The Association of Programmed Death 1 Gene Polymorphisms of PD1.3 G/A and PD1.5 C/T with Risk of COVID-19 in an Iranian Population: A Case-Control Study.

Programmed death 1 (PD-1) has a central role in maintaining T cell tolerance and terminating cellular responses after eliminating antigens. Variation in PD-1 gene products caused by polymorphisms has been linked to several malignancies and autoimmune diseases. However, there is little known about the effects of its single-nucleotide polymorphisms (SNPs) on viral infections, particularly COVID-19. The primary aim of this study was to explore the function of genotypes, alleles, and haplotypes of two SNPs within the programmed cell death protein 1 (PDCD1) gene at PD1.3 G/A and PD1.5 C/T on susceptibility to COVID-19 in an Iranian population. The secondary objective was to evaluate the effects of these SNPs on the outcome of the disease. We got blood samples from COVID-19 patients (n = 195) and healthy subjects (n = 500) for genotypic determination of PD1.3 G/A (rs11568821) and PD1.5 C/T (rs2227981) SNPs, using the polymerase chain reaction-restriction fragment length polymorphism method, and constructed four haplotypes for PDCD1 SNPs. We used Pearson's chi-squared test, Fisher's exact test, and T-test for this study and incorporated effect sizes of odds ratio (OR) and standardized mean difference. The frequency of CT genotype of PD1.5 was meaningfully higher in COVID-19 patients (49.2%) than in healthy subjects (37.4%) (p = 0.005). However, these significant differences were not observed in the frequencies of PD1.3 genotypes between the two groups (p > 0.05). Of all estimated haplotypes for PDCD1, only AT was significantly and largely associated with COVID-19 susceptibility (p = 0.01, OR: 7.79 [95% confidence interval = 1.56-38.79]), however, this finding is inconclusive. In addition, the present study showed that the PD1.3 and PD1.5 SNPs were not associated with the outcome of the disease (p > 0.05). These results may propose that the PD1.5 CT genotype and AT haplotype of PDCD1 indecisively contribute to COVID-19 susceptibility in the Iranian population.

Characterizing the immune responses of those who survived or succumbed to COVID-19: Can immunological signatures predict outcome?

BACKGROUND: Immunodeficiency has pivotal role in the pathogenesis of coronavirus disease 2019 (COVID-19). Several studies have indicated defects in the immune system of COVID-19 patients at different disease stages. Therefore, this study investigated whether alters in immune responses of COVID-19 patients may be considered as predicting factors for disease outcome. METHODS: The percentages of innate and adoptive immune cells in the recovered and dead patients with COVID-19, and healthy subjects were determined by flow cytometry. The levels of pro- and anti-inflammatory cytokines and other immune factors were also measured by enzyme-linked immunosorbent assay. RESULTS: At the first day of hospitalization, the frequencies of CD56dim CD16+ NK cells and CD56bright CD16dim/- NK cells in patients who died during treatment were significantly increased compared to recovered and healthy individuals (P < 0.0001). The recovered and dead patients had a significant increase in monocyte number in comparison with healthy subjects (P < 0.05). No significant change was observed in Th1 cell numbers between the recovered and dead patients while Th2, Th17 cell, and Treg percentages in death cases were significantly lower than healthy control and those recovered, unlike exhausted CD4 + and CD8 + T cells and activated CD4 + T cells (P < 0.0001-0.05). The activated CD8 + T cell was significantly higher in the recovered patients than healthy individuals (P < 0.0001-0.05). IL-1α, IL-1ß, IL-6, and TNF-α levels in patients were significantly increased (P < 0.0001-0.01). However, there were no differences in TNF-α and IL-1ß levels between dead and recovered patients. Unlike TGF-ß1 level, IL-10 was significantly increased in recovered patients (P < 0.05). Lymphocyte numbers in recovered patients were significantly increased compared to dead patients, unlike ESR value (P < 0.001-0.01). CRP value in recovered patients significantly differed from dead patients (P < 0.001). CONCLUSION: Changes in frequencies of some immune cells and levels of some immune factors may be considered as predictors of mortality in COVID-19 patients.

Immune system changes during COVID-19 recovery play key role in determining disease severity.

Coronavirus disease 2019 (COVID-19), an acute respiratory infection, is largely associated with dysregulation and impairment of the immune system. This study investigated how the immune system changes were related to disease severity in COVID-19 patients. The frequencies of different immune cells and levels of pro- and anti-inflammatory cytokines in whole blood of participants were determined by flow cytometry and enzyme-linked immunosorbent assay, respectively. The values of other inflammatory agents were also studied. In the late recovery stage, unlike CD56high CD16+/- NK cells and monocytes, CD56low CD16+ NK cell numbers were increased (P < 0.0001-0.05). Th1, Th2, and Th17 cell percentages were significantly lower in patients than healthy control (P < 0.0001-0.05), while their frequencies were increased following disease recovery (P < 0.0001-0.05). The numbers of Tregs, activated CD4+ T cells, and exhausted CD8+ T cells were significantly decreased during a recovery (P < 0.0001-0.05). No significant change was observed in exhausted CD4+ T cell number during a recovery (P > 0.05). B cell showed an increased percentage in patients compared to healthy subjects (P < 0.0001-0.05), whereas its number was reduced following recovery (P < 0.0001-0.05). IL-1α, IL-1ß, IL-6, TNF-α, and IL-10 levels were significantly decreased in the late recovery stage (P < 0.0001-0.05). However, TGF-ß1 level was not significantly changed during the recovery (P > 0.05). Lymphocyte numbers in patients were significantly decreased (P < 0.001), unlike ESR value (P < 0.001). Lymphocyte number was negatively correlated to ESR value and Th2 number (P < 0.05), while its association with monocyte was significantly positive at the first day of recovery (P < 0.05). The immune system changes during the disease recovery to improve and regulate immune responses and thereby may associate with the reduction in disease severity.