Lymphocyte B Subtypes in Peripheral Blood: A Prognostic Biomarker for COVID-19 Patients.

BACKGROUND: In view of the scientific gap in knowledge of the involvement of the B-cell compartment and clinical prognostic in SARS-CoV-2 infection, this work aims to evaluate the B-cell subsets and the presence of specific IgM and IgG, as well as neutralizing antibodies against SARS-CoV-2, in unvaccinated patients diagnosed with COVID-19. METHODS: This study included 133 patients with COVID-19. Cellular components were assessed by flow cytometry, and immunoglobulin levels and reactivity were measured by indirect enzyme-linked immunosorbent assay. RESULTS: Our results showed no changes in less differentiated B cells. However, non-switched memory B cells (NS-MBCs) and class-switched memory B cells (CS-MBCs) were reduced in the patients with moderate disease. Also, plasmablasts and double-negative (DN) or "atypical" memory B cells were increased in groups of patients with moderate to critical conditions. In addition, the production of IgM, IgG, and neutralizing antibodies against SARS-CoV-2 demonstrated a positive correlation between the positivity of antibodies against SARS-CoV-2 and disease severity. Besides being related to the development of a more severe course of the disease, the increase in DN B-cell count also contributed to a poorer disease outcome in patients with a higher percentage of these cells. On the other hand, we observed an increase in the absolute number of CS-MBCs in patients with greater chances of survival. CONCLUSIONS: This study demonstrates that the B-cell compartment may contribute to the development of clinical symptoms of COVID-19, with changes in B-cell subset counts linked to disease course and patient prognosis.

T cell maturation is significantly affected by SARS-CoV-2 infection.

Coronavirus disease 2019 (COVID-19) is a respiratory tract infection caused by the new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). An adequate T cell response is essential not only for fighting disease but also for the creation of immune memory. Thus, the present study aims to evaluate the T cells of patients with moderate, severe and critical COVID-19 not only at the time of illness but also 2 months after diagnosis to observe whether changes in this compartment persist. In this study, 166 COVID-19 patients were stratified into moderate/severe and critical disease categories. The maturation and activation of T cells were evaluated through flow cytometry. In addition, Treg cells were analysed. Until 15 days after diagnosis, patients presented a reduction in absolute and relative T lymphocyte counts. After 2 months, in moderate/severe patients, the counts returned to a similar level as that of the control group. In convalescent patients who had a critical illness, absolute T lymphocyte values increased considerably. Patients with active disease did not show differentiation of T cells. Nonetheless, after 2 months, patients with critical COVID-19 showed a significant increase in CD4+ EMRA (CD45RA+ effector memory) T lymphocytes. Furthermore, COVID-19 patients showed delayed T cell activation and reduced CD8+ suppressor T cells even 2 months after diagnosis. A reduction in CD4+ Treg cells was also observed, and their numbers returned to a similar level as that of healthy controls in convalescent patients. The results demonstrate that COVID-19 patients have a delayed activation and differentiation of T cells. In addition, these patients have a great reduction of T cells with a suppressor phenotype.

The anti-inflammatory activity of 2-iminothiazolidines: evidence for macrophage repolarization.

Nowadays, macrophages are recognized as key cells involved in chronic inflammatory conditions, and play central roles in all inflammatory diseases and cancer. Due to their extensive involvement in the pathogenesis of inflammatory diseases, they are now considered a relevant therapeutic target in the development of new therapeutic strategies. 2-Iminothiazolidines are associated with important anti-inflammatory activity and represent a rich source for the development of new drugs and treatments. Our research focuses on evaluating the anti-inflammatory capacity of these compounds and their relationship with M1/M2 macrophage polarization. The results demonstrate that 2-iminothiazolidines have the capacity to decrease the levels of anti-inflammatory biomarkers, such as cytokines (IL-1ß, TNF-α, and IL-6), nitric oxide synthase (with impact on NOx production), and COX-2, following a significant decline in NF-kB activation. We also observed an increase in levels of anti-inflammatory cytokines (IL-4 and IL-13) in the in vitro model of RAW 264.7 macrophages induced by LPS. Moreover, this is the first report, suggesting that the anti-inflammatory activity of 2-iminothiazolidines is associated with the ability to enhance phagocytosis, increase Arginase-1 and CD206 expression, and increase the secretion of IL-10. Furthermore, an in vivo study using the acute lung injury model induced by LPS proved the anti-inflammatory activity of a selected 2-iminothiazolidine, named methyl 2-(benzoylimino)-3-methyl-4-(4-nitrobenzyl)-1,3-thiazolidine-4-carboxylate. All these results, taken together, lead us to hypothesize that the mechanism of anti-inflammatory effect observed with this compound is closely related to the ability of this compound to produce macrophage repolarization, from the M1 to the M2 phenotype.

