Severe COVID-19 patients develop acute respiratory distress syndrome that may progress to cytokine storm syndrome, organ dysfunction, and death. Considering that neutrophil extracellular traps (NETs) have been described as important mediators of tissue damage in inflammatory diseases, we investigated whether NETs would be involved in COVID-19 pathophysiology. A cohort of 32 hospitalized patients with a confirmed diagnosis of COVID-19 and healthy controls were enrolled. The concentration of NETs was augmented in plasma, tracheal aspirate, and lung autopsies tissues from COVID-19 patients, and their neutrophils released higher levels of NETs. Notably, we found that viable SARS-CoV-2 can directly induce the release of NETs by healthy neutrophils. Mechanistically, NETs triggered by SARS-CoV-2 depend on angiotensin-converting enzyme 2, serine protease, virus replication, and PAD-4. Finally, NETs released by SARS-CoV-2–activated neutrophils promote lung epithelial cell death in vitro. These results unravel a possible detrimental role of NETs in the pathophysiology of COVID-19. Therefore, the inhibition of NETs represents a potential therapeutic target for COVID-19.

Severe cases of COVID-19 are characterized by a strong inflammatory process that may ultimately lead to organ failure and patient death. The NLRP3 inflammasome is a molecular platform that promotes inflammation via cleavage and activation of key inflammatory molecules including active caspase-1 (Casp1p20), IL-1β, and IL-18. Although participation of the inflammasome in COVID-19 has been highly speculated, the inflammasome activation and participation in the outcome of the disease are unknown. Here we demonstrate that the NLRP3 inflammasome is activated in response to SARS-CoV-2 infection and is active in COVID-19 patients. Studying moderate and severe COVID-19 patients, we found active NLRP3 inflammasome in PBMCs and tissues of postmortem patients upon autopsy. Inflammasome-derived products such as Casp1p20 and IL-18 in the sera correlated with the markers of COVID-19 severity, including IL-6 and LDH. Moreover, higher levels of IL-18 and Casp1p20 are associated with disease severity and poor clinical outcome. Our results suggest that inflammasomes participate in the pathophysiology of the disease, indicating that these platforms might be a marker of disease severity and a potential therapeutic target for COVID-19.

Many studies have reported that patients with psychosis, even before drug treatment, have mildly raised levels of blood cytokines relative to healthy controls. In contrast, there is a remarkable scarcity of studies investigating the cellular basis of immune function and cytokine changes in psychosis. The few flow-cytometry studies have been limited to counting the proportion of the major classes of monocyte and lymphocytes without distinguishing their pro- and anti-inflammatory subsets. Moreover, most of the investigations are cross-sectional and conducted with patients on long-term medication. These features make it difficult to eliminate confounding of illness-related changes by lifestyle factors, disease duration, and long exposure to antipsychotics. This article focuses on regulatory T cells (Tregs), cornerstone immune cells that regulate innate and adaptive immune forces and neuroimmune interactions between astrocytes and microglia. Tregs are also implicated in cardio-metabolic disorders that are common comorbidities of psychosis. We have recently proposed that Tregs are hypofunctional (‘h-Tregs’) in psychosis driven by our clinical findings and other independent research. Our h-Treg-glial imbalance hypothesis offers a new account for the co-occurrence of systemic immune dysregulation and mechanisms of psychosis development. This article extends our recent review, the h-Treg hypothesis, to cover new discoveries on Treg-based therapies from pre-clinical findings and their clinical implications. We provide a detailed characterisation of Treg studies in psychosis, identifying important methodological limitations and perspectives for scientific innovation. The outcomes presented in this article reaffirms our proposed h-Treg state in psychosis and reveals emerging preclinical research suggesting the potential benefit of Treg-enhancing therapies. There is a clear need for longitudinal studies conducted with drug-naïve or minimally treated patients using more sophisticated techniques of flow-cytometry, CyTOF expression markers, and in vitro co-culture assays to formally test the suppressive capacity of Tregs. Investment in Treg research offers major potential benefits in targeting emerging immunomodulatory treatment modalities on person-specific immune dysregulations.

