Biology subjects

Nguyen, K. L.

Publications and source records attributed to Nguyen, K. L..

7 recordsLinked to original sources

bioRxiv2026

Bacteroides intestinalis-Driven Arabinoxylan Fermentation Mitigates Inflammatory and Metabolic Dysfunction

Insufficient dietary fiber intake is closely linked to gut microbiome dysfunction and increased risk of noncommunicable diseases. Synergistic synbiotics, pairing defined microbes with their dietary substrates, offer a precise strategy to restore microbiome function. Here, we show that pairing the human colonic commensal Bacteroides intestinalis with insoluble wheat arabinoxylan (inWAX) yields pronounced metabolic and anti-inflammatory benefits. Using mono-associated gnotobiotic mice and high-fat diet-induced obese mice, we demonstrate that this synbiotic enhances resistance to intestinal inflammation and improves glucose homeostasis. Mechanistically, this synbiotic increases production of 6-hydroxylated bile acids with anti-diabetic and anti-steatotic effects. It also promotes microbial transformation of phenolic compounds and redirects protein metabolism toward neuroactive metabolites. These metabolic shifts are accompanied by transcriptional remodeling in the colon, spleen and liver, involving induction of genes essential for circadian rhythm, lipid metabolism, immune defense, and bile acid 6-hydroxylation. Notably, Y chromosome-linked genes associated with epigenetic regulation and protein turnover are also induced, suggesting a potential sex-specific response to synbiotics. Together, our findings establish a mechanistic framework for targeted synbiotic interventions to combat inflammatory and metabolic disorders.

microbiology↗

bioRxiv2025

Hippocampal CA3 Nex/Neurod6+ neuron-specific TNFR2 alleviates chronic neuropathic pain by sex-dependently engaging opioid and endocannabinoid pathways

Chronic neuropathic pain (CNP) develops as a result of persistent neuroinflammation and maladaptive synaptic plasticity in the central nervous system following nerve injury. While tumor necrosis factor receptor 2 (TNFR2) signaling has been extensively studied in pain resolution, the expression of this receptor on specific neuronal populations and molecular pathways involved in spontaneous pain recovery still remains poorly defined. In this study, we investigated the role of TNFR2 signaling within hippocampal Nex/Neurod6 pyramidal neurons in promoting recovery from chronic constriction injury (CCI), a well-established rodent model of neuropathic pain. To achieve neuron-specific deletion of TNFR2, we generated tamoxifen-inducible conditional knockout mice (NexCreERT2:TNFR2F/F). We demonstrate that knocking out TNFR2 from Nex neurons prevents spontaneous pain recovery in both males and females. Thus, establishing that a supraspinal TNFR2 neuroimmune axis is necessary for pain recovery. Exogenous administration of a TNFR2 agonist at 7, 10, and 13 dpi (i.p.) significantly improved mechanical withdrawal thresholds in both sexes of wild-type mice but did not alleviate pain in Nex-specific TNFR2 knockouts, indicating that neuronal TNFR2 expression is required for TNFR2-mediated analgesia. Bulk RNA sequencing of hippocampal tissue collected at six weeks after CCI revealed that TNFR2 activation upregulates genes such as Pomc, involved in the opioid pathway, and oleoyl-ACP-hydrolase (OLAH), involved in the endocannabinoid pathway. Consistent with these findings, immunostaining and Western blot analyses showed that TNFR2 agonism restored cornu ammonis (CA3) region POMC and {beta}-endorphin protein levels that were otherwise suppressed after CCI. Behavioral experiment demonstrated that systemic blockade of the {micro}-opioid receptor with naltrexone (administered daily from 7-21 dpi (s.c.)) completely prevented TNFR2-mediated pain recovery in males but only partially in females. In contrast, inhibition of cannabinoid 1 receptor (CB1R) signaling with AM251 (administered at 7, 14, and 21 dpi (i.p.)) abolished TNFR2-driven analgesia in both sexes. Together, these results reveal that hippocampal TNFR2 signaling in Nex/Neurod6 neurons is critical in recovery from chronic neuropathic pain. TNFR2 activation promotes analgesia by engaging endogenous {beta}-endorphin/{micro}-opioid and endocannabinoid pathways in a sex-dependent manner, establishing TNFR2 agonism as a promising non-addictive therapeutic approach for chronic pain resolution. SignificanceChronic neuropathic pain (CNP) results from persistent neuroimmune signaling and is driven by maladaptive circuit plasticity. Due to the complexity of factors contributing to CNP, it often leaves patients with few treatment options, which, unfortunately, are either temporary or might be addictive. We have characterized a novel supraspinal mechanism through which tumor necrosis factor receptor 2 (TNFR2) signaling, specifically in hippocampal Neurod6/Nex+ expressing pyramidal neurons, is necessary for pain recovery following nerve injury. Pharmacological activation of TNFR2 in these neurons alleviates pain by engaging both endogenous opioid and endocannabinoid signaling pathways. We specifically demonstrate that TNFR2 agonism upregulates proopiomelanocortin (POMC) expression and {beta}-endorphin levels in the hippocampus. We further identify that pharmacological inhibition of either the -opioid receptor or cannabinoid 1 (CB1) receptor is sufficient to impair the effectiveness of TNFR2 agonist mediated pain resolution. Our findings thus uncover a novel neuroimmune mechanism where the TNFR2 agonist, exogenously activating the pro-resolving TNFR2, mitigates CNP by releasing endogenous pain neuromodulators. Here, we highlight that TNFR2 agonism could serve as a non-addictive therapeutic strategy for the resolution of chronic neuropathic pain.

