Perforin, COVID-19 and a possible pathogenic auto-inflammatory feedback loop

Induction Therapies Determine the Distribution of Perforin and Granzyme B Transcripts in Kidney Transplant Recipients

Peripheral blood mononuclear cells contain secretory granules with Perforin and Granzyme B for defense against pathogens. The objective of the present study was to compare the effects of immunosuppressive induction therapies on Perforin and Granzyme B transcripts in kidney transplant recipients. Transcripts were determined in 408 incident kidney transplant recipients eight days posttransplant using quantitative real-time PCR. Compared to 90 healthy subjects, the median Perforin transcripts were lower in kidney transplant recipients with blood-group ABO-incompatible donors (N = 52), compatible living donors (N = 130), and deceased donors (N = 226) (25.7%; IQR, 6.5% to 46.0%; 31.5%; IQR, 10.9% to 57.7%; and 35.6%; IQR, 20.6% to 60.2%; respectively; p = 0.015 by the Kruskal-Wallis test). Kidney transplant recipients who were treated with thymoglobulin (N = 64) had significantly lower Perforin as well as Granzyme B compared to all other induction therapies (N = 344) (each p < 0.001). Receiver operator characteristics analysis showed that both Perforin (area under curve, 0.919) and Granzyme B (area under curve, 0.915) indicated thyroglobulin-containing induction therapies. Regression analysis showed that both reduction in plasma creatinine and human leukocyte antigen mismatches were positively associated with elevated Perforin/Granzyme B transcript ratio posttransplant. We conclude clinical parameters and therapies affect Perforin and Granzyme B transcripts posttransplant.

Infectious Diseases Evaluation of the Child With Suspected Hemophagocytic Lymphohistiocytosis

Hemophagocytic lymphohistiocytosis (HLH) is a syndrome of excessive and maladaptive inflammation. In this review, we discuss how the clinical and laboratory features of HLH overlap with infection and propose a diagnostic and treatment strategy to identify patients with infections mimicking HLH.

Deciphering the host genetic factors conferring susceptibility to severe COVID-19 using exome sequencing

The COVID-19 pandemic remains a significant public health concern despite the new vaccines and therapeutics. The clinical course of acute SARS-CoV-2 infection is highly variable and influenced by several factors related to the virus and the host. Numerous genetic studies, including candidate gene, exome, and genome sequencing studies, genome-wide association studies, and other omics efforts, have proposed various Mendelian and non-Mendelian associations with COVID-19 course. In this study, we conducted whole-exome sequencing on 90 unvaccinated patients from Turkey with no known comorbidities associated with severe COVID-19. Of these patients, 30 had severe, 30 had moderate, and 30 had mild/asymptomatic disease. We identified rare variants in genes associated with SARS-CoV-2 susceptibility and pathogenesis, with an emphasis on genes related to the regulation of inflammation, and discussed these in the context of the clinical course of the patients. In addition, we compared the frequencies of common variants between each group. Even though no variant remained statistically significant after correction for multiple testing, we observed that certain previously associated genes and variants showed significant associations before correction. Our study contributes to the existing literature regarding the genetic susceptibility to SARS-CoV-2. Future studies would be beneficial characterizing the host genetic properties in different populations.

Temporal Dynamics of Serum Perforin and Granzyme during the Acute Phase of SARS-CoV-2 Infection

BACKGROUND

As many SARS-CoV-2 infections are asymptomatic, it could be useful to be able to determine how much time has passed since infection. We explored the changes in the temporal levels of T cell-related proteins (including perforin and granzymes) in the sera of patients with SARS-CoV-2 infection using a commercially available assay.

METHODS

This study enrolled 36 patients infected with SARS-CoV-2 and 20 healthy control participants. Blood samples were collected at three different times based on the number of days since symptom onset (early phase: 1-5 days, mid-phase: 6-10 days, late phase: 11-18 days). We assessed the temporal changes in the serum levels of perforin and granzymes in patients with SARS-CoV-2 infection by comparing the results with those obtained in the healthy control group.

RESULTS

We identified a significantly low level of perforin in the early phase of SARS-CoV-2 infection (p < 0.01), which was restored to normal during the mid- and late phases of the infection. However, there was no difference in the temporal change in the level of granzymes in SARS-CoV-2-infected patients compared to the healthy control group.

CONCLUSIONS

This finding suggests that SARS-CoV-2 infection paralyzed the perforin expression in the early period immediately after infection. Thus, serum perforin is a potential marker for identifying the acute phase of SARS-CoV-2 infection.

