Immune responses and pathogenesis of SARS‐CoV‐2 during an outbreak in Iran: Comparison with SARS and MERS

The beginning of 2020 has seen the emergence of COVID‐19, an outbreak caused by a novel coronavirus, SARS‐CoV‐2, an important pathogen for humans. There is an urgent need to better understand this new virus and to develop ways to control its spread. In Iran, the first case of the COVID‐19 was reported after spread from China and other countries. Fever, cough, and fatigue were the most common symptoms of this virus. In worldwide, the incubation period of COVID‐19 was 3 to 7 days and approximately 80% of infections are mild or asymptomatic, 15% are severe, requiring oxygen, and 5% are critical infections, requiring ventilation. To mount an antiviral response, the innate immune system recognizes molecular structures that are produced by the invasion of the virus. COVID‐19 infection induces IgG antibodies against N protein that can be detected by serum as early as day 4 after the onset of disease and with most patients seroconverting by day 14. Laboratory evidence of clinical patients showed that a specific T‐cell response against SARS‐CoV‐2 is important for the recognition and killing of infected cells, particularly in the lungs of infected individuals. At present, there is no specific antiviral therapy for COVID‐19 and the main treatments are supportive. In this review, we investigated the innate and acquired immune responses in patients who recovered from COVID‐19, which could inform the design of prophylactic vaccines and immunotherapy for the future.     

Evaluation of sex‐related hormones and semen characteristics in reproductive‐aged male COVID‐19 patients

In the past several months, the outbreak of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2)‐associated infection (coronavirus disease 2019 [COVID‐19]) developed rapidly and has turned into a global pandemic. Although SARS‐CoV‐2 mainly attacks respiratory systems, manifestations of multiple organs have been observed. A great concern was raised about whether COVID‐19 may affect male reproductive functions. In this study, we collected semen specimens from 12 male COVID‐19 patients for virus detection and semen characteristics analysis. No SARS‐CoV‐2 was found in semen specimens. Eight out of 12 patients had normal semen quality. We also compared the sex‐related hormone levels between 119 reproductive‐aged men with SARS‐CoV‐2 infection and 273 age‐matched control men. A higher serum luteinizing hormone (LH) and a lower ratio of testosterone (T) to LH were observed in the COVID‐19 group. Multiple regression analysis indicated that serum T: LH ratio was negatively associated with white blood cell counts and C‐reactive protein levels in COVID‐19 patients. It's the first report about semen assessment and sex‐hormone evaluation in reproductive‐aged male COVID‐19 patients. Although further study is needed to clarify the reasons and underlying mechanisms, our study presents an abnormal sex hormone secretion among COVID‐19 patients, suggesting that attention should be paid to reproductive function evaluation in the follow‐up.     

Clinical exacerbation of SARS‐CoV2 infection after fingolimod withdrawal

The role of disease‐modifying therapies in patients with autoimmune disorders during severe acute respiratory syndrome coronavirus 2 (SARS‐CoV2) infection is controversial. Immunocompromised patients could have a more severe coronavirus disease‐2019 (COVID‐19) due to the absence of an adequate immune response against the SARS‐CoV‐2. However, therapies that act on immune response could play a protective role by dampening the cytokine‐release syndrome. Fingolimod is a drug used for immune therapy in patients with multiple sclerosis (MS) through the sequestration of activated lymphocytes in the lymph nodes. We report the case of a 57‐year‐old man with relapsing‐remitting MS treated with fingolimod that showed a reactivation of COVID‐19 with signs of hyperinflammation syndrome after fingolimod withdrawal. Our case suggests that discontinuation of fingolimod during COVID‐19 could imply a worsening of SARS‐CoV2 infection.     

