Podocan unraveled: Understanding its role in tumor proliferation and smooth muscle regulation.

Podocan, a small leucine-rich repeat protein, is expressed in HIV-associated nephropathy, the cardiovascular system, and smooth muscle. Studies have linked PODN and PODNL to cancers such as osteosarcoma, glioma, and stomach cancer. Research has primarily focused on podocan's role in renal podocytes, injured smooth muscle cells, and various tumor cells. Bioinformatics studies have examined the role of PODN as a biomarker in tumors. Our research summarizes the modulatory role of podocan in smooth muscle and tumor proliferation through its suppression of cell proliferation and promotion of cell differentiation via various signaling pathways, including Wnt/ß-catenin, TGF-ß, and Akt/mTOR. We aim to provide a comprehensive overview of PODN's involvement in smooth muscle, cardiovascular system, and tumors by integrating current and past research. This review aims to enhance understanding and inform in the diagnosis, prognosis, and treatment of various diseases.

Fibrogenesis in Human Mucosa and Muscularis Precision-Cut Intestinal Slices.

In Crohn's Disease (CD), intestinal fibrosis is a prevalent yet unresolved complication arising from chronic and transmural inflammation. The histological assessment of CD intestines shows changes in tissue morphology in all the layers, including the mucosa and muscularis. This study aimed to determine the differences in fibrogenesis between mucosa and muscularis. Human precision-cut intestinal slices (hPCIS) were prepared from human intestine mucosa and muscularis and treated with TGF-ß1 and/or PDGF-BB for 72 h. Gene and protein expression and matrix metalloproteinase (MMP) activity were determined. The basal gene expression of various fibrosis markers was higher in muscularis compared to mucosa hPCIS. During incubation, Pro-Collagen-1A1 secretion increased in muscularis but not in mucosa hPCIS. MMP gene expression increased during incubation in mucosa and muscularis hPCIS, except for MMP9, MMP12, and MMP13 in muscularis hPCIS. Incubation with TGF-ß1 caused increased COL1A1 expression in the mucosa but not in muscularis hPCIS. In muscularis hPCIS, TGF-ß1 treatment caused a decrease in MMP1 and CTSK expression, while MMP13 was increased. In the presence of TGF-ß1, protease inhibitor expression was stable, except for SERPINE1, which was increased in muscularis hPCIS. We conclude that fibrogenesis is more pronounced in muscularis hPCIS compared to mucosa hPCIS, especially when stimulated with TGF-ß1.

[Pathological changes in the muscular tissue of the colon in diverticular disease]. / Patologicheskie izmeneniya myshechnoi tkani v stenke tolstoi kishki pri divertikulyarnoi bolezni.

The high incidence of colonic diverticular disease (DD) in the general population is a serious public health problem. According to statistics, DD is among the top five most common colorectal diseases. Complicated course of DD is observed in 12-15% of patients, and in 10.7% of cases can lead to death. Algorithms and recommendations for predicting the complicated course of DD for further prevention have not been developed. OBJECTIVE: Comparative analysis of clinical data and structural characteristics of the colonic muscular tissue in patients with different course of DD and without colonic diverticula to identify morphological predictors of a complicated DD. MATERIAL AND METHODS: A comparative analysis of clinical data, pathomorphological and ultrastructural changes of the colonic musculature in the surgical material from 68 patients undergoing left-sided hemicolectomy was carried out. RESULTS: The operative material of 37 patients with complicated course of DD, 19 with uncomplicated course of DD and 12 without diverticula was analyzed. In men, this disease occurs at a younger age than in women (Median age of men 49 (39.5; 61) years, women 66.5 (58; 81) years; U=178, p<0.001). It was shown that the area occupied by connective tissue fibres in the colonic musculature in patients with a complicated DD was 5 times greater (15%) than in observations with an uncomplicated DD (3%) and 50 times greater than in cases without colonic diverticula (0.3%; p<0.001). CONCLUSION: The present study demonstrates age- and sex-specific features of DD, as well as significant differences in the prevalence of fibrosis of the colonic musculature, which can be considered as a potential predictor of a complicated course of DD.

