Biology subjects

Brown, B.

Publications and source records attributed to Brown, B..

At least 19 recordsLinked to original sources

bioRxiv2026

Glucocorticoid receptor activation reorganizes Wnt/LEF1 regulatory circuitry associated with therapeutic response in B-cell acute lymphoblastic leukemia

Glucocorticoids (GCs) are foundational to B-cell acute lymphoblastic leukemia (B-ALL) therapy, yet how glucocorticoid receptor (GR) activation interacts with lineage regulatory circuitry to shape therapeutic response remains incompletely understood. Using LEF1 to interrogate canonical Wnt regulatory circuitry, we show that GR activation reorganizes GR+LEF1 elements into recruitment, retention, and dissociation states. LEF1 dissociates from Wnt-responsive regulatory elements while being recruited to GRE-rich GR-associated elements that progressively acquire chromatin accessibility, H3K27ac, BRD4 and BRG1. RUNX1 and AP-1 show class-dependent redistribution across LEF1-defined states, extending organization beyond LEF1. GR+LEF1 reorganization is observed in patient-derived B-ALL. GR+LEF1 elements lose accessibility in GC-resistant B-ALL and during diagnosis-to-relapse evolution, with recruitment elements enriched for remodeling. Perturbation of resistance-associated GR+LEF1 elements at BIM and BMF alters GC-induced apoptotic signaling. Together, these findings identify Wnt/LEF1 circuitry as an interface through which therapeutic GR activation reorganizes the B-ALL regulatory landscape into states associated with glucocorticoid response and resistance.

cancer biology↗

bioRxiv2026

Early electrical stimulation promotes functional recovery after volumetric muscle loss

Volumetric muscle loss (VML) injuries overwhelm the inherent regenerative capacity of skeletal muscle, causing persistent functional deficits with no routinely effective therapies. Electrical stimulation (ES) has been shown to preserve muscle structure in other injury models, but technical barriers have prevented daily delivery during the acute post-injury window when critical regenerative programs are established. Here, we developed a fully implantable bioelectronic system with nanoporous platinum-modified electrodes enabling daily therapeutic stimulation and electromyographic recording without repeated anesthesia in a rat tibialis anterior VML model. Animals receiving ES during the acute post-injury period (10 sessions over days 0-14) showed sustained functional improvement, reaching 90% of baseline torque at 8 weeks compared to 71% in unstimulated controls. This recovery reflected enhanced remodeling of injured muscle rather than synergistic muscle compensation. Histological analysis revealed coordinated early increases in vascularization, pro-regenerative macrophages, and satellite cells. These findings establish early ES as a promising intervention for promoting muscle regeneration after catastrophic injury.

bioengineering↗

bioRxiv2025

Macrophage-to-Myofibroblast Transition (MMT)- an adverse response to polypropylene mesh implanted for pelvic organ prolapse repair surgery in a non-human primate model

Surgical repair of pelvic organ prolapse (POP) is often augmented by polypropylene mesh to provide mechanical support to the vagina and improve anatomical outcomes as compared to native tissue repair. However, POP repair surgeries utilizing PPM have complications (most often pain or mesh exposure into the vagina) in over 10% of cases. Previous work has demonstrated that tensioning of meshes with certain geometries (diamond and hexagon pores), results in both planar (pore collapse) and nonplanar (wrinkles) deformations, significantly altering textile properties and impacting the host response. To further investigate the impact of mesh deformation on the host response, we implanted mesh in a validated non-human primate model via sacrocolpopexy with stable flat (square pores, N=20) versus deformed geometries (mesh loaded on the diamond prior to implantation resulting in collapsed pores and wrinkles, N=20). To investigate the impact of tension independent of deformation, we implanted on and off tension (10N, N=10 in each group). We hypothesized that more stable geometries trigger a healing response that achieves homeostasis while deformed mesh, by increasing the amount of material in contact with the host, triggers a maladaptive remodeling response with the formation of myofibroblasts. After twelve weeks, we found that mesh deformations and the absence of tension increase the amount of mesh per area on the vagina (mesh burden) and reproduced clinical complications (mesh exposure and vaginal thinning). Interestingly, MMT cells, or myofibroblasts co-expressing a macrophage marker (CD68), were seen to significantly increase in response to mesh burden, as well as respond hyper-locally to the mesh fiber interface. We observed decreased collagen density and more immature matrix deposited in conditions with higher MMT cell presence, showing more disorganization in deposited matrix with increased mesh burden, and the loss of tension. TGF-{beta}1, in both active and latent forms, increased with increasing mesh burden, and highest expression was observed in conditions precipitating the highest percentage of MMT cells, a possible mechanism of transdifferentiation. This study showed the importance of PPM mesh properties on mesh burden following tensioning, impact on MMT transdifferentiation, and the downstream effect of these changes on the host response and healing outcomes.

