Biology subjects

Trivedi, S.

Publications and source records attributed to Trivedi, S..

17 recordsLinked to original sources

bioRxiv2026

Supercharged binding modules can modulate engineered poly(ethylene terephthalate) hydrolase thermostability and functional persistence

Poly(ethylene terephthalate) (PET) is a highly recalcitrant polyester plastic whose resistance to degradation has contributed to widespread environmental accumulation. Enzymatic PET depolymerization has emerged as a promising bioremediation strategy, but PET hydrolysis remains challenging due to the insoluble and semi-crystalline nature of PET and the poor thermostability of many PET hydrolases at elevated temperatures. Here, several electrostatically supercharged PET binding modules (PBM) were fused to a PET-hydrolyzing Cutinase Catalytic Domain (CD) from the thermophilic microbe Thermobifida fusca to investigate how engineered PBM surface charge influences PET hydrolysis behavior. All PBM designs were derived from a native T. fusca family-2a carbohydrate binding module (CBM) as starting template. Since PET exhibited a substantially negative zeta potential, and accordingly, all positively supercharged PBMs displayed the strongest PET binding interactions in pull-down binding assays. However, stronger PET binding did not translate to improved hydrolysis activity for the fusion constructs. Instead, a slightly negatively charged PBM-CD fusion (D2 construct) exhibited activity comparable to the Cutinase CD on finely milled PET powder while showing substantially improved activity on intact PET discs, suggesting potential advantages for depolymerization of minimally processed PET feedstocks. Thermostability analysis identified an approximately 10 {degrees}C increase in melting temperature for the D2 fusion construct, corresponding to enhanced catalytic persistence and a shifted optimal hydrolysis temperature. Consequently, this construct exhibited an approximately 2-fold increase in long-term hydrolysis activity on milled PET and up to a 10-fold increase on intact PET discs, even at high solids loadings, compared to the native Cutinase CD. Collectively, these findings demonstrate that thermostability, rather than adsorption to PET alone, is a dominant factor governing functional persistence of PET hydrolases.

bioengineering↗

bioRxiv2025

Rehabilitation drives functional reorganization of intact corticospinal-supraspinal projections following partial spinal cord injury

Spinal cord injury (SCI) disrupts corticospinal tract (CST) connectivity and impairs skilled voluntary movement. However, most human SCIs are anatomically incomplete, allowing spared CST pathways to engage in rehabilitation-mediated plasticity to promote functional recovery. How voluntary rehabilitation engages and reorganizes the supraspinal targets of the intact CST remains incompletely understood. Here, we combined unilateral pyramidotomy (uPyX) in male and female mice with continuous voluntary complex-wheel running to test whether fine motor-dependent rehabilitation drives supraspinal CST plasticity. uPyX mice rapidly resumed wheel running after a transient deficit. In contrast to lesion-only controls, rehabilitation significantly improved skilled forelimb performance on the horizontal ladder rung task. Immunohistochemical c-Fos labeling confirmed that complex-wheel running robustly activated the intact forelimb CST in motor cortex. Whole-brain CST projection mapping using intersectional viral vector tracing revealed targeted supraspinal reorganization localized to medullary motor nuclei. Three nuclei - the lateral paragigantocellular reticular nucleus (LPGi), gigantocellular reticular nucleus, alpha part (GiA), and ventral medullary reticular nucleus (MdV) - exhibited significant lesion- and/or rehabilitation-induced increases in CST innervation. Rehabilitation-driven CST sprouting correlated with regional c-Fos activation, indicating activity-dependent remodeling. Notably, CST projection density in the MdV, critical for skilled forelimb control, correlated with functional recovery. These findings identify a set of spinally-projecting medullary nuclei as key sites of rehabilitation-induced CST plasticity and highlight the MdV as a potential mediator of restored motor function. This work defines how voluntary rehabilitation reorganizes spared corticospinal pathways and provides targets for optimizing activity-based interventions after SCI. Significance StatementEffective rehabilitation after spinal cord injury (SCI) must harness the plasticity of spared motor pathways, yet the supraspinal circuits that support rehabilitation-mediated recovery remain unknown. Using a model that preserves voluntary motor engagement, we show that continuous fine motor-dependent rehabilitation activates intact corticospinal neurons and drives highly specific remodeling of their supraspinal terminals. Rehabilitation selectively strengthens CST inputs to motor regions of the medulla, particularly the ventral medullary reticular nucleus (MdV), and CST plasticity within this region predicts enhanced behavioral recovery. These findings highlight the MdV as a central locus by which rehabilitation re-establishes descending control of the impaired limb, providing mechanistic insight to guide targeted, circuit-based rehabilitation therapies for incomplete SCI.

