Endothelial dysfunction plays a central role in COVID-19 pathogenesis, by affecting vascular homeostasis and worsening thromboinflammation. This imbalance may contribute to blood–brain barrier (BBB) disruption, which has been reported in long COVID-19 patients with neurological sequelae. The kallikrein–kinin system (KKS) generates bradykinin (BK), a proinflammatory peptide that induces microvascular leakage via B2R. Under inflammatory conditions, BK is converted to Des-Arg-BK (DABK), which activates B1R, a receptor upregulated in inflamed tissues. DABK is degraded by ACE2, the main SARS-CoV-2 receptor; thus, viral binding and ACE2 downregulation may lead to DABK/B1R imbalance. Here, we investigated these interactions using human brain microvascular endothelial cells (HBMECs), as a model of the BBB. Since endothelial cell lines express low levels of ACE2, HBMECs were modified with an ACE2-carrying pseudovirus. SARS-CoV-2 replication was confirmed by RNA, protein expression, and infectious particles release. Infection upregulated cytokines and endothelial permeability, enhancing viral and leukocyte transmigration. Additionally, viral replication impaired ACE2 function in HBMECs, amplifying the response to DABK, increasing nitric oxide (NO) production, and further disrupting endothelial integrity. Our findings reveal a mechanism by which SARS-CoV-2 impacts the BBB and highlights the ACE2/KKS/B1R axis as a potential contributor to long COVID-19 neurological symptoms.

COVID-19 has a broad spectrum of clinical manifestations. We assessed the impact of single nucleotide polymorphisms (SNPs) of inflammasome genesas risk factors for progression toCOVID-19 critical outcomes, such as mechanical ventilation support (MVS) or death.The study included 451 hospitalized individuals followed up at the INI/FIOCRUZ, Rio de Janeiro, Brazil, from 06/2020 to 03/2021. SNPs genotyping was determined by Real-Time PCR. We analyzed risk factors for progression to MVS (n = 174[38.6 %]) or death (n = 175[38.8 %])as a result of COVID-19 by Cox proportional hazardmodels.Slower progression toMVSwas associated with allele G (aHR = 0.66;P = 0.005) or the genotype G/G (aHR = 0.391;P = 0.006) in the NLRP3 rs10754558 or the allele G (aHR = 0.309;P = 0.004) in the IL1βrs1143634, while C allele in the NLRP3 rs4612666 (aHR = 2.342;P = 0.006) or in the rs10754558 (aHR = 2.957;P = 0.005) were associated with faster progression to death. Slower progression to death was associated to allele G (aHR = 0.563;P = 0.006) or the genotype A/G (aHR = 0.537;P = 0.005) in the CARD8 rs6509365; the genotype A/C in the IFI16 rs1101996 (aHR = 0.569;P = 0.011); the genotype T/T (aHR = 0.394;P = 0.004) or allele T (aHR = 0.68;P = 0.006) in the NLRP3 rs4612666, and the genotype G/G (aHR = 0.326;P = 0.005) or allele G (aHR = 0,68;P = 0.014) in the NLRP3 rs10754558. Our results suggest that inflammasome genetic variations might influence the critical clinical course of COVID-19.

The SARS-CoV-2 spike protein interacts with ACE2, a key receptor within the renin-angiotensin-aldosterone system (RAAS), which plays a critical role in maintaining vascular homeostasis, regulating blood pressure, and modulating inflammation. An observational study analyzed the gene expression profiles of RAAS receptors and associated miRNAs in 88 hospitalized COVID-19 patients and 20 healthy controls, comparing the acute and post-acute phases to assess their impact on disease severity and recovery. Our findings revealed an association between reduced MAS1 expression in both advanced age (P = 0.03) and the need for oxygen supplementation (P = 0.04). Additionally, reduced ACE expression was associated with worse mortality outcomes (P = 0.01). Notably, ACE2 and TMPRSS2 expression was significantly decreased (P < 0.0001) in individuals requiring oxygen supplementation and in those with diabetes mellitus during both the acute and post-COVID-19 phases, further highlighting the impact of these conditions on RAAS. The miRNA analysis revealed significant downregulation of miR-200c (P = 0.005), miR-let-7 (P = 0.01), and miR-122 (P = 0.03) in acute-phase COVID-19 patients. This dysregulation contributes to the inflammatory response and highlights the interaction between viral entry and immune regulation. These results underscore the significance of the ACE2/Ang-(1–7)/MAS1 axis in inflammation regulation and suggest that targeting this pathway may have therapeutic potential. Our study provides valuable insights into the molecular mechanisms of COVID-19 pathogenesis and identifies the modulation of RAAS receptors and miRNAs as promising biomarkers for disease severity and potential therapeutic interventions. Not applicable

