Biology subjects

Sadler, K. E.

Publications and source records attributed to Sadler, K. E..

14 recordsLinked to original sources

bioRxiv2026

Antibiotics modulate activity of mouse and human dorsal root ganglia neurons

Antibiotics are among the most prescribed medications worldwide, yet their direct effects on eukaryotic tissues remain largely unexplored. Here, we used in vitro calcium imaging to determine if clinically relevant concentrations of common antibiotics alter mouse and human dorsal root ganglion (DRG) neuron activity. We found that {beta}-lactams, macrolides, and tetracyclines induce calcium flux in sensory neurons within minutes of application. Regardless of antibiotic class, neuronal responses depend on extracellular calcium entry. Pharmacological manipulations further revealed that cephalexin responses depend on TRPA1 activity whereas doxycycline responses require mitochondrial reactive oxygen species (ROS) production. These findings demonstrate that clinically relevant concentrations of antibiotics directly modulate sensory neuron activity through divergent mechanisms, thus expanding our current understanding of antibiotic side effects.

neuroscience↗

bioRxiv2026

Predicting Pain Using a Data-Driven Agent-Based Model of the Bilateral Central Amygdala

Sensory processing in the amygdala is a complex, dynamic process. Decades of surgical, electrical, pharmacological, optogenetic, and chemogenetic in vivo manipulations have revealed the nociceptive functions of anatomically- and genetically-restricted neuronal populations. In parallel, molecular and electrophysiological approaches have allowed for high-resolution, temporal examination of nociceptive-induced alterations in amygdala plasticity. Computational integration of this data is critical for future therapeutic development; in practice, these models would allow for in silico prediction of amygdala activity following injury, and in a reciprocal fashion, changes in pain-like behaviors following manipulation of discrete amygdala neuronal populations. To this end, we developed a three-dimensional computer model of the bilateral central nucleus of the amygdala (CeA). We employed agent-based modelling to integrate wet-lab data from two CeA cell populations: Calcitonin Gene-Related Peptide Receptor (CGRPR; Calcrl) expressing cells and Protein Kinase C delta (PKC{delta}; Prkcd) expressing cells. We integrated the spatial location, connectivity, neuronal activity, and electrophysiological properties of these neurons in our realistic bilateral model architecture. Our model captures properties of the amygdala that drive pain modulation, including hemisphere-specific physiological differences, and generates predictions of nociception related to bladder injury. Predictions from the model were compared retrospectively to pain outcomes during manipulation of CGRPR-expressing neurons in whole mice. These comparisons show strong alignment between our model and in vivo outcomes. Significance StatementNociceptive processing in the amygdala emerges from interactions among cell types. No framework has been developed that recapitulates this complexity. Here, we generated a 3-D agent-based computational model of the bilateral central amygdala (CeA) using data that accounts for pain-associated changes in neuronal physiology, cellular identity, anatomical positioning, and temporal specificity. The model revealed that hemispheric differences in intrinsic CeA neuronal excitability are dominant drivers of nociceptive output. Furthermore, when manipulated to mimic injury-associated plasticity, the model accurately predicted behavioral outcomes. This model is a publicly available computational tool that predicts hemisphere-targeted pain therapy efficacy. Moreover, the flexibility of this framework will allow future adaptations to other brain areas and disease contexts.

neuroscience↗

bioRxiv2026

Adipose-driven complement-lipid reprogramming controls nociceptive vulnerability in obesity-associated osteoarthritis

Obesity amplifies osteoarthritis (OA) pain disproportionately to joint damage, creating a major unmet clinical need for non-opioid interventions that act beyond the joint. Using OA as a translational model, we integrated serum multi-omics in obese mice with surgically induced OA and genetic and adipose-reconstitution models of complement factor D (FD). In humans, we analyzed longitudinal metabolomics data from the IDEA weight-loss trial and conducted functional studies in dorsal root ganglion (DRG) neurons. Adipose-derived FD emerged as a regulator of systemic immunometabolic state: FD deficiency in obese mice worsened pain sensitivity whereas restoring circulating FD normalized pain and inflammatory markers without altering joint structure. Cross-species lipid profiling identified conserved shifts in linoleic acid versus arachidonic acid-derived lipids that were associated with pain phenotypes in mice and with pain improvement in humans. Defined lipid cocktails modulated excitability and TRPV1 sensitivity in human DRG neurons, and transcriptomics of knee-innervating DRGs revealed diet and FD-dependent activation of complement and neuronal excitability pathways. Together, these findings define an adipose-complement-lipid axis that regulates nociceptive vulnerability independent of joint damage and identify extra-articular targets for translational, non-opioid OA pain therapies. One Sentence SummaryWe identify an adipose-complement-lipid axis that systemically regulates sensory neuron sensitization, providing a mechanistic basis for pain-structure discordance in obesity-associated osteoarthritis.