neuroscience↗

bioRxiv2025

There is an I in team: individual improvements in supercharged cellulase cocktail facilitates cooperative cellulose degradation

Lignocellulosic biomass is a vastly abundant renewable carbon source for biofuel production but its conversion to fermentable sugars is significantly hindered by an inherent recalcitrance to enzymatic degradation. Pretreatment technologies are successful in alleviating some challenges related to substrate recalcitrance, yet enzymes like cellulases still exhibit poor activity on highly crystalline and insoluble cellulose. Both cellulose and lignin present several issues with productive enzyme binding and efficient catalytic turnover. To address these bottlenecks, we employed protein supercharging to rationally design a glycosyl hydrolase (GH) family-6 exocellulase (Cel6B) and its native fused family-2a carbohydrate binding module (CBM2a) from the thermophilic cellulolytic microbe Thermobifida fusca. A total of 16 supercharged variants were designed across both GH/CBM domains and a chimeric library of 32 constructs, including the native enzyme, were synthesized and expressed in E. coli. The entire library of supercharged enzymes was tested for activity on several cellulosic substrates to identify one key construct, D5 CBM2a - WT Cel6B, that had a positively supercharged CBM2a that showed 2-3-fold higher activity on all substrates tested at pH 5.5. Purified enzyme assays confirmed that exocellulases behave quite different from their endocellulase counterparts when supercharged using similar protocols. Still, the purified D5 CBM2a - WT Cel6B mutant showed a 2.3-fold improvement in specific activity compared to native enzyme on crystalline cellulose. Analysis of melt curves depict that, while all other constructs tested have one distinct melt peak near the expected CBM melting point, domain melting is decoupled for the D5 CBM2a mutant. This effect reveals an intrinsic melting temperature of the Cel6B CD nearly 18 {degrees}C higher than the coupled melting temperature of the full-length enzyme. This unexpected catalytic domain stabilization effect of supercharged CBM2a domain is likely the driving force for activity improvements seen for this exocellulase that is otherwise prone to stalling and denaturation on the cellulose surface during processive catalytic turnover cycles. When combining this supercharged exocellulase construct with its endocellulase counterpart, our results show that supercharged enzymes that show the highest activity alone, produced the best synergistic partners. This study highlights another successful implementation of protein supercharging strategy for cellulases and provides another key piece towards building an effective synergistic cellulase cocktail for lignocellulosic biomass deconstruction.

bioengineering↗

bioRxiv2025

Urinary Exosomal miRNA Profiling Reveals Sensitive Non-Invasive Diagnosis of Bladder Cancer

