Acetylcholine, Fatty Acids, and Lipid Mediators Are Linked to COVID-19 Severity.

Lipid and cholinergic mediators are inflammatory regulators, but their role in the immunopathology of COVID-19 is still unclear. Here, we used human blood and tracheal aspirate (TA) to investigate whether acetylcholine (Ach), fatty acids (FAs), and their derived lipid mediators (LMs) are associated with COVID-19 severity. First, we analyzed the perturbation profile induced by SARS-CoV-2 infection in the transcriptional profile of genes related to the ACh and FA/LM pathways. Blood and TA were used for metabolomic and lipidomic analyses and for quantification of leukocytes, cytokines, and ACh. Differential expression and coexpression gene network data revealed a unique transcriptional profile associated with ACh and FA/LM production, release, and cellular signaling. Transcriptomic data were corroborated by laboratory findings: SARS-CoV-2 infection increased plasma and TA levels of arachidonic acid, 5-hydroxy-6E,8Z,11Z,14Z-eicosatetraenoic acid, 11-hydroxy-5Z,8Z,12E,14Z-eicosatetraenoic acid, and ACh. TA samples also exhibited high levels of PGE2, thromboxane B2, 12-oxo-5Z,8Z,10E,14Z-eicosatetraenoic acid, and 6-trans-leukotriene B4 Bioinformatics and experimental approaches demonstrated robust correlation between transcriptional profile in Ach and FA/LM pathways and parameters of severe COVID-19. As expected, the increased neutrophil-to-lymphocyte ratio, neutrophil counts, and cytokine levels (IL-6, IL-10, IL-1ß, and IL-8) correlated with worse clinical scores. Glucocorticoids protected severe and critical patients and correlated with reduced Ach levels in plasma and TA samples. We demonstrated that pulmonary and systemic hyperinflammation in severe COVID-19 are associated with high levels of Ach and FA/LM. Glucocorticoids favored the survival of patients with severe/critical disease, and this effect was associated with a reduction in ACh levels.

The turning point of COVID-19 severity is associated with a unique circulating neutrophil gene signature.

COVID-19 has a broad spectrum of clinical manifestations associated with the host immune response heterogeneity. Despite the advances in COVID-19 research, it is still crucial to seek a panel of molecular markers that enable accurate stratification of COVID-19 patients. Here, we performed a study that combined analysis of blood transcriptome, demographic data, clinical aspects and laboratory findings from 66 participants classified into different degrees of COVID-19 severity and healthy subjects. We identified a perturbation in blood-leukocyte transcriptional profile associated with COVID-19 aggravation, which was mainly related to processes that disfavoured lymphocyte activation and favoured neutrophil activation. This transcriptional profile stratified patients according to COVID-19 severity. Hence, it enabled identification of a turning point in transcriptional dynamics that distinguished disease outcomes and non-hospitalized from hospitalized moderate patients. Central genes of this unique neutrophil signature were S100A9, ANXA3, CEACAM6, VNN1, OLFM4, IL1R2, TCN1 and CD177. Our study indicates the molecular changes that are linked with the differing clinical aspects presented by humans when suffering from COVID-19, which involve neutrophil activation.

Divergent androgenic modulation of SARS-CoV-2 infection cooperates with dysregulated immune response to dictate worse COVID-19 outcomes in men.