bioengineering↗

bioRxiv2025

African Green Monkeys Respond to Synthetic AB Oligomers with Persistent Alzheimers-like Activation

Wild African green monkeys (AGMs) provide a promising alternative to congenic rodent models because of their closer evolutionary relationship to humans and natural genetic variation. They share key physiological and biochemical traits with humans, including lifespan, neuroanatomy, vascular structure, and inflammatory responses. Unlike rodents, AGMs naturally develop Alzheimers-like amyloid-{beta} (A{beta}) plaques and tau tangles with age. Immunohistochemical studies further show that AGMs inoculated with synthetic A{beta} oligomers (A{beta}O) exhibit hyperphosphorylated tau and neuroinflammation one year later, in the absence of overt neurodegeneration. The AGM body size permits collection of cerebrospinal fluid (CSF) and CSF derived extracellular vesicles (EV) from living individuals, which are key sources of Alzheimers disease biomarkers that can be monitored during disease progression. Here, we evaluate A{beta}O treated AGMs at the systems level using proteomics of CSF and phosphatidylserine affinity isolated EVs (EVps). We optimized a workflow to obtain paired CSF and EVps proteomics from <1 mL volumes, i.e. comparable to human liquid biopsy. Our measurements reveal robust, persistent AD-like responses at the biochemical level without overt loss of cognitive function. As such, these findings in AGMs suggest potential alternatives for disease tracking or point to protective mechanisms for limiting disease progression in AD. HighlightsO_LIDual proteomics of African green monkeys transiently challenged with synthetic A{beta} oligomers (A{beta}O) C_LIO_LIPhosphotidylserine (TIM4) based workflow enables CSF and EV profiling using clinical volumes C_LIO_LIOne year post-A{beta}O: vascular-inflammatory pathways rise; neuronal-axonal pathways fall C_LIO_LIA{beta}Os drive human-AD-like proteome shifts on time scales shorter than cognitive decline C_LI In briefWild African green monkeys (AGMs) offer a translational model for early Alzheimers biology, with physiology more similar to humans. We transiently exposed AGMs to synthetic A{beta} oligomers and, 12 months later, profiled paired proteomes from whole CSF and a CSF subcompartment enriched for extracellular vesicles. Despite no overt cognitive decline, AGM proteomes showed persistent Alzheimers-like remodeling, particularly in vascular, inflammatory, and neuronal systems. Parallel analysis of the CSF subcompartment revealed proteins and pathways under-represented in bulk CSF, sharpening disease-relevant signals and candidate biomarkers. This systems-level, longitudinal study establishes AGMs as a powerful platform for liquid biopsy discovery and illuminates basic biology of molecular responses to soluble A{beta} oligomers accompany and potentially protect against neurodegeneration.

systems biology↗

bioRxiv2025

Sex-Specific Links Between Low Choline, Metabolic Dysfunction, andNeuropathology in Obesity: Insights from Humans and the 3xTg-AD MouseModel of Alzheimer's disease.

