Biology subjects

Venugopal, G.

Publications and source records attributed to Venugopal, G..

4 recordsLinked to original sources

bioRxiv2025

Guanylate-Binding Proteins Promote Host Defense Against Leishmania major by Balancing iNOS/Arg-1 in Myeloid Cells

Cutaneous leishmaniasis (CL) is a debilitating neglected tropical disease characterized by lesions that can range from self-healing to permanent disfigurations. A predominant Th1 response, which stimulates IFN-{gamma} production, is crucial for parasite control during self-healing CL. While IFN-{gamma} primarily activates macrophages to produce nitric oxide via inducible nitric oxide synthase (iNOS) leading to parasite control, IFN-{gamma} also activates other downstream pathways involved in cell autonomous immunity. One such pathway is the activation of guanylate binding proteins (GBPs), a class of interferon inducible GTPases. However, the role of GBPs during CL has been minimally explored. Utilizing RNA-Seq we found that Leishmania major infection leads to the upregulation of several GBPs in C57Bl/6 mice. In vitro studies using GBPChr3 knockout (KO), and C57Bl/6 control mice reveal that bone marrow-derived macrophages (BMDMs) from KO mice exhibit higher parasite burdens following IFN-{gamma} treatment, independent of GBP localization to the parasite. Single-cell RNA-Seq identifies macrophages as the primary expressers of GBPs during L. major infection in vivo. In vivo, GBPChr3 KO mice display increased disease severity and parasite load. GBPChr3 KO macrophages and monocytes show elevated ARG-1 and reduced iNOS expression, indicating a shift toward a parasite-permissive environment that supports parasite growth. These findings highlight a critical role for GBPs in immune-mediated control of CL.

immunology↗

bioRxiv2024

HIF-alpha signaling mediates the macrophage inflammatory response during Leishmania major infection

Cutaneous leishmaniasis (CL) contributes significantly to the global burden of neglected tropical diseases, with 12 million people currently infected with Leishmania parasites. CL encompasses a range of disease manifestations, from self-healing skin lesions to permanent disfigurations. Currently there is no vaccine available, and many patients are refractory to treatment, emphasizing the need for new therapeutic targets. Previous work demonstrated macrophage HIF--mediated lymphangiogenesis is necessary to achieve efficient wound resolution during murine L. major infection. Here, we investigate the role of macrophage HIF- signaling independent of lymphangiogenesis. We sought to determine the relative contributions of the parasite and the host-mediated inflammation in the lesional microenvironment to myeloid HIF- signaling. Because HIF- activation can be detected in infected and bystander macrophages in leishmanial lesions, we hypothesize it is the hosts inflammatory response and microenvironment, rather than the parasite, that triggers HIF- activation. To address this, macrophages from mice with intact HIF- signaling (LysMCreARNTf/+) or mice with deleted HIF- signaling (LysMCreARNTf/f) were subjected to RNASequencing after L. major infection and under pro-inflammatory stimulus. We report that L. major infection alone is enough to induce some minor HIF--dependent transcriptomic changes, while infection with L. major in combincation with pro-inflammatory stimuli induces numerous transcriptomic changes that are both dependent and independent of HIF- signaling. Additionally, by coupling transcriptomic analysis with several pathway analyses, we found HIF- suppresses pathways involved in protein translation during L. major infection in a pro-inflammatory environment. Together these findings show L. major induces a HIF--dependent transcriptomic program, but HIF- only suppresses protein translation in a pro-inflammatory environment. Thus, this work indicates the host inflammatory response, rather than the parasite, largely contributes to myeloid HIF- signaling during Leishmania infection.

microbiology↗

bioRxiv2024

Enhanced translational activity is linked to lymphatic endothelial cell activation in cutaneous leishmaniasis

