Covid-19 Infection and the Host Genetic Predisposition: Does it Exist?

Androgens in SARS-CoV-2 coronavirus infections

Recent molecular biology findings have shown that for the penetration of the SARS-CoV-2 coronavirus into host cells, a key role is played by protease serine 2, the activity of which is dependent on androgens. The important role of androgens is also evidenced by clinical observations that men in some age categories are infected by this novel coronavirus up to two times more frequently than women. In addition, men with androgenic alopecia tend to have more serious clinical courses, while men with androgen deprivation as a result of prostate cancer treatments tend to have milder courses. This is in line with the fact that preadolescent children are only rarely sickened with serious forms of SARS-CoV-2 infections. Even though these observations may be explained by other factors, many authors have hypothesized that lowered androgen levels and blocking their activity using anti-androgen medication may moderate the course of the viral infection in intermediately- to critically-affected cases. Clearly, it would be important for androgen deprivation to block not just gonadal androgens, but also adrenal androgens. On the other hand, low androgen levels are considered to be a risk factor for the course of SARS-CoV-2 infections, either because low androgen levels have a general effect on anabolic-catabolic equilibrium and energy metabolism, or because of the ability of testosterone to modify the immune system. It is not yet clear if infection with this novel coronavirus might induce hypogonadism, leading to undesirable side effects on male fertility.

Alveolar type II cells and pulmonary surfactant in COVID-19 era

In this review, we discuss the role of pulmonary surfactant in the host defense against respiratory pathogens, including novel coronavirus SARS-CoV-2. In the lower respiratory system, the virus uses angiotensin-converting enzyme 2 (ACE2) receptor in conjunction with serine protease TMPRSS2, expressed by alveolar type II (ATII) cells as one of the SARS-CoV-2 target cells, to enter. ATII cells are the main source of surfactant. After their infection and the resulting damage, the consequences may be severe and may include injury to the alveolar-capillary barrier, lung edema, inflammation, ineffective gas exchange, impaired lung mechanics and reduced oxygenation, which resembles acute respiratory distress syndrome (ARDS) of other etiology. The aim of this review is to highlight the key role of ATII cells and reduced surfactant in the pathogenesis of the respiratory form of COVID-19 and to emphasize the rational basis for exogenous surfactant therapy in COVID-19 ARDS patients.

Effects of selected inherited factors on susceptibility to SARS-CoV-2 infection and COVID-19 progression

Genetic predispositions may influence geographical and interethnic differences in COVID-19 prevalence and mortality in affected populations. Of the many genes implicated in COVID-19 progression, a substantial number have no direct functional link on virus transfer/viability or on the host immune system. To address this knowledge deficit, a large number of in silico studies have recently been published. However, the results of these studies often contradict the findings of studies involving real patients. For example, the ACE2 has been shown to play an important role in regulating coronavirus entry into cells, but none of its variations have been directly associated with COVID-19 susceptibility or severity. Consistently was reported that increased risk of COVID-19 is associated with blood group A and with the APOE4 allele. Among other genes with potential impacts are the genes for CCR5, IL-10, CD14, TMPRSS2 and angiotensin-converting enzyme. Variants within the protein-coding genes OAS1 and LZTFL1 (transferred to the human genome from Neanderthals) are understood to be among the strongest predictors of disease severity. The intensive research efforts have helped to identify the genes and polymorphisms that contribute to SARS-CoV-2 infection and COVID-19 severity.

SARS-CoV-2 viral load assessment in lung transplantation

In the era of COVID-19 pandemic, organ transplantation programs were facing serious challenges. The lung transplantation donor pool was extremely limited and SARS-CoV-2 viral load assessment has become a crucial part of selecting an optimal organ donor. Since COVID-19 is a respiratory disease, the viral load is thought to be more important in lung transplantations as compared to other solid organ transplantations. We present two challenging cases of potential lung donors with a questionable COVID-19 status. Based on these cases, we suggest that the cycle threshold (Ct) value should always be requested from the laboratory and the decision whether to proceed with transplantation should be made upon complex evaluation of diverse criteria, including the nasopharyngeal swab and bronchoalveolar lavage PCR results, the Ct value, imaging findings and the medical history. However, as the presence of viral RNA does not ensure infectivity, it is still to be clarified which Ct values are associated with the viral viability. Anti-SARS-CoV-2 IgA antibodies may support the diagnosis and moreover, novel methods, such as quantifying SARS-CoV-2 nucleocapsid antigen in serum may provide important answers in organ transplantations and donor selections.

