American journal of physiology. Gastrointestinal and liver physiology最新文献

Defecatory dysfunction (DD) is a common cause of chronic constipation resulting from functional abnormalities or structural pelvic pathologies. Accurate diagnosis requires combining anorectal manometry (ARM), balloon expulsion test (BET), and defecography. This study evaluates the diagnostic utility of these modalities and explores uncertainties in their performance and interpretation. This retrospective study included 325 adult patients assessed for DD between 2020 and 2023. All patients went through ARM, BET in the left lateral position, and defecography. Statistical associations between test outcomes were analyzed to assess diagnostic concordance and significance. A strong correlation was observed between ARM and defecography, with 65% of patients with normal anal relaxation on ARM achieving normal rectal evacuation on defecography (P < 0.0001). Conversely, patients with paradoxical contraction during ARM demonstrated a higher likelihood of evacuation failure. BET demonstrated high specificity but limited sensitivity in association with relaxation on ARM and evacuation on defecography. BET failure did not demonstrate a significant association with the presence of pelvic floor pathologies. Combining ARM, BET, and defecography provides a comprehensive framework for diagnosing DD, addressing its functional and structural components. This integrated approach facilitates targeted interventions, ultimately improving clinical outcomes.NEW & NOTEWORTHY This study demonstrates that anal relaxation on anorectal manometry significantly correlates with rectal evacuation on defecography, supporting its physiological relevance. Balloon expulsion in the left lateral position shows high specificity but low sensitivity for defecatory dysfunction. Notably, balloon expulsion test (BET) failure was not associated with anatomical abnormalities. An integrated diagnostic approach using anorectal manometry (ARM), BET, and defecography enhances accuracy in distinguishing functional from structural causes of pelvic floor dysfunction.

The Western diet (WD) has been associated with various pathologies, largely due to chronic inflammatory responses triggered by insulin spikes and excess cholesterol. However, the effects of maternal WD on offspring are currently understudied. We hypothesize that maternal WD consumption in baboons induces a hyperinflammatory state in offspring, leading to compromised intestinal barrier function. Intestinal tissue was harvested from olive baboon (Papio anubis) 0.9 gestation fetuses and juveniles (age 2-3 yr), whose mothers were fed either a high-fat/high-sugar WD or a control diet (CD) of standard monkey chow. RNA and protein were isolated and analyzed for markers of inflammation and apoptosis. Intestinal organoids (enteroids) were generated from these bowel samples and subsequently subjected to hypoxia and LPS to simulate necrotizing enterocolitis (NEC). RNA was extracted and similarly examined for inflammatory markers and markers of apoptosis. Enteroids were plated onto TransWellTM plates to evaluate barrier function. Immunohistochemistry and immunofluorescence were used to evaluate barrier proteins. The intestinal tissue of baboon fetuses and juveniles of mothers fed a Western diet exhibited evidence of a hyperinflammatory state. Although not all cytokines reached our significance set a priori at P < 0.05, interleukin-8 (IL-8) and Interferon γ (IFNγ) were significantly elevated. This trend was stable across generations. Offspring from the Western diet group exhibited decreased barrier function based on transepithelial resistance measurements. Maternal consumption of a Western diet during gestation in olive baboons leads to a generalized inflammatory state and weakened intestinal barrier function in offspring, with potential long-term health implications.NEW & NOTEWORTHY Our research examines a currently understudied area of the maternal/fetal relationship. This is especially pertinent, given the rampant access to high-fat/high-sugar foods in the Western diet. It is also noteworthy due to the findings of decreased barrier function among those in the Western diet group. This decreased function and hyperinflammatory state can prime neonates for various pathologies, such as necrotizing enterocolitis.