Ketogenic Diet and Ketone Bodies as Clinical Support for the Treatment of SARS-CoV-2-Review of the Evidence

One of the proposed nutritional therapies to support drug therapy in COVID-19 is the use of a ketogenic diet (KD) or ketone bodies. In this review, we summarized the evidence from tissue, animal, and human models and looked at the mechanisms of action of KD/ketone bodies against COVID-19. KD/ketone bodies were shown to be effective at the stage of virus entry into the host cell. The use of β-hydroxybutyrate (BHB), by preventing the metabolic reprogramming associated with COVID-19 infection and improving mitochondrial function, reduced glycolysis in CD4+ lymphocytes and improved respiratory chain function, and could provide an alternative carbon source for oxidative phosphorylation (OXPHOS). Through multiple mechanisms, the use of KD/ketone bodies supported the host immune response. In animal models, KD resulted in protection against weight loss and hypoxemia, faster recovery, reduced lung injury, and resulted in better survival of young mice. In humans, KD increased survival, reduced the need for hospitalization for COVID-19, and showed a protective role against metabolic abnormalities after COVID-19. It appears that the use of KD and ketone bodies may be considered as a clinical nutritional intervention to assist in the treatment of COVID-19, despite the fact that numerous studies indicate that SARS-CoV-2 infection alone may induce ketoacidosis. However, the use of such an intervention requires strong scientific validation.

A metabolic blueprint of COVID-19 and long-term vaccine efficacy

Viruses are obligatory protein-coated units and often utilize the metabolic functions of the cells they infect. Viruses hijack cellular metabolic functions and cause consequences that can range from minor to devastating, as we have all witnessed during the COVID-19 pandemic. For understanding the virus-driven pathogenesis and its implications on the host, the cellular metabolism needs to be elucidated. How SARS-CoV-2 triggers metabolic functions and rewires the metabolism remains unidentified but the implications of the metabolic patterns are under investigation by several researchers. In this review, we have described the SARS-CoV-2-mediated metabolic alterations from in vitro studies to metabolic changes reported in victims of COVID-19. We have also discussed potential therapeutic targets to diminish the viral infection and suppress the inflammatory response, with respect to evidenced studies based on COVID-19 research. Finally, we aimed to explain how we could extend vaccine-induced immunity in people by targeting the immunometabolism.

Epidemiology and Clinical Presentation of COVID-19 in Older Adults

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection remains asymptomatic in 33% to 90% of older adults depending on their immune status from prior infection, vaccination, and circulating strain. Older adults symptomatic with SARS-CoV-2 often both present atypically, such as with a blunted fever response, and develop more severe disease. Early and late reports showed that older adults have increased severity of coronavirus disease 2019 (COVID-19) with higher case fatality rates and higher intensive care needs compared with younger adults. Infection and vaccine-induced antibody response and long-term effects of COVID-19 also differ in older adults.

Possibility of averting cytokine storm in SARS-COV 2 patients using specialized pro-resolving lipid mediators

Fatal "cytokine storms (CS)" observed in critically ill COVID-19 patients are consequences of dysregulated host immune system and over-exuberant inflammatory response. Acute respiratory distress syndrome (ARDS), multi-system organ failure, and eventual death are distinctive symptoms, attributed to higher morbidity and mortality rates among these patients. Consequent efforts to save critical COVID-19 patients via the usage of several novel therapeutic options are put in force. Strategically, drugs being used in such patients are dexamethasone, remdesivir, hydroxychloroquine, etc. along with the approved vaccines. Moreover, it is certain that activation of the resolution process is important for the prevention of chronic diseases. Until recently Inflammation resolution was considered a passive process, rather it's an active biochemical process that can be achieved by the use of specialized pro-resolving mediators (SPMs). These endogenous mediators are an array of atypical lipid metabolites that include Resolvins, lipoxins, maresins, protectins, considered as immunoresolvents, but their role in COVID-19 is ambiguous. Recent evidence from studies such as the randomized clinical trial, in which omega 3 fatty acid was used as supplement to resolve inflammation in COVID-19, suggests that direct supplementation of SPMs or the use of synthetic SPM mimetics (which are still being explored) could enhance the process of resolution by regulating the aberrant inflammatory process and can be useful in pain relief and tissue remodeling. Here we discussed the biosynthesis of SPMs, & their mechanistic pathways contributing to inflammation resolution along with sequence of events leading to CS in COVID-19, with a focus on therapeutic potential of SPMs.