UnstructuredmiRNAs represent a transformative advancement in both research and clinical management of urinary bladder cancer (UBC), emerging as clinically significant molecular targets with the potential to revolutionize existing diagnostic standards. This study exploited the robust stability of miRNAs and profiled urinary miRNAs in UBC patients and controls through miRNA sequencing, revealing an expanded and altered miRNA repertoire in cancer samples. Validation in an independent cohort revealed fold changes for miR-6724-5p, miR-1273h-5p, miR-7704, miR-200-5p, and miR-10400-5p ranged from [~]46 to [~]2,777 (p < 0.01). Stage-specific analyses highlighted dynamic miRNA expression linked to tumor progression. Diagnostic evaluation identified an optimal three-miRNA panel comprising miR-6724-5p, miR-10400-5p, and miR-7704, achieving diagnostic accuracies (AUC > 70%) and high sensitivity (>90%). These data demonstrate the potential of urinary mature miRNAs as robust biomarkers for non-invasive detection and monitoring of UBC in early stages, supporting their translation into clinical diagnostic assays pending larger prospective studies. StructuredO_ST_ABSBackgroundC_ST_ABSUrinary microRNAs (miRNAs) are promising candidates due to their molecular stability and disease-specific expression. miRNAs represent a transformative advancement in both research and clinical management of urinary bladder cancer (UBC), emerging as actionable molecular targets with the potential to revolutionize existing diagnostic standards. MethodsSmall RNA sequencing was performed on urine samples from UBC patients and healthy controls to profile miRNA expression. Mature miRNAs were prioritized by exclusion of precursor forms using computational filtering. Validation by quantitative RT-PCR was conducted on an independent, age-matched cohort (n = 45). Diagnostic potential of candidate miRNAs was assessed by receiver operating characteristic (ROC) curves and area under the curve (AUC) analyses. ResultsSequencing identified 865 known and 11 novel miRNAs, with UBC samples showing greater miRNA diversity (708 known miRNAs) compared to controls (540). Ten miRNAs were significantly dysregulated in UBC (p < 0.05). Validation revealed fold changes for miR-6724-5p, miR-1273h-5p, miR-7704, miR-200-5p, and miR-10400-5p ranged from [~]46 to [~]2,777 (p < 0.01). Stage-specific analyses highlighted dynamic miRNA expression linked to tumor progression. A three-miRNA panel (miR-6724-5p, miR-10400-5p, miR-7704) demonstrated superior diagnostic performance (AUC > 70%, sensitivity > 90%). ConclusionMature urinary miRNAs exhibit reproducible, stage-specific dysregulation in UBC and a combinatorial panel offers sensitive, specific non-invasive detection. These findings warrant further multicenter validation for clinical application.

cancer biology↗

bioRxiv2025

Non-Invasive Diagnostic Evaluation of Urinary Exosomal Let-7c Cluster Expression in Bladder Cancer Using Machine Learning Approaches

BackgroundBladder cancer (BCa) diagnosis typically relies on invasive cystoscopy, which is effective but costly and uncomfortable. Urinary microRNAs (miRNAs), especially exosomal ones, are promising non-invasive biomarkers due to their stability in biological fluids and disease specificity. However, challenges such as population variability, methodological inconsistencies and normalization issues hinder their clinical translation, emphasizing the need for innovative approaches to enhance diagnostic performance. ObjectiveTo evaluate the diagnostic potential of urinary exosomal let-7c cluster (let-7c-5p, miR-99a-5p and miR-125b-5p) in BCa patients by integrating miRNA expression data with Machine Learning (ML) models. MethodsUrine samples were collected from 66 participants, including 50 BCa patients and 16 healthy controls (HC). Exosomal miRNAs were isolated and quantified using Quantitative Real-Time-Polymerase-Chain-Reaction (qRT-PCR). Statistical analysis and hypothesis tests were conducted to explore the nature and diagnostic relevance of individual biomarkers. A logistic regression classifier was applied to evaluate both the combined and differential diagnostic capabilities of the selected biomarkers. Accuracy, precision, recall and AU-ROC scores were used to assess model performance. Bioinformatics analysis was performed to identify pathways associated with the features prioritized by the ML models, ensuring their relevance to BCa. ResultsThe result revealed significant differentiation between BCa patients and HC, with miR-99a-5p (p=0.013, AU-ROC=0.71) and miR-125b-5p (p=0.047, AU-ROC=0.64) demonstrating reliable diagnostic performance (let-7c-5p showed weaker discrimination, AU-ROC=0.65, p>0.1). The logistic regression ML model achieved an accuracy of 80.0% (AU-ROC=0.86, recall=100%) in distinguishing cancer from HC and 53.3% (AU-ROC=0.63) when applied to miRNA-only grade classification. When clinical variables were integrated with miRNA expression, performance improved to 73.3% accuracy (AU-ROC=0.61) for high-versus low-grade differentiation. Across Ta-T2, miR-99a-5p displayed relatively better separation, whereas let-7c-5p and miR-125b-5p showed weak stage-related differences. The integration of bioinformatics analysis confirmed the biological relevance of these miRNAs in BCa-related pathways, including PI3K-Akt, p53, NF-{kappa}B and RAS/MAPK signaling, with hub genes such as TP53, MYC, EGFR, and CCND1 identified, further validating the diagnostic utility of the selected biomarkers. ConclusionUrinary let-7c cluster miRNAs demonstrate promising diagnostic potential when analyzed with ML models, offering a non-invasive alternative to conventional methods. These findings highlight the promise of ML-based approaches alongside molecular markers for advancing clinical diagnostics in BCa.

