Intestinal proinflammatory macrophages induce a phenotypic switch in interstitial cells of Cajal

Mesenchymal Stem Cells Attenuates Hirschsprung diseases - Associated Enterocolitis by Reducing M1 Macrophages Infiltration via COX-2 Dependent Mechanism

OBJECTIVE AND DESIGN

Hirschsprung disease-associated enterocolitis (HAEC) is a common life-threatening complication of Hirschsprung disease (HSCR). We aimed to investigate the effectiveness, long-term safety and the underlying mechanisms of Mesenchymal stem cells (MSCs) based therapy for HAEC.

MATERIAL OR SUBJECTS

Specimens from HSCR and HAEC patients were used to assess the inflammatory condition. Ednrb knock-out mice was used as HAEC model. MSCs was intraperitoneally transplanted into HAEC mice. The therapy effects, long-term outcome, safety and toxicity and the mechanism of MSCs on the treatment of HAEC were explored in vivo and in vitro.

RESULTS

Intestinal M1 macrophages infiltration and severe inflammation condition were observed in HAEC. After the injection of MSCs, HAEC mice showed significant amelioration of the inflammatory injury and inhibition of M1 macrophages infiltration. The expression levels of pro-inflammatory cytokines (TNF-α and IFN-γ) were decreased and anti-inflammatory cytokines (IL-10 and TGF-β) were increased. In addition, we found that effective MSCs homing to the inflamed colon tissue occurred without long-term toxicity response. However, COX-2 inhibitor could diminish the therapeutic effects of MSCs. Using MSCs and macrophages co-culture system, we identified that MSCs could alleviate HAEC by inhibiting M1 macrophages activation through COX-2-dependent MAPK/ERK signaling pathway.

CONCLUSIONS

MSCs ameliorate HAEC by reducing M1 macrophages polarization via COX-2 mediated MAPK/ERK signaling pathway, thus providing novel insights and potentially promising strategy for the treatment or prevention of HAEC.

Efficient enzyme-free method to assess the development and maturation of the innate and adaptive immune systems in the mouse colon

Researchers who aim to globally analyze the gastrointestinal immune system via flow cytometry have many protocol options to choose from, with specifics generally tied to gut wall layers of interest. To get a clearer idea of the approach we should use on full-thickness colon samples from mice, we first undertook a systematic comparison of three tissue dissociation techniques: two based on enzymatic cocktails and the other one based on manual crushing. Using flow cytometry panels of general markers of lymphoid and myeloid cells, we found that the presence of cell-surface markers and relative cell population frequencies were more stable with the mechanical method. Both enzymatic approaches were associated with a marked decrease of several cell-surface markers. Using mechanical dissociation, we then developed two minimally overlapping panels, consisting of a total of 26 antibodies, for serial profiling of lymphoid and myeloid lineages from the mouse colon in greater detail. Here, we highlight how we accurately delineate these populations by manual gating, as well as the reproducibility of our panels on mouse spleen and whole blood. As a proof-of-principle of the usefulness of our general approach, we also report segment- and life stage-specific patterns of immune cell profiles in the colon. Overall, our data indicate that mechanical dissociation is more suitable and efficient than enzymatic methods for recovering immune cells from all colon layers at once. Additionally, our panels will provide researchers with a relatively simple tool for detailed immune cell profiling in the murine gastrointestinal tract, regardless of life stage or experimental conditions.

Common Pathophysiological Mechanisms and Treatment of Diabetic Gastroparesis

Diabetic gastroparesis (DGP) is a common complication of diabetes mellitus, marked by gastrointestinal motility disorder, a delayed gastric emptying present in the absence of mechanical obstruction. Clinical manifestations include postprandial fullness and epigastric discomfort, bloating, nausea, and vomiting. DGP may significantly affect the quality of life and productivity of patients. Research on the relationship between gastrointestinal dynamics and DGP has received much attention because of the increasing prevalence of DGP. Gastrointestinal motility disorders are closely related to a variety of factors including the absence and destruction of interstitial cells of Cajal, abnormalities in the neuro-endocrine system and hormone levels. Therefore, this study will review recent literature on the mechanisms of DGP and gastrointestinal motility disorders as well as the development of prokinetic treatment of gastrointestinal motility disorders in order to give future research directions and identify treatment strategies for DGP.