Prepyloric gastric antral muscular ring in an infant.

We present a unique case of a prepyloric gastric muscular ring, a pathology distinct from a gastric web. There is scarcity of literature on this topic, nearly all cases of prepyloric antral rings or webs published in literature are mucosal or submucosal in nature with no evidence of muscle hypertrophy. Given the prevalence of pyloric stenosis as the most common gastric outlet malformation in neonates, gastric rings and webs are not readily considered in the differential diagnosis of gastric outlet obstruction. While most cases of gastric outlet obstruction are diagnosed radiologically, less common pathologies will be confirmed with direct visual inspection during surgery. The term "congenital gastric outlet obstruction" has been used to encompass rare cases, making it appropriate to include a muscular ring in this category. We propose the term "gastric ring" be used with a semantic modifier of "muscular" versus "submucosal/mucosal" to avoid confusion.

T cell and airway smooth muscle interaction: a key driver of asthmatic airway inflammation and remodeling.

Cross talk between T cells and airway smooth muscle (ASM) may play a role in modulating asthmatic airway inflammation and remodeling. Infiltrating T cells have been observed within the ASM bundles of asthmatics, and a wide range of direct and indirect interactions between T cells and ASM has been demonstrated using various in vitro and in vivo model systems. Contact-dependent mechanisms such as ligation and activation of cellular adhesion and costimulatory molecules, as well as the formation of lymphocyte-derived membrane conduits, facilitate the adhesion, bidirectional communication, and transfer of materials between T and ASM cells. T cell-derived cytokines, particularly of the Th1, Th2, and Th17 subsets, modulate the secretome, proliferation, and contractility of ASM cells. This review summarizes the mechanisms governing T cell-ASM cross talk in the context of asthma. Understanding the underlying mechanistic basis is important for directing future research and developing therapeutic interventions targeted toward this complex interaction.

From diverticulosis to complicated diverticular disease: Progression of myogenic alterations and oxidative imbalance.

BACKGROUND: The natural history and pathophysiology of diverticular disease (DD) are still uncertain. An ex-vivo human complicated DD (cDD) model has recently shown a predominant transmural oxidative imbalance. The present study aims to evaluate whether the previously described alterations may precede the symptomatic form of the disease. METHODS: Colonic surgical samples obtained from patients with asymptomatic diverticulosis (DIV), complicated DD, and controls were systematically and detailed morphologically and molecularly analyzed. Therefore, histologic, histomorphometric, immunohistochemical evaluation, and gene and protein expression analysis were performed to characterize colonic muscle changes and evaluate chronic inflammation, oxidative imbalance, and hypoxia. Functional muscle activity was tested on strips and isolated cells in response to contractile and relaxant agents. KEY RESULTS: Compared with controls, DD showed a marketed increase in muscle layer thickness, smooth muscle cell syncytium disarray, and increased interstitial fibrosis; moreover, the observed features were more evident in the cDD group. These changes mainly affected longitudinal muscle and were associated with altered contraction-relaxation dynamics and fibrogenic switch of smooth muscle cells. Chronic lymphoplasmacytic inflammation was primarily evident in the mucosa and spared the muscle. A transmural increase in carbonylated and nitrated proteins, with loss of antioxidant molecules, characterized both stages of DD, suggesting early oxidative stress probably triggered by recurrent ischemic events, more pronounced in cDD, where HIF-1 was detected in both muscle and mucosa. CONCLUSION & INFERENCES: The different DD clinical scenarios are part of a progressive process, with oxidative imbalance representing a new target in the management of DD.

Muscular hyperplasia in Crohn's disease strictures: through thick and thin.

Fibrostenosing Crohn's disease (CD) represents a challenging clinical condition characterized by the development of symptomatic strictures within the gastrointestinal tract. Despite therapeutic advancements in managing inflammation, the progression of fibrostenotic complications remains a significant concern, often necessitating surgical intervention. Recent investigations have unveiled the pivotal role of smooth muscle cell hyperplasia in driving luminal narrowing and clinical symptomatology. Drawing parallels to analogous inflammatory conditions affecting other organs, such as the airways and blood vessels, sheds light on common underlying mechanisms of muscular hyperplasia. This review synthesizes current evidence to elucidate the mechanisms underlying smooth muscle cell proliferation in CD-associated strictures, offering insights into potential therapeutic targets. By highlighting the emerging significance of muscle thickening as a novel therapeutic target, this review aims to inform future research endeavors and clinical strategies with the goal to mitigate the burden of fibrostenotic complications in CD and other conditions.

