Function (Oxford, England)最新文献

The cellular biology of macrophages underpins the multitude of roles that these cells undertake under homeostatic and inflammatory conditions. Macrophages populate all tissues where they contribute to organ physiology while acting as sensors of health and triggering inflammation in response to organ dysfunction, trauma and infection. Sharing key characteristics such as a highly developed endocytic compartment, secretion of growth factors and cytokines, motility and antigen presentation, macrophages undergo specific adaptations in each niche guided by environmental clues that result in diverse phenotypes that support tissue-specific roles such as iron recycling, synaptic pruning, bone reabsorption and processing of lung surfactant.This review will provide an overview of macrophage biology and heterogeneity that underpin their contribution to homeostasis and inflammation to illustrate their importance as therapeutic targets in a wide range of inflammatory diseases.

Time-restricted feeding (TRF), which confines food intake to specific time periods without altering nutrient content or reducing calories, has shown promise in improving cardiometabolic health. This study tested whether a two-week TRF intervention during the active (dark) period could reverse long-term effects of a high fat diet (HFD) on liver mitochondrial function, steatosis, and metabolism in mice. Male C57BL/6J mice were fed either a normal fat diet (NFD, 10% kcal fat) or a HFD (45% kcal fat) ad libitum for 18 weeks, followed by two weeks of active period TRF. Assessments included whole-body metabolism, gene expression, histopathology, plasma lipid levels, and mitochondrial bioenergetic function. Chronic HFD feeding abolished the day-night difference in the respiratory exchange ratio (RER), altered 24-h expression rhythms of clock, lipid, and mitochondrial metabolism genes in the liver, and eliminated diurnal variation in liver mitochondrial bioenergetics. TRF partially restored RER rhythmicity without altering body composition or reducing caloric intake in HFD mice. TRF also restored 24-h expression rhythms in clock and several metabolic genes, normalized liver and plasma triglyceride oscillations, and reduced small droplet macrosteatosis in livers of HFD mice. Importantly, TRF improved liver mitochondrial respiration and reduced circulating levels of mitochondrial transcription factor A (mtTFA), a mitochondrially-derived damage-associated molecule pattern (mtDAMP), indicating reduced mitochondrial injury in HFD mice. These findings suggest that TRF can rapidly reverse HFD-induced disruptions in metabolic and mitochondrial function, offering a promising new non-pharmacologic strategy for improving liver health in obesity-related metabolic disease.

Nanobodies, also known as single-domain antibodies, have become powerful tools in research, diagnosis and therapy. Sourced from the heavy chain of camelid Heavy chain-only antibodies, this domain retains many important characteristics of full-length antibodies while being ~10 times smaller in molecular weight. Nanobody discovery has seen expansive development over the recent past, via both conventional antigen-exposed and completely synthetic repertoires. Along these lines, binding properties of candidates can be evolved by subsequent mutation and selection cycles to adjust their specificity and avidity. Due to their small size and compact structure, nanobodies can reach cryptic sites not accessible to conventional antibodies and also show superior tissue penetration. This penetrance, alongside their ease of handling, has made nanobodies ideal candidates for a myriad of immunotherapeutic and drug delivery applications. Furthermore, their small size imparts minimal linkage errors when conjugated to a fluorophore, making nanobodies ideal tools for high resolution imaging techniques. Most importantly, nanobodies can be stably expressed in living cells to bind, block or modify intracellular targets, enabling study of proteins in a native context at unprecedented detail. In this Review, we present the latest developments in nanobody technology and discuss applications in bioimaging, therapy, and intracellular protein study.

We recently reported [Peng YJ, Nanduri J, Wang N, Xie Z, Fox AP, Prabhakar NR. Function (Oxf) 6: zqaf020, 2025] that fentanyl activates carotid body (CB) afferents via kappa opioid receptors (KORs), while CB denervation exacerbates, coadministration of fentanyl with a KOR agonist attenuates opioid-induced respiratory depression (OIRD). These findings indicated that CB chemoreflex activation by fentanyl may counteract OIRD. The present study investigated the cellular mechanisms underlying CB afferent activation by fentanyl. We hypothesized that Ca²⁺ signaling in glomus cells mediates CB activation by fentanyl. Using Fura-2 calcium imaging in rat glomus cells, we observed that fentanyl increased intracellular Ca²⁺ even in the absence of extracellular calcium. Pretreatment with thapsigargin, which depletes internal Ca²⁺ stores, abolished Ca²⁺ response, suggesting that fentanyl releases Ca²⁺ from intracellular stores. In human embryonic kidney cells expressing KOR and G protein alpha q subunit (Gαq), fentanyl promoted KOR-Gαq complex formation and stimulated phospholipase C (PLC), elevating inositol trisphosphate (IP₃) levels in the CB. Pharmacological blockade of KOR, Gαq, PLC, or IP₃ receptors prevented both the rise in [Ca²⁺]_i and CB afferent activation. Collectively, these results identify a previously uncharacterized KOR-Gαq-PLC-IP₃R-Ca²⁺ signaling pathway in glomus cells that mediates CB afferent activation by fentanyl, providing new mechanistic insight into how CB chemoreflex activation by fentanyl may mitigate OIRD.