The growing prevalence of obesity, a risk factor for disorders such as Alzheimers Disease (AD), raises concerns about the effects on cognitive health. AD currently impacts 6.9 million Americans aged 65 and older and is characterized by the presence of amyloid beta (A{beta}) plaques, neurofibrillary tau tangles, and neuroinflammation, all of which contribute to cognitive impairment. Insulin resistance, common in both obesity and AD, disrupts brain glucose metabolism and accelerates neurodegeneration. Understanding the factors that link these conditions could lead to new strategies for combating disease. Notably, the B-like vitamin choline is necessary for fat metabolism and has been shown to help reduce obesity incidence. However, [~]90% of Americans are deficient, and decreases in this nutrient have been associated with cognitive decline. Here, we examined circulating choline levels, inflammation, and metabolic dysfunction in human participants with obesity (BMI > 30) compared to normal BMIs (18.5-24.9), as well as in 3xTg-AD mice, an AD model, fed a choline-deficient diet throughout adulthood. Our results revealed that obese participants exhibited significantly lower circulating choline levels compared to those with a healthy BMI. Lower choline levels correlated with higher %Body fat and increased markers of insulin resistance. Elevated inflammatory cytokines in obese participants were also seen in 3xTg-AD mice on a choline-deficient diet, which exhibited significant weight gain and metabolic dysfunction. AD-like pathology was also exacerbated in choline deficient 3xTg-AD mice. These findings underscore the relationship between low choline levels, obesity, insulin resistance, and cognitive decline risk. Adequate choline intake may mitigate the risk of obesity, potentially preventing cognitive decline and associated diseases. HighlightsO_LIObesity is linked to increased insulin resistance (IR) and systemic inflammation, both of which are recognized risk factors for Alzheimers disease (AD). C_LIO_LIWomen exhibit lower circulating choline levels compared to men, and obese individuals display significantly lower choline levels than those with a healthy BMI. C_LIO_LILower circulating choline levels are linked to a higher body fat percentage, increased markers of IR and liver dysfunction, as well as heightened systemic inflammation. C_LIO_LI3xTg-AD mice on a choline-deficient diet experience considerable weight gain, metabolic dysfunction, heightened systemic inflammation, and AD-like pathology, resembling the conditions observed in obese human participants. C_LI

pathology↗

bioRxiv2025

Drug repurposing reveals Posaconazole as a CYP11A1 inhibitor enhancing anti-tumour immunity

Steroid hormones regulate cell physiology and immune function, with dysregulated steroidogenesis promoting cancer progression by supporting tumour growth and suppressing anti-tumour immunity. Targeting CYP11A1, the first and rate-limiting enzyme in steroid biosynthesis, has shown promise in cancer therapy, but safe and effective inhibitors remain an unmet need. Undertaking in silico structure-based drug repurposing approach, we found Posaconazole as an inhibitor of CYP11A1. The docking pose analysis showed that Posaconazole can form multiple hydrogen bonds and hydrophobic interactions with the key residues at the binding site and the cofactor, stabilising the protein-ligand complex. We validated its inhibition efficiency in cell-based assays. In a mouse model of lung metastasis, we demonstrated that Posaconazole restricts metastatic cancer growth by stimulating anti-tumour immunity. These findings highlight Posaconazoles potential as a research tool to study steroidogenesis and as a candidate for further preclinical and clinical evaluation in pathological conditions associated with local steroid production, such as steroidogenic tumours.

immunology↗

bioRxiv2024

Bispecific antibody targeting of lipid nanoparticles

Lipid nanoparticles (LNP) are the most clinically advanced non-viral gene delivery system. While progress has been made for enhancing delivery, cell specific targeting remains a challenge. Targeting moieties such as antibodies can be chemically-conjugated to LNPs however, this approach is complex and has challenges for scaling up. Here, we developed an approach to generate antibody-conjugated LNPs that utilizes a bispecific antibody (bsAb) as the targeting bridge. As a docking site for the bsAb, we generated LNPs with a short epitope, derived from hemagglutinin antigen (HA), embedded in the PEG component of the particle (LNPHA). We generated bsAb in which one domain binds HA and the other binds different cell surface proteins, including PD-L1, CD4, CD5, and SunTag. Non-chemical conjugation of the bsAb and LNP resulted in a major increase in the efficiency and specificity of transfecting cells expressing the cognate target. LNP/bsAb mediated a 4-fold increase in in vivo transfection of PD-L1 expressing cancer cells, and a 26-fold increase in ex vivo transfection of quiescent primary human T cells. Additionally, we created a universal bsAb recognizing HA and anti-rat IgG2, enabling LNP tethering to off-the-shelf antibodies such as CD4, CD8, CD20, CD45, and CD3. By utilizing a molecular dock and bsAb technology, these studies demonstrate a simple and effective strategy to generate antibody-conjugated LNPs, enabling precise and efficient mRNA delivery.

bioengineering↗

bioRxiv2024

Transcriptomic Landscape and Immune Microenvironment AroundWound Bed Define Regenerative versus Non-regenerative Outcomesin Mouse Digit Amputation

