Resveratrol attenuates staphylococcal enterotoxin B-activated immune cell metabolism via upregulation of miR-100 and suppression of mTOR signaling pathway.

Acute Respiratory Distress Syndrome (ARDS) is triggered by a variety of insults, such as bacterial and viral infections, including SARS-CoV-2, leading to high mortality. In the murine model of ARDS induced by Staphylococcal enterotoxin-B (SEB), our previous studies showed that while SEB triggered 100% mortality, treatment with Resveratrol (RES) completely prevented such mortality by attenuating inflammation in the lungs. In the current study, we investigated the metabolic profile of SEB-activated immune cells in the lungs following treatment with RES. RES-treated mice had higher expression of miR-100 in the lung mononuclear cells (MNCs), which targeted mTOR, leading to its decreased expression. Also, Single-cell RNA-seq (scRNA seq) unveiled the decreased expression of mTOR in a variety of immune cells in the lungs. There was also an increase in glycolytic and mitochondrial respiration in the cells from SEB + VEH group in comparison with SEB + RES group. Together these data suggested that RES alters the metabolic reprogramming of SEB-activated immune cells, through suppression of mTOR activation and its down- and upstream effects on energy metabolism. Also, miR-100 could serve as novel potential therapeutic molecule in the amelioration of ARDS.

SARS-CoV-2 Spike Does Not Possess Intrinsic Superantigen-like Inflammatory Activity.

Multisystem inflammatory syndrome in children (MIS-C) is a rare hyperinflammatory disease occurring several weeks after SARS-CoV-2 infection. The clinical similarities between MIS-C and the toxic shock syndrome, together with the preferential expansion of T cells with a T-cell receptor variable ß chain (TCRVß) skewing, suggested a superantigen theory of MIS-C. For instance, recent in silico modelling evidenced the presence of a highly conserved motif within SARS-CoV-2 spike protein similar in structure to the superantigenic fragment of staphylococcal enterotoxin B (SEB). However, experimental data on the superantigenic activity of the SARS-CoV-2 spike have not yet been provided. Here, we assessed the superantigenic activity of the SARS-CoV-2 spike by analysing inflammatory cytokine production in both Jurkat cells and the peripheral blood CD4+ T cells stimulated with the SARS-CoV-2 spike or SEB as a control. We found that, unlike SEB, the SARS-CoV-2 spike does not exhibit an intrinsic superantigen-like activity.

Endocannabinoid Anandamide Attenuates Acute Respiratory Distress Syndrome through Modulation of Microbiome in the Gut-Lung Axis.

Acute respiratory distress syndrome (ARDS) is a serious lung condition characterized by severe hypoxemia leading to limitations of oxygen needed for lung function. In this study, we investigated the effect of anandamide (AEA), an endogenous cannabinoid, on Staphylococcal enterotoxin B (SEB)-mediated ARDS in female mice. Single-cell RNA sequencing data showed that the lung epithelial cells from AEA-treated mice showed increased levels of antimicrobial peptides (AMPs) and tight junction proteins. MiSeq sequencing data on 16S RNA and LEfSe analysis demonstrated that SEB caused significant alterations in the microbiota, with increases in pathogenic bacteria in both the lungs and the gut, while treatment with AEA reversed this effect and induced beneficial bacteria. AEA treatment suppressed inflammation both in the lungs as well as gut-associated mesenteric lymph nodes (MLNs). AEA triggered several bacterial species that produced increased levels of short-chain fatty acids (SCFAs), including butyrate. Furthermore, administration of butyrate alone could attenuate SEB-mediated ARDS. Taken together, our data indicate that AEA treatment attenuates SEB-mediated ARDS by suppressing inflammation and preventing dysbiosis, both in the lungs and the gut, through the induction of AMPs, tight junction proteins, and SCFAs that stabilize the gut-lung microbial axis driving immune homeostasis.

MyD88 and beyond: a perspective on MyD88-targeted therapeutic approach for modulation of host immunity.