molecular biology↗

bioRxiv2024

miRNA Biomarkers in Prostate Cancer: Leveraging Machine Learning for Improved Diagnostic Accuracy

Prostate cancer (PCa) diagnosis often relies on prostate-specific antigen (PSA) testing, but its high false-positive rates often lead to unnecessary biopsies. MicroRNAs (miRNAs) have emerged as promising non-invasive biomarkers for cancer detection due to their stability in biological fluid and disease specificity. Despite their potential, the clinical translation of miRNAs as non-invasive cancer biomarkers is hindered by several challenges - population-based variability, environmental Factors, methodological Inconsistencies, lack of standardization, normalization Issues, and complexity of the biological System. These factors significantly impact the consistency of miRNA expression readouts, particularly in terms of Ct-values, across different studies, which in turn affects the determination of cutoff values that are crucial in a diagnostic setup. This preliminary study offers a pilot demonstration for integrating miRNA biomarker expression with machine learning (ML), which can help identify patterns and improve classification, potentially reducing the reliance on fixed cutoff values in certain contexts and pave the path to wider clinical translation. We analyzed the expression of key miRNAs (miR-21-5p, miR-221-3p, and miR-141-3p) in blood samples from patients with PCa and benign prostatic hyperplasia (BPH). Utilizing a Random Forest classifier, we achieved an accuracy of 77.42%, a precision of 86.21%, a recall of 71.43%, and an AUC-ROC score of 0.78. The application of ML enabled us to leverage complex features, such as combinations and ratios of miRNA expression data, which enhanced the robustness and reliability of the diagnostic model. Additionally, bioinformatics analysis of the preferential features identified by the ML model confirmed the biological relevance of these miRNAs in PCa-related pathways, further supporting their potential as clinical biomarkers. In the future, ML is poised to significantly enhance diagnostic performance compared to traditional linear analyses of a limited set of biomarkers. While our study did not explore multiple populations or the effects of methodological variables, it highlights the potential of ML by demonstrating improved accuracy and eliminating the need for cutoff values. This capability could broaden the applicability of miRNA-based diagnostics, making them more reliable and actionable in clinical settings. However, to fully realize this potential, further validation with larger and more diverse cohorts is essential. Overall, this study lays the groundwork for utilizing ML-enhanced miRNA panels as powerful tools for the early and non-invasive diagnosis of PCa in future clinical practice. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=130 SRC="FIGDIR/small/618146v1_ufig1.gif" ALT="Figure 1"> View larger version (38K): org.highwire.dtl.DTLVardef@2eddd9org.highwire.dtl.DTLVardef@e6d6c8org.highwire.dtl.DTLVardef@11eea0forg.highwire.dtl.DTLVardef@989c15_HPS_FORMAT_FIGEXP M_FIG C_FIG