pharmacology and toxicology↗

bioRxiv2025

ER oxidoreductin-1α and unfolded protein response as sex-dependent drivers of cardiorenal dysfunction in experimental autoimmune encephalomyelitis

BackgroundMultiple sclerosis (MS) is associated with increased cardiovascular and renal morbidity, but mechanisms linking CNS autoimmunity to peripheral organ injury remain poorly defined. We tested the hypothesis that experimental autoimmune encephalomyelitis (EAE) induces cardiorenal dysfunction via sex-specific dysregulation of endoplasmic reticulum (ER) oxidoreductases and unfolded protein response (UPR) signaling. MethodsAdult female and male C57BL/6J mice [10-12 weeks] and IRE1C148S knock-in mice underwent non-pertussis toxin EAE (nPTX-EAE) induced with 100{micro}g MOG35-55 in CFA and 200{micro}g heat-inactivated MTB with a booster at 7 days. Controls received all components except MOG. Motor scoring was done daily and EN460 (ERO1 inhibitor, 10 mg/kg IP) was given twice weekly beginning at 10DPI. Echocardiography and renal Doppler (Vevo 2100) were performed at 36-38DPI with primary outcomes of LV systolic/diastolic function and renal perfusion with tissue collected at 40DPI. LV and kidney were analyzed via western blot for ERO1, PDIA1, Prdx4, 4HNE, and BiP. Data are expressed as mean {+/-} SEM with two-way ANOVA/Tukeys post hoc or Mann Whitney test performed and outliers identified by ROUT (Q=1%). ResultsSixty-seven percent of immunized mice developed motor deficits. At 36-38DPI, EAE reduced ejection fraction and fractional shortening while increasing IVCT, IVRT, and myocardial performance index without hypertrophy. Renal resistive index increased and end-diastolic velocity decreased in addition to reduced Bowmans space at 40DPI. Females showed upregulated LV ERO1 and 4HNE while males exhibited reduced PDI and Prdx4 paired with elevated BiP. EN460 attenuated cardiac and renal dysfunction and lowered LV ERO1/4HNE in females, but not males. IRE1C148S mitigated cardiac dysfunction in males and restore renal indices in both sexes. ConclusionsnPTX-EAE causes clinically relevant, sex-specific cardiorenal dysfunction linked to distinct ER stress/UPR alterations. ERO1 inhibition protects females, whereas enhanced IRE1 activity protects males and kidneys across sexes, supporting sex-specific ER stress-targeted therapies for MS-associated cardiorenal disease.

molecular biology↗

bioRxiv2024

PTBP1 mediates Sertoli cell actin cytoskeleton organization by regulating alternative splicing of actin regulators

Spermatogenesis is a biological process within the testis that produces haploid spermatozoa for the continuity of species. Sertoli cells are somatic cells in the seminiferous epithelium that orchestrate spermatogenesis. Cyclic reorganization of Sertoli cell actin cytoskeleton is vital for spermatogenesis, but the underlying mechanism remains largely unclear. Here, we report that RNA-binding protein PTBP1 controls Sertoli cell actin cytoskeleton reorganization by programming alternative splicing of actin cytoskeleton regulators. This splicing control enables ectoplasmic specializations, the actin-based adhesion junctions, to maintain the blood-testis barrier and support spermatid transport and transformation. Particularly, we show that PTBP1 promotes actin bundle formation by repressing the inclusion of exon 14 of Tnik, a kinase present at the ectoplasmic specialization. Our results thus reveal a novel mechanism wherein Sertoli cell actin cytoskeleton dynamics is controlled post-transcriptionally by utilizing functionally distinct isoforms of actin regulatory proteins, and PTBP1 is a critical regulatory factor in generating such isoforms.

molecular biology↗

bioRxiv2023

TNFR1/p38αMAPK signaling in Nex+ supraspinal neurons regulates sex-specific chronic neuropathic pain