In the mouse distal terminal phalanx (P3), it remains unclear why amputation at less than 33% of the digit results in regeneration, while amputation exceeding 67% leads to non-regeneration. Unraveling the molecular mechanisms underlying this disparity could provide crucial insights for regenerative medicine. In this study, we aim to investigate the tissues within the wound bed to understand the tissue microenvironment associated with regenerative versus non-regenerative outcomes. We employed a P3-specific amputation model in mice, integrated with time-series RNA-seq and a macrophage assay challenged with pro- and anti-inflammatory cytokines, to explore these mechanisms. Our findings revealed that non-regenerative digits exhibit a greater intense early transcriptional response in the wound bed compared to regenerative ones. Furthermore, early macrophage phenotypes differ distinctly between regenerative and non-regenerative outcomes. Regenerative digits also display unique co-expression modules related to Bone Morphogenetic Protein 2 (BMP2). The differentially expressed genes (DEGs) between regenerative and non-regenerative digits are enriched in targets of several transcription factors, such as HOXA11 and HOXD11 from the HOX gene family, showing a time-dependent pattern of enrichment. These transcription factors, known for their roles in bone regeneration, skeletal patterning, osteoblast activity, fracture healing, angiogenesis, and key signaling pathways, may act as master regulators of the regenerative gene signatures. Additionally, we developed a deep learning AI model capable of predicting post-amputation time and level from RNA-seq data, with potential applications in personalized treatment strategies and assessing the impact of interventions on regenerative outcomes.

developmental biology↗

bioRxiv2024

Dendritic cells accelerate CAR T cells in irradiated tumors through chimeric synapses

The persistence of adoptively transferred T cells is vital for anti-tumor efficacy. Chimeric antigen receptor (CAR) T cells can persist indefinitely when delivered to patients with B cell cancers and can confer long-term remission. For patients with solid tumors, however, sustaining CAR T cell activity remains a major challenge. This has been attributed in part to the immune microenvironment within solid tumors, though the contribution of specific immune subsets to resistance to CAR T cells is not clear. Here we resolve how the immunology of irradiated tumors dramatically enhances persistence and efficacy of CAR T cells targeted to advanced lung metastases in a syngeneic mouse model. Remarkably, CAR T cell persistence depended critically on dendritic cells (DC) that underwent trogocytic "antigen-dressing" of tumor target antigens and stimulated CAR T cells through the chimeric receptor. Furthermore, tumor irradiation increased antigen-dressing onto DCs. In the absence of functional DCs, CAR T cell activity in irradiated tumor was short-lived and tumors relapsed. These findings establish a critical mechanism through which DCs maintain the CAR T cell pool in irradiated tumors, thus supporting translation of this approach to advance CAR T cell therapy for solid tumors.

immunology↗

bioRxiv2024

Wound state monitoring by multiplexed, electrochemical, real-time, localized, inflammation-tracking nitric oxide sensor (MERLIN)

Nitric oxide (NO) released endogenously by induced nitric oxide synthase (iNOS) in macrophages is a key regulatory biomarker for wound inflammation. Detecting NO directly on the wound bed is challenging due to its short half-life time (6 - 50 s), low physiological concentration (nM - {micro}M) and interferences in the complex wound environment. Existing NO sensors suffer from limitations such as rigid substrates, single point of detection and complex measurement setup. Here we present a compliant, multiplexed, electrochemical, real-time, localized, inflammation-tracking nitric oxide sensor (MERLIN) array for in vivo spatiotemporal measurement of NO, with high sensitivity (15.6 {+/-} 5.0 nA/M for 1.5 mm diameter electrodes), selectivity against nitrites (ca. 27900-fold), ascorbic acid (ca. 3800-fold), and uric acid (ca. 6900-fold), and low limit of detection (8.00 nM). We developed a robust device fabrication protocol, comprehensive and highly reproducible in vitro characterization yielding a consistent device performance deployed for wound healing diagnostics. MERLIN spatiotemporally tracked NO on rat skin wounds for 7 days and results indicated that NO peaks on day 3, in line with previously reported iNOS activity. MERLIN allows spatial mapping of the NO gradient across the wound bed, which can be used to provide diagnostic information to assist wound care.

bioengineering↗

bioRxiv2024

Modeling Protein Conformations by Guiding AlphaFold2 with Distance Distributions. Application to Double Electron Electron Resonance (DEER) Spectroscopy.