Various HIV-1 env genetic and biochemical features impact the elicitation of cross-reactive neutralizing antibodies in natural infections. Thus, we aimed to investigate cross-neutralizing antibodies in individuals infected with HIV-1 env subtypes B, F1, C or the B/Bbr variant as well as env characteristics. Therefore, plasma samples from Brazilian chronically HIV-1 infected individuals were submitted to the TZM-bl neutralization assay. We also analyzed putative N-glycosylation sites (PNGLs) and the size of gp120 variable domains in the context of HIV-1 subtypes prevalent in Brazil. We observed a greater breadth and potency of the anti-Env neutralizing response in individuals infected with the F1 or B HIV-1 subtypes compared with the C subtype and the variant B/Bbr. We observed greater V1 B/Bbr and smaller V4 F1 than those of other subtypes (p<0.005), however neither was there a correlation verified between the variable region length and neutralization potency, nor between PNLG and HIV-1 subtypes. The enrichment of W at top of V3 loop in weak neutralizing response viruses and the P in viruses with higher neutralization susceptibility was statistically significant (p = 0.013). Some other signatures sites were associated to HIV-1 subtype-specific F1 and B/Bbr samples might influence in the distinct neutralizing response. These results indicate that a single amino acid substitution may lead to a distinct conformational exposure or load in the association domain of the trimer of gp120 and interfere with the induction power of the neutralizing response, which affects the sensitivity of the neutralizing antibody and has significant implications for vaccine design.

Tests for the detection of the humoral immune response to HIV-1 have to be standardized and established, demanding regional efforts. For this purpose the neutralizing antibody (NAb) assay for HIV-1 in TZM-bl cells was introduced in Brazil. Twenty plasma samples from HIV-1-infected individuals were assayed : 10 progressors and 10 long-term nonprogressors. These were tested against eight env -pseudotyped viruses (psVs) in the TZM-bl NAb assay and against HIV-1 strain HTLV/IIIB (HIV-1 IIIB) in primary lymphocytes. Forty-four percent of the samples showed neutralizing titers for psVs and 55% for HIV-1 IIIB. Plasma from progressors showed a broader neutralization and a higher potency. The introduction of these reference reagents encourages the participation of Brazil in future comparative assessments of anti-HIV-1 antibodies.

Between 2016 and 2018, Brazil faced a yellow fever (YF) outbreak, which led to an expansion of vaccination coverage. The coexistence of the YF outbreak and the HIV-1 epidemic in Brazil raised concerns regarding the immune response and vaccine effectiveness in individuals living with HIV (PLWH). The aim of this study was to investigate the immune response to YF vaccination in PLWH and HIV-uninfected individuals as controls. Transcript levels of immunomodulatory molecules, including IL-6, IL-10, IL-21, TGF-beta, CD19, CD163, miR-21, miR146, and miR-155, were measured using RT-qPCR. TCD4+ cells were evaluated by cytometry, and neutralizing antibody (Nab) titers were detected by a micro plaque-reduction neutralization test. The findings of our study revealed several noteworthy observations. First, there was a notable reduction in the circulation of TCD4+ cells postvaccination. Among people living with HIV (PLWH), we observed an increase in the expression of IL-10 following vaccination, while IL-6 expression was diminished in PLWH with lower TCD4+ counts. Furthermore, we identified the downregulation of CD19 and TGF-beta, along with the upregulation of IL-21 and CD163. Notably, we observed positive correlations between the levels of IL-10/IL-21, IL-10/CD163, and IL-6/CD19. Additionally, there was a positive correlation between miRNAs 146 and 155. It is important to emphasize that all participants exhibited robust neutralizing antibody responses after receiving 17DD YF vaccination. In this context, the gene expression data presented can be useful for biomarker studies of protective antibodies induced by YF vaccination. This study sheds light on immune mechanisms in individuals living with HIV and YF vaccination.