Forsythia suspensa polyphenols regulate macrophage M1 polarization to alleviate intestinal inflammation in mice

BACKGROUND

Inflammatory bowel disease (IBD) was a chronic intestinal disease related to autoimmunity, and its pathogenesis was complex. Forsythia suspensa (F. suspensa) had good anti-inflammatory and antioxidant effects. The active component polyphenols had significant effects in the treatment of intestinal inflammation. Researches had found that polarization, pyroptosis and apoptosis of macrophages can drive the occurrence and development of colitis.

PURPOSE

In this study, we examined whether F. suspensa polyphenols (FPP) mitigated DSS-induced colitis, and explored its potential mechanisms.

METHODS

The potential targets of F. suspensa in intestinal inflammation were predicted through network pharmacology. Using LPS and IFN-γ induced macrophage M1 polarization in J774A.1 cells. Macrophage polarization was detected through RT-qPCR, flow cytometry and ELISA. Ulcerative colitis (UC) in mice was induced by 2.5% DSS for 7 days, and then oral administrated different doses of FPP for another 7 days. Then we assessed the body weight, diarrhea, bleeding in stool, colon length, cytokines of serum and pathology of colon. The effects of FPP on the gut microbiota in mice also tested and evaluated.

RESULTS

Our results showed that the main active ingredient of F. suspensa in protecting intestinal inflammation were polyphenols and F. suspensa was multi-targeted in the treatment of intestinal inflammation. FPP inhibited M1 polarization and polarizes towards M2 in J774A.1 cells. FPP inhibited pyroptosis and apoptosis to exert anti-inflammatory effects. FPP had a good protective effect on DSS induced UC in mice. In unison, FPP inhibited M1 polarization, apoptosis, and pyroptosis in UC mice. FPP regulated intestinal homeostasis in mice with UC by improving the gut microbiota and enhancing the intestinal metabolites short-chain fatty acid (SCFAs).

CONCLUSIONS

These data indicated that FPP may alleviate UC by inhibiting M1 polarization in mice. Collectively, these findings suggest that the reduction of colitis by FPP may related to macrophage polarization, pyroptosis and apoptosis.

Stroke Alters the Function of Enteric Neurons to Impair Smooth Muscle Relaxation and Dysregulates Gut Transit

BACKGROUND

Gut dysmotility is common after ischemic stroke, but the mechanism underlying this response is unknown. Under homeostasis, gut motility is regulated by the neurons of the enteric nervous system that control contractile/relaxation activity of muscle cells in the gut wall. More recently, studies of gut inflammation revealed interactions of macrophages with enteric neurons are also involved in modulating gut motility. However, whether poststroke gut dysmotility is mediated by direct signaling to the enteric nervous system or indirectly via inflammatory macrophages is unknown.

METHODS AND RESULTS

We examined these hypotheses by using a clinically relevant permanent intraluminal midcerebral artery occlusion experimental model of stroke. At 24 hours after stroke, we performed in vivo and ex vivo gut motility assays, flow cytometry, immunofluorescence, and transcriptomic analysis. Stroke-induced gut dysmotility was associated with recruitment of muscularis macrophages into the gastrointestinal tract and redistribution of muscularis macrophages away from myenteric ganglia. The permanent intraluminal midcerebral artery occlusion model caused changes in gene expression in muscularis macrophages consistent with an altered phenotype. While the size of myenteric ganglia after stroke was not altered, myenteric neurons from post-permanent intraluminal midcerebral artery occlusion mice showed a reduction in neuronal nitric oxide synthase expression, and this response was associated with enhanced intestinal smooth muscle contraction ex vivo. Finally, chemical sympathectomy with 6-hydroxydopamine prevented the loss of myenteric neuronal nitric oxide synthase expression and stroke-induced slowed gut transit.