The enteric nervous system (ENS) continues to be exposed to various disturbances throughout life, which causes apoptosis in the ENS. Therefore, it is assumed that neurogenesis is induced to maintain the neuronal network in the adult ENS. However, these underlying mechanisms are largely unknown. We aimed to investigate adult neurogenesis in the dextran sodium sulfate (DSS)-induced colitis mouse colon. Male C57BL/6N mice (12-wk-old) were administered 2% DSS in their drinking water for 8 days. After DSS treatment, cross-sections and longitudinal muscle and myenteric plexus preparations from the colon were used for immunohistochemistry. The segments of colons were mounted in organ baths and then exposed to a voltage-gated sodium channel activator veratridine. In the motility study, veratridine-induced colonic contractions were significantly suppressed in DSS-induced colitis mice compared with normal mice. Immunohistochemical analyses revealed that the proportion of nitrergic neurons per ganglion was significantly increased in the colons of DSS-induced colitis mice compared with normal mice. Furthermore, the proportion of Sox2 (new-born neuron marker)-positive neurons per ganglion was not significantly different between normal mice and DSS-induced colitis mice, whereas the proportion of Sox2-positive nitrergic neurons to Sox2-positive neurons per ganglion was significantly increased in the colons of DSS-induced colitis mice compared with normal mice. In addition, NOS inhibitor significantly enhanced veratridine-induced colonic contractions in DSS-induced colitis mice compared with normal mice. These findings suggested that colitis caused an imbalance in the enteric neural circuit composed of excitatory neurons and inhibitory neurons in the myenteric plexus of the colon, which resulted in colonic dysmotility.NEW & NOTEWORTHY ENS continues to be exposed to various disturbances throughout life, which causes adult apoptosis in the ENS. In this study, the frequency of adult neurogenesis was not altered by colitis, whereas colitis selectively induced adult neurogenesis of nNOS-positive inhibitory motor neurons in the myenteric plexus of the colon by preferential adult neurogenesis, indicating that colitis caused an imbalance in the enteric neural circuit composed of excitatory neurons and inhibitory neurons, which resulted in colonic dysmotility.

Inflammatory bowel diseases (IBDs), including Crohn's disease and ulcerative colitis, are debilitating and complex chronic gastrointestinal disorders that affect not only the gut but also extraintestinal organs, including the heart. The gut-heart cross talk has garnered increasing attention in recent years; however, the molecular mechanisms underlying this complex interplay remain poorly understood. This review explores the gut-heart axis, focusing on how IBD disrupts gut microbiota homeostasis and promotes cardiac remodeling through systemic inflammation and various mediators, ultimately contributing to the onset or progression of heart failure. IBD compromises the integrity of the intestinal barrier, allowing microbial metabolites such as trimethylamine N-oxide and phenylacetylglutamine, along with inflammatory cytokines and microRNAs (miRNAs) (e.g., miR-155, miR-21, and let-7a), to enter the circulation and contribute to cardiac remodeling and heart failure. We identify dysfunction of nucleotide-binding oligomerization domain-containing protein 2 as a critical link between gut immunity and cardiovascular pathology. In addition, we discuss emerging microbiome-based therapeutic strategies, including fecal microbiota transplantation and IL-23 inhibitors, aimed at restoring gut homeostasis and mitigating cardiovascular risk. By integrating molecular mechanisms, clinical evidence, and therapeutic approaches, this review underscores the pivotal role of gut dysbiosis in cardiac dysfunction and offers new perspectives for managing cardiac dysfunction in patients with IBD.