Molecular mechanisms linking missense ACTG2 mutations to visceral myopathy.

Visceral myopathy is a life-threatening disease characterized by muscle weakness in the bowel, bladder, and uterus. Mutations in smooth muscle γ-actin (ACTG2) are the most common cause of the disease, but the mechanisms by which the mutations alter muscle function are unknown. Here, we examined four prevalent ACTG2 mutations (R40C, R148C, R178C, and R257C) that cause different disease severity and are spread throughout the actin fold. R178C displayed premature degradation, R148C disrupted interactions with actin-binding proteins, R40C inhibited polymerization, and R257C destabilized filaments. Because these mutations are heterozygous, we also analyzed 50/50 mixtures with wild-type (WT) ACTG2. The WT/R40C mixture impaired filament nucleation by leiomodin 1, and WT/R257C produced filaments that were easily fragmented by smooth muscle myosin. Smooth muscle tropomyosin isoform Tpm1.4 partially rescued the defects of R40C and R257C. Cryo-electron microscopy structures of filaments formed by R40C and R257C revealed disrupted intersubunit contacts. The biochemical and structural properties of the mutants correlate with their genotype-specific disease severity.

Smooth muscle hyperplasia in protein kinase C-fused blue naevi: Report of 12 cases.

BACKGROUND AND AIMS: PKC-fused blue naevi are a recently described group of melanocytic tumours that have distinctive morphological features, including a pigmented epithelioid melanocytoma-like junctional component or a dermal biphasic architecture associating with naevocytoid nests surrounded by dendritic and spindled pigmented melanocytes (so-called 'combined common and blue naevus'). There have been reports of smooth muscle hyperplasia in a hamartoma-like pattern in cases of combined blue naevi without genetic exploration. MATERIALS AND METHODS: Herein, we describe 12 cases of protein kinase C (PKC)-fused blue tumours associated with a co-existing smooth muscle hyperplasia, identified from a total of 98 PKC-fused melanocytic tumours. Archived slides of PKC-fused blue naevi with haematoxylin, eosin and phloxin staining, immunohistochemistry and molecular confirmation of a PKC-fusion by fluorescence in-situ hybridisation (FISH) or RNAseq were re-evaluated for identification of notable smooth muscle hyperplasia. Fifty-one of these slides had already been studied in a previous publication from our group. RESULTS: The hyperplasia ranged from hypertrophic arrector pili muscles to extensive horizontal bundles of disorganised fibres constantly associated and limited within a biphasic dermal melanocytic component. At least one arrector pili muscle was always visible within the tumour, with occasionally direct extension of the hyperplastic fibres from the main muscle body. These muscle fibres were devoid of a PKC-fusion signal by FISH. PKC molecules are involved in the regulation of smooth muscle function, offering an explanatory framework. CONCLUSIONS: These data suggest incorporating smooth muscle hyperplasia as a diagnostic morphological feature of PKC-fused blue melanocytic tumours.

Evaluation of Neuromuscular Morphometry of the Vaginal Wall Using Protein Gene Product 9.5 (Pgp 9.5) and Smooth Muscle α-Actin (Sma) in Patients with Posterior Vaginal Wall Prolapse.