physiology↗

bioRxiv2025

Peripheral nerve-targeting and pain-promoting transcriptomic signatures in early Guillain-Barr&eacute syndrome

Guillain-Barre syndrome (GBS) is an autoimmune disorder that causes weakness, sensory loss, autonomic dysfunction, and chronic neuropathic pain. The mediators responsible for driving early autoimmune injury in the most common GBS variant, acute inflammatory demyelinating polyradiculoneuropathy (AIDP), remain incompletely understood. We performed single-cell and bulk RNA sequencing on peripheral blood mononuclear cells collected from early untreated AIDP-variant GBS patients and healthy controls to comprehensively deduce leukocyte transcriptome alterations and predict disease- and pain-driving interactions between pathogenic leukocytes and peripheral nervous system cells. We found that classical, intermediate, and non-classical monocytes were expanded and upregulated genes associated with type I and II interferons, JAK/STAT signaling, and NLRP3 inflammasome engagement. CD8+ T cells were highly proliferative and likewise upregulated JAK/STAT signaling. CD4+FOXP3+ regulatory T cells upregulated PRDM1 and CD74 in a signature that may indicate functional exhaustion. A subpopulation of highly activated intermediate monocytes upregulated genes related to angiogenesis and oncostatin M. Differential expression-based cell-cell interaction analysis between GBS leukocytes, Schwann cells, and sensory neurons predicted engagement of ligand-receptor pairs with nerve integrity and pain functions, including epiregulin, interferon-beta, adrenomedullin, clusterin, IL-6, IL-15, and CCL4. Functional validation demonstrated that CCL4 sensitizes human sensory neurons in vitro. These results unearth molecular interactions by which specific leukocyte populations in AIDP-variant GBS may participate in peripheral nerve injury and drive neuropathic pain. Many of these targets may be amenable to therapeutic modulation using available approved and investigational drugs, potentially providing drug repurposing opportunities.

neuroscience↗

bioRxiv2025

Enabling wider access to human molecular neuroscience research in pain: A simple preservation method for human dorsal root ganglion neurons in Hibernate A media

The use of human dorsal root ganglion (DRG) from organ donors opens the door for research into the molecular biology and physiology of human nociceptors; however, there are barriers to working with this tissue including logistical difficulties and limited access. We present an approach using Hibernate media to temporarily store either whole DRGs or dissociated DRG neurons prior to culturing and functional testing. Dissociation of DRGs following temporary storage (4-16hrs) in Hibernate media resulted in similar neuronal and immune cell yield as acutely dissociated DRGs. Neurons derived from DRGs stored in Hibernate media prior to dissociation exhibited similar electrophysiological properties and capsaicin responses as acutely dissociated DRG neurons. Similarly, neurons from acutely dissociated DRGs stored in Hibernate media (>24hrs) and shipped to geographically distant laboratories produced neuronal cultures displaying comparable electrophysiological properties as acutely cultured neurons. This approach overcomes insurmountable logistical burdens and increases access to freshly recovered human DRGs.

neuroscience↗

bioRxiv2025

Life-long hydroxyurea treatment decreases chronic sickle cell disease pain

Chronic sickle cell disease (SCD) pain mechanisms remain critically understudied, even though more than 50% of patients develop this symptom as their disease progresses. Despite high face validity, there are critical gaps in transgenic SCD mouse model characterization and implementation that must be addressed in order to increase the translational relevance of these animals. First, it is unclear when the chronic pain phenotype first develops in these mice. Second, there are no studies that have measured chronic pain in animals following standard-of-care drug regimens. Herein, we address both of these gaps by performing reflexive pain behavior tests in hydroxyurea-treated Townes HbSS and HbAA mice from postnatal day 10 to 6 months of age. Hydroxyurea (HU), a compound that increases circulating levels of fetal hemoglobin (HbF), is a life-long therapy prescribed to individuals with SCD beginning as early as age 9 months. Here, we demonstrate that chronic mechanical hypersensitivity develops in Townes HbSS mice between P21-P28, a time frame that follows the HbF-to-HbS switch. When initiated at birth, HU treatment limits the extent of chronic mechanical pain development in HbSS mice. HU analgesic effects can be attributed to decreased innate immune tone in the periphery; life-long HU treatment decreases circulating monocyte counts in HbSS mice and reverses sensitization of TRPA1, a lipopolysaccharide receptor, in HbSS nociceptors. In conclusion, these studies provide additional support for early implementation of HU in SCD disease management, and furthermore, identify the LPS-TRPA1 signaling axis as a novel analgesic target for chronic SCD pain.