BACKGROUND: Sex-determined differences are rarely addressed in the management of diseases, despite well-known contrasting outcomes between female and male patients. In COVID-19 there is a remarkable disparity, with higher rates of mortality and more severe acute disease in men compared to women, who are mostly affected by long COVID-19. Furthermore, whether androgens play a protective or detrimental role in COVID-19 is still a matter of debate. Hence, the adequate management of the disease, especially regarding men presenting acute disease aggravation, still needs important data to elucidate the interplay between sex hormones and host immune responses that drive the worse evolution in male patients. METHODS: A cohort of 92 controls and 198 non-severe and severe COVID-19 patients, from both sexes, was assessed for clinical outcomes, plasma steroids, gonadotropins, sex hormone binding globulin (SHBG) and immune mediators, before vaccination. These data were correlated with the global gene expression of blood leukocytes. The androgen receptor (AR) signaling pathway was investigated by transcriptomics and tracheal aspirate was obtained from severe patients for SARS-COV-2 quantification in the respiratory tract. The interplay among clinical, endocrine and immunological data deciphered the sex differences in COVID-19. Importantly, statistical analyses, using 95% confidence interval, considered confounding factors such as age and comorbidities, to definitely parse the role of androgens in the disease outcome. RESULTS: There were notable contrasting levels of testosterone and dihydrotestosterone (DHT) throughout the disease course in male but not female patients. Inflammatory mediators presented significant negative correlations with testosterone, which was partially dependent on age and diabetes in men. Male subjects with severe COVID-19 had a significant up regulation of the AR signaling pathway, including modulation of TMPRSS2 and SRD5A1 genes, which are related to the viral infection and DHT production. Indeed, men had a higher viral load in the tracheal aspirate and levels of DHT were associated with increased relative risk of death. In contrast, the testosterone hormone, which was notably reduced in severe disease, was significantly related with susceptibility to COVID-19 worsening in male patients. Secondary hypogonadism was ruled out in the male severe COVID-19 subjects, as FSH, LH, and SHBG levels were not significantly altered. Instead, these subjects tended to have increased gonadotropin levels. Most interestingly, in this study we identified, for the first time, combined sets of clinical and immunoendocrine parameters that together predicted progression from non-severe to severe COVID-19 in men. One of the limitations of our study was the low or undetectable levels of DHT in many patients. Then, the evaluation of enzymes related to biosynthesis and signaling by androgens was mandatory and reiterated our findings. CONCLUSIONS: These original results unraveled the disease immunoendocrine regulation, despite vaccination or comorbidities and pointed to the fundamental divergent role of the androgens testosterone and DHT in the determination of COVID-19 outcomes in men. Therefore, sex-specific management of the dysregulated responses, treatments or public health measures should be considered for the control of COVID-19 pandemic.

The Interplay among Glucocorticoid Therapy, Platelet-Activating Factor and Endocannabinoid Release Influences the Inflammatory Response to COVID-19.

COVID-19 is associated with a dysregulated immune response. Currently, several medicines are licensed for the treatment of this disease. Due to their significant role in inhibiting pro-inflammatory cytokines and lipid mediators, glucocorticoids (GCs) have attracted a great deal of attention. Similarly, the endocannabinoid (eCB) system regulates various physiological processes including the immunological response. Additionally, during inflammatory and thrombotic processes, phospholipids from cell membranes are cleaved to produce platelet-activating factor (PAF), another lipid mediator. Nonetheless, the effect of GCs on this lipid pathway during COVID-19 therapy is still unknown. This is a cross-sectional study involving COVID-19 patients (n = 200) and healthy controls (n = 35). Target tandem mass spectrometry of plasma lipid mediators demonstrated that COVID-19 severity affected eCBs and PAF synthesis. This increased synthesis of eCB was adversely linked with systemic inflammatory markers IL-6 and sTREM-1 levels and neutrophil counts. The use of GCs altered these lipid pathways by reducing PAF and increasing 2-AG production. Corroborating this, transcriptome analysis of GC-treated patients blood leukocytes showed differential modulation of monoacylglycerol lipase and phospholipase A2 gene expression. Altogether, these findings offer a breakthrough in our understanding of COVID-19 pathophysiology, indicating that GCs may promote additional protective pharmacological effects by influencing the eCB and PAF pathways involved in the disease course.

Plasma Sphingomyelin Disturbances: Unveiling Its Dual Role as a Crucial Immunopathological Factor and a Severity Prognostic Biomarker in COVID-19.