Immunopathology and immunotherapeutic strategies in severe acute respiratory syndrome coronavirus 2 infection

The outbreak of coronavirus disease 2019 (COVID‐19) and pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2), has become a major concern globally. As of 14 April 2020, more than 1.9 million COVID‐19 cases have been reported in 185 countries. Some patients with COVID‐19 develop severe clinical manifestations, while others show mild symptoms, suggesting that dysregulation of the host immune response contributes to disease progression and severity. In this review, we have summarized and discussed recent immunological studies focusing on the response of the host immune system and the immunopathology of SARS‐CoV‐2 infection as well as immunotherapeutic strategies for COVID‐19. Immune evasion by SARS‐CoV‐2, functional exhaustion of lymphocytes, and cytokine storm have been discussed as part of immunopathology mechanisms in SARS‐CoV‐2 infection. Some potential immunotherapeutic strategies to control the progression of COVID‐19, such as passive antibody therapy and use of interferon αβ and IL‐6 receptor (IL‐6R) inhibitor, have also been discussed. This may help us to understand the immune status of patients with COVID‐19, particularly those with severe clinical presentation, and form a basis for further immunotherapeutic investigations.     

The impact of the SARS‐CoV‐2 infection,with special reference to the hematological setting

Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) is a disease known from a few months, caused by a recently arisen virus and, consequently, it is little known. The disease has a benign course in most infected subjects (children and young adults), is often symptomatic in adults over the age of 50 and often serious and life threatening in people with comorbidities and the elderly. The few data published on coronavirus disease‐2019 (COVID‐19) in the blood‐oncology field report a serious clinical presentation, a serious course of the disease, and a high mortality rate, as has also been reported for other cancer contexts. The current strategy for treating patients with SARS‐CoV‐2 includes antivirals that are effective against other viral infections and drugs that can moderate the cytokine storm. There is no specific vaccine and consequently all possible precautions must be taken to prevent SARS‐CoV‐2 infection in the areas of oncology, oncohematology, and bone marrow transplantation. In this reviewer's article, we report the information currently available on SARS‐CoV‐2 infection to help young doctors and hematologists to successfully manage patients with COVID‐19.     

The cytokine storm and COVID‐19

Coronavirus disease 2019 (COVID‐19), which began in Wuhan, China, in December 2019, has caused a large global pandemic and poses a serious threat to public health. More than 4 million cases of COVID‐19, which is caused by the severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2), have been confirmed as of 11 May 2020. SARS‐CoV‐2 is a highly pathogenic and transmissible coronavirus that primarily spreads through respiratory droplets and close contact. A growing body of clinical data suggests that a cytokine storm is associated with COVID‐19 severity and is also a crucial cause of death from COVID‐19. In the absence of antivirals and vaccines for COVID‐19, there is an urgent need to understand the cytokine storm in COVID‐19. Here, we have reviewed the current understanding of the features of SARS‐CoV‐2 and the pathological features, pathophysiological mechanisms, and treatments of the cytokine storm induced by COVID‐19. In addition, we suggest that the identification and treatment of the cytokine storm are important components for rescuing patients with severe COVID‐19.     

SARS‐CoV‐2 replicating in nonprimate mammalian cells probably have critical advantages for COVID‐19 vaccines due to anti‐Gal antibodies: A minireview and proposals

Glycoproteins of enveloped viruses replicating in nonprimate mammalian cells carry α‐1,3‐galactose (α‐Gal) glycans, and can bind to anti‐Gal antibodies which are abundant in humans. The antibodies have protected humans and their ancestors for millions of years, because they inhibit replication of many kinds of microbes carrying αGal glycans and aid complements and macrophages to destroy them. Therefore, severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) replicating in nonprimate mammalian cells (eg, PK‐15 cells) carry αGal glycans and could be employed as a live vaccine for corona virus 2019 (COVID‐19). The live vaccine safety could be further enhanced through intramuscular inoculation to bypass the fragile lungs, like the live unattenuated adenovirus vaccine safely used in US recruits for decades. Moreover, the immune complexes of SARS‐CoV‐2 and anti‐Gal antibodies could enhance the efficacy of COVID‐19 vaccines, live or inactivated, carrying α‐Gal glycans. Experiments are imperatively desired to examine these novel vaccine strategies which probably have the critical advantages for defeating the pandemic of COVID‐19 and preventing other viral infectious diseases.     