Inflammatory biomarkers on an LPS-induced RAW 264.7 cell model: a systematic review and meta-analysis.

INTRODUCTION: Several experimental models have been designed to promote the development of new anti-inflammatory drugs. The in vitro model using RAW 264.7 cells has been widely used. However, there is still no consensus on which inflammatory mediators should initially be measured to screen for possible anti-inflammatory effects. To determine the rationality of measuring inflammatory mediators together with NO, such as the levels of tumor necrosis factor (TNF)-α, and interleukins (IL) 1ß and 6, we carried out this systematic review (SR) and meta-analysis (MA). METHODOLOGY: We conducted this SR and MA in accordance with the Preferred Reporting of Systematic Reviews and Meta-Analysis and the Cochrane Handbook for Systematic Reviews of Intervention. This review was registered in the Open Science Framework ( https://doi.org/10.17605/OSF.IO/8C3HT ). RESULTS: LPS-induced cells produced high NO levels compared to non-LPS induced, and this production was not related to cell density. TNF-α, IL-1ß, and IL-6, also showed high levels after cells had been stimulated with LPS. Though with some restrictions, all studies were reliable, as the risk of bias was detected in the test compounds and systems. CONCLUSION: Measurement of NO levels may be sufficient to screen for possible anti-inflammatory action in the context of LPS-induced RAW 264.7 cells.

The relationship between peripheral immune response and disease severity in SARS-CoV-2-infected subjects: A cross-sectional study.

Coronavirus disease 2019 (COVID-19) is a respiratory infection caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and marked by an intense inflammatory response and immune dysregulation in the most severe cases. In order to better clarify the relationship between peripheral immune system changes and the severity of COVID-19, this study aimed to evaluate the frequencies and absolute numbers of peripheral subsets of neutrophils, monocytes, and dendritic cells (DCs), in addition to quantifying the levels of inflammatory mediators. One hundred fifty-seven COVID-19 patients were stratified into mild, moderate, severe, and critical disease categories. The cellular components and circulating cytokines were assessed by flow cytometry. Nitric oxide (NOx) and myeloperoxidase (MPO) levels were measured by colourimetric tests. COVID-19 patients presented neutrophilia, with signs of emergency myelopoiesis. Alterations in the monocytic component were observed in patients with moderate to critical illness, with an increase in classical monocytes and a reduction in nonclassical monocytes, in addition to a reduction in the expression of HLA-DR in all subtypes of monocytes, indicating immunosuppression. DCs, especially plasmacytoid DCs, also showed a large reduction in moderate to critical patients. COVID-19 patients showed an increase in MPO, interleukin (IL)-12, IL-6, IL-10, and IL-8, accompanied by a reduction in IL-17A and NOx. IL-10 levels ≥14 pg/ml were strongly related to the worst outcome, with a sensitivity of 78·3% and a specificity of 79·1%. The results of this study indicate the presence of systemic effects induced by COVID-19, which appear to be related to the pathophysiology of the disease, highlighting the potential of IL-10 as a possible prognostic biomarker for COVID-19.

Phenolic profile and in vitro anti-inflammatory activity of Mimosa scabrella Bentham honeydew honey in RAW 264.7 murine macrophages.