CONCLUSIONS

Our findings demonstrate that activation of the sympathetic nervous system after stroke is associated with reduced neuronal nitric oxide synthase expression in myenteric neurons, resulting in impaired smooth muscle relaxation and dysregulation of gut transit.

Effects of weaning on intestinal longitudinal muscle-myenteric plexus function in piglets

Weaning piglets usually suffer from severe diarrhea (commonly known as postweaning diarrhea, PWD) along with intestinal motility disorder. Intestinal peristalsis is mainly regulated by the longitudinal muscle-myenteric plexus (LM-MP). To understand the relationship between intestinal LM-MP function and the development of PWD, we compared the intestinal electrical activity, and the transcriptional profile of the LM-MP between 21-day-old piglets (just weaned, n=7) and 24-day-old piglets (suffered the most severe weaning stress, n=7). The results showed that 24-day-old piglets exhibited different degrees of diarrhea. A significant increase in the slow-wave frequency in the ileum and colon was observed in 24-day-old piglets, while c-kit expression in the intestinal LM-MPs was significantly decreased, indicating that PWD caused by elevated slow-wave frequency may be associated with loss of c-kit. The real-time quantitative PCR (RT-qPCR) and enzyme-linked immunosorbent assay (ELISA) showed that intestinal LM-MPs in 24-day-old piglets may undergo inflammation and oxidative stress. Significant increases in 8-hydroxy-2'-deoxyguanosine and decreases in thioredoxin suggest that weaning may lead to DNA damage in the LM-MP of 24-day-old piglets. In addition, activating transcription factor 3 was significantly upregulated, indicating nerve damage in the LM-MP of 24-day-old piglets. The transcriptomic results showed that most of the differentially expressed genes in the ileal LM-MP after weaning were downregulated and closely related to the cell cycle process. Subsequent RT-qPCR analysis showed that the relative expression of p21 was upregulated, while the expression of cyclin A2, cyclin B1, and proliferating cell nuclear antigen was downregulated in the ileal and colonic LM-MP of 24-day-old piglets, suggesting that weaning may inhibit cell proliferation and cause G1/S cell cycle arrest in ileal and colonic LM-MP. In conclusion, weaning may lead to cell cycle arrest by causing DNA damage in the LM-MP, impairing intestinal motility regulation, and ultimately leading to diarrhea in piglets.

Ca2+ dynamics in interstitial cells: foundational mechanisms for the motor patterns in the gastrointestinal tract

The gastrointestinal (GI) tract displays multiple motor patterns that move nutrients and wastes through the body. Smooth muscle cells (SMCs) provide the forces necessary for GI motility, but interstitial cells, electrically coupled to SMCs, tune SMC excitability, transduce inputs from enteric motor neurons, and generate pacemaker activity that underlies major motor patterns, such as peristalsis and segmentation. The interstitial cells regulating SMCs are interstitial cells of Cajal (ICC) and PDGF receptor (PDGFR)α+ cells. Together these cells form the SIP syncytium. ICC and PDGFRα+ cells express signature Ca2+-dependent conductances: ICC express Ca2+-activated Cl- channels, encoded by Ano1, that generate inward current, and PDGFRα+ cells express Ca2+-activated K+ channels, encoded by Kcnn3, that generate outward current. The open probabilities of interstitial cell conductances are controlled by Ca2+ release from the endoplasmic reticulum. The resulting Ca2+ transients occur spontaneously in a stochastic manner. Ca2+ transients in ICC induce spontaneous transient inward currents and spontaneous transient depolarizations (STDs). Neurotransmission increases or decreases Ca2+ transients, and the resulting depolarizing or hyperpolarizing responses conduct to other cells in the SIP syncytium. In pacemaker ICC, STDs activate voltage-dependent Ca2+ influx, which initiates a cluster of Ca2+ transients and sustains activation of ANO1 channels and depolarization during slow waves. Regulation of GI motility has traditionally been described as neurogenic and myogenic. Recent advances in understanding Ca2+ handling mechanisms in interstitial cells and how these mechanisms influence motor patterns of the GI tract suggest that the term "myogenic" should be replaced by the term "SIPgenic," as this review discusses.