Encephalitic syndrome and anosmia in COVID‐19: Do these clinical presentations really reflect SARS‐CoV‐2 neurotropism? A theory based on the review of 25 COVID‐19 cases

Since the discovery of coronavirus disease 2019 (COVID‐19), a disease caused by the new coronavirus severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2), the pathology showed different faces. There is an increasing number of cases described as (meningo)encephalitis although evidence often lacks. Anosmia, another atypical form of COVID‐19, has been considered as testimony of the potential of neuroinvasiveness of SARS‐CoV‐2, though this hypothesis remains highly speculative. We did a review of the cases reported as brain injury caused by SARS‐CoV‐2. Over 98 papers found, 21 were analyzed. Only four publications provided evidence of the presence of SARS‐CoV‐2 within the central nervous system (CNS). When facing acute neurological abnormalities during an infectious episode it is often difficult to disentangle neurological symptoms induced by the brain infection and those due to the impact of host immune response on the CNS. Cytokines release can disturb neural cells functioning and can have in the most severe cases vascular and cytotoxic effects. An inappropriate immune response can lead to the production of auto‐antibodies directed toward CNS components. In the case of proven SARS‐CoV‐2 brain invasion, the main hypothesis found in the literature focus on a neural pathway, especially the direct route via the nasal cavity, although the virus is likely to reach the CNS using other routes. Our ability to come up with hypotheses about the mechanisms by which the virus might interact with the CNS may help to keep in mind that all neurological symptoms observed during COVID‐19 do not always rely on CNS viral invasion.     

Angiotensin‐converting enzyme 2: The old door for new severe acute respiratory syndrome coronavirus 2 infection

Coronavirus (CoV) disease 2019 (COVID‐19) is an ongoing pandemic caused by severe acute respiratory syndrome CoV 2 (SARS‐CoV‐2). The highly contagious SARS‐CoV‐2 belongs to the genus Betacoronavirus, and it is phylogenetically closely related to SARS‐CoV, a human CoV that caused an outbreak back in 2002 to 2003. Both SARS‐CoV‐2 and SARS‐CoV enter human cells via the interactions between viral crown‐like spike protein and human angiotensin‐converting enzyme 2 (ACE2) receptor. Here, we aim to review the involvement of ACE2 in human CoV infections by discussing the roles of ACE2 in CoV evolution, cross‐species transmissibility, and COVID‐19 susceptibility. We also provide our perspectives on COVID‐19 treatment and prevention.     

The “scar” of a pandemic: Cumulative incidence of COVID‐19 during the first trimester of pregnancy

Congenitally‐ or perinatally‐acquired viral infections can be harmful to the fetus but data are limited about prevalence and outcomes of coronavirus disease 2019 (COVID‐19) disease during the first trimester of pregnancy. We report epidemiologic data from a study investigating a cohort of women who became pregnant just before or during the COVID‐19 pandemic. We recruited 138 consecutive pregnant women attending for first trimester screening (11‐13 weeks of gestation) at Sant'Anna Hospital, Turin, Piedmont, Italy, during the plateau and the falling phase of the COVID‐19 epidemic curve. Patients were tested for severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) immunoglobulin M/immunoglobulin G antibody levels and SARS‐CoV‐2 detection in sera and nasopharyngeal swab samples. COVID‐19 cumulative incidence during the first trimester was of 10.1% with high prevalence of asymptomatic patients (42.8%). Similar to the course of the disease in non pregnant adults, 80% to 90% of infections were not severe.The prevalence of reported symptoms was four‐fold higher in SARS‐CoV‐2 positive patients (57%) than in those negative (13%) (P < .001), suggesting that direct self‐testing should open doors to confirmatory testing for COVID‐19. Our findings support the need for COVID‐19 screening in early pregnancy in epidemic areas to plan materno‐fetal health surveillance programs.     

The clinical characteristics of pediatric inpatients with SARS‐CoV‐2 infection: A meta‐analysis and systematic review

