Biology subjects

Klug, N. R.

Publications and source records attributed to Klug, N. R..

7 recordsLinked to original sources

bioRxiv2026

Preserving Nanotherapy-Induced Allogeneic Murine Islet Graft Tolerance During Distal Methicillin-Resistant Staphylococcus aureus Skin Infection

Eliminating lifelong immunosuppression can make islet transplantation a durable alternative to insulin therapy for type 1 diabetes. As short-course tolerogenic regimens are developed to replace lifelong immunosuppression, it is critical to test their robustness against perturbations such as hospital-acquired infections, which transplant recipients routinely encounter. Herein, we investigated whether rapamycin-loaded polymersomes (rPS), a subcutaneous nanotherapy that induces long-term murine islet allograft survival, can preserve host defenses in a Methicillin-resistant Staphylococcus aureus (MRSA) skin infection, and whether the resulting immune response from this distal infection relative to graft location erodes rPS-induced tolerance. rPS maintained neutrophil antibacterial activity despite inhibiting oxidative mechanisms in vitro, and rPS-treated mice demonstrated normal recovery following MRSA challenge. However, MRSA skin infection caused a decline of ~43% in recipient survival for rPS-treated mice, despite surviving recipients retaining glucose-stimulated insulin responsiveness. This erosion of allograft acceptance coincided with a burst of IL-6 within 24h of the infection followed by elevated TNF-[a] and neutrophilia at 13 days post-infection. Combining rPS with a single dose of methylprednisolone reduced IL-6 and TNF- without altering neutrophilia, nearly doubling survival among infected recipients to 80%. Our findings demonstrate that partial dampening of inflammatory insults can restore superior islet allograft acceptance following perioperative infection.

bioengineering↗

bioRxiv2026

Nanotherapy-mediated biased antigen-presenting cell reprogramming supports T cell anergy to prevent type 1 diabetes

Engineering immune tolerance using endogenously expressed autoantigens could enable early intervention in autoimmune disease. Present therapies suppress T cells to slow disease progression. Here, we develop rapamycin-loaded poly(ethylene glycol)-b-poly(propylene sulfide) polymersomes (rPS) to modulate antigen-presenting cells (APCs) during disease-associated antigen presentation. The rPS morphology enables lymphatic drainage following subcutaneous administration to access APCs in draining lymph nodes. Treatment reduced APC costimulatory marker coexpression and shifted CD4+ T cells toward an FR4hi CD73hi anergic phenotype. In a type 1 diabetes (T1D) nonobese diabetic (NOD) mouse model, rPS significantly delayed disease onset relative to the standard of care and selectively prevented hyperglycemia. Mediation via APCs, rPS avoids adverse effects including transient lymphopenia. These findings demonstrate how biomaterial-directed drug delivery can reshape APC--T cell interactions, supporting an antigen-agnostic strategy for delaying autoimmune diabetes without systemic lymphocyte depletion.

bioengineering↗

bioRxiv2026

G-protein coupled receptor activity mediates detrusor smooth muscle phasic contractility through regulation of membrane potential

The urinary bladder functions to store and release urine, yet how the sensation of bladder fullness is conveyed and perceived to the central nervous system is not understood. During bladder filling, the detrusor smooth muscle (DSM) generates phasic contractions, resulting in pressure fluctuations within the bladder. These transient pressure events drive bursts of afferent nerve activity, yet the underlying mechanism leading to rhythmic contractions remains unclear. Here, we examined the role of Gq protein-coupled receptor (GqPCR) activity on DSM excitability and contractility. Using ex vivo pressurized urinary bladder preparations and sharp microelectrode experiments on bladder strips from mice, we evaluated whole bladder transient pressure events, whole bladder DSM Ca2+ activity, and membrane potential in bladder strips. We found that global inhibition of urinary bladder GqPCR activity with YM-254890 abates phasic contractility and transient pressure events through a reduction in DSM Ca2+ activity and propagation of Ca2+ waves. Further, we found inhibition of GqPCR significantly hyperpolarizes DSM, reducing action potentials and decreasing excitability, and activation of protein kinase C restores membrane potential to baseline levels. These findings highlight that GqPCR activity mediates DSM excitability and contractility in such a way as to result in phasic detrusor contractions and transient pressure events.