Establishment and identification of an animal model of Hirschsprung disease in suckling mice

BACKGROUND

Hirschsprung disease (HSCR) is a congenital intestinal malformation. Previous HSCR animal model needs invasive operation on adult animal. The aim of this study is to establish an early-onset animal model which is consistent with the clinical manifestation of HSCR patients.

METHODS

The neonatal mice were randomly divided into the benzalkonium chloride (BAC) group, treated with BAC via enema, and the control group, treated with saline. Weight changes, excretion time of carmine, CT scan, hematoxylin-eosin staining and immunofluorescence staining were used to evaluate the effect of the model. Differentially expressed genes (DEGs) in the HSCR mice were analyzed by using DAVID 6.8 database and compared with DEGs from HSCR patients.

RESULTS

The weight of mice was lower and the excretion time of carmine was longer in the BAC group. Moreover, distal colon stenosis and proximal colon enlargement appeared in the BAC group. Neurons in the distal colon decreased significantly after 4 weeks of BAC treatment and almost disappeared completely after 12 weeks. Transcriptome profiling of the mouse model and HSCR patients is similar in terms of altered gene expression.

CONCLUSIONS

An economical and reliable HSCR animal model which has similar clinical characteristics to HSCR patients was successfully established.

IMPACT

The animal model of Hirschsprung disease was first established in BALB/c mice. This model is an animal model of early-onset HSCR that is easy to operate and consistent with clinical manifestations. Transcriptome profiling of the mouse model and HSCR patients is similar in terms of altered gene expression.

Lactic acid bacteria in relieving constipation: mechanism, clinical application, challenge, and opportunity

Constipation is a prevalent gastrointestinal symptom that can considerably affect a patients' quality of life. Although several drugs have been used to treat constipation, they are associated with high costs, side effects, and low universality. Therefore, alternative intervention strategies are urgently needed. Traditional lactic acid bacteria (LAB), such as Bifidobacterium and Lactobacillus, play a vital role in regulating intestinal microecology and have demonstrated favorable effects in constipation; however, a comprehensive review of their constipation relief mechanisms is limited. This review summarizes the pathogenesis of constipation and the relationship between intestinal motility and gut microbiota, elucidates the possible mechanism by which LAB alleviates of constipation through a systematic summary of animal and clinical research, and highlights the challenges and applications of LAB in the treatment of constipation. Our review can improve our understanding of constipation, and advance targeted microecological therapeutic agents, such as LAB.

The Crucial Role of the Interstitial Cells of Cajal in Neurointestinal Diseases

Neurointestinal diseases result from dysregulated interactions between the nervous system and the gastrointestinal (GI) tract, leading to conditions such as Hirschsprung's disease and irritable bowel syndrome. These disorders affect many people, significantly diminishing their quality of life and overall health. Central to GI motility are the interstitial cells of Cajal (ICC), which play a key role in muscle contractions and neuromuscular transmission. This review highlights the role of ICC in neurointestinal diseases, revealing their association with various GI ailments. Understanding the functions of the ICC could lead to innovative perspectives on the modulation of GI motility and introduce new therapeutic paradigms. These insights have the potential to enhance efforts to combat neurointestinal diseases and may lead to interventions that could alleviate or even reverse these conditions.

Abnormally elevated expression of ACTA2 of circular smooth muscle leads to hyperactive contraction in aganglionic segments of HSCR

BACKGROUND

Actin Alpha 2 (ACTA2) is expressed in intestinal smooth muscle cells (iSMCs) and is associated with contractility. Hirschsprung disease (HSCR), one of the most common digested tract malformations, shows peristaltic dysfunction and spasm smooth muscles. The arrangement of the circular and longitudinal smooth muscle (SM) of the aganglionic segments is disorganized. Does ACTA2, as a marker of iSMCs, exhibit abnormal expression in aganglionic segments? Does the ACTA2 expression level affect the contraction function of iSMCs? What are the spatiotemporal expression trends of ACTA2 during different developmental stages of the colon?