Cell membrane-coated human hair nanoparticles for precise disease therapies

Precision medicine is the ultimate goal for current disease therapies, including tumor and infection. The lack of specific targeted drugs for liver cancer and the lack of specific anti-infective drugs in the treatment of diabetic foot ulcer with infection (DFI) are the representative obstacles in those 2 major diseases currently plaguing human beings. Inventing natural biocompatible polymers derived from natural materials is one of the main development directions of current bio-medical materials. Though previous studies have demonstrated the potential application values of human black hair-derived nanoparticles (HNP) in cancer, methicillin-resistant Staphylococcus aureus (MRSA) infection, and thrombosis scenarios treatments, it still has not solved the problem of low local therapeutic concentration and general targeting ability. Here, we firstly modified the HNP with membrane encapsulations, which endowed these dual-pure natural bio-fabricated materials with better targeting ability at the disease sites with no reduction in photothermal therapy (PTT) effect. HNP coated by red blood cell membrane loaded with DSPE-PEG-cRGD peptide for the therapeutic application of liver cancer greatly prolonged in vivo circulation time and enhanced local targeting efficacy as well as low toxicity; HNP coated by the murine macrophage cell membrane (RAWM) for the DFIs treatment greatly promoted the adhesive ability of HNP on the bacteria and thereby improved the killing effect. Briefly, the appropriate cell membranes camouflaged HNP nanomedicine has the characteristics of excellent photothermal effect, an all-natural source with excellent biocompatibility and easy access, which is expected to have huge potential in both benign and malignant diseases.

Identifying Immunological and Clinical Predictors of COVID-19 Severity and Sequelae by Mathematical Modeling

Since its emergence as a pandemic in March 2020, coronavirus disease (COVID-19) outcome has been explored via several predictive models, using specific clinical or biochemical parameters. In the current study, we developed an integrative non-linear predictive model of COVID-19 outcome, using clinical, biochemical, immunological, and radiological data of patients with different disease severities. Initially, the immunological signature of the disease was investigated through transcriptomics analysis of nasopharyngeal swab samples of patients with different COVID-19 severity versus control subjects (exploratory cohort, n=61), identifying significant differential expression of several cytokines. Accordingly, 24 cytokines were validated using a multiplex assay in the serum of COVID-19 patients and control subjects (validation cohort, n=77). Predictors of severity were Interleukin (IL)-10, Programmed Death-Ligand-1 (PDL-1), Tumor necrosis factors-α, absolute neutrophil count, C-reactive protein, lactate dehydrogenase, blood urea nitrogen, and ferritin; with high predictive efficacy (AUC=0.93 and 0.98 using ROC analysis of the predictive capacity of cytokines and biochemical markers, respectively). Increased IL-6 and granzyme B were found to predict liver injury in COVID-19 patients, whereas interferon-gamma (IFN-γ), IL-1 receptor-a (IL-1Ra) and PD-L1 were predictors of remarkable radiological findings. The model revealed consistent elevation of IL-15 and IL-10 in severe cases. Combining basic biochemical and radiological investigations with a limited number of curated cytokines will likely attain accurate predictive value in COVID-19. The model-derived cytokines highlight critical pathways in the pathophysiology of the COVID-19 with insight towards potential therapeutic targets. Our modeling methodology can be implemented using new datasets to identify key players and predict outcomes in new variants of COVID-19.

Perforin, COVID-19 and a possible pathogenic auto-inflammatory feedback loop

During COVID‐19 infection, reduced function of natural killer (NK) cells can lead to both compromised viral clearance and dysregulation of the immune response. Such dysregulation leads to overproduction of cytokines, a raised neutrophil/lymphocyte ratio and monocytosis. This in turn increases IL‐6 expression, which promotes scar and thrombus formation. Excess IL‐6 also leads to a further reduction in NK function through downregulation of perforin expression, therefore forming a pathogenic auto‐inflammatory feedback loop. The perforin/granzyme system of cytotoxicity is the main mechanism through which NK cells and cytotoxic T lymphocytes eliminate virally infected host cells, as well as being central to their role in regulating immune responses to microbial infection. Here, we present epidemiological evidence suggesting an association between perforin expression and resistance to COVID‐19. In addition, we outline the manner in which a pathogenic auto‐inflammatory feedback loop could operate and the relationship of this loop to genes associated with severe COVID‐19. Such an auto‐inflammatory loop may be amenable to synergistic multimodal therapy.