We describe a modified version of AlphaFold2 that incorporates experiential distance distributions into the network architecture for protein structure prediction. Harnessing the OpenFold platform, we fine-tuned AlphaFold2 on a small number of structurally dissimilar proteins to explicitly model distance distributions between spin labels determined from Double Electron-Electron Resonance (DEER) spectroscopy. We demonstrate the performance of the modified AlphaFold2, referred to as DEERFold, in switching the predicted conformations guided by experimental or simulated distance distributions. Remarkably, the intrinsic performance of AlphaFold2 substantially reduces the number and the accuracy of the widths of the distributions needed to drive conformational selection thereby increasing the experimental throughput. The blueprint of DEERFold can be generalized to other experimental methods where distance constraints can be represented by distributions.

bioinformatics↗

bioRxiv2024

12/15-Lipoxygenases mediate neuropathic-like pain hypersensitivity in female mice

It is estimated that chronic neuropathic pain conditions exhibit up to 10% prevalence in the general population, with increased incidence in females. However, nonsteroidal inflammatory drugs (NSAIDs) are ineffective, and currently indicated prescription treatments such as opioids, anticonvulsants, and antidepressants provide only limited therapeutic benefit. In the current work, we extended previous studies in male rats utilizing a paradigm of central Toll-like receptor 4 (TLR4)-dependent, NSAID-unresponsive neuropathic-like pain hypersensitivity to male and female C57BL/6N mice, uncovering an unexpected hyperalgesic phenotype in female mice following intrathecal (IT) LPS. In contrast to previous reports in female C57BL/6J mice, female C57BL/6N mice displayed tactile and cold allodynia, grip force deficits, and locomotor hyperactivity in response to IT LPS. Congruent with our previous observations in male rats, systemic inhibition of 12/15-Lipoxygenases (12/15-LOX) in female B6N mice with selective inhibitors - ML355 (targeting 12-LOX-p) and ML351 (targeting 15-LOX-1) - completely reversed allodynia and grip force deficits. We demonstrate here that 12/15-LOX enzymes also are expressed in mouse spinal cord and that 12/15-LOX metabolites produce tactile allodynia when administered spinally (IT) or peripherally (intraplantar in the paw, IPLT) in a hyperalgesic priming model, similar to others observations with the cyclooxygenase (COX) metabolite Prostaglandin E2 (PGE2). Surprisingly, we did not detect hyperalgesic priming following IT administration of LPS, indicating that this phenomenon likely requires peripheral activation of nociceptors. Collectively, these data suggest that 12/15-LOX enzymes contribute to neuropathic-like pain hypersensitivity in rodents, with potential translatability as druggable targets across sexes and species using multiple reflexive and non-reflexive outcome measures.

pharmacology and toxicology↗

bioRxiv2024

Examining Cognitive Performance in Mice using the Open-Source Operant Feeding Device FED3

Cognitive impairments are prevalent in various neurological disorders, including chronic pain conditions, and pose significant therapeutic challenges. Preclinical rodent models serve as valuable tools for investigating the underlying mechanisms of and treatments for cognitive dysfunction. However, factors such as stress, age, sex, and disease duration present challenges to reliably capturing cognitive deficits in rodents. Here, we present a comprehensive and high-throughput protocol utilizing the open-source operant Feeding Experimentation Device 3 (FED3) for assessing cognitive performance in mice. We developed a data pipeline to streamline data compilation and analysis, and established operating conditions for a six-test cognitive battery which can be completed in as few as 20 days. We validated our testing procedures using bilateral orbitofrontal cortical lesions to capture deficits in executive function, and demonstrated the feasibility of assessing cognitive function in aged mice of both sexes to identify genotypic and sex-specific effects. Overall, our findings demonstrate that the FED3 is a versatile tool for evaluating cognitive function in mice, offering a low-cost, high-throughput approach for preclinical studies of neurological disorders. We anticipate that this protocol will facilitate broader implementation of cognitive testing in rodent models and contribute to the understanding and treatment of cognitive dysfunction in neurological diseases.