Serine/threonine phosphatases, protein phosphatases 1 and 2A (PP1 and PP2A), play important roles in mediating cellular signaling in different tissues to different stimuli, including glycogen metabolism, protein synthesis/growth, and secretion. However, the roles of PP1/PP2A in pancreatic acinar cell secretion/growth are both unclear and controversial. To address this issue, in the present study, we examined the ability of gastrointestinal hormones/growth factors (GFs) to activate PP1 and PP2A and the signaling cascades involved in rat pancreatic acini and the pancreatic acinar tumor cell line, AR42J cells. PP1 and PP2A were both detected in pancreatic acini and AR42J cells. In acini, PP1 and PP2A were activated by pancreatic secretagogues-stimulating phospholipase C (bombesin, CCK-8, and carbachol) and endothelin and by pancreatic GFs (insulin, hepatocyte growth factor, epidermal growth factor, basic fibroblast growth factor, platelet-derived growth factor, and insulin-like growth factor 1). Full CCK-8 activation of PP1/PP2A required activation of both high- and low-affinity CCK1-receptor states. Using specific PP1 and PP2 assays, in both acini and AR42J cells, experimental conditions were established, where calyculin A, a known nonselective PP1/PP2A inhibitor, inhibited activation of both, whereas okadaic acid and fostriecin inhibited only PP2A activation and tautomycetin inhibited only PP1 activation. Under these conditions, CCK-stimulated enzyme secretion and stimulation of p44/42, a key mediator of growth, required PP2A activation, without activation of PP1. Using specific siRNA for PP1/PP2A in AR42J cells, similar results were found. These results establish that only PP2A activation is essential for CCK-mediated stimulation of growth and enzyme secretion in pancreatic acinar cells and pancreatic acinar AR42J tumor cells.NEW & NOTEWORTHY Despite more than 10 studies, the roles of the serine/threonine phosphatases, PP1/PP2A, in pancreatic acinar cell-secretion/growth remain controversial. This study demonstrates that both PP1/PP2A are present in rat pancreatic acini and in pancreatic acinar tumor-AR42J cells. Both phosphatases are activated by pancreatic secretagogues, stimulating PLC, and by pancreatic growth factors. Using specific inhibitory conditions for PP1/PP2A (inhibitors, siRNA studies), only PP2A activation is needed for CCK-8-stimulated enzyme secretion and growth signaling cascades in pancreatic acinar cells.

Together, the costal and crural diaphragm constitute the primary respiratory muscle in mammals, but functionally, they are distinct. The crural segment has additional gastrointestinal function, wrapped around the esophagus at the esophagogastric junction, contributing to the esophageal sphincter. Emesis is an expulsive process that requires the coordinated action of multiple muscles to rapidly force out gastric contents. The simultaneous mechanical action and neural activation of the diaphragm segments during the process of emesis, especially expulsion, is uncertain. Detailed divergence of the crural diaphragm to sphincter function during emesis has not been studied. In six awake, spontaneously breathing canines, electrical activity and corresponding muscle shortening of the costal and crural diaphragm were measured at five phases of emesis (rest, early prodrome, mid prodrome, late prodrome, and expulsion) induced by apomorphine. Overall, baseline muscle length decreased and baseline EMG increased progressively from rest through prodrome for both costal and crural, but at expulsion, the crural segment diverged, lengthening abruptly. Shortening and EMG activity per breath for costal changed slightly throughout emesis; crural shortening and EMG activity increased abruptly at expulsion. The divergent action of crural during expulsion developed sequentially through each breath. Also, neuromechanical coupling of the segments reversed at expulsion, with contractility of the crural surpassing that of the costal. These measurements confirm a disparate action of crural diaphragm, compared with costal, to facilitate expulsion. During the process of emesis, although the costal persists as an obligatory respiratory muscle, the crural converts from respiratory muscle to opening sphincter.NEW & NOTEWORTHY Although the diaphragm is known as a primary respiratory muscle, the two diaphragm sections, the costal and crural, have notably different functions. This study elucidates the essential role of the crural diaphragm during emesis, a gastrointestinal process. During emesis, the crural diaphragm abandons respiratory function and transmutes to act as an esophageal sphincter. Meanwhile, the costal diaphragm continues ventilatory function.