Background and Objectives: This study aims to compare the neuromuscular structure of the vagina in women with posterior vaginal wall prolapse with the neuromuscular structure of the vagina in women without prolapse, to determine the difference, and to demonstrate the role of neuromuscular structure in the physiopathology of prolapse. Materials and Methods: In this prospective study, women aged between 40 and 75 years who had not undergone any vaginal surgery and had not undergone any abdominal prolapse surgery were included. Thirty-one women diagnosed with rectocele on examination were included in the study group. Thirty-one patients who underwent vaginal intervention and hysterectomy for reasons other than rectocele (colposcopy, conization, etc.) without anterior or posterior wall prolapse were included in the control group. Biopsy material was obtained from the epithelium of the posterior wall of the vagina, including the fascia that fits the Ap point. Immunohistochemical staining with Protein Gene Product 9.5 and smooth muscle α-actin was performed in the pathology laboratory. The epithelial thickness measurement and smooth muscle density parameters obtained with these immunohistochemical stainings were compared between the two groups. The collected data were analyzed using the SPSS 23 package program. p values less than 0.05 were considered statistically significant. Results: In the control group, muscle thickness and the number of nerves per mm2 of fascia were statistically significantly higher than in the study group (p < 0.05). Conclusions: We found that smooth muscle tissue and the number of nerves per mm2 of fascia were decreased in posterior vaginal wall prolapse compared to the general population. Based on the correlation coefficients, age was the parameter that most affected the degree of prolapse, followed by parity, number of live births, and number of vaginal deliveries.

Long-term follow-up of TREK-1 KO mice reveals the development of bladder hypertrophy and impaired bladder smooth muscle contractility with age.

Stretch-activated two-pore domain K+ (K2P) channels play important roles in many visceral organs, including the urinary bladder. The TWIK-related K+ channel TREK-1 is the predominantly expressed K2P channel in the urinary bladder of humans and rodents. Downregulation of TREK-1 channels was observed in the urinary bladder of patients with detrusor overactivity, suggesting their involvement in the pathogenesis of voiding dysfunction. This study aimed to characterize the long-term effects of TREK-1 on bladder function with global and smooth muscle-specific TREK-1 knockout (KO) mice. Bladder morphology, bladder smooth muscle (BSM) contractility, and voiding patterns were evaluated up to 12 mo of age. Both sexes were included in this study to probe the potential sex differences. Smooth muscle-specific TREK-1 KO mice were used to distinguish the effects of TREK-1 downregulation in BSM from the neural pathways involved in the control of bladder contraction and relaxation. TREK-1 KO mice developed enlarged urinary bladders (by 60.0% for males and by 45.1% for females at 6 mo; P < 0.001 compared with the age-matched control group) and had a significantly increased bladder capacity (by 137.7% at 12 mo; P < 0.0001) and compliance (by 73.4% at 12 mo; P < 0.0001). Bladder strips isolated from TREK-1 KO mice exhibited decreased contractility (peak force after KCl at 6 mo was 1.6 ± 0.7 N/g compared with 3.4 ± 2.0 N/g in the control group; P = 0.0005). The lack of TREK-1 channels exclusively in BSM did not replicate the bladder phenotype observed in TREK-1 KO mice, suggesting a strong neurogenic origin of TREK-1-related bladder dysfunction.NEW & NOTEWORTHY This study compared voiding function and bladder phenotypes in global and smooth muscle-specific TREK-1 KO mice. We found significant age-related changes in bladder contractility, suggesting that the lack of TREK-1 channel activity might contribute to age-related changes in bladder smooth muscle physiology.

Downregulation of protein phosphatase 2Aα in asthmatic airway smooth muscle.