genomics↗

bioRxiv2024

Systematic Targeting of Protein Complexes with Molecular COUPLrs

Molecular glues that engage protein complexes have transformed the study of cell biology and have had a direct impact on clinical oncology. However, the identification of new glue classes and their corresponding protein complexes has remained largely serendipitous. To overcome this challenge, we report the development of molecular COUPLrs, elaborated small molecules flanked by two cysteine-reactive warheads, as well as CONNECT, an integrated chemical proteomic platform for target deconvolution. By profiling a library of molecular COUPLrs across 13 cancer cell lines, we uncovered hundreds of proteins that can be coupled together, including in some cases in mutant selective fashions. We develop an advanced COUPLr for the oncogene EML4-ALK, which engages the fusion outside of its kinase domain, restricts protein dynamics, and disrupts EML4-ALK signaling. Collectively, molecular COUPLrs substantially expand the scope of proteins that can be chemically connected, providing an unbiased approach to identify small molecules that target protein complexes.

systems biology↗

bioRxiv2024

Loop-Mediated Isothermal Amplification Assays for the Detection of Antimicrobial Resistance Elements in Vibrio cholerae

The bacterium Vibrio cholerae causes diarrheal illness and can acquire genetic material leading to multiple drug resistance (MDR). Rapid detection of resistance-conferring mobile genetic elements helps avoid the prescription of ineffective antibiotics. Colorimetric loop-mediated isothermal amplification (LAMP) assays provide a rapid and cost-effective means for detection at point-of-care, but it can be difficult to design primer sets, determine target specificity, and interpret subjective color changes. We developed an algorithm for the in silico design and evaluation of LAMP assays within the open-source PCR Signature Erosion Tool (PSET) and a computer vision application for the quantitative analysis of colorimetric outputs. As an example, we generated new LAMP assays targeting drug resistance in V. cholerae and evaluated existing ones based on in silico target specificity and in vitro testing. Improvements in the design and testing of LAMP assays, with heightened target specificity and a simple analysis platform, increase utility for in-field applications.

molecular biology↗

bioRxiv2024

Distinct intersecting pathways link homolog pairing to initiation of meiotic chromosome synapsis

Faithful meiotic segregation requires pairwise alignment of the homologous chromosomes and Synaptonemal Complex assembly (SC) at their interface. Here, we investigate on new factors that promote and coordinate these events during C. elegans meiosis. We identify BRA-2 (BMP Receptor Associated family member 2) as an interactor of HIM-17, previously shown to promote double-strand break formation. We found that loss of bra-2 specifically impairs synapsis licensing without affecting homologs recognition, SC maintenance or chromosome movement. Double mutant analysis revealed a previously unrecognized role for HIM-17 in promoting homolog pairing under dysfunctional SC assembly, without perturbing nuclear envelope recruitment of factors required for chromosome movement. We provide evidence that bra-2 and him-17 act in distinct pathways, exerting partially redundant functions in SC licensing, as well as separable roles in regulating homologs pairing. Altogether, our findings unveil novel mechanisms that ensure stabilization of homologous chromosome interaction via SC licensing upon homology assessment.