The anti-inflammatory activity is mainly attributed to the phenolic compounds. Once the geographical location affects the phenolic content of honeys, a relationship between the collection spot and the anti-inflammatory effect of bracatinga (Mimosa scabrella Bentham) honeydew honeys was hypothesized. The inhibitory effect of 14 honey samples on NOx, TNF-α, IL-6, IL-12p70, MCP-1, INF-γ, and IL-10 in RAW 264.7 macrophages inflamed by LPS was evaluated. Fourteen phenolic compounds were identified, mainly syringic acid and rutin. Ten honeys inhibited nitrite production; at least six downregulated TNF-α, IL-12p70, MCP-1, and IFN-γ; only four honey samples inhibited IL-6; and one honey sample inhibited IL-10 levels, showing their variable effects on the inflammatory markers. Principal component analysis grouped samples according to the phenolic content and downregulation of specific inflammatory markers. The bracatinga honeydew honey effectiveness was associated with geographical location, as samples from areas with higher density and diversity of plants had a more significant anti-inflammatory effect. PRACTICAL APPLICATIONS: The present research study investigated the anti-inflammatory potential of bracatinga honeydew honey samples collected from regions with different vegetation coverages. Honey samples collected from locations presenting greater forest diversity and density inhibited inflammatory markers more efficiently. This study reinforces the role of the bracatinga honeydew honey in preventing inflammatory processes and the importance of preserving forests so that products with a greater diversity of compounds and consequently more active can be obtained.

Investigation of phenolic compounds, antioxidant and anti-inflammatory activities in stingless bee honey (Meliponinae).

The objective of this study was to investigate and quantify the composition phenolic, reducing capacity, the free radical scavenging activity, as well as, the anti-inflammatory effect evaluated against lipopolysaccharides-stimulated RAW264.7 macrophages through modulation of inflammatory mediators, in eight stingless bee honey types (Meliponinae) from southern Brazil. Stingless bee honey did not show to be cytotoxic at the tested concentrations (1-100 µM) and also reduced nitric oxide and the secretion of the pro-inflammatory cytokine in the inflamed macrophages. Two honey samples showed the ability to increase the secretion of anti-inflammatory cytokine (interleukin-10), suggesting a significant anti-inflammatory effect. All these findings indicate that stingless bee honey could be an important source of natural compounds presenting anti-inflammatory and antioxidant effect, which could would provide health benefits when included in the diet.

Evidence That the Anti-Inflammatory Effect of Rubiadin-1-methyl Ether Has an Immunomodulatory Context.

BACKGROUND: In spite of the latest therapeutic developments, no effective treatments for handling critical conditions such as acute lung injuries have yet been found. Such conditions, which may result from lung infections, sepsis, multiple trauma, or shock, represent a significant challenge in intensive care medicine. Seeking ways to better deal with this challenge, the scientific community has recently devoted much attention to small molecules derived from natural products with anti-inflammatory and immunomodulatory effects. AIMS: In this context, we investigated the anti-inflammatory effect of Rubiadin-1-methyl ether isolated from Pentas schimperi, using an in vitro model of RAW 264.7 macrophages induced by LPS and an in vivo model of acute lung injury (ALI) induced by LPS. METHODS: The macrophages were pretreated with the compound and induced by LPS (1 µg/mL). After 24 h, using the supernatant, we evaluated the cytotoxicity, NOx, and IL-6, IL-1ß, and TNF-α levels, as well as the effect of the compound on macrophage apoptosis. Next, the compound was administered in mice with acute lung injury (ALI) induced by LPS (5 mg/kg), and the pro- and anti-inflammatory parameters were analyzed after 12 h using the bronchoalveolar lavage fluid (BALF). RESULTS: Rubiadin-1-methyl ether was able to inhibit the pro-inflammatory parameters studied in the in vitro assays (NOx, IL-6, and IL-1ß) and, at the same time, increased the macrophage apoptosis rate. In the in vivo experiments, this compound was capable of decreasing leukocyte infiltration; fluid leakage; NOx; IL-6, IL-12p70, IFN-γ, TNF-α, and MCP-1 levels; and MPO activity. In addition, Rubiadin-1-methyl ether increased the IL-10 levels in the bronchoalveolar lavage fluid (BALF). CONCLUSIONS: These findings support the evidence that Rubiadin-1-methyl ether has important anti-inflammatory activity, with evidence of an immunomodulatory effect.