Airway smooth muscle cell (ASM) is renowned for its involvement in airway hyperresponsiveness through impaired ASM relaxation and bronchoconstriction in asthma, which poses a significant challenge in the field. Recent studies have explored different targets in ASM to alleviate airway hyperresponsiveness, however, a sizeable portion of patients with asthma still experience poor control. In our study, we explored protein phosphatase 2 A (PP2A) in ASM as it has been reported to regulate cellular contractility by controlling intracellular calcium ([Ca2+]i), ion channels, and respective regulatory proteins. We obtained human ASM cells and lung tissues from healthy and patients with asthma and evaluated PP2A expression using RNA-Seq data, immunofluorescence, and immunoblotting. We further investigated the functional importance of PP2A by determining its role in bronchoconstriction using mouse bronchus and human ASM cell [Ca2+]i regulation. We found robust expression of PP2A isoforms in human ASM cells with PP2Aα being highly expressed. Interestingly, PP2Aα was significantly downregulated in asthmatic tissue and human ASM cells exposed to proinflammatory cytokines. Functionally, FTY720 (PP2A agonist) inhibited acetylcholine- or methacholine-induced bronchial contraction in mouse bronchus and further potentiated isoproterenol-induced bronchial relaxation. Mechanistically, FTY720 inhibited histamine-evoked [Ca2+]i response and myosin light chain (MLC) phosphorylation in the presence of interleukin-13 (IL-13) in human ASM cells. To conclude, we for the first time established PP2A signaling in ASM, which can be further explored to develop novel therapeutics to alleviate airway hyperresponsiveness in asthma.NEW & NOTEWORTHY This novel study deciphered the expression and function of protein phosphatase 2Aα (PP2Aα) in airway smooth muscle (ASM) during asthma and/or inflammation. We showed robust expression of PP2Aα in human ASM while its downregulation in asthmatic ASM. Similarly, we demonstrated reduced PP2Aα expression in ASM exposed to proinflammatory cytokines. PP2Aα activation inhibited bronchoconstriction of isolated mouse bronchi. In addition, we unveiled that PP2Aα activation inhibits the intracellular calcium release and myosin light chain phosphorylation in human ASM.

TGFß2 mediates oxidative stress-induced epithelial-to-mesenchymal transition of bladder smooth muscle.

Bladder outlet obstruction (BOO) is the primary clinical manifestation of benign prostatic hyperplasia, the most common urinary system disease in elderly men, and leads to associated lower urinary tract symptoms. Although BOO is reportedly associated with increased systemic oxidative stress (OS), the underlying mechanism remains unclear. The elucidation of this mechanism is the primary aim of this study. A Sprague-Dawley rat model of BOO was constructed and used for urodynamic monitoring. The bladder tissue of rats was collected and subjected to real-time reverse transcription-quantitative polymerase chain reaction (RT-qPCR), histological examination, and immunohistochemical staining. Through bioinformatics prediction, we found that transforming growth factor ß2 (TGFß2) expression was upregulated in rats with BOO compared with normal bladder tissue. In vitro analyses using primary bladder smooth muscle cells (BSMCs) revealed that hydrogen peroxide (H2O2) induced TGFß2 expression. Moreover, H2O2 induced epithelial-to-mesenchymal transition (EMT) by reducing E-cadherin, an endothelial marker and CK-18, a cytokeratin maker, and increasing mesenchymal markers, including N-cadherin, vimentin, and α-smooth muscle actin (α-SMA) levels. The downregulation of TGFß2 expression in BSMCs using siRNA technology alleviated H2O2-induced changes in EMT marker expression. The findings of the study indicate that TGFß2 plays a crucial role in BOO by participating in OS-induced EMT in BSMCs.

Optogenetic Activation of Cholinergic Enteric Neurons Reduces Inflammation in Experimental Colitis.

BACKGROUND & AIMS: Intestinal inflammation is associated with loss of enteric cholinergic neurons. Given the systemic anti-inflammatory role of cholinergic innervation, we hypothesized that enteric cholinergic neurons similarly possess anti-inflammatory properties and may represent a novel target to treat inflammatory bowel disease. METHODS: Mice were fed 2.5% dextran sodium sulfate (DSS) for 7 days to induce colitis. Cholinergic enteric neurons, which express choline acetyltransferase (ChAT), were focally ablated in the midcolon of ChAT::Cre;R26-iDTR mice by local injection of diphtheria toxin before colitis induction. Activation of enteric cholinergic neurons was achieved using ChAT::Cre;R26-ChR2 mice, in which ChAT+ neurons express channelrhodopsin-2, with daily blue light stimulation delivered via an intracolonic probe during the 7 days of DSS treatment. Colitis severity, ENS structure, and smooth muscle contractility were assessed by histology, immunohistochemistry, quantitative polymerase chain reaction, organ bath, and electromyography. In vitro studies assessed the anti-inflammatory role of enteric cholinergic neurons on cultured muscularis macrophages. RESULTS: Ablation of ChAT+ neurons in DSS-treated mice exacerbated colitis, as measured by weight loss, colon shortening, histologic inflammation, and CD45+ cell infiltration, and led to colonic dysmotility. Conversely, optogenetic activation of enteric cholinergic neurons improved colitis, preserved smooth muscle contractility, protected against loss of cholinergic neurons, and reduced proinflammatory cytokine production. Both acetylcholine and optogenetic cholinergic neuron activation in vitro reduced proinflammatory cytokine expression in lipopolysaccharide-stimulated muscularis macrophages. CONCLUSIONS: These findings show that enteric cholinergic neurons have an anti-inflammatory role in the colon and should be explored as a potential inflammatory bowel disease treatment.