Cutaneous leishmaniasis (CL) is a significant public health problem leading to permanently disfiguring skin lesions caused by Leishmania parasites. Lesion severity stems from an excessive host inflammatory response that prevents healing. Here, we characterized the transcriptional and translational responses of lymphatic endothelial cells (LECs) during murine CL using historical single-cell RNA sequencing data combined with flow cytometry and in vivo puromycin incorporation to assess translational activity. We identified upregulation of antigen presentation pathways including MHC-I, MHC-II, and immunoproteasome transcripts in dermal LECs from Leishmania major-infected mice compared to naive controls. LECs also exhibited increased expression of guanylate binding proteins and interferon-inducible genes, indicative of immune activation. Moreover, our findings demonstrate that LECs in leishmanial lesions displayed heightened translational activity relative to LECs from uninflamed ears, and LEC translational activity was highest in activated LECs. Furthermore, LEC translational activity exceeded that of other cell types within the lesion microenvironment. Validating the transcriptomic data, LECs in lesions expressed elevated MHC-II and programmed death-ligand 1 (PDL-1), supporting their potential role in antigen presentation. Functional assays using DQ-OVA confirmed that LECs from leishmanial lesions efficiently uptake and process antigens, highlighting their capability as antigen presenting cells in the inflamed dermal microenvironment. Overall, our study reveals the activation status of LECs in leishmanial lesions, shedding light on their potential role in shaping local immunity and inflammation in a variety of skin diseases.

microbiology↗

bioRxiv2021

In vivo reprogramming of murine host immune response genes following Leishmania major infection.

Leishmania parasites cause cutaneous leishmaniasis (CL), a pathologic disease characterized by disfiguring, ulcerative skin lesions. Both parasite and host gene expression following infection with various Leishmania species has been investigated in vitro, but global transcriptional analysis following L. major infection in vivo is lacking. Thus, we conducted a comprehensive transcriptomic profiling study combining bulk RNA sequencing (RNA-Seq) and single-cell RNA sequencing (scRNA-Seq) to identify global changes in gene expression in vivo following L. major infection. Bulk RNA-Seq analysis revealed that host immune response pathways like the antigen processing and presentation pathway were significantly enriched amongst differentially expressed genes (DEGs) upon infection, while ribosomal pathways were significantly downregulated in infected mice compared to naive controls. scRNA-Seq analyses revealed cellular heterogeneity including distinct resident and recruited cell types in the skin following murine L. major infection. Within the individual immune cell types, several DEGs indicative of many interferon induced GTPases and antigen presentation molecules were significantly enhanced in the infected ears including macrophages (Gbp2, H2-K1, H2-Aa, H2-Ab1), resident macrophages (H2-K1, H2-D1, Gbp4, Gbp8, Gbp2), and inflammatory monocytes (Gbp2, Gbp5, Gbp7, Gbp3). Ingenuity Pathway Analysis of scRNA-Seq data indicated the antigen presentation pathway was increased with infection, while EIF2 signaling is the top downregulated pathway followed by eIF4/p70S6k and mTOR signaling in multiple cell types including macrophages, BECs, and LECs. Altogether, this transcriptomic profile highlights known recruitment of myeloid cells to lesions and recognizes a previously undefined role for EIF2 signaling in murine L. major infection in vivo. Author summaryLeishmania major cause cutaneous leishmaniasis, which is characterized by disfiguring, ulcerative skin lesions. Here, we show murine L. major-directed reprogramming of the host transcriptome in vivo. Our bulk RNA-Seq analyses revealed upregulation of antigen processing and presentation pathway, while the host ribosomal pathway was downregulated following L. major infection. Similarly, scRNA-Seq analyses revealed the upregulation of transcripts responsible for antigen presentation and host defense proteins like guanylate binding proteins (GBPs) alongside the downregulation of EIF2 signalling at the site of L. major infection. Overall, our transcriptomic dataset not only provides the comprehensive list of gene expression at the single-cell resolution, and highlights a previously undefined role for EIF2 signalling during murine L. major infection in vivo.

immunology↗