Projections from the paraventricular nucleus (PVN) of the hypothalamus to the nucleus of the solitary tract (nTS) facilitate the peripheral chemoreflex. A significant proportion of this projection is composed of corticotropin-releasing hormone (CRH) neurons. Orexin neurons in the perifornical hypothalamus augment the peripheral chemoreflex, project to the PVN, and facilitate the hypoxia-induced activation of nTS-projecting CRH neurons. We hypothesized that nTS-projecting CRH neurons are necessary for the full reflex, and that orexin facilitates the reflex via the CRH-nTS pathway. We chemogenetically silenced or activated nTS-projecting CRH neurons during normoxia and acute hypoxia. For each rat, reflex strength was tested in both inactive and active phases as the activity of orexin neurons is phase dependent. Testing was done following vehicle, Compound 21 (1 mg/kg) to activate Gi- or Gq-DREADDs, and after systemic Ox1R blockade (SB-334867; 1 mg/kg). We performed immunohistochemistry to assess how chemogenetic manipulation of nTS-projecting CRH neurons influenced their activation by hypoxia (via cFos). Activating the CRH-nTS pathway had no effect on the chemoreflex in either phase. Silencing the pathway in the active phase, but not inactive phase, reduced the strength of the reflex by ∼50% and prevented further inhibition by Ox1R blockade, suggesting orexin acts via Ox1R on CRH neurons. Pathway silencing reduced the proportion of nTS-projecting CRH neurons activated by hypoxia, consistent with the effects of pathway silencing on the reflex. These data suggest that orexin augments the peripheral chemoreflex in the active phase via the CRH-nTS pathway.

The quantity of physiological data has grown exponentially, yielding insights into mechanisms of phenotypic and disease pathways. Among the powerful tools for physiological omics is the study of RNA, where broad sequencing of RNA leads to hypothesis generation and testing while providing observational discovery. Emphasis has been placed on RNA molecules that code for proteins, even though they represent a minority of total RNA. Diverse sequencing methods have rapidly expanded the identification of non-protein-coding molecules, including nonsense-mediated decay and long non-coding RNAs (lncRNA), which now represent the most diverse class of RNA. Increasing attention needs to be paid to the data processing of RNA sequencing to interpret transcript-level mapping data in the context of protein biology, as many protein-coding genes have diverse noncoding transcripts. Over the past several years, single-cell and spatial transcriptomics have yielded unprecedented insights into cellular, tissue, and organ physiology. Building on these advancements, bulk RNA sequencing tools have begun producing robust deconvolution methods that enhance the analysis of human genes, the detection of foreign RNA from bacteria and viruses, and provide deep insights into complex immunological events, such as B- and T-cell recombination. Over a million RNA-sequencing datasets have been generated, providing resources for data scientists to reprocess data and expand larger databases. From model organisms to complex human diseases, RNA sequencing resources continue to transform our knowledge of the complexity of personalized disease insights. Observational science is at the core of physiology, and growth of RNA sequencing represents a significant tool for physiologists.

Baroreflex responsiveness and orthostatic stability in humans can be assessed by a variety of approaches, including exposure to graded levels of lower body negative pressure (LBNP). However, such approaches have limited applicability in animal studies owing to the need to anesthetize or sedate the animal. We recently reported a novel approach for the assessment of baroreceptor responsiveness in the awake rat using LBNP and presented preliminary findings that 3% isoflurane anesthesia completely blocked the normally robust baroreflex. In the present study, we sought to extend these findings by studying the effects of several common anesthetics on LBNP responsiveness. Blood pressure (BP) and heart rate (HR) responses to progressive levels of LBNP were first made in awake rats (male and female), followed by measurements under various anesthetics regimens: 1) pentobarbital; 2) ketamine plus xylazine; 3) isoflurane at 3%, 2%, and 1.5%; 4) urethane delivered as an intraperitoneal bolus, slow intraperitoneal infusion, and slow intravenous infusion. As previously reported, BP in awake rats was well maintained up to -15 mmHg LBNP, accompanied by a robust baroreflex tachycardia. Despite varying effects on steady-state BP and HR, all of the anesthetics tested severely or completely blocked the ability to maintain BP during LBNP and completely blocked reflex tachycardia. BP, but not reflex tachycardia, during LBNP was partially preserved only in those rats treated with intravenous urethane. These data confirm that the functional baroreflexes that normally maintain BP during orthostatic challenge are blocked by commonly used anesthetics.

Inflammation is a critical immune response to tissue injury or infection, involving a cascade of molecular and cellular events. This review examines acute inflammation, focusing on the key receptors, signaling pathways, mediators, and cellular players involved in the response throughout the body. The latter part of the review narrows its focus to kidney inflammation, a vital organ often affected by both sterile and nonsterile insults. By exploring the roles of immune and nonimmune cells, this review highlights general inflammatory mechanisms and their impact on kidney-specific pathophysiology.