Is there impact of the SARS-CoV-2 pandemic on steroidogenesis and fertility?

In December of 2019, several cases of unknown atypical respiratory diseases emerged in Wuhan, Hubei Province in China. After preliminary research, it was stated that the disease is transmittable between humans and was named COVID-19. Over the course of next months, it spread all over the world by air and sea transport and caused a global pandemic which affects life of everyone now-a-days. A large number of countries, have since been forced to take precautions such as curfews, lockdowns, wearing facemasks etc. Even with vaccines being produced in mass numbers, lack of targeted therapy continues to be a major problem. According to studies so far it seems that elderly people are more vulnerable to severe symptoms while children tend to by asymptomatic or have milder form the disease. In our review, we focused on gathering data about the virus itself, its characteristics, paths of transmission, and its effect on hormone production and secretion. In such, there is insufficient information in the literature worldwide, especially the ones that focus on the effect of COVID-19 on individual organs systems within the human body. Hence, the present evidence-based study focused on the possible effects of COVID-19 on adrenal gland and gonads i.e. on the process of steroidogenesis and fertility.

Inhibitory immune checkpoint molecules and exhaustion of T cells in COVID-19

COVID-19 (Coronavirus Disease) is an infectious disease caused by the coronavirus SARS-CoV-2 (Severe acute respiratory syndrome Coronavirus 2), which belongs to the genus Betacoronavirus. It was first identified in patients with severe respiratory disease in December 2019 in Wuhan, China. It mainly affects the respiratory system, and in severe cases causes serious lung infection or pneumonia, which can lead to the death of the patient. Clinical studies show that SARS-CoV-2 infection in critical cases causes acute tissue damage due to a pathological immune response. The immune response to a new coronavirus is complex and involves many processes of specific and non-specific immunity. Analysis of available studies has shown various changes, especially in the area of specific cellular immunity, including lymphopenia, decreased T cells (CD3+, CD4+ and CD8+), changes in the T cell compartment associated with symptom progression, deterioration of the condition and development of lung damage. We provide a detailed review of the analyses of immune checkpoint molecules PD-1, TIM-3, LAG-3 CTLA-4, TIGIT, BTLA, CD223, IDO-1 and VISTA on exhausted T cells in patients with asymptomatic to symptomatic stages of COVID-19 infection. Furthermore, this review may help to better understand the pathological T cell immune response and improve the design of therapeutic strategies for patients with SARS-CoV-2 infection.

CCR5Delta32 deletion as a protective factor in Czech first-wave COVID-19 subjects

Infection by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes coronavirus disease (COVID-19), has spread widely around the globe. Significant inter-individual differences have been observed during the course of the infection, which suggests that genetic susceptibility may be a contributing factor. CC chemokine receptor 5 (CCR5), which acts as a co-receptor for the entry of HIV-1 into cells, is promising candidate whose can have an influence on SARS-CoV-2 infection. A genetic mutation known as CCR5Delta32, consisting of a 32-nucleotide deletion, encodes a truncated protein that protects homozygous carriers of the deletion from HIV-1 infection. Similarly, inhibition of CCR5 seems to be protective against COVID-19. In our study, we successfully genotyped 416 first-wave SARS-CoV-2-positive infection survivors (164 asymptomatic and 252 symptomatic) for CCR5?32, comparing them with a population based sample of 2,404 subjects. We found the highest number (P=0.03) of CCR5Delta32 carriers in SARS-CoV-2-positive/COVID-19-asympto-matic subjects (23.8 %) and the lowest number in SARS-CoV-2-positive/COVID-19-symptomatic patients (16.7 %), with frequency in the control population in the middle (21.0 %). We conclude that the CCR5?32 I/D polymorphism may have the potential to predict the severity of SARS-CoV-2 infection.