Patatin-like phospholipase domain-containing protein 3 (PNPLA3) p.I148M is a well-established variant associated with metabolic dysfunction-associated steatotic liver disease (MASLD) and metabolic dysfunction-associated steatohepatitis (MASH). Conflicting in vitro and in vivo data about the impact of the variant suggest that the PNPLA3 p.I148M variant could be gain- or loss-of-function, or neomorphic. Most in vitro models used to study MASLD are cancer-derived hepatoma cell lines such as HepG2 and Huh7, which already endogenously express the homozygous PNPLA3 p.I148M variant. This highlights the need to develop models that better reflect disease and allow comparisons with wild-type cells. Clustered regularly interspaced short palindromic repeats (CRISPR) prime editing was used to introduce the PNPLA3 p.I148M gene variant into a healthy-derived immortalized human hepatocyte (IHH) cell line to generate a new in vitro model of MASLD that would better reflect PNPLA3-associated MASLD/MASH. Heterozygous and homozygous PNPLA3 p.I148M IHH cell lines were generated and validated with Sanger sequencing. Mutant cell lines exhibited lipid accumulation, increased cluster of differentiation 36 (CD36) gene expression and a decline in carnitine palmitoyltransferase 1 alpha (CPT1A) gene expression compared with the wild-type control, basally or in the presence of free fatty acid (FFA)-induced steatosis. The homozygous PNPLA3 p.I148M IHH cell line also demonstrated reduced PNPLA3 gene and protein expression compared with the wild-type control. We have developed a new human hepatocyte cell line and in vitro model to help understand PNPLA3-associated steatotic liver disease and provide a new resource for developing potential therapeutics.NEW & NOTEWORTHY We have developed a novel in vitro model for studying the PNPLA3 p.I148M variant in steatotic liver disease using a normal, healthy-derived hepatocyte cell line, which does not endogenously express the variant. We show that carrying the homozygous PNPLA3 p.I148M variant results in reduced PNPLA3 gene and protein expression, more lipid accumulation, increased lipid uptake, and reduced mitochondrial lipid oxidation-associated gene expressions and altered expression of genes associated with lipid synthesis and transport.

Metabolic dysfunction-associated steatotic liver disease (MASLD) affects ∼40% of adults, but causal mechanisms remain elusive. Preclinical models implicate the gut microbiota in MASLD pathogenesis, yet translation to humans is hampered by variability in microbial composition. We addressed this gap by investigating whether stable, quantitative gut phenotypes, including microbiota encroachment, are pathological features of MASLD. Sigmoid colon biopsies were collected from participants with and without imaging-defined MASLD. Mucus immunostaining was paired with fluorescent in situ hybridization to image and quantify the distance separating bacteria from the colonic epithelium (i.e., encroachment). Secondary outcomes included intestinal permeability, colon histopathology, and insulin resistance. RNA sequencing was combined with weighted gene network correlation analysis to explore correlations between colonic gene expression and clinical endpoints. Microbiota encroachment did not differentiate participants with MASLD (n = 13 with simple steatosis, n = 13 with fibrosis stage <4) from controls (n = 12; P = 0.20). Circulating lipopolysaccharide and flagellin-specific immunoglobulins (intestinal permeability), and colon histopathology were similar across cohorts (P = 0.23, P = 0.11, and P = 0.73, respectively). Microbiota encroachment and adipose tissue insulin resistance (Adipo-IR) were correlated with a colonic gene network regulating insulin and lipid metabolism (Pearson's r = -0.33, P = 0.04 and r = 0.47, P = 0.003, respectively). Pathway analysis of this network revealed genes involved in hepatic steatosis (P = 3.95E-06) and liver cell proliferation (P = 0.0003), suggesting a gut-adipose-liver cross talk. Microbiota encroachment and related gut phenotypes do not correlate with MASLD severity. However, colonic expression of genes related to insulin signaling and lipid metabolism links microbiota encroachment to Adipo-IR and MASLD. Future research should investigate how colonic gene products interact with microbiota-focused MASLD mechanisms.NEW & NOTEWORTHY In a first-in-human study, we observed that colonic expression of insulin and lipid-related genes may bridge the pathophysiology of colonic microbiota encroachment with adipose tissue insulin resistance and metabolic dysfunction-associated steatotic liver disease.