physiology↗

bioRxiv2026

Artery Like Smooth Muscle Drives Contractile Function in Dural Venous Sinuses

The dural venous sinuses are the main conduit for cerebral blood flow to drain from the head back to the heart. Pathology of these sinuses has significant impacts on cerebral blood volume and intracranial pressure, indicating that these veins have an important role in cerebral hemodynamics. Active and modifiable mechanisms of sinus diameter control may present an opportunity for physiological or pathological regulation of venous blood flow. Here, we characterized the molecular and anatomical properties of dural vascular smooth muscle cells (SMCs) using RNA-sequencing and immunohistochemistry, demonstrating that artery-like SMCs are exclusive to sinus vessels. An ex vivo pressurized sinus preparation from mice was used to functionally characterize the vasodynamics of the sinus and its corresponding bridging veins. We found that the sinus contains dynamically contractile SMCs and constricts to both pressure and contractile agonists, while the bridging veins do not. We further demonstrated that these sinus SMCs exhibit dynamic calcium signaling that is responsive to contractile stimuli. These results reveal a contractile SMC phenotype localized to dural venous sinuses and demonstrate that sinus vessels possess active, artery-like mechanisms for regulating cerebral venous outflow.

physiology↗

bioRxiv2026

Electromechanical Dynamics and Myogenic Responses in Cerebral Smooth Muscle Cells and Capillary Pericytes

Cerebral blood flow (CBF) control is essential for normal brain function and is disrupted in pathological conditions. Arterial diameters are tightly regulated to provide on demand increases in blood flow in regions of neuronal activity. Pericytes (PCs) exhibit robust myogenic tone and may also respond to neuronal activity to fine-tune local resistance and blood flow. Thus, mural control of microcirculatory resistance may extend beyond arteries and arterioles. Yet, PCs electrophysiology and contractility have not been thoroughly characterized, and this prohibits an integrated view of brain blood flow control. In this study, we develop a detailed mathematical model of mural cell electrophysiology, Ca2+ dynamics and biomechanics. The model is informed by electrophysiological data in smooth muscle cells (SMCs) or PCs and predictions are compared against pressure-induced responses in isolated arterioles and capillaries, respectively. Simulations recapitulate myogenic constrictions and examine differences in contractile dynamics as we move from arterioles to proximal and distal capillaries. In arteriole-to-capillary transitional (ACT) zone PCs, increased mechanosensitivity, more Ca2+ influx through non-selective cation (NSC) channels and/or a higher sensitivity of the contractile apparatus to Ca2+ can compensate for reduced L-type voltage-operated (VOCC) Ca2+ influx and allow for robust constrictions at the lower operating pressures of capillaries relative to the arterioles. A significant Ca2+ influx through NSC relative to VOCC, however, can decouple the PCs contractile apparatus from electrical signaling. Vasoactivity to chemomechanical stimuli along the arteriole to capillary axis is progressively driven by VOCC-independent Ca2+ influx and Ca2+ sensitization with slow kinetics. The proposed cell model can form the basis for detailed multiscale and multicellular models that will examine physiological function at a single vessel or vascular network levels and investigate CBF control in health and in disease. Key pointsO_LIA mural cell model of electrophysiology, calcium (Ca2+) dynamics and biomechanics is informed by data and adapted for modeling cerebral arteriole smooth muscle cells and capillary pericytes. C_LIO_LIIon channel activities are characterized by patch-clamp electrophysiology in isolated cerebral smooth muscle cell and pericytes, and capillary and arteriole electromechanical responses to transmural pressure changes are assessed using novel ex vivo preparations. C_LIO_LIMyogenic constrictions in arterioles can be reproduced by pressure-induced non-selective cation channel (NSC) activation that depolarizes the cell, opens L-type Ca2+ channels (VOCCs) and increases Ca2+ influx. C_LIO_LIRobust myogenic constrictions in arteriole-to-capillary transition (ACT) zone pericytes may reflect significant Ca2+ influx through NSC, increased mechanosensitivity, or higher sensitivity of the contractile apparatus to Ca2+, potentially compensating for reduced VOCC density relative to arteriolar smooth muscle. C_LIO_LIA significant contribution of NSC relative to VOCC in Ca2+ influx, can decouple the contractile apparatus from electrical signaling. C_LIO_LIThe model shows how gradients in ionic activities, mechanosensitivity and/or Ca2+ sensitivity can alter contractile phenotype and electromechanical coupling along the arteriole to capillary continuum. C_LIO_LIThe proposed model can form the basis for detailed multiscale and multicellular models that will investigate cerebral blood flow control in health and in disease. C_LI

