prevent return to normal life. Frequency estimates of long COVID after mild/moderate infection are generally in the 5-20% range, and tend to be higher in women. Long COVID also affects the young, with 5 to 10% of infected adolescent reporting persisting symptoms, even though the initial SARS-CoV-2 infection may have been benign and not always associated with seroconversion. Preexisting immunity induced by COVID vaccination decreases the risk of long COVID occurrence in some but not all studies. Reinfection by SARS-CoV-2 is still associated with a risk of post-acute sequelae, suggesting that the risk of long COVID is not abolished in a highly preinfected population. Long COVID symptoms tend to decrease over time, but close to 10% of COVID-19 patients still experience at least one persisting symptom one year after infection. Worryingly, long COVID symptoms may persist for at least three years, with debilitating symptoms still present in a subset of patients infected in the initial 2020 wave of the pandemic. Considering the high cumulative incidence of SARS-CoV-2 infection worldwide, long COVID is now considered as a significant public health concern.

The etiology of long COVID remains poorly understood and is currently the object of a major research effort. One major hypothesis focuses on the persistence of a SARS-CoV-2 reservoir, either in the form of hidden virus replicating at low levels in sanctuary sites, or in the form of non-replicative viral remnants that would chronically stimulates the antiviral response. The punctual detection of viral RNA and/or viral proteins in autopsy material, olfactory mucosa, and gut biopsies months after the acute infection stage supports the possibility of viral persistence. The presence of viral material may in turn explain moderate but persistent signs of chronic activation in long COVID, including increased levels of circulating inflammatory mediators, changed patterns of cytokine production by CD4+ T cells, and induction of activation and exhaustion markers in CD8+ T cells. A lack of viral control and ensuing chronic inflammation may point to an intrinsically inefficient antiviral response to SARS-CoV-2, a notion that we aimed to explore in the present study. Intriguingly, long COVID has also been associated with the reactivation of Epstein-Barr virus and other herpesviruses, highlighting the possibility of a relatively broad impairment of antiviral responses. Conversely, excessive immune responses with an autoimmune component have also been proposed to play a role in long COVID. It is well documented that acute viral infections are generally followed by a wave of bystander immune activation, which can trigger undesirable immune responses against self-antigens. Auto-antibodies to a variety of self-proteins, including nuclear antigens and G-protein coupled surface receptors, have been reported in a subset of long COVID patients, but no consistent autoantibody pattern has been associated to long COVID so far. Paradoxically, autoantibodies to chemokines were recently reported to be decreased, rather than increased, in long COVID patients compared to patients who recovered from COVID-19, supporting the notion of a moderate but detectable impairment of immune responses in long COVID.

Alternative etiologies proposed for long COVID include persistent tissue damage induced early during the acute stage of infection. The variety of organs targeted by SARS-CoV-2 (lungs, heart, gut, brain, kidneys) may help explain the pleiomorphic nature of long COVID symptoms. A possible role for endotheliopathy, leading to disseminated microvascular clots and impaired vascular function, may also account for multiple organ system involvement. An impairment of cellular metabolism has been reported in the brain of long COVID patients, which may help explain fatigue as well as dysautonomic and cognitive signs of long COVID. The abnormal activation of mastocytes may also contribute to dysautonomia. These proposed mechanisms are not mutually exclusive, as for instance impaired immunity may facilitate viral neuroinvasion and metabolism dysregulation. Unsupervised analyses of electronic heath record data suggest the occurrence of distinct subtypes of long COVID, with predominant cardiac, respiratory, neurological, or digestive symptoms. It is thus possible that distinct etiologies underly the diverse array of symptoms in long COVID.

The role of T cell responses in protecting against severe COVID-19 has been clearly established, with an association between the rapid induction of functional SARS-CoV-2-specific T cells in the acute stage and rapid viral clearance. Preexisting T cells induced by common cold coronavirus and able to crossreact to SARS-CoV-2 antigens are thought to prevent COVID-19 in certain cases of abortive seronegative infections. In contrast, the role of T cell responses in long COVID remains unclear, with reports of exacerbated T cell cytotoxicity and dysregulated cytokine secretion capacity, signs of abnormal T cell activation and exhaustion, or, in certain cases, presence of weak or undetectable T cell responses. Whether altered T cell functions contribute to an immunopathogenic process or to a failure at controlling viral replication remains an open question. To address these issues, we set to further explore the nature of T cell responses in long COVID, using a primary CD4+ T cell line approach that can reveal weak responses that may be missed in ex vivo T cell assays.