Millions of people were infected with the coronavirus disease 2019 (COVID‐19) all over the world. Data on clinical symptoms of pediatric inpatients with COVID‐19 infection were unclear. The aim of study was to investigate the clinical features of pediatric inpatients with severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection. PubMed, EMBASE, and the Cochrane Library were searched to seek for studies providing details on pediatric inpatients with SARS‐CoV‐2 infection which were published from 1st January to 21st April 2020. Studies with more than five pediatric inpatients were included in our meta‐analysis.This study was registered in the PROSPERO database (CRD42020183550). As the results shown, fever (46%) and cough (42%) were the main clinical characters of pediatric inpatients with SARS‐CoV‐2 infection and the other clinical characters, such as diarrhea, vomiting, nasal congestion, and fatigue account for 10% in pediatric inpatients. The proportion of asymptomatic cases was 0.42 (95% confidence interval [CI]: 0.27‐0.59) and severe cases was 0.03 (95% CI: 0.01‐0.06). For the laboratory result, leukopenia (21%) and lymphocytosis (22%) were the mainly indicators for pediatric inpatients, followed by high aspartate aminotransferase (19%), lymphopenia (16%), high alanine aminotransferase (15%), high C‐reactive protein (17%), leukocytosis (13%), high D‐dimer (12%) and high creatine kinase‐MB (5%). Regard to chest imaging features, unilateral and bilateral accounts for 22% in pediatric inpatients, respectively. In conclusion, compared with adult inpatients with SARS‐CoV‐2 infection, the pediatric inpatients had mild clinical characters, lab test indicators, and chest imaging features. More clinical studies focus on the pediatric patients with SARS‐CoV‐2 infection in other countries should be conducted.     

A brief review of interplay between vitamin D and angiotensin‐converting enzyme 2: Implications for a potential treatment for COVID‐19

The novel coronavirus disease 2019 (COVID‐19) is rapidly expanding and causing many deaths all over the world with the World Health Organization (WHO) declaring a pandemic in March 2020. Current therapeutic options are limited and there is no registered and/or definite treatment or vaccine for this disease or the causative infection, severe acute respiratory coronavirus 2 syndrome (SARS‐CoV‐2). Angiotensin‐converting enzyme 2 (ACE2), a part of the renin‐angiotensin system (RAS), serves as the major entry point into cells for SARS‐CoV‐2 which attaches to human ACE2, thereby reducing the expression of ACE2 and causing lung injury and pneumonia. Vitamin D, a fat‐soluble‐vitamin, is a negative endocrine RAS modulator and inhibits renin expression and generation. It can induce ACE2/Ang‐(1‐7)/MasR axis activity and inhibits renin and the ACE/Ang II/AT1R axis, thereby increasing expression and concentration of ACE2, MasR and Ang‐(1‐7) and having a potential protective role against acute lung injury (ALI)/acute respiratory distress syndrome (ARDS). Therefore, targeting the unbalanced RAS and ACE2 down‐regulation with vitamin D in SARS‐CoV‐2 infection is a potential therapeutic approach to combat COVID‐19 and induced ARDS.     

Multisystem inflammatory syndrome in children related to COVID‐19: A New York City experience

In December 2019, the 2019, a novel coronavirus disease (COVID‐19) caused by severe acute respiratory syndrome coronavirus‐2 (SARS‐CoV‐2) first emerged in Wuhan, China. This has now spread worldwide and was declared a pandemic by March 2020. Initially, the pediatric population was described as a low risk for severe COVID‐19. However, reports have emerged recently of cases of COVID‐19 in children with a systemic inflammatory disease, with features that overlap with Kawasaki disease (KD). We describe the first 15 cases with the multi‐systeminflammatory syndrome in children (MIS‐C), temporally related to COVID‐19, who presented for care to a tertiary pediatric referral center in New York City. We discuss the disproportionate burden of disease among Hispanic/Latino and Black/African American ancestry, the distinct cytokine signature across the disease spectrum (IL‐1/IL‐6), and the potential role and pathogenesis of SARS‐CoV‐2 in this new clinical entity.     

SARS‐CoV‐2 infection causes pulmonary shunt by vasodilatation

Patients with severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) may present a significant hypoxemia. The exactly mechanism of such hypoxemia in patients with coronavirus disease 2019 (COVID‐19) is not well described. It has been suggested that microthrombosis contributes to this mechanism, increasing pulmonary dead space. However, dead spaces would not be sensible to oxygen supplementation, and also, enlargement of pulmonary vessels it has been evidenced. Shunt mechanism by vasodilatation, instead, could explain decubitus dependence in oxygenation by blood redistribution as observed in these patients, and moreover, would be more sensible to oxygen supplementation than dead spaces. We hypothesized that SARS‐CoV‐2 causes an intrapulmonary vascular dilatation (IPVD), determining a shunt mechanism by vasodilatation. We performed contrast‐enhanced transthoracic echocardiography to search IPVD shunt in patients with confirmed COVID‐19, hospitalized in an intensive care unit. Ten patients were recruited; one patient was excluded due to low quality of echocardiographic image, and nine patients were included. IPVD was found in seven (78%) patients, with different grades, including patient with normal compliance and the one without invasive ventilation. We demonstrated that shunt by IPVD is present among patients with COVID‐19, and this mechanism is probably implicated in significant hypoxemia observed.     