METHODS

Immunohistochemical staining was used to detect the expression of ACTA2 in iSMCs of children with HSCR and Ednrb-/- mice, and the small interfering RNAs (siRNAs) knockdown technique was employed to investigate how Acta2 affected the systolic function of iSMCs. Additionally, Ednrb-/- mice were used to explore the changes in the expression level of iSMCs ACTA2 at different developmental stages.

RESULTS

The expression of ACTA2 is higher in circular SM in the aganglionic segments of HSCR patients and Ednrb-/- mice than in normal control children and mice. Down regulation of Acta2 weakens the contraction ability of intestinal smooth muscle cells. Abnormally elevated expression of ACTA2 of circular smooth muscle occurs since embryonic day 15.5 (E15.5d) in aganglionic segments of Ednrb-/- mice.

CONCLUSIONS

Abnormally elevated expression of ACTA2 in the circular SM leads to hyperactive contraction, which may cause the spasm of aganglionic segments in HSCR.

The macrophages regulate intestinal motility dysfunction through the PGE2 Ptger3 axis during Klebsiella pneumonia sepsis

Introduction

Gut motility dysfunction, the most common complication of post-septic organ dysfunction, depends on immune and neuronal cells. This study aimed to investigate the mechanisms that activate these cells and the contribution of macrophages to the recovery of intestinal motility dysfunction after sepsis.

Materials and methods

Postoperative gut motility dysfunction was induced by establishing Klebsiella pneumonia sepsis in mice with selective deletion of neutrophils and macrophages in the gut. The distribution of orally administered fluorescein isothiocyanate-dextran and carmine excretion time was used to determine the severity of small bowel disease. The effect of macrophages on intestinal motility was evaluated after prostaglandin E2 therapy.

Results

We found that muscular neutrophil infiltration leading to neuronal loss in the intestine muscle triggered intestinal motility dysfunction after pneumonia sepsis; however, reduced neutrophil infiltration did not improve intestinal motility dysfunction. Moreover, macrophage depletion aggravated gut motility dysfunction. The addition of macrophages directly to a smooth muscle was responsible for the recovery of intestinal motility.

Conclusion

Our results suggest that a direct interaction between macrophages and smooth muscle is neurologically independent of the restoration of intestinal dysmotility.

Abnormal enteric nervous system and motor activity in the ganglionic proximal bowel of Hirschsprung's disease

Hirschsprung's disease (HSCR) is a congenital defect in which the enteric nervous system (ENS) does not develop in the distal bowel, requiring surgical removal of the portions of bowel without ENS ganglia ('aganglionic') and reattachment of the 'normal' proximal bowel with ENS ganglia. Unfortunately, many HSCR patients have persistent dysmotility (e.g., constipation, incontinence) and enterocolitis after surgery, suggesting that the remaining bowel is not normal despite having ENS ganglia. Anatomical and neurochemical alterations have been observed in the ENS-innervated proximal bowel from HSCR patients and mice, but no studies have recorded ENS activity to define the circuit mechanisms underlying post-surgical HSCR dysfunction. Here, we generated a HSCR mouse model with a genetically-encoded calcium indicator to map the ENS connectome in the proximal colon. We identified abnormal spontaneous and synaptic ENS activity in proximal colons from GCaMP-Ednrb ^-/- mice with HSCR that corresponded to motor dysfunction. Many HSCR-associated defects were also observed in GCaMP-Ednrb ^+/- mice, despite complete ENS innervation. Results suggest that functional abnormalities in the ENS-innervated bowel contribute to post-surgical bowel complications in HSCR patients, and HSCR-related mutations that do not cause aganglionosis may cause chronic colon dysfunction in patients without a HSCR diagnosis.