neuroscience↗

bioRxiv2024

A method for focused ultrasound (FUS) neuromodulation with simultaneous electroencephalogram recordings in awake, head-fixed mice with temporal lobe epilepsy

Transcranial focused ultrasound (FUS) may be a promising neuromodulation technology for treating people with epilepsy whose seizures are drug resistant. Prior studies have shown seizure suppression in animal studies using FUS. However, most of these studies were performed in evoked seizure models and not in animal models of epilepsy. Evoked seizure models do not exhibit the pathophysiology of epilepsy and do not exhibit spontaneous recurrent seizures, which define epilepsy. For translation to humans, there is a critical need to determine the specific FUS stimulation parameters that reduce spontaneous recurrent seizures in a chronic disease model of epilepsy. To achieve this goal, we developed and optimized an approach to determine the effects of ultrasonic stimulation on metrics of seizure-like events (SLEs) in awake, head-fixed mice within the intrahippocampal kainate (IHK) mouse model of temporal lobe epilepsy (TLE). A proof-of-principle study demonstrated that two target (bilateral and contralateral to the kainic acid injection site) stimulation conditions and two FUS parameter sets (low and high pressure) could be combined with the ability to simultaneously record hippocampal electroencephalograms. We also provide a method for analysis of the effects of FUS stimulation on the metrics of SLEs (interevent duration, SLE duration, and spike frequency).

bioengineering↗

bioRxiv2024

The genome of Przewalski's horse (Equus ferus przewalskii)

The Przewalskis horse (Equus ferus przewalskii) is an endangered equid native to the steppes of central Asia. After becoming extinct in the wild, multiple conservation efforts convened to preserve the species including captive breeding programs, reintroduction and monitoring systems, protected lands, and cloning. Availability of a highly contiguous reference genome is essential to support these continued efforts. We used Oxford Nanopore sequencing to produce a scaffold-level 2.5 Gb nuclear assembly and 16,002 bp mitogenome from a captive Przewalskis mare. All assembly drafts were generated from 111 Gb of sequence from a single PromethION R10.4.1 flow cell. The mitogenome contained 37 genes in the standard mammalian configuration and was 99.63% identical to the domestic horse (Equus caballus). The nuclear assembly, EquPr2, contained 2,146 scaffolds with an N50 of 85.1 Mb, 43X mean depth, and BUSCO quality score of 98.92%. EquPr2 successfully improves upon the existing Przewalskis horse reference genome (Burgud), with 25-fold fewer scaffolds, a 166-fold larger N50, and phased pseudohaplotypes. Modified basecalls revealed 79.5% DNA methylation and 2.1% hydroxymethylation globally. Allele-specific methylation analysis between pseudohaplotypes revealed 226 differentially methylated regions (DMRs) in known imprinted genes and loci not previously reported as imprinted. The heterozygosity rate of 0.165% matches previous estimates for the species and compares favorably to other endangered animals. This improved Przewalskis horse assembly will serve as a valuable resource for conservation efforts and comparative genomics investigations.

genomics↗

bioRxiv2023

The tissue-resident regulatory T cell pool is shaped by transient multi-tissue migration and a conserved residency program

The tissues are the site of many of the most important immunological reactions, yet the immunology of the tissues has remained relatively opaque. Recent studies have identified Foxp3+ regulatory T cells (Tregs) in several non-lymphoid tissues. These tissue-resident populations have been ascribed unique characteristics based on comparisons to lymphoid Tregs. Here we performed a systematic analysis of the Treg population residing in non-lymphoid organs throughout the body, revealing shared phenotypes, transient residency and common molecular dependencies. Further, tissue Tregs from different non-lymphoid organs shared T cell receptor (TCR) sequences, with functional capacity to drive multi-tissue Treg entry. Finally, tissue Tregs extracted from non-lymphoid organs were tissue-agnostic on re-entry, without homing preference for their tissue of origin. Together these results demonstrate that the tissue-resident Treg pool in most non-lymphoid organs, other than the gut, is largely constituted by broadly self-reactive Tregs, characterised by transient multi-tissue migration and a common residency program.

immunology↗

bioRxiv2023

Three-dimensional reconstructions of mechanosensory end organs suggest a unifying mechanism underlying dynamic, light touch