Upregulation of soluble tumor necrosis factor (sTNF) cytokine signaling through TNF receptor 1 (TNFR1) and subsequent neuronal hyperexcitability are observed in both animal models and human chronic neuropathic pain (CNP) (Clark et al., 2013; Empl et al., 2001; Ji et al., 2018; Lindenlaub and Sommer, 2003). To test the hypothesis that supraspinal circuitry is critical to pain chronification, we studied the intersect between supraspinal TNFR1 mediated neuronal signaling and sex specificity by selectively removing TNFR1 in Nex+ neurons in adult mice (NexCreERT2::TNFR1f/f). We determined that following chronic constriction injury (CCI), pain resolves in males; however, female acute pain transitions to chronic. Subsequently, we investigated two downstream pathways, p38MAPK and NF-{kappa}B, important in TNFR1 signaling and injury response. We detected p38MAPK and NF-{kappa}B activation in male cortical tissue; however, p38MAPK phosphorylation was reduced in NexCreERT2::TNFR1f/f males. We observed similar behavioral results following CCI in NexCreERT2::p38MAPKf/f mice. Previously, we established estrogens ability to modulate sTNF/TNFR1 signaling in CNP, which may contribute to female prevalence of CNP (Bouhassira et al., 2008; Claiborne et al., 2006; de Mos et al., 2007; Del Rivero et al., 2019; Li et al., 2009). To explore the intersection between estrogen and inflammation in CNP we used a combination therapy of an estrogen receptor {beta} (ER {beta}) inhibitor with a sTNF/TNFR1 or general p38MAPK inhibitor. We determined both combination therapies lend "male-like" therapeutic relief to females following CCI. These data suggest that TNFR1/p38MAPK signaling in Nex+ neurons in CNP is male-specific and lack of therapeutic efficacy following sTNF inhibition in females is due to ER {beta} interference. These studies highlight sex-specific differences in pathways important to pain chronification and elucidate potential therapeutic strategies that would be effective in both sexes.

neuroscience↗

bioRxiv2021

PTBP1/HNRNP I controls intestinal epithelial cell regeneration by maintaining stem cell survival and stemness

Properly controlled intestinal epithelial cell regeneration is not only vital for protection against insults from environmental hazards but also crucial for preventing intestinal cancer. Intestinal stem cells located in the crypt region provide the driving force for epithelial regeneration, and thus their survival and death must be precisely regulated. We show here that polypyrimidine tract binding protein 1 (PTBP1, also called heterogeneous nuclear ribonucleoprotein I, or HNRNP I), an RNA-binding protein that post-transcriptionally regulates gene expression, is critical for intestinal stem cell survival and stemness. Mechanistically, we show that PTBP1 inhibits the expression of PHLDA3, an AKT repressor, and thereby maintains AKT activity in the intestinal stem cell compartment to promote stem cell survival and proliferation. Furthermore, we show that PTBP1 inhibits the expression of PTBP2, a paralog of PTBP1 that is known to induce neuron differentiation, through repressing inclusion of alternative exon 10 to Ptbp2 transcript. Loss of PTBP1 results in a significant upregulation of PTBP2, which is accompanied by splicing changes in genes that are important for neuronal cell development. This finding suggests that PTBP1 prevents aberrant differentiation of intestinal stem cells into neuronal cells through inhibiting PTBP2. Our results thus reveal a novel mechanism whereby PTBP1 maintains intestinal stem cell survival and stemness through the control of gene function post-transcriptionally.

molecular biology↗

bioRxiv2020

Perforin-2 limits pathogen proliferation at the maternal-fetal interface

Placental immune responses are highly regulated to strike a balance between protection and tolerance. For relatively mild infections, protection encompasses both the mother and fetus; however, during worsening conditions, protection becomes exclusively reserved for the mother. Previously, we and others have shown that the host factor Perforin-2 plays a central role in protecting mice and cells against infection. Here, we analyzed Perforin-2 activity in the mouse placenta to determine whether Perforin-2 plays a similarly protective role. We show that Perforin-2 is critical for inhibiting Listeria monocytogenes colonization of the placenta and fetus and that this protection is due to both maternal and fetal-encoded Perforin-2. Perforin-2 mRNA is readily detectable in individual immune cells of the decidua and these levels are further enhanced specifically in decidual macrophages during high-dose infections that result in fetal expulsion. Unexpectedly, inductive Perforin-2 expression in decidual macrophages did not occur during milder infections in which fetal viability remained intact. This pattern of expression significantly differed from that observed in splenic macrophages in which inductive Perforin-2 expression was observed in both high and mild infection conditions. In the placenta, inductive Perforin-2 expression in decidual macrophages was co-incident with their polarization from a M2 to M1 phenotype that normally occurs in the placenta during high-burden infections. Our results suggest that Perforin-2 is part of a host response that is protective either for both the mother and fetus in milder infections or exclusively for the mother during high-dose infections.

immunology↗