cell biology↗

bioRxiv2024

MAIT Cells Modulate Innate Immune Cells and Inhibit Colon Cancer Growth

Mucosal-associated invariant T (MAIT) cells are innate-like T cells that can be activated by microbial antigens and cytokines and are abundant in mucosal tissues including the colon. MAIT cells have cytotoxic and pro-inflammatory functions and have potentials for use as adoptive cell therapy. However, studies into their anti-cancer activity, including their role in colon cancer, are limited. Using an animal model of colon cancer, we show that peritumoral injection of in vivo-expanded MAIT cells into RAG1-/- mice with MC38-derived tumors inhibits tumor growth compared to control. Multiplex cytokine analyses show that tumors from the MAIT cell-treated group have higher expression of markers for eosinophil-activating cytokines, suggesting an association between eosinophil recruitment and tumor inhibition. In a human peripheral leukocyte co-culture model, we show that leukocytes stimulated with MAIT ligand show an increase in eotaxin-1 production and activation of eosinophils, associated with increased cancer cell killing. In conclusion, we show that MAIT cells have a protective role in a murine colon cancer model, associated with modulation of the immune response to cancer, potentially involving eosinophil-associated mechanisms. Our results highlight the potential of MAIT cells for non-donor restricted colon cancer immunotherapy. Brief summaryIn models of colon cancer, MAIT cells have anti-tumor activity, associated with increased production of proinflammatory and eosinophil-modulating cytokines.

cancer biology↗

bioRxiv2023

Increasing chemotherapeutic efficacy using doxorubicin and sodium bicarbonate releasing injectable chitosan-polyethylene glycol hydrogels

Modulation of pH is crucial to maintaining the chemical homeostasis of biological environments. The irregular metabolic pathways exhibited by cancer cells result in the production of acidic byproducts that are excreted and accumulate in the extracellular tumor microenvironment, reducing its pH. As a consequence of the lower pH in tumors, cancer cells increase the expression of metastatic phenotypes and chemotherapeutic resistance. A significant limitation in current cancer therapies is the inability to locally deliver the chemotherapy, leading to significant damage to healthy cells in systemic administration. To overcome these challenges, we present an injectable chitosan-polyethylene glycol hydrogel that is dual-loaded with doxorubicin and sodium bicarbonate providing alkaline buffering of extracellular acidity and simultaneous chemotherapeutic delivery to increase chemotherapeutic efficacy. We conducted in vitro studies of weak base chemotherapeutic and alkaline buffer release from the hydrogel. The release of doxorubicin from hydrogels increased in a low pH environment and was dependent on the encapsulated sodium bicarbonate concentration. We investigated the influence of pH on doxorubicin efficacy and viability of MCF-7 and MDA-MB-231 breast cancer cell lines. The results show a 2 to 3 fold increase in IC50 values from neutral pH to low pH, showing decreased cancer cell viability at neutral pH as compared to acidic pH. The IC50 results were shown to correlate with a decrease in intracellular uptake of doxorubicin at low pH. The proposed hydrogels were confirmed to be non-toxic to healthy MCF-10A mammary epithelial cells. Rheological studies were performed to verify that the dual loaded hydrogels were injectable. The mechanical and release properties of the hydrogels were maintained after extended storage. The chemotherapeutic activity of doxorubicin was evaluated in the presence of the proposed pH regulating hydrogels. The findings suggest a promising non-toxic, biodegradable hydrogel buffer delivery system that can achieve two simultaneous important goals of local acidosis neutralization and chemotherapeutic release.

bioengineering↗

bioRxiv2022

PARG establishes a functional module with BRCA1-BARD1 that controls DNA repair pathway choice during gametogenesis

During meiosis, accurate chromosome segregation relies on the formation of programmed DNA double-strand breaks (DSBs). These are in turn repaired by homologous recombination (HR), generating physical attachments between the parental chromosomes called crossovers (COs). Fewer breaks yield recombinant outcomes, while CO-independent mechanisms are employed for repairing the majority of lesions. The balance between different repair pathways is crucial to ensure genome fidelity and to preserve its integrity. We show that Caenorhabditis elegans BRC-1/BRCA1-BRD-1/BARD1 and PARG-1/PARG form a complex in vivo, that is essential for accurate DNA repair in the germline. Contemporary depletion of BRC-1 and PARG-1 causes synthetic lethality due to reduced CO formation and impaired DSB repair, as evidenced by hindered RPA-1 removal and presence of aberrant chromatin bodies in diakinesis nuclei, whose formation depends on spo-11 function. These factors largely co-localize and undergo independent loading in developing oocytes, consistent with operating in different pathways. Abrogation of KU- or Theta-mediated end joining elicits opposite effects in brc-1; parg-1 doubles, highlighting differential involvement of DNA repair pathways and suggesting a profound impact in influencing DNA repair pathway choice by BRC-1-PARG-1. Importantly, lack of PARG-1 catalytic activity suppresses untimely accumulation of RAD-51 foci in brc-1 mutants but is only partially required to maintain fertility. Altogether, our data show that BRC-1/BRD-1-PARG-1 joined function is essential to keep genome integrity in meiotic cells by regulating multiple DNA repair pathways.