Specialized mechanosensory end organs within mammalian skin--hair follicle-associated lanceolate complexes, Meissner corpuscles, and Pacinian corpuscles--enable our perception of light, dynamic touch1. In each of these end organs, fast-conducting mechanically sensitive neurons, called A{beta} low-threshold mechanoreceptors (A{beta} LTMRs), associate with resident glial cells, known as terminal Schwann cells (TSCs) or lamellar cells, to form complex axon ending structures. Lanceolate-forming and corpuscle-innervating A{beta} LTMRs share a low threshold for mechanical activation, a rapidly adapting (RA) response to force indentation, and high sensitivity to dynamic stimuli1-6. How mechanical stimuli lead to activation of the requisite mechanotransduction channel Piezo27-15 and A{beta} RA-LTMR excitation across the morphologically dissimilar mechanosensory end organ structures is not understood. Here, we report the precise subcellular distribution of Piezo2 and high-resolution, isotropic 3D reconstructions of all three end organs formed by A{beta} RA-LTMRs determined by large volume enhanced Focused Ion Beam Scanning Electron Microscopy (FIB-SEM) imaging. We found that within each end organ, Piezo2 is enriched along the sensory axon membrane and is minimally or not expressed in TSCs and lamellar cells. We also observed a large number of small cytoplasmic protrusions enriched along the A{beta} RA-LTMR axon terminals associated with hair follicles, Meissner corpuscles, and Pacinian corpuscles. These axon protrusions reside within close proximity to axonal Piezo2, occasionally contain the channel, and often form adherens junctions with nearby non-neuronal cells. Our findings support a unified model for A{beta} RA-LTMR activation in which axon protrusions anchor A{beta} RA-LTMR axon terminals to specialized end organ cells, enabling mechanical stimuli to stretch the axon in hundreds to thousands of sites across an individual end organ and leading to activation of proximal Piezo2 channels and excitation of the neuron.

neuroscience↗

bioRxiv2022

A Genetic and Immunohistochemical Analysis of H. Pylori Phenotypes and p27 expression in Adenocarcinoma Patients in Jordan

Stomach (gastric) cancer is one of the most prevalent and deadly cancers worldwide and the vast majority of gastric cancers are adenocarcinomas. Based on prior research, there is an association between Helicobacter pylori (H. pylori) infection and the frequency of duodenal ulcer, distal gastric adenocarcinoma, mucosa-associated lymphoid tissue lymphoma, and antral gastritis. H. pylori virulence and toxicity factors have been identified to significantly influence the clinical outcomes of H. pylori infection and gastric adenocarcinoma. However, it is unclear exactly how different strains of H. pylori infection affect gastric adenocarcinoma. Current research suggests this involves tumor suppressor genes, like p27, but also H. Pylori toxic proteins. Therefore, we quantified known H. Pylori genotypes within adenocarcinoma patients to establish the prevalence of known toxins that include cytotoxin-associated gene A (cagA) and vacuolating cytotoxin A (vacA) within patients of variable diagnosis. This analysis used gastrectomy samples which were validated for DNA viability. The incidence of H. Pylori in adenocarcinoma patients in Jordan was established to be 54.5% positive (ureA gene) with cagA genotype occurrence at 57.1% but also vacA gene ratios 24.7%:22.1%: 14.3%:14.3%. (vacAs1:vacAs2: vacAm1:vacAm2). We found statistically significant evidence that p27 was dysregulated and suppressed within nearly all H. Pylori vacA genotypes but also that 24.6% of H. Pylori samples analyzed had a different bacterial genotype and curiously that p27 protein expression was retained in 12% of tested adenocarcinoma H. Pylori samples. This is suggestive that p27 could be used as a prognostic indicator but also that an unknown genotype could be contributing to the regulatory effects of p27 protein within this bacterial and cellular environment. Key ContributionIn Jordan, this is the first retrospective study to use validated viable gastrectomy tissue samples rather than tissue biopsies to characterize each of the currently defined H. pylori strains in patients with variable gastric cancer diagnosis whilst also comparing results with p27 expression within 8 years using these laboratory techniques. ConclusionsBased on these results, a reduction in p27 expression in H. pylori-infected men and women of all ages may be associated with the occurrence of gastric adenocarcinomas. Therefore, p27 may represent a key diagnostic marker and predictor of adenocarcinoma prognosis in such individuals and may find use for guiding subsequent treatment decisions.

microbiology↗