Biology subjects

Lima, M. R. D.

Publications and source records attributed to Lima, M. R. D..

4 recordsLinked to original sources

bioRxiv2026

microRNA-721 is a host regulator of TNF-IRF1 axis in Leishmania infected macrophage

MicroRNAs (miRNAs) are small noncoding RNAs that play critical roles in regulating immune responses and have emerged as potential biomarkers and therapeutic targets in complex diseases. Leishmaniasis is a neglected disease that compromises host immunity and is associated with challenging treatments regimens. Leishmania amazonensis (L. amazonensis), an intracellular protozoan parasite, causes cutaneous leishmaniasis by replicating inside mammalian macrophages to establish infection. In this context, miRNAs have emerged as vital post-transcriptional factors that regulate the inflammatory landscape during infection. In this study, we aimed to analyze the function of miR-721 in macrophages during L. amazonensis infection by integrating in silico miR-721 target prediction with RNAseq data from macrophages of two distinct mouse genotypes, resistant C57BL/6 and susceptible BALB/c. We found that miR-721 is induced in macrophages infected with L. amazonensis, but is not in LPS-stimulated macrophages, suggesting a TLR4-independent activation. Integrating miR-721 target prediction with comparative transcriptomic analyses in resistant C57BL/6 and susceptible BALB/c models revealed the TNF-IRF1 axis as a primary miR-721-associated regulatory network. Specifically, miR-721 is predicted to target the 3UTRs of Tnf and Irf1 to suppress the inflammatory response. Functional inhibition of miR-721 successfully restored Tnf and Irf1 expression and reduced the amastigote burden over 24 hours. Furthermore, we showed that the miR-721/TNF-IRF1 axis regulates downstream genes associated with macrophage response, such as Serpine1, Csf1, Cd69 and Maf. Our work demonstrated that Leishmania induces miR-721, which negatively modulates the TNF-IRF1 axis, thereby suppressing the immune response and favoring parasite persistence. While C57BL/6 macrophages exhibit a robust activation of the TNF-IRF1 network, promoting inflammatory response, BALB/c macrophage showed a breakdown of this network. This was associated with post-transcriptional suppression of inflammatory responses, thereby favoring parasite persistence. These findings link miR-721 to the establishment of macrophage polarization, providing relevant insights into the mechanisms of parasite subversion of the host immune response.

immunology↗

bioRxiv2026

Single-cell RNA sequencing of CTLA-4 and PD-1 blockade in pulmonary paracoccidioidomycosis highlights a protective transcriptional program mediated by activated Th17 cells, neutrophils and macrophages

Pulmonary paracoccidioidomycosis (PCM) relies on a finely balanced lung-immune network in which Th17, Treg, neutrophils, and macrophages orchestrate fungal control and tissue integrity. Furthermore, within the context of single-cell sequencing, little is known about how immune checkpoint inhibition modulates this balance during systemic mycosis. In a previous study we verified that the blockade of checkpoint molecules (CTLA-4 and PD-1) restores protective immunity that reduces fungal loads, tissue pathology and mortality of infected mice. Here, we have further studied this model by single-cell RNA sequencing on lung leukocytes from mice infected with Paracoccidioides brasiliensis and treated with anti-CTLA-4 or anti-PD-1 antibodies to define the cellular and molecular consequences of checkpoint blockade in vivo. We generated a high-resolution atlas covering T cells, neutrophils, macrophages/monocytes, B cells, NK cells, and epithelial subsets. Checkpoint inhibition consistently remodeled the CD4 T cell compartment toward a Th17-enriched program, with reduced interleukin-10 expressing Treg frequencies and a prominent interleukin-17A (IL-17), C-C chemokine receptor type 2, CXC chemokine (CXC) receptor type 6, CD44 (Il17aCcr2Cxcr6Cd44) signature. This shift was accompanied by the expansion and activation of neutrophils and macrophages expressing tumor necrosis factor and chemokines (including CXC motif chemokine ligand (Cxcl1, Cxcl2 and Ccl4), microbicidal-associated genes (S100 calcium-binding protein A8 and A9), and regulatory mediators such as secretory leukocyte protease inhibitor and interleukin-15. Ligand-receptor and trajectory analyses revealed a reinforced Th17-myeloid communication axis, particularly under CTLA-4 blockade, converging on IL17-centered inflammatory circuits while attenuating canonical Treg checkpoints (cytotoxic T-lymphocyte-associated protein 4, programmed cell death protein 1, interleukin-10). Together, these data demonstrate that anti-CTLA-4 and anti-PD-1 immunotherapies profoundly rewire the lung-immune microenvironment during PCM, amplifying effector Th17-neutrophil-macrophage networks that benefits protective antifungal activity Our work provides a mechanistic framework for evaluating immune checkpoint inhibitors in chronic fungal infections.