genetics↗

bioRxiv2022

Use of a MAIT activating ligand, 5-OP-RU, as a mucosal adjuvant in a murine model of Vibrio cholerae O1 vaccination.

BackgroundMucosal-associated invariant T (MAIT) cells are innate-like T cells enriched in the mucosa with capacity for B cell help. We hypothesize that targeting MAIT cells, using a MAIT activating ligand as an adjuvant, could improve mucosal vaccine responses to bacterial pathogens. MethodsWe utilized murine models of Vibrio cholerae vaccination to test the adjuvant potential of the MAIT activating ligand, 5-(2-oxopropylideneamino)-6-D-ribitylaminouracil (5-OP-RU). We measured V. cholerae-specific antibody and antibody-secreting cell responses, and used flow cytometry to examine MAIT cell and B cell phenotype, in blood, bronchoalveolar lavage fluid (BALF), and mucosal tissues, following intranasal vaccination with live V. cholerae O1 or a V. cholerae O1 polysaccharide conjugate vaccine. ResultsWe report significant expansion of MAIT cells in the lungs of 5-OP-RU treated mice, and increases in BALF V. cholerae O-specific-polysaccharide IgG responses in our conjugate vaccine model adjuvanted with low-dose 5-OP-RU. No significant differences in humoral responses were found in our live V. cholerae vaccination model. ConclusionsUsing a murine model, we demonstrate the potential, as well as the limitations, of targeting MAIT cells to improve antibody responses to a mucosal cholera vaccine. Our study highlights the need for future research optimizing MAIT cell targeting for improving mucosal vaccines. One Sentence SummaryTargeting mucosal-associated invariant T (MAIT) cells with a mucosal adjuvant in an intranasal cholera vaccine model resulted in significant expansion of lung MAIT cells, but limited improvements in cholera-specific antibody responses.

immunology↗

bioRxiv2021

Fetal neural progenitors process TLR signals from bacterial components to enhance proliferation and rework brain development

Bacterial cell wall, a universal pathogen-associated molecular pattern (PAMP), crosses the placenta into the fetal brain. We determined that PAMPs interact with TLR2/6 on murine fetal neural progenitor cells (NPCs) to induce overexpansion of all neocortical layers leading to a larger, folded cortex and abnormal postnatal behavior. The NPC overexpansion originated at E10 and targeted ventricular radial glia (vRG), the primary NPC, by shortening cell cycle and increasing self-renewal. The mechanism involved two novel signaling pathways in NPCs mediated by recognition of bacterial PAMPs by TLR2/6 including: a) loss of primary cilia, activation of hedgehog signaling, and increased FOXG1 and b) increased PI3K/AKT activity. These findings reveal PAMP/TLR2/6 acts as a morphogen in fetal neurodevelopment. In addition, the loss of Tlr2 or Tlr6 without pathogenic challenge, increased the number of neurons, establishing the requirement for an endogenous TLR2 signal for normal neurodevelopment in the embryo.

neuroscience↗

bioRxiv2020

A novel subset of follicular helper-like MAIT cells has capacity for B cell help and antibody production in the mucosa.