Long COVID patients were recruited from the observational PERSICOR cohort established at the Hôtel Dieu hospital at the beginning of the pandemic. Importantly, patients were recruited before vaccination, which enabled the study of endogenous SARS-CoV-2-specific responses unperturbed by exogenous antigenic stimulation. Early studies had shown that one third of the long COVID patients in the PERSICOR cohort were seronegative by spike ELISA assay, while their spectrum of symptoms was as severe as that of seropositive patients. This contrasted with the lower rate of seronegative infection seen in the general population of COVID-19 patients, which ranged from 2 to 24% depending on the study. As seronegative patients represented a substantial part of the cohort and had rarely been included in previous long COVID reports, we chose to study this group in parallel to that of seropositive patients. Using highly sensitive antibody and T cell assays, we could document immunological signs of a previous SARS-CoV-2 infection in half of ELISA-seronegative long COVID patients, suggesting the presence of an insufficient antiviral adaptive response in this group. In contrast, seropositive long COVID patients showed persistently high antibody and CD4+ T cell responses, that did not differ in magnitude and breadth from those of individuals who had recovered from COVID-19. These findings provide evidence for divergent antiviral adaptive responses in long COVID, pointing to distinct pathogenic mechanisms underlying symptom persistence.

 

◆Neurological risks of COVID-19 in women: the complex immunology underpinning sex differences【Frontiers in Immunology　2023年11月14日】

The COVID-19 pandemic has uncovered many mysteries about SARS-CoV-2, including its potential to trigger abnormal autoimmune responses. Emerging evidence suggests women may face higher risks from COVID-induced autoimmunity manifesting as persistent neurological symptoms. Elucidating the mechanisms underlying this female susceptibility is now imperative. We synthesize key insights from existing studies on how COVID-19 infection can lead to immune tolerance loss, enabling autoreactive antibodies and lymphocyte production. These antibodies and lymphocytes infiltrate the central nervous system. Female sex hormones like estrogen and X-chromosome mediated effects likely contribute to dysregulated humoral immunity and cytokine profiles among women, increasing their predisposition. COVID-19 may also disrupt the delicate immunological balance of the female microbiome. These perturbations precipitate damage to neural damage through mechanisms like demyelination, neuroinflammation, and neurodegeneration – consistent with the observed neurological sequelae in women. An intentional focus on elucidating sex differences in COVID-19 pathogenesis is now needed to inform prognosis assessments and tailored interventions for female patients. From clinical monitoring to evaluating emerging immunomodulatory therapies, a nuanced women-centered approach considering the hormonal status and immunobiology will be vital to ensure equitable outcomes. Overall, deeper insights into the apparent female specificity of COVID-induced autoimmunity will accelerate the development of solutions mitigating associated neurological harm.

1 Introduction

The COVID-19 pandemic, caused by the novel coronavirus SARS-CoV-2 has been associated with autoimmune responses in some patients. Autoimmunity arises when the immune system loses tolerance to self-antigens and produces autoantibodies attacking host tissues. Both cellular and humoral autoimmune reactions have been described in COVID-19 patients. For example, anti-interferon autoantibodies capable of impairing antiviral responses are detected in approximately 10.2% of severe COVID-19 cases. Additionally, SARS-CoV-2 binding to tissue antigens may induce cross-reactivity of immune cells and subsequent autoimmune damage in organs like the Livers and nervous system. Understanding the autoimmune aspects of COVID-19 is crucial, as they may exacerbate disease severity and cause prolonged symptoms in recovered patients.

