Biology subjects

Ujagar, N.

Publications and source records attributed to Ujagar, N..

4 recordsLinked to original sources

bioRxiv2026

Endocrine-Adapted Pituitary Macrophages Regulate Gonadotropin Secretion through CXCL5-CXCR2-MAPK Signaling

Chronic inflammation disrupts hormonal balance in the Hypothalamic-Pituitary-Gonadal (HPG) axis, contributing to reproductive disorders. While immune cells in the hypothalamus and ovaries have been extensively studied, their impact on the pituitary remains largely unexplored. Our research identifies pituitary macrophages (PitMacs) as the dominant pituitary immune cell population with a role in regulating reproductive gonadotropin secretion both in vitro and in vivo. Using a targeted AAV-based depletion strategy, we demonstrate that a reduction of PitMacs decreases serum gonadotropins, luteinizing hormone (LH) and follicle-stimulating hormone (FSH), in female mice. PitMacs are transcriptomically distinct from other tissue-resident macrophages and harbor a unique translational program that reflects the pituitarys endocrine identity, including active translation of growth hormone (Gh) and prolactin (Prl). Cytokine profiling identified CXCL5 and IFN-{gamma} as key PitMac-derived mediators of gonadotropin regulation. Mechanistically, CXCL5 signals through CXCR2 to activate the MAPK pathway, converging with Gonadotropin-Releasing Hormone (GnRH) signaling in a time-dependent manner to regulate LH secretion and GnRH receptor surface expression. These findings establish PitMacs as essential endocrine-immune integrators, opening new avenues for understanding inflammation-driven reproductive disorders. One Sentence SummaryPituitary macrophages are unique hormone-producing immune cells that regulate hormone secretion via cytokine signaling.

immunology↗

bioRxiv2025

Toll-like Receptor 4 Contributes to PCOS-like Metabolic and Reproductive Pathogenesis

Polycystic ovary syndrome (PCOS) is a reproductive disorder with heterogeneous symptoms and severity. Despite extensive research documenting chronic immune dysfunction as a hallmark of PCOS, the specific molecular mechanisms driving immune activation and its connection to the syndromes diverse symptoms remain poorly understood. Emerging evidence suggests that gut-derived bacterial endotoxins, particularly lipopolysaccharide (LPS), may breach the intestinal barriers in PCOS patients and trigger systemic inflammation through Toll-like receptor 4 (TLR4), a pattern recognition receptor of the innate immune system. This study investigated whether TLR4 serves as a critical mechanistic driver of PCOS pathogenesis by examining the effect of genetic TLR4 knockout (TLR4-/-) in a letrozole (LET)-induced mouse model of PCOS. Our results demonstrate that TLR4 deficiency reduces many PCOS-like symptoms, including elevated luteinizing hormone, anovulation, and metabolic dysfunction. TLR4 knockout also preserved estrous cycling and fertility, improved glucose tolerance, maintained gut barrier integrity, and reduced inflammatory markers in LET-treated females. These findings establish TLR4 as a key mediator orchestrating PCOSs multi-system pathology, positioning TLR4 as a critical convergence point rather than affecting individual symptoms in isolation. This novel work reveals that TLR4-mediated inflammation drives multiple PCOS pathologies, opening avenues for targeted anti-inflammatory treatments in women with this disorder. Significance StatementPolycystic ovary syndrome (PCOS) affects up to 15% of reproductive-age women worldwide. This study reveals that TLR4, an innate immune receptor, is key to the pathophysiology of PCOS-like symptoms in female mice. When TLR4 was genetically deleted, mice treated with letrozole to induce PCOS-like symptoms maintained normal weight, glucose regulation, estrous cycling, and fertility. The improvements coincided with preserved gut barrier breakdown and reduced inflammation. These findings identify TLR4 as a key mediator between gut health, immune activation, and PCOS pathophysiology, suggesting that targeting TLR4 could offer new therapeutic approaches for this common but poorly understood syndrome affecting millions of women.

immunology↗

bioRxiv2025

T cells are necessary for development of PCOS reproductive symptoms in a letrozole-induced mouse model of PCOS

Polycystic ovary syndrome (PMOS) is a complex reproductive disorder with clear genetic susceptibilities that impact the heterogeneous clinical presentation of symptoms and severity through unknown mechanisms. Chronic inflammation is linked to PMOS, but a clear cause-and-effect relationship between immune mediators and PMOS phenotypes has yet to be demonstrated. This study employed a comprehensive systems immunology approach, utilizing a letrozole-induced PMOS mouse model to identify changes in inflammatory factors associated with PMOS symptoms. By analyzing immune cells and secreted cytokines from 22 different mouse strains, we identified T cells and TNF-{beta} as associated with PMOS-like phenotypes, regardless of genetic background. We used a knockout of TCR to show that functional T cells are necessary for development of pathologically elevated luteinizing hormone (LH) in letrozole-treated female mice. In women with PMOS, we observed elevated TNF-{beta} transcripts in immune cells from women with PMOS. Finally, we demonstrate that TNF-{beta} increased Lhb mRNA in a female mouse gonadotrope-derived cell line, suggesting that TNF-{beta} may directly modulate gonadotrope gene expression and may contribute to elevated LH in PMOS-like conditions. These findings support a requirement for functional {beta} T cells in LET-induced LH elevation in a PMOS-like mouse model and identify TNF-{beta} as a candidate immune mediator for further investigation. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=190 SRC="FIGDIR/small/631835v2_ufig1.gif" ALT="Figure 1"> View larger version (90K): org.highwire.dtl.DTLVardef@14dcf2aorg.highwire.dtl.DTLVardef@15bdc67org.highwire.dtl.DTLVardef@1e2f718org.highwire.dtl.DTLVardef@1cc5c16_HPS_FORMAT_FIGEXP M_FIG C_FIG One Sentence SummaryFunctional {beta} T cells are linked to LET-induced LH elevation in a PMOS-like mouse model, uncovering candidate immune mechanisms for further study.

immunology↗

bioRxiv2024

Phollow: Visualizing Gut Bacteriophage Transmission within Microbial Communities and Living Animals

Bacterial viruses (known as "phages") shape the ecology and evolution of microbial communities, making them promising targets for microbiome engineering. However, knowledge of phage biology is constrained because it remains difficult to study phage transmission dynamics within multi-member communities and living animal hosts. We therefore created "Phollow": a live imaging-based approach for tracking phage replication and spread in situ with single-virion resolution. Combining Phollow with optically transparent zebrafish enabled us to directly visualize phage outbreaks within the vertebrate gut. We observed that virions can be rapidly taken up by intestinal tissues, including by enteroendocrine cells, and quickly disseminate to extraintestinal sites, including the liver and brain. Moreover, antibiotics trigger waves of interbacterial transmission leading to sudden shifts in spatial organization and composition of defined gut communities. Phollow ultimately empowers multiscale investigations connecting phage transmission to transkingdom interactions that have the potential to open new avenues for viral-based microbiome therapies.

microbiology↗