Mucosal-associated invariant T (MAIT) cells are innate-like T lymphocytes that aid in protection against bacterial pathogens at mucosal surfaces via release of inflammatory cytokines and cytotoxic molecules. Recent evidence suggests MAIT cells are capable of providing B cell help. In this study, we describe a previously unreported population of CXCR5+ T follicular helper (Tfh)-like MAIT cells, MAITfh, that have the capacity to provide B cell help within mucosal lymphoid organs. MAITfh cells are preferentially located near germinal centers in human tonsils and express the classical Tfh-associated transcription factor, B-cell lymphoma 6 (BCL-6), co-stimulatory markers, inducible T cell costimulatory (ICOS) and programmed death receptor 1 (PD-1), and cytokines, interleukin (IL)-21. Furthermore, we demonstrate the ability of MAIT cells to provide B cell help in vivo following mucosal challenge with Vibrio cholerae. Specifically, we show that adoptive transfer of MAIT cells into {beta} T cell-deficient mice promoted B cell differentiation and increased serum V. cholerae-specific IgA responses. Our data demonstrate the capacity of MAIT cells to participate in adaptive immune responses, and suggest that MAIT cells may be potential targets for mucosal vaccines. One Sentence SummaryWe identified and characterized a novel subset of T follicular helper-like MAIT (MAITfh) cells that has the capacity to provide B cell help, and show the sufficiency of MAIT cells to promote production of pathogen-specific IgA antibodies and B cell differentiation in mucosal challenge.

immunology↗

bioRxiv2020

Intestinal infection results in impaired lung innate immunity to secondary respiratory infection.

BackgroundPneumonia and diarrhea are among the leading causes of death worldwide, and epidemiological studies have demonstrated that diarrhea is associated with an increased risk of subsequent pneumonia. Our aim was to determine the impact of intestinal infection on innate immune responses in the lung. MethodsUsing a mouse model of intestinal infection by Salmonella enterica serovar Typhimurium (S. Typhimurium (ST)), we investigated how infection in the gut compartment can modulate immunity in the lungs and impact susceptibility to bacterial (Klebsiella pneumoniae (KP)) challenge. ResultsWe found alterations in frequencies of innate immune cells in lungs of intestinally-infected mice compared to uninfected mice. On subsequent challenge with K. pneumoniae we found that mice with prior intestinal infection have higher lung bacterial burden and inflammation, increased neutrophil margination, and neutrophil extracellular traps (NETs), but lower overall numbers of neutrophils, compared to mice without prior intestinal infection. Total numbers of dendritic cells, innate-like T cells, and natural killer cells were not different between mice with and without prior intestinal infection. ConclusionsTogether, these results suggest that intestinal infection impacts lung innate immune responses, most notably neutrophil characteristics, potentially resulting in increased susceptibility to secondary pneumonia. Article summaryWe show, in a mouse model, that prior intestinal infection with Salmonella Typhimurium leads to increased susceptibility to respiratory Klebsiella pneumoniae infection, which is associated with altered neutrophil responses.

immunology↗

bioRxiv2020

Mucosal-associated invariant T (MAIT) cells mediate protective host responses in sepsis

Sepsis is a systemic inflammatory response to infection and a leading cause of death. Mucosal-associated invariant T (MAIT) cells are innate-like T cells enriched in mucosal tissues that recognize bacterial ligands. We investigated MAIT cells during clinical and experimental sepsis, and their contribution to host responses. In experimental sepsis, MAIT-deficient mice had significantly increased mortality and bacterial load, and reduced tissue-specific cytokine responses. MAIT cells of WT mice expressed lower levels of IFN-{gamma} and IL-17a during sepsis compared to sham surgery, changes not seen in non-MAIT T cells. MAIT cells of patients presenting with sepsis were significantly reduced in frequency, more activated, and had decreased IFN-{gamma} production when stimulated, compared to healthy donors and paired 90-day post-sepsis samples. Our data suggest that MAIT cells are highly activated and become dysfunctional during clinical sepsis, and contribute to tissue-specific cytokine responses that are protective against mortality during experimental sepsis.

physiology↗