Emerging evidence suggests that COVID-19 can trigger autoimmune responses through several mechanisms. Viral infections often provoke autoimmunity via molecular mimicry, wherein viral antigens resemble self-antigens. SARS-CoV-2 proteins may share sequences or structures with host proteins, leading to cross-reactivity of antibodies or T cells. Additionally, the severe inflammation and cytokine storm induced by COVID-19 may cause the breakdown of self-tolerance. Elevated levels of cytokines like IL-6, IL-17, and TNF-α can stimulate auto-reactive lymphocytes. SARS-CoV-2 infection can also prompt neutrophil extracellular trap (NET) formation and release of danger-associated molecular patterns (DAMPs), further enhancing immune dysregulation. Identifying the pathways leading to autoimmunity following COVID-19 is imperative to improve understanding and management of the disease.

Autoimmune responses have been shown to impact and damage both the central and peripheral nervous systems. Autoimmune diseases like multiple sclerosis, Guillain-Barre syndrome, involve neural inflammation, demyelination, and neurodegeneration. Autoantibodies can also directly attack neurons and synaptic connections, disrupting neural signaling. Moreover, increasing evidence indicates that acute infections can also elicit autoantibodies to cause cross-reactivity against the nervous system. Therefore, the autoimmune reactions associated with COVID-19 infection may similarly lead to neurological damage. Elucidating how autoimmunity induced by SARS-CoV-2 affects the nervous system is critical for managing neurological sequelae.

COVID-19 may disproportionately impact the female nervous system. While there is no evidence that women infected with SARS-CoV-2 have higher rates of acute neurological complications like stroke, female sex has been identified as an independent risk factor for developing long COVID syndromes. Additionally, neuropsychiatric symptoms such as anxiety and depression are commonly reported neurological manifestations of long COVID, with a higher proportion of women experiencing these symptoms compared to men. The mechanisms underlying this female propensity for neuro-COVID sequelae are still unclear. However, sex differences in immune responses and hormonal influences may contribute to increased susceptibility of the female nervous system to long-term damage mediated by COVID-19. Moreover, autoimmune diseases like multiple sclerosis and rheumatoid arthritis that affect the nervous system are more prevalent in women.

 

◆Semen proteomics reveals alterations in fertility-related proteins post-recovery from COVID-19【Frontiers in Physiology　2023年11月9日】

Introduction: Changes to sperm quality and decline in reproductive function have been reported in COVID-19-recovered males. Further, the emergence of SARS-CoV-2 variants has caused the resurgences of COVID-19 cases globally during the last 2 years. These variants show increased infectivity and transmission along with immune escape mechanisms, which threaten the already burdened healthcare system. However, whether COVID-19 variants induce an effect on the male reproductive system even after recovery remains elusive.

Methods: We used mass-spectrometry-based proteomics approaches to understand the post-COVID-19 effect on reproductive health in men using semen samples post-recovery from COVID-19. The samples were collected between late 2020 (1st wave, n = 20), and early-to-mid 2021 (2nd wave, n = 21); control samples were included (n = 10). During the 1st wave alpha variant was prevalent in India, whereas the delta variant dominated the second wave.

Results: On comparing the COVID-19-recovered patients from the two waves with control samples, using one-way ANOVA, we identified 69 significantly dysregulated proteins among the three groups. Indeed, this was also reflected by the changes in sperm count, morphology, and motility of the COVID-19- recovered patients. In addition, the pathway enrichment analysis showed that the regulated exocytosis, neutrophil degranulation, antibacterial immune response, spermatogenesis, spermatid development, regulation of extracellular matrix organization, regulation of peptidase activity, and regulations of calcium ion transport were significantly dysregulated. These pathways directly or indirectly affect sperm parameters and function. Our study provides a comprehensive landscape of expression trends of semen proteins related to male fertility in men recovering from COVID-19.

Discussion: Our study suggests that the effect of COVID-19 on the male reproductive system persists even after recovery from COVID-19. In addition, these post-COVID-19 complications persist irrespective of the prevalent variants or vaccination status.