The continuous emergence of infectious pathogens along with antimicrobial resistance creates a need for an alternative approach to treat infectious diseases. Targeting host factor(s) which are critically involved in immune signaling pathways for modulation of host immunity offers to treat a broad range of infectious diseases. Upon pathogen-associated ligands binding to the Toll-like/ IL-1R family, and other cellular receptors, followed by recruitment of intracellular signaling adaptor proteins, primarily MyD88, trigger the innate immune responses. But activation of host innate immunity strongly depends on the correct function of MyD88 which is tightly regulated. Dysregulation of MyD88 may cause an imbalance that culminates to a wide range of inflammation-associated syndromes and diseases. Furthermore, recent reports also describe that MyD88 upregulation with many viral infections is linked to decreased antiviral type I IFN response, and MyD88-deficient mice showed an increase in survivability. These reports suggest that MyD88 is also negatively involved via MyD88-independent pathways of immune signaling for antiviral type I IFN response. Because of its expanding role in controlling host immune signaling pathways, MyD88 has been recognized as a potential drug target in a broader drug discovery paradigm. Targeting BB-loop of MyD88, small molecule inhibitors were designed by structure-based approach which by blocking TIR-TIR domain homo-dimerization have shown promising therapeutic efficacy in attenuating MyD88-mediated inflammatory impact, and increased antiviral type I IFN response in experimental mouse model of diseases. In this review, we highlight the reports on MyD88-linked immune response and MyD88-targeted therapeutic approach with underlying mechanisms for controlling inflammation and antiviral type I IFN response. HIGHLIGHTS: • Host innate immunity is activated upon PAMPs binding to PRRs followed by immune signaling through TIR domain-containing adaptor proteins mainly MyD88. • Structure-based approach led to develop small-molecule inhibitors which block TIR domain homodimerization of MyD88 and showed therapeutic efficacy in limiting severe inflammation-associated impact in mice. • Therapeutic intervention of MyD88 also showed an increase in antiviral effect with strong type I IFN signaling linked to increased phosphorylation of IRFs via MyD88-independent pathway. • MyD88 inhibitors might be potentially useful as a small-molecule therapeutics for modulation of host immunity against inflammatory diseases and antiviral therapy. • However, prior clinical use of more in-depth efforts should be focused for suitability of the approach in deploying to complex diseases including COPD and COVID-19 in limiting inflammation-associated syndrome to infection.

Resveratrol-mediated attenuation of superantigen-driven acute respiratory distress syndrome is mediated by microbiota in the lungs and gut.

Acute Respiratory Distress Syndrome (ARDS) is triggered by a variety of agents, including Staphylococcal Enterotoxin B (SEB). Interestingly, a significant proportion of patients with COVID-19, also develop ARDS. In the absence of effective treatments, ARDS results in almost 40% mortality. Previous studies from our laboratory demonstrated that resveratrol (RES), a stilbenoid, with potent anti-inflammatory properties can attenuate SEB-induced ARDS. In the current study, we investigated the role of RES-induced alterations in the gut and lung microbiota in the regulation of ARDS. Our studies revealed that SEB administration induced inflammatory cytokines, ARDS, and 100% mortality in C3H/HeJ mice. Additionally, SEB caused a significant increase in pathogenic Proteobacteria phylum and Propionibacterium acnes species in the lungs. In contrast, RES treatment attenuated SEB-mediated ARDS and mortality in mice, and significantly increased probiotic Actinobacteria phylum, Tenericutes phylum, and Lactobacillus reuteri species in both the colon and lungs. Colonic Microbiota Transplantation (CMT) from SEB-injected mice that were treated with RES as well as the transfer of L. reuteri into recipient mice inhibited the production of SEB-mediated induction of pro-inflammatory cytokines such as IFN-γ and IL-17 but increased that of anti-inflammatory IL-10. Additionally, such CMT and L. reuteri recipient mice exposed to SEB, showed a decrease in lung-infiltrating mononuclear cells, cytotoxic CD8+ T cells, NKT cells, Th1 cells, and Th17 cells, but an increase in the population of regulatory T cells (Tregs) and Th3 cells, and increase in the survival of mice from SEB-mediated ARDS. Together, the current study demonstrates that ARDS induced by SEB triggers dysbiosis in the lungs and gut and that attenuation of ARDS by RES may be mediated, at least in part, by alterations in microbiota in the lungs and the gut, especially through the induction of beneficial bacteria such as L. reuteri.

Recent advances in sensitive surface-enhanced Raman scattering-based lateral flow assay platforms for point-of-care diagnostics of infectious diseases.

This review reports the recent advances in surface-enhanced Raman scattering (SERS)-based lateral flow assay (LFA) platforms for the diagnosis of infectious diseases. As observed through the recent infection outbreaks of COVID-19 worldwide, a timely diagnosis of the disease is critical for preventing the spread of a disease and to ensure epidemic preparedness. In this regard, an innovative point-of-care diagnostic method is essential. Recently, SERS-based assay platforms have received increasing attention in medical communities owing to their high sensitivity and multiplex detection capability. In contrast, LFAs provide a user-friendly and easily accessible sensing platform. Thus, the combination of LFAs with a SERS detection system provides a new diagnostic modality for accurate and rapid diagnoses of infectious diseases. In this context, we briefly discuss the recent application of LFA platforms for the POC diagnosis of SARS-CoV-2. Thereafter, we focus on the recent advances in SERS-based LFA platforms for the early diagnosis of infectious diseases and their applicability for the rapid diagnosis of SARS-CoV-2. Finally, the key issues that need to be addressed to accelerate the clinical translation of SERS-based LFA platforms from the research laboratory to the bedside are discussed.