SARS-CoV-2 infection triggers distinct patterns of disease development characterized by significant alterations in host regulatory responses. Severe cases exhibit profound lung inflammation and systemic repercussions. Remarkably, critically ill patients display a "lipid storm", influencing the inflammatory process and tissue damage. Sphingolipids (SLs) play pivotal roles in various cellular and tissue processes, including inflammation, metabolic disorders, and cancer. In this study, we employed high-resolution mass spectrometry to investigate SL metabolism in plasma samples obtained from control subjects (n = 55), COVID-19 patients (n = 204), and convalescent individuals (n = 77). These data were correlated with inflammatory parameters associated with the clinical severity of COVID-19. Additionally, we utilized RNAseq analysis to examine the gene expression of enzymes involved in the SL pathway. Our analysis revealed the presence of thirty-eight SL species from seven families in the plasma of study participants. The most profound alterations in the SL species profile were observed in patients with severe disease. Notably, a predominant sphingomyelin (SM d18:1) species emerged as a potential biomarker for COVID-19 severity, showing decreased levels in the plasma of convalescent individuals. Elevated SM levels were positively correlated with age, hospitalization duration, clinical score, and neutrophil count, as well as the production of IL-6 and IL-8. Intriguingly, we identified a putative protective effect against disease severity mediated by SM (d18:1/24:0), while ceramide (Cer) species (d18:1/24:1) and (d18:1/24:0)were associated with increased risk. Moreover, we observed the enhanced expression of key enzymes involved in the SL pathway in blood cells from severe COVID-19 patients, suggesting a primary flow towards Cer generation in tandem with SM synthesis. These findings underscore the potential of SM as a prognostic biomarker for COVID-19 and highlight promising pharmacological targets. By targeting sphingolipid pathways, novel therapeutic strategies may emerge to mitigate the severity of COVID-19 and improve patient outcomes.

Matrix Metalloproteinases on Severe COVID-19 Lung Disease Pathogenesis: Cooperative Actions of MMP-8/MMP-2 Axis on Immune Response through HLA-G Shedding and Oxidative Stress.

Patients with COVID-19 predominantly have a respiratory tract infection and acute lung failure is the most severe complication. While the molecular basis of SARS-CoV-2 immunopathology is still unknown, it is well established that lung infection is associated with hyper-inflammation and tissue damage. Matrix metalloproteinases (MMPs) contribute to tissue destruction in many pathological situations, and the activity of MMPs in the lung leads to the release of bioactive mediators with inflammatory properties. We sought to characterize a scenario in which MMPs could influence the lung pathogenesis of COVID-19. Although we observed high diversity of MMPs in lung tissue from COVID-19 patients by proteomics, we specified the expression and enzyme activity of MMP-2 in tracheal-aspirate fluid (TAF) samples from intubated COVID-19 and non-COVID-19 patients. Moreover, the expression of MMP-8 was positively correlated with MMP-2 levels and possible shedding of the immunosuppression mediator sHLA-G and sTREM-1. Together, overexpression of the MMP-2/MMP-8 axis, in addition to neutrophil infiltration and products, such as reactive oxygen species (ROS), increased lipid peroxidation that could promote intensive destruction of lung tissue in severe COVID-19. Thus, the inhibition of MMPs can be a novel target and promising treatment strategy in severe COVID-19.

sTREM-1 Predicts Disease Severity and Mortality in COVID-19 Patients: Involvement of Peripheral Blood Leukocytes and MMP-8 Activity.

Uncontrolled inflammatory responses play a critical role in coronavirus disease (COVID-19). In this context, because the triggering-receptor expressed on myeloid cells-1 (TREM-1) is considered an intrinsic amplifier of inflammatory signals, this study investigated the role of soluble TREM-1 (sTREM-1) as a biomarker of the severity and mortality of COVID-19. Based on their clinical scores, we enrolled COVID-19 positive patients (n = 237) classified into mild, moderate, severe, and critical groups. Clinical data and patient characteristics were obtained from medical records, and their plasma inflammatory mediator profiles were evaluated with immunoassays. Plasma levels of sTREM-1 were significantly higher among patients with severe disease compared to all other groups. Additionally, levels of sTREM-1 showed a significant positive correlation with other inflammatory parameters, such as IL-6, IL-10, IL-8, and neutrophil counts, and a significant negative correlation was observed with lymphocyte counts. Most interestingly, sTREM-1 was found to be a strong predictive biomarker of the severity of COVID-19 and was related to the worst outcome and death. Systemic levels of sTREM-1 were significantly correlated with the expression of matrix metalloproteinases (MMP)-8, which can release TREM-1 from the surface of peripheral blood cells. Our findings indicated that quantification of sTREM-1 could be used as a predictive tool for disease outcome, thus improving the timing of clinical and pharmacological interventions in patients with COVID-19.