immunology↗

bioRxiv2022

T cell-specific P2RX7 favors lung parenchymal CD4+ T cell accumulation in response to severe lung infections

CD4+ T cells are key components of the immune response during lung infections and can mediate protection against tuberculosis (TB) or influenza. However, CD4+ T cells can also promote lung pathology during these infections, making it unclear how these cells control such discrepant effects. Using mouse models of hypervirulent TB and influenza, we observed that exaggerated accumulation of parenchymal CD4+ T cells promotes lung damage. Low numbers of lung CD4+ T cells, in contrast, are sufficient to protect against hypervirulent TB. In both situations, lung CD4+ T cell accumulation is mediated by CD4+ T cell-specific expression of the extracellular ATP (eATP) receptor P2RX7. P2RX7 upregulation in lung CD4+ T cells promotes expression of the chemokine receptor CXCR3 and favors in situ proliferation. Our findings suggest that direct sensing of lung eATP by CD4+ T cells is critical to induce tissue CD4+ T cell accumulation and pathology during lung infections. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=168 SRC="FIGDIR/small/508603v1_ufig1.gif" ALT="Figure 1"> View larger version (46K): org.highwire.dtl.DTLVardef@a4cdaborg.highwire.dtl.DTLVardef@1ba95e1org.highwire.dtl.DTLVardef@c60984org.highwire.dtl.DTLVardef@19ac0af_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2021

SARS-CoV-2 Infection Impacts Carbon Metabolism and Depends on Glutamine for Replication in Syrian Hamster Astrocytes

Coronaviruses belong to a well-known family of enveloped RNA viruses and are the causative agent of the common cold. Although the seasonal coronaviruses do not pose a threat to human life, three members of this family, i.e., SARS-CoV, MERS-CoV and recently, SARS-CoV2, may cause severe acute respiratory syndrome and lead to death. Unfortunately, COVID-19 has already caused more than 4.4 million deaths worldwide. Although much is better understood about the immunopathogenesis of the lung disease, important information about systemic disease is still missing, mainly concerning neurological parameters. In this context, we sought to evaluate immunometabolic changes using in vitro and in vivo models of hamsters infected with SARS-CoV-2. Here we show that, besides infecting hamsters astrocytes, SARS-CoV-2 induces changes in protein expression and metabolic pathways involved in carbon metabolism, glycolysis, mitochondrial respiration, and synaptic transmission. Interestingly, many of the differentially expressed proteins are concurrent with proteins that correlate with neurological diseases, such as Parkinsonss disease, multiple sclerosis, amyotrophic lateral sclerosis, and Huntingtons disease. Metabolic analysis by high resolution real-time respirometry evidenced hyperactivation of glycolysis and mitochondrial respiration. Further metabolomics analysis confirmed the consumption of many metabolites, including glucose, pyruvate, glutamine, and alpha ketoglutarate. Interestingly, we observed that glutamine was significantly reduced in infected cultures, and the blockade of mitochondrial glutaminolysis significantly reduced viral replication and pro-inflammatory response. SARS-CoV-2 was confirmed in vivo as hippocampus, cortex, and olfactory bulb of intranasally infected hamsters were positive for viral genome several days post-infection. Altogether, our data reveals important changes in overall protein expression, mostly of those related to carbon metabolism and energy generation, causing an imbalance in important metabolic molecules and neurotransmitters. This may suggest that some of the neurological features observed during COVID-19, as memory and cognitive impairment, may rely on altered energetic profile of brain cells, as well as an unbalanced glutamine/glutamate levels, whose importance for adequate brain function is unquestionable.

immunology↗