Mesenteric fibrosis in patients with small intestinal neuroendocrine tumors is associated with enrichment of alpha-smooth muscle actin-positive fibrosis and COMP-expressing stromal cells.

Neuroendocrine tumors of the small intestine (SI-NETs) often develop lymph node metastasis (LNM)-induced mesenteric fibrosis (MF). MF can cause intestinal obstruction as well as ischemia and render surgical resection technically challenging. The underlying pathomechanisms of MF are still not well understood. We examined mesenteric LNM and the surrounding stroma compartment from 24 SI-NET patients, including 11 with in situ presentation of strong MF (MF+) and 13 without MF (MF-). Differential gene expression was assessed with the HTG EdgeSeq Oncology Biomarker Panel comparing MF+ with MF- within LNM and paired stromal samples, respectively. Most interesting differentially expressed genes were validated by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) in combination with validation of associated protein levels utilizing immunohistochemistry (IHC) staining of MF+ and MF- formalin-fixed, paraffin-embedded (FFPE) patient samples. Overall, 14 genes measured with a 2549-gene expression panel were differentially expressed in MF+ patients compared to MF-. Of those, nine were differentially expressed genes in LNM and five genes in the stromal tissue (>2-fold change, p < .05). The top hits included increased COMP and COL11A1 expression in the stroma of MF+ patients compared to MF-, as well as decreased HMGA2, COL6A6, and SLC22A3 expression in LNM of MF+ patients compared to LNM of MF- patients. RT-qPCR confirmed high levels of COMP and COL11A1 in stroma samples of MF+ compared to MF- patients. IHC staining confirmed the enrichment of α-smooth muscle actin-positive fibrosis in MF+ compared to MF- patients with corresponding increase of COMP-expressing stromal cells in MF+. Since COMP is associated with the known driver for fibrosis development transforming growth factor beta and with a cancer-associated fibroblasts enriched environment, it seems to be a promising new target for MF research.

Distribution of smooth muscle actin and collagen in superficial peritoneal endometriotic lesions varies from the surrounding microenvironment.

RESEARCH QUESTION: Do different subtypes of superficial peritoneal endometriotic lesions exist, based on the presence and morphology of smooth muscle, collagen fibres and immune cell populations? DESIGN: A retrospective cohort study of 24 patients, from across the menstrual cycle, with surgically and histologically confirmed endometriosis. Immunofluorescence was used to delineate the CD10 stromal area of lesions (n = 271 lesions from 67 endometriotic biopsies), and then smooth muscle actin (SMA) positive tissue and immune cell populations (CD45+ and CD68+) were quantified within and adjacent to these lesions. Second harmonic generation microscopy was used to evaluate the presence and morphology of type-1 collagen fibres within and surrounding lesions. RESULTS: Overall, immune cell numbers and the area of SMA and collagen within endometriotic lesions tended to be low, but a spectrum of presentations significantly varied, particularly in the adjacent tissue microenvironment, based on lesion locations, the morphology of endometriotic gland profiles, or both. Lesions in which collagen fibres formed well aligned capsules around the CD10+ stromal border were identified compared with lesions in which collagen fibre distribution was random. Considerable inter- and intra-patient variability in the morphology of SMA and collagen was observed within and surrounding lesions. CONCLUSION: These data demonstrate considerable diversity in the presence of immune cells and morphology of SMA and collagen within, but even more so, surrounding endometriotic lesions, even within individual patients. This heterogeneity, especially within individual patients, presents a challenge to incorporating these cell and tissue types into any new endometriosis classification systems or prognostic approaches.