physiology↗

bioRxiv2025

Male-specific analgesic effects of minocycline in sickle cell disease are mediated by microglia and the microbiome

Over 50% of individuals with sickle cell disease (SCD) experience chronic pain that is phenotypically distinct from their acute, vaso-occlusive crisis pain. Chronic SCD pain is commonly managed with opioid-based drugs that are associated with unwanted side effects, incomplete pain relief, and - in this population - accessibility issues. Thus, new treatments for chronic SCD pain are desperately needed. Here, we examined the analgesic efficacy of acute minocycline treatment in transgenic SCD mice. SCD mice exhibit gut dysbiosis and chronic inflammation. Therefore, we hypothesized that minocycline would provide robust analgesia in this model given the drugs antibiotic and anti-inflammatory properties respectively. Six days of minocycline treatment reversed chronic mechanical hypersensitivity only in male SCD mice. We identified two potential mechanisms underlying these sex-specific effects. First, we observed increased microgliosis only in the dorsal horn of male SCD mice. Minocycline treatment had opposite effects on microglial number in male and female SCD spinal cords. Second, minocycline treatment altered the gut microbiota in a sex-specific fashion; fecal microbiota transplant (FMT) from minocycline-treated female SCD mice induced widespread pain in recipients whereas FMT from minocycline-treated male SCD mice did not. In summary, these experiments highlight novel sex-specific mechanisms of minocycline analgesia and support future exploration of minocycline use for SCD pain management, but only in male patients.

neuroscience↗

bioRxiv2025

The vaginal microbiome drives endometriosis pain

Despite being one of two cardinal disease symptoms, endometriosis pain is poorly understood. Using a validated mouse model, we demonstrate that endometriosis-associated vaginal dysbiosis is sufficient to induce pain in the absence of disease pathology. In addition, intravaginal antibiotic treatment and vaginal microbiome transplant from healthy control animals reverses pain in endometriosis mice.

microbiology↗

bioRxiv2023

Keratinocyte Piezo1 drives paclitaxel-induced mechanical hypersensitivity

Recent work demonstrates that epidermal keratinocytes are critical for normal touch sensation. However, it is unknown if keratinocytes contribute to touch evoked pain and hypersensitivity following tissue injury. Here, we used inhibitory optogenetic and chemogenetic techniques to determine the extent to which keratinocyte activity contributes to the severe neuropathic pain that accompanies chemotherapeutic treatment. We found that keratinocyte inhibition largely alleviates paclitaxel-induced mechanical hypersensitivity. Furthermore, we found that paclitaxel exposure sensitizes mouse and human keratinocytes to mechanical stimulation through the keratinocyte mechanotransducer Piezo1. These findings demonstrate the contribution of non-neuronal cutaneous cells to neuropathic pain and pave the way for the development of new pain-relief strategies that target epidermal keratinocytes and Piezo1. SummarySensitization of the keratinocyte mechanotransducer Piezo1 drives paclitaxel-induced touch pain.

neuroscience↗

bioRxiv2023

Gut microbiota and metabolites drive chronic sickle cell disease pain

Pain is a debilitating symptom and leading reason for hospitalization of individuals with sickle cell disease. Chronic sickle cell pain is poorly managed because the biological basis is not fully understood. Using transgenic sickle cell mice and fecal material transplant, we determined that the gut microbiome drives persistent sickle cell pain. In parallel patient and mouse analyses, we identified bilirubin as one metabolite that induces sickle cell pain by altering vagus nerve activity. Furthermore, we determined that decreased abundance of the gut bacteria Akkermansia mucinophila is a critical driver of chronic sickle cell pain. These experiments demonstrate that the sickle cell gut microbiome drives chronic widespread pain and identify bacterial species and metabolites that should be targeted for chronic sickle cell disease pain management. One-Sentence SummaryGut microbes and metabolites drive chronic sickle cell disease pain by altering vagus nerve activity.