Extrapulmonary complications of COVID‐19: A multisystem disease?

The outbreak of coronavirus disease 2019 (COVID‐19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2), has been recently declared a pandemic by the World Health Organization. In addition to its acute respiratory manifestations, SARS‐CoV‐2 may also adversely affect other organ systems. To date, however, there is a very limited understanding of the extent and management of COVID‐19‐related conditions outside of the pulmonary system. This narrative review provides an overview of the current literature about the extrapulmonary manifestations of COVID‐19 that may affect the urinary, cardiovascular, gastrointestinal, hematological, hematopoietic, neurological, or reproductive systems. This review also describes the current understanding of the extrapulmonary complications caused by COVID‐19 to improve the management and prognosis of patients with COVID‐19.     

Characterization of cytotoxic T‐lymphocyte epitopes and immune responses to SARS coronavirus spike DNA vaccine expressing the RGD‐integrin‐binding motif

Integrins are critical for initiating T‐cell activation events. The integrin‐binding motif Arg‐Gly‐Asp (RGD) was incorporated into the pcDNA 3.1 mammalian expression vector expressing the codon‐optimized extracellular domain of SARS coronavirus (SARS‐CoV) spike protein, and tested by immunizing C57BL/6 mice. Significant cell‐mediated immune responses were characterized by cytotoxic T‐lymphocyte ⁵¹Cr release assay and interferon‐gamma secretion ELISPOT assay against RMA‐S target cells presenting predicted MHC class I H2‐Kb epitopes, including those spanning residues 884–891 and 1116–1123 within the S2 subunit of SARS‐CoV spike protein. DNA vaccines incorporating the Spike‐RGD/His motif or the Spike‐His construct generated robust cell‐mediated immune responses. Moreover, the Spike‐His DNA vaccine construct generated a significant antibody response. Immunization with these DNA vaccine constructs elicited significant cellular and humoral immune responses. Additional T‐cell epitopes within the SARS‐CoV spike protein that may contribute to cell‐mediated immunity in vivo were also identified. J. Med. Virol. 81:1131–1139, 2009. © 2009 Wiley‐Liss, Inc.     

Diagnostic efficacy of anti‐SARS‐CoV‐2 IgG/IgM test for COVID‐19: A meta‐analysis

The serological testing of anti‐SARS‐CoV‐2 immunoglobulin G (IgG) and/or IgM is widely used in the diagnosis of COVID‐19. However, its diagnostic efficacy remains unclear. In this study, we searched for diagnostic studies from the Web of Science, PubMed, Embase, CNKI, and Wanfang databases to calculate the pooled diagnostic accuracy measures using bivariate random‐effects model meta‐analysis. As a result, 22 from a total of 1613 articles, including 2282 patients with SARS‐CoV‐2 and 1485 healthy persons or patients without SARS‐CoV‐2, were selected for a meta‐analysis. Pooled sensitivity, specificity, and area under curve of the summary receiver operator curve (SROC) were: (a) 0.85 (95% confidence interval [CI]: 0.79‐0.90), 0.99 (95% CI: 0.98‐1.00), and 0.99 (95% CI: 0.97‐0.99) for anti‐SARS‐CoV‐2 IgG and (b) 0.74 (95% CI: 0.65‐0.81), 0.99 (95% CI: 0.97‐1.00), and 0.95 (95% CI: 0.93‐0.97) for IgM. A subgroup analysis among detection methods indicated the sensitivity of IgG and IgM using enzyme‐linked immunosorbent assay were slightly lower than those using gold immunochromatography assay (GICA) and chemiluminescence immunoassay (P > .05). These results showed that the detection of anti‐SARS‐CoV‐2 IgG and IgM had high diagnostic efficiency to assist the diagnosis of SARS‐CoV‐2 infection. And, GICA might be used as the preferred method for its accuracy and simplicity.