Update on the Pathogenesis of the Hirschsprung-Associated Enterocolitis

Despite the significant progress that has been made in terms of understanding the pathophysiology and risk factors of Hirschsprung-associated enterocolitis (HAEC), the morbidity rate has remained unsatisfactorily stable, and clinical management of the condition continues to be challenging. Therefore, in the present literature review, we summarized the up-to-date advances that have been made regarding basic research on the pathogenesis of HAEC. Original articles published between August 2013 and October 2022 were searched in a number of databases, including PubMed, Web of Science, and Scopus. The keywords "Hirschsprung enterocolitis", "Hirschsprung's enterocolitis", "Hirschsprung's-associated enterocolitis", and "Hirschsprung-associated enterocolitis" were selected and reviewed. A total of 50 eligible articles were obtained. The latest findings of these research articles were grouped into gene, microbiome, barrier function, enteric nervous system, and immune state categories. The present review concludes that HAEC is shown to be a multifactorial clinical syndrome. Only deep insights into this syndrome, with an accrual of knowledge in terms of understanding its pathogenesis, will elicit the necessary changes that are required for managing this disease.

Interstitial cells of Cajal in gastrointestinal inflammatory diseases

The gastrointestinal (GI) tract is a vital organ that digests food, absorbs nutrients, and excretes waste. Normal GI motility is the basis for these functions. The interstitial cells of Cajal (ICC) in the GI muscularis layer promote GI motility together with the enteric nervous system and smooth muscle cells. Since GI motility results from complex coordination of these heterogeneous cells, failure of any one of them can lead to GI dysmotility. Knowledge about ICC in physiological conditions has accumulated in recent decades, while the pathophysiology of ICC in GI inflammatory diseases, such as inflammatory bowel disease, is not well understood. In this review, we summarize the previous studies about the pathophysiological changes of ICC in inflammatory diseases and discuss the inflammatory mediators that induce ICC dysfunction.

Neuroimmune regulation in Hirschsprung's disease associated enterocolitis

Neuroimmune pathways are important part of the regulation of inflammatory response. Nerve cells regulate the functions of various immune cells through neurotransmitters, and then participate in the inflammatory immune response. Hirschsprung's disease (HD) is a congenital abnormal development of intestinal neurons, and Hirschsprung-associated enterocolitis (HAEC) is a common complication, which seriously affects the quality of life and even endangers the lives of children. Neuroimmune regulation mediates the occurrence and development of enteritis, which is an important mechanism. However, there is a lack of review on the role of Neuroimmune regulation in enterocolitis associated with Hirschsprung's disease. Therefore, this paper summarizes the characteristics of the interaction between intestinal nerve cells and immune cells, reviews the neuroimmune regulation mechanism of Hirschsprung's disease associated enterocolitis (HAEC), and looks forward to the potential clinical application value.

Neonatal development of intestinal neuroimmune interactions

Interactions between the enteric nervous system (ENS), immune system, and gut microbiota regulate intestinal homeostasis in adults, but their development and role(s) in early life are relatively underexplored. In early life, these interactions are dynamic, because the mucosal immune system, microbiota, and the ENS are developing and influencing each other. Moreover, disrupting gut microbiota and gut immune system development, and potentially ENS development, by early-life antibiotic exposure increases the risk of diseases affecting the gut. Here, we review the development of the ENS and immune/epithelial cells, and identify potential critical periods for their interactions and development. We also highlight knowledge gaps that, when addressed, may help promote intestinal homeostasis, including in the settings of early-life antibiotic exposure.