1 Introduction

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) driven coronavirus disease 2019 (COVID-19) pandemic has greatly affected healthcare structures globally. With 616 million cases reported till October 2022 (WHO dashboard, 2022), the pandemic has also forced the research and medical community to work in collaboration to understand the virus. As the COVID-19 pandemic progressed, it brought to the fore the extra-pulmonary effects of COVID-19. Although discussed widely, the exact mechanism of the post-COVID-19 sequelae remains elusive. These extrapulmonary effects of COVID-19 are supported by two schools of thought 1) the effects are results of direct interaction with the virus and 2) indirect effects due to the systemic inflammation or other factors such as drugs given during the infection (Nie et al., 2021). Most of the direct interaction of the virus with organs other than the lungs is attributed to the fact that angiotensin-converting enzyme 2 (ACE2) and transmembrane protease, serine 2 (TMPRSS2) expression, which are critical for viral entry into the cell, are expressed in many other organs of the body (Dong et al., 2020). Interestingly, the expression of ACE2 and TMPRSS2 is very high in the testes. Also, reportedly males have a higher susceptibility to testing positive for COVID-19 (Yadav et al., 2021). Additionally, some studies have reported changes in the sperm and semen parameters post-COVID-19 (Ardestani Zadeh and Arab, 2021; Maleki and Tartibian, 2021; Mintziori et al., 2022). Therefore, studying the effect of COVID-19 on male reproductive health becomes crucial.

We designed a study to evaluate the implication of effects of COVID-19 on male reproductive health and infertility that persists after recovery. Our previously published study (Ghosh et al., 2022) was a pilot study to understand the post-COVID-19 effect on the male reproductive system. In this study, the semen samples were collected from patients who have recovered from COVID-19 and compared the alterations in the proteome with that of healthy individuals with no history of COVID-19. The study for the first time provided a comprehensive overview of alteration in whole semen proteome. Human semen constitutes secretions from the testis, epididymis, and male accessory glands such as seminal vesicles, prostate, and Cowper’s gland. The change in sperm formation, motility, and shape was attributed to alterations in proteins like semenogelin 1(SEMG1), cluster of differentiation 59 (CD59), prosaposin (PSAP), zona pellucida binding protein (ZPBP), sperm equatorial segment protein 1 (SPESP1), Dipeptidase 3 (DPEP3), sperm surface protein (SPA17), Outer dense fiber protein 2 (ODF2), and Neuropilin 1 (NRP1). These proteins are mapped to different pathways associated with spermatogenesis, motility, and fertilization. The study thus showed that the COVID-19 complications post recovery transcend beyond the respiratory complications. In addition, it emphasized the need to study the implication of COVID-19 on male reproductive health (Ghosh et al., 2022).

However, there have been incidences of COVID-19 resurgence driven by emerging SARS-CoV-2 strains, which have altered infectivity. This resurgence of COVID-19 has been popularly termed as “waves”. Different countries have reported such waves at different times (Wei et al., 2022). In India, apart from the initial wave from March to September 2020, driven by wildtype phenotype, there have been two incidences of resurgences driven by the delta and omicron variants (Kunal and Aditi, 2021). The delta variant was identified in 62% of the samples in April and 94% in May. This was also parallel to the advent of the second wave in India (Chakraborti et al., 2023). Delta variant has so far been reported to increase infectivity due to the mutations, although a few studies so far have reported changes in the pathogenesis of the virus (Harvey et al., 2021). The implications of these emerging variants on post-COVID-19 extrapulmonary complications also remain elusive. Another important thing that might have an impact on COVID-19 complications is the vaccine. Although vaccines can protect against variants or from infection, the exact effect of these vaccines on reducing the post-COVID-19 sequelae remains elusive (Taquet et al., 2022). Especially in India, where the vaccination campaign has received a huge response but with some setbacks due to misconceptions regarding the side effects of vaccines (Baig et al., 2022; Bansal et al., 2022). Therefore, understanding the effect of the variants and vaccines post-COVID-19 complications becomes crucial.

Post the initial COVID-19 wave, India witnessed another COVID-19 wave driven by the delta variant in April and May 2021. The delta was highly prevalent during the duration of sampling. Therefore, we believe that the patients from the second wave were prominently infected with the delta variant. As this variant was prevalent during the time of cohort recruitment and sample collection. In addition, India had also started the vaccination campaign by January 2021. Therefore, to understand the effect of variants and vaccines on the male reproductive system we collected semen samples from recovered patients infected during the two waves of COVID-19 in India.