Although the literature shows that an increase in both the number and suppressive function of CD4⁺forkhead box P3 (FOXP3)⁺ T-regulatory cells (Tregs) during sepsis contributes to an immunosuppressed state, little is known about the identity of these cells. Using the sepsis mouse model of cecal ligation and puncture (CLP), we analyzed the frequency and molecular signature of the T-cell immunoglobulin and ITIM domain (TIGIT)⁺ and TIGIT⁻ Treg subsets, using flow cytometry and quantitative polymerase chain reaction. In addition, ST2^−/− and signal transducer and activator of transcription 6 (STAT6)^−/− mice were submitted to CLP or recombinant interleukin 33 (IL-33) treatment to investigate the mechanism whereby TIGIT⁺ Tregs differentiate during sepsis. Sepsis was marked by the sustained expansion of the highly suppressive TIGIT⁺ Treg subset, which expresses Helios, neuropilin 1, and high levels of Tnfrsf18 and Pdcd1 at 15 days after CLP. The increase in TIGIT⁺ Tregs was accompanied by higher susceptibility to nosocomial bacteria challenge, suggesting their association with post sepsis immunosuppression. Mechanistically, we found that the ST2 deletion abrogated the expansion of the TIGIT⁺ Treg subset during sepsis. Furthermore, treatment with recombinant IL-33 resulted in the expansion of TIGIT⁺ Tregs depending on the STAT6 and M2 macrophages. These findings demonstrated that only the TIGIT⁺ Tregs remain stably expanded at the late phase of sepsis. Moreover, the expansion of TIGIT⁺ Tregs is dependent on the IL-33/ST2/STAT6/M2 macrophage axis.

Propolis is known for its immunomodulatory properties. We investigated the effects of three recently developed propolis extract formulations: polar propolis fraction (PPF), soluble propolis dry extract (PSDE), and microencapsulated propolis extract (MPE), and some of their components, on pro- and anti-inflammatory cytokine production in a macrophage model. Bone marrow cell-derived macrophages (BMDM) in cell culture were E. coli lipopolysaccharide (500 ng/mL) stimulated for two hours and subsequently incubated for 20 hours with one of the three propolis extract formulations (1, 10, 25, 50, 100 and 300 µg/mL) or with isolated propolis components (caffeic acid, p-coumaric acid, artepillin C, or baccharin) (10, 25, 50 and 100 µg/mL) to determine how they affected secretion of the pro-inflammatory cytokines IL-6 and TNF-α, and the anti-inflammatory cytokine, IL-10. PPF increased IL-6 and IL-10 levels. PSDE increased IL-6 and IL-10 at lower concentrations, while at higher concentrations it increased TNF-α and decreased IL-10. MPE increased IL-10. Caffeic acid and PPF increased both IL-6 and IL-10. Artepillin C and PSDE decreased IL-10. Baccharin and MPE increased IL-10. Baccharin also decreased IL-6. p-coumaric acid did not affect secretion of these cytokines. Pro- and anti-inflammatory cytokine production by the different propolis extracts differed; however, all three propolis extract formulations have potential as immunomodulatory agents in food supplement and pharmaceutical products.

This study investigated the anti-caries and anti-inflammatory effects of mouthwash formulations containing Punica granatum (pomegranate) peel extract (PPE), sodium-trimetaphosphate, and low concentrations of fluoride. PPE was characterized using high-performance liquid chromatography (ellagic acid and punicalagin). Total phenolics were quantified among formulations, and their stability was analyzed for 28 days. The formulation effects were evaluated as follows: (1) inorganic component concentration and reduced demineralization on bovine enamel blocks subjected to pH cycling; (2) anti-biofilm effect on dual-biofilms of Streptococcus mutans ATCC 25175 and Candida albicans ATCC 10231 treated for 1 and 10 min, respectively; and (3) cytotoxicity and production of inflammatory mediators (interleukin-6 and tumor necrosis factor-alpha). The formulation containing 3% PPE, 0.3% sodium-trimetaphosphate, and 225 ppm of fluoride resulted in a 34.5% surface hardness loss; a 13% (treated for 1 min) and 36% (treated for 10 min) biofilm reduction in S. mutans; a 26% (1 min) and 36% (10 min) biofilm reduction in C. albicans; absence of cytotoxicity; and anti-inflammatory activity confirmed by decreased interleukin-6 production in mouse macrophages. Thus, our results provide a promising prospect for the development of an alcohol-free commercial dental product with the health benefits of P. granatum that have been recognized for a millennium.