neuroscience↗

bioRxiv2021

Contextual control of conditioned pain tolerance and endogenous analgesic systems: Evidence for sex-based differences in endogenous opioid engagement

The mechanisms underlying the transition from acute to chronic pain are unclear but may involve the persistence or strengthening of pain memories acquired in part through associative learning. Contextual cues, which comprise the surrounding environment where events occur, were recently described as a critical regulator of pain memory; both rodents and humans exhibit increased pain sensitivity in environments recently associated with a single painful experience. It is unknown, however, how repeated exposure to an acute painful unconditioned stimulus in a distinct context modifies pain sensitivity or the expectation of pain in that environment. To answer this question, we conditioned mice to associate distinct contexts with either repeated administration of a mild visceral pain stimulus (intraperitoneal injection of acetic acid) or vehicle injection over the course of three days. On the final day of experiments animals received either an acid injection or vehicle injection prior to being placed into both contexts. In this way, contextual control of pain sensitivity and pain expectation could be tested respectively. Both male and female mice developed context-dependent conditional pain tolerance, a phenomenon mediated by endogenous opioid signaling. However, when expecting the presentation of a painful stimulus in a given context, males exhibited conditional hypersensitivity whereas females exhibited endogenous opioid-mediated conditional analgesia. Successful determination of the brain circuits involved in this sexually dimorphic anticipatory response may allow for the manipulation of pain memories, which may contribute to the development of chronic pain states.

neuroscience↗

bioRxiv2020

Piezo1 Mediates Keratinocyte Mechanotransduction

Epidermal keratinocytes mediate touch sensation by detecting and encoding tactile information to sensory neurons. However, the specific mechanotransducers that enable keratinocytes to respond to mechanical stimulation are unknown. Here, we found that the mechanically-gated ion channel Piezo1 is the major keratinocyte mechanotransducer. Keratinocyte expression of Piezo1 is critical for normal sensory afferent firing and behavioral responses to mechanical stimuli.

neuroscience↗

bioRxiv2020

Transient receptor potential canonical 5 (TRPC5) mediates inflammatory mechanical pain

Persistent tactile pain is a poorly managed symptom of inflammatory and neuropathic injury. To develop therapies for this maladaptive sensation, the underlying molecular mediators must be identified. Using knockout mice and pharmacological inhibitors, we identified transient receptor canonical 5 (TRPC5) as a key contributor to the persistent tactile pain that occurs in many inflammatory and neuropathic preclinical rodent models. TRPC5 inhibition was effective in injuries associated with elevated levels of the bioactive phospholipid lysophosphatidylcholine (LPC). Exogenous application of LPC induced TRPC5-dependent behavioral mechanical allodynia, neuronal mechanical hypersensitivity, and spontaneous pain. In vitro, LPC activated both homomeric mouse and human TRPC5 channels, which upon examination of human dorsal root ganglia tissue, were expressed in 75% of human sensory neurons. Based on these results, TRPC5 inhibitors should be pursued as personalized therapy for spontaneous and tactile pain in conditions where elevated LPC is a biomarker.

neuroscience↗

bioRxiv2020

Keratinocytes are required for normal cold and heat sensation

Keratinocytes are the most abundant cell type in the epidermis, the most superficial layer of the skin. Historically, epidermal-innervating sensory neurons were thought to be the exclusive detectors and transmitters of environmental stimuli. However, recent work from our lab and others has demonstrated that keratinocytes are also critical for normal mechanotransduction and mechanically-evoked behavioral responses in mice. Here, we asked whether keratinocyte activity is also required for normal cold and heat sensation. We first observed cold-induced activity in mouse, rat, hibernating 13-lined ground squirrel, and human keratinocytes and determined that keratinocyte cold activity is conserved across mammalian species. Next, using transgenic mouse tissues and pharmacological tools, we determined that keratinocyte cold responses require the release of intracellular calcium through one or more unknown cold-sensitive proteins. This cold-induced keratinocyte activity is required for normal cold sensation as optogenetic inhibition of epidermal cells reduced reflexive behavioral responses to cold stimuli. Keratinocyte inhibition also decreased reflexive behavioral responses to heat stimuli. Lastly, we demonstrated that epidermal ATP-P2X4 signaling is required for normal cold and heat sensation. Based on these data and our previous findings, keratinocyte purinergic signaling is a modality-conserved amplification system that is required for normal somatosensation in vivo.

neuroscience↗