physiology↗

bioRxiv2025

Adenosine and acute low oxygen conditions suppress urinary bladder contractility through the activation of adenosine 2B receptors and large-conductance calcium-activated potassium channels

Under healthy conditions the urinary bladder undergoes relatively long periods of filling with well-spaced voiding events to ensure proper storage and removal of urine respectively. During the filling phase, distinct contractile events in detrusor urinary smooth muscle (UBSM) elicit transient non-voiding pressure events and associated bursts in afferent nerve activity to relay the sensation of bladder fullness. The mechanisms that regulate UBSM excitability and associated non-voiding pressure events under physiological and pathological conditions are poorly understood. Here we investigated the role of adenosine signaling in regulating urinary bladder contractility. Using an ex vivo pressurized bladder preparation from mice and patch-clamp electrophysiology in isolated UBSM we evaluated whole bladder transient pressure events, whole bladder detrusor Ca2+ activity, and single UBSM ion channel activity. We found that adenosine suppresses bladder activity through activation of A2B adenosine receptors and downstream activation of large-conductance calcium-activated potassium (BKCa) channels. We further demonstrated that acute exposure to low oxygen conditions using a chemical oxygen scavenger potently suppresses bladder contractility through the A2B receptor pathway. These results highlight the prominent role adenosine receptors and downstream potassium channels play in regulating urinary bladder contractility in physiological and pathological contexts.

physiology↗

bioRxiv2021

Electro-Metabolic Sensing Through Capillary ATP-Sensitive K+ Channels and Adenosine to Control Cerebral Blood Flow

The dense network of capillaries composed of capillary endothelial cells (cECs) and pericytes lies in close proximity to all neurons, ideally positioning it to sense neuro/glial-derived compounds that regulate regional and global cerebral perfusion. The membrane potential (VM) of vascular cells serves as the essential output in this scenario, linking brain activity to vascular function. The ATP-sensitive K+ channel (KATP) is a key regulator of vascular VM in other beds, but whether brain capillaries possess functional KATP channels remains unknown. Here, we demonstrate that brain capillary ECs and pericytes express KATP channels that robustly control VM. We further show that the endogenous mediator adenosine acts through A2A receptors and the Gs/cAMP/PKA pathway to activate capillary KATP channels. Moreover, KATP channel stimulation in vivo causes vasodilation and increases cerebral blood flow (CBF). These findings establish the presence of KATP channels in cECs and pericytes and suggest their significant influence on CBF. HIGHLIGHTSO_LICapillary network cellular components--endothelial cells and pericytes--possess functional KATP channels. C_LIO_LIActivation of KATP channels causes profound hyperpolarization of capillary cell membranes. C_LIO_LICapillary KATP channels are activated by exogenous adenosine via A2A receptors and cAMP-dependent protein kinase. C_LIO_LIKATP channel activation by adenosine or synthetic openers increases cerebral blood flow. C_LI

neuroscience↗