Immune Response Gaps Linked to SARS-CoV-2 Infection: Cellular Exhaustion, Senescence, or Both?

The COVID-19 pandemic, promoted by the SARS-CoV-2 respiratory virus, has resulted in widespread global morbidity and mortality. The immune response against this pathogen has shown a thin line between protective effects and pathological reactions resulting from the massive release of cytokines and poor viral clearance. The latter is possibly caused by exhaustion, senescence, or both of TCD8+ cells and reduced activity of natural killer (NK) cells. The imbalance between innate and adaptive responses during the early stages of infection caused by SARS-CoV-2 contributes to the ineffective control of viral spread. The present study evaluated the tissue immunoexpression of the tissue biomarkers (Arginase-1, CCR4, CD3, CD4, CD8, CD20, CD57, CD68, CD138, IL-4, INF-α, INF-γ, iNOS, PD-1, Perforin and Sphingosine-1) to understand the cellular immune response triggered in patients who died of COVID-19. We evaluated twenty-four paraffin-embedded lung tissue samples from patients who died of COVID-19 (COVID-19 group) and compared them with ten lung tissue samples from patients who died of H1N1pdm09 (H1N1 group) with the immunohistochemical markers mentioned above. In addition, polymorphisms in the Perforin gene were genotyped through Real-Time PCR. Significantly increased tissue immunoexpression of Arginase, CD4, CD68, CD138, Perforin, Sphingosine-1, and IL-4 markers were observed in the COVID-19 group. A significantly lower immunoexpression of CD8 and CD57 was also found in this group. It is suggested that patients who died from COVID-19 had a poor cellular response concerning viral clearance and adaptive response going through tissue repair.

MO321: The Critical Role of Cytokine Dysregulation in Acute Kidney Injury Development in Patients With COVID-19

BACKGROUND AND AIMS

One of the complications described in critically ill patients in intensive care units with severe COVID-19 was acute kidney injury (AKI). The pathophysiology of AKI in patients with COVID-19 is multifactorial. In addition to the direct virulence of SARS-CoV-2 in renal cells, the tissue inflammation and local immune cell infiltration, cytokine storm, secondary infections and nephrotoxicity associated drugs may contribute to AKI [1]. Mounting evidence throughout the pandemic suggests that patients with severe COVID-19 may have a cytokine storm syndrome, one of the possible causes of AKI in these patients [2]. The present prospective cohort study analysed the correlation between circulating cytokine profile and estimated glomerular filtration rate (eGFR) in patients with COVID-19.

METHOD

After signing the informed consent, patients positive for SARS-CoV-2 infection (n = 74) had blood samples (n = 139) collected at hospital admission until the day of the outcome. ELISA measured the cytokines IL-10, IL-4, L-6, TNF-α and IFN-γ, and the eGFR was calculated by the CKD-EPI Cystatin C equation. Statistics description: Continuous variables were checked for normality and presented as mean ± standard deviation or median and interquartile range. The association between continuous variables is shown in scatterplots, and a predicted response with 95% confidence interval (95% CI) is plotted using fractional polynomials. For linear correlations, we obtained P-values using Pearson's correlation coefficient.

RESULTS

There is a more significant distribution of eGFR below 90 mL/min in the population studied, associated with older patients. Glomerular filtration rates were negatively correlated with age as expected (–0.60; P < 0.0001). Lower eGFR was correlated with levels of proinflammatory cytokines such as IL-6 (–0.33; P < .0007) and TNF- α (–0.21; P < .03); but without positive correlation with IL-10 (0.04; P < 0.68) or IFN-γ (–0.14; P < .16), even though higher IFN-γ levels have been linked to a worse prognosis in patients with severe COVID-19 [3]. Curiously, a positive correlation was observed between lower eGFR and IL-4 levels.

CONCLUSION

These results demonstrate that a shift in the immune response profile, cytokines with a Th2 profile such as IL-4, and cytokines with systemic functions such as IL-6 and TNF-α can be related to renal failure. The elucidation of the potential pathophysiological mechanisms of AKI associated with COVID-19 as well as monitoring of cytokine levels can (a) help to identify patients with severe COVID-19 at risk of loss of renal function, (b) provide information on specific therapeutic strategies.

IFN-γ is an independent risk factor associated with mortality in patients with moderate and severe COVID-19 infection

BACKGROUND

Innate and adaptive immune responses have been evaluated in infected patients with COVID-19. The severity of the disease has been supposed to be associated with some profile not reported with other bacterial and viral pneumonia. We proposed a study in patients with moderate to severe COVID-19 infection to evaluate the interleukin patterns and its role as prognosis factors.

METHODS

A prospective cohort with moderate and severe cases of COVID-19 infection from June to July 2020. Blood samples from patients were collected regularly to evaluate IFN-γ, TNF-α, IL-4, IL-6, and IL-10. Clinical, laboratory, radiological data, and outcomes were recorded. The outcome variable was in-hospital death, survival, mechanical ventilation, and admission at the intensive care unit. Data are presented in median and interquartile range [IQR].

RESULTS

We evaluated the Th1 and Th2 responses according to evolution, distinguishing possible predictive markers. The IFN-γ median of 323 pg/mL [IQR 166-570] was found in patients who died and 208 pg/mL [IQR 155-392] in the survival group (p = 0.017). IFN-γ was also higher in the early stages of the disease (394 pg/mL [IQR 229-575] against 162 pg/mL [IQR 117-259], p < 0.001). IL-4 that was increased in late-stage (182 pg/mL [IQR 162-199] against 131 pg/mL [IQR 124-152], p < 0.001) but not associated with mortality. Also, death was also related to male gender (relative risk = 1.5 [95 % confidence interval = 1.1-2.0]).

CONCLUSION

Our results suggest that the activation of the host immune response between Th1 or Th2 in COVID-19 infection may be related to the final result between discharge or death. This implies an attempt to control cytokines, such as IFN-γ, with combined therapies for clinical treatment.