Hirschsprung-Associated Enterocolitis: Transformative Research from Bench to Bedside

Hirschsprung disease (HSCR) is a congenital disease that is characterized by the absence of intrinsic ganglion cells in the submucosal and myenteric plexuses of the distal colon and is the most common cause of congenital intestinal obstruction. Hirschsprung-associated enterocolitis (HAEC) is a life-threatening complication of HSCR, which can occur either before or after surgical resection of the aganglionic bowel. Even though HAEC is a leading cause of death in HSCR patients, its etiology and pathophysiology remain poorly understood. Various factors have been associated with HAEC, including the mucus barrier, microbiota, immune function, obstruction of the colon, and genetic variations. In this review, we examine our current mouse model of HAEC and how it informs our understanding of the disease. We also describe current emerging research that highlights the potential future of HAEC treatment.

Overabundance of Veillonella parvula promotes intestinal inflammation by activating macrophages via LPS-TLR4 pathway

Hirschsprung’s disease-associated enterocolitis (HAEC) is the most common complication of Hirschsprung’s disease (HSCR). The microbiome pattern of intestinal flora in HAEC patients was significantly abnormal compared to that in HSCR patients. The overabundance of V. parvula was detected in the gut of HAEC patients. To elucidate the pathological mechanisms of the overabundance of V. parvula, we established and analyzed inflammatory models induced by LPS or single-bacterial strain transplantation in vivo. The transplantation of V. parvula induced inflammatory response in the colon of mice. Besides, we found that LPS from V. parvula can significantly impair the barrier function of colonic epithelial cells and then activate macrophages which impaired pacemaker function of interstitial cells of Cajal (ICCs). It was thus a vicious cycle, where the macrophage-related inflammation caused by V. parvula via LPS-TLR4 pathway damaged the intestinal motility, which further aggravated the intestinal flora dysbiosis and promoted the development of HAEC. Itaconic acid could break the vicious cycle by inhibiting the activation of macrophages. It could be a potential therapeutic strategy for HAEC patients with intestinal flora dysbiosis.

Role of Macrophages and Mast Cells as Key Players in the Maintenance of Gastrointestinal Smooth Muscle Homeostasis and Disease

The gut contains the largest macrophage pool in the body, with populations of macrophages residing in the mucosa and muscularis propria of the gastrointestinal (GI) tract. Muscularis macrophages (MMs), which are located within the muscularis propria, interact with cells essential for GI function, such as interstitial cells of Cajal, enteric neurons, smooth muscle cells, enteric glia, and fibroblast-like cells, suggesting that these immune cells contribute to several aspects of GI function. This review focuses on the latest insights on the factors contributing to MM heterogeneity and the functional interaction of MMs with other cell types essential for GI function. This review integrates the latest findings on macrophages in other organs with increasing knowledge of MMs to better understand their role in a healthy and diseased gut. We describe the factors that contribute to (muscularis macrophage) MM heterogeneity, and the nature of MM interactions with cells regulating GI function. Finally, we also describe the increasing evidence suggesting a critical role of another immune cell type, the mast cell, in normal and diseased GI physiology.

Enterocolitis Is a Risk Factor for Bowel Perforation in Neonates With Hirschsprung's Disease: A Retrospective Multicenter Study

BACKGROUND AND AIM

We evaluated the clinical features of neonatal Hirschsprung's disease (HD)-associated bowel perforation (perforated HD) and investigated risk factors related to it.

METHODS

We retrospectively collected clinical data of neonates (<1 month of age) with perforated HD from multicenters in China from January 2006 to December 2019. A total of 142 patients (6.7%) with perforated HD were enrolled in the study. A 1:2 matching method was used to compare the clinical information of HD patients with and without bowel perforation during the neonatal period. The risk factors for bowel perforation were identified using univariate and multivariate logistic risk regression analyses.

RESULTS

Perforation site was present in the proximal ganglionic bowel in 101 (71.1%) cases and the distal aganglionosis segment in 41 (28.9%) cases. Adjacent marginal tissue from the perforated intestine revealed varying degrees of inflammatory cell infiltration, and the severity of enterocolitis was higher in the proximal ganglionic bowel than in the distal aganglionosis segment (p < 0.05). In the univariable and multivariable logistic analyses, clinical symptoms, such as vomiting (adjusted OR = 2.06, 95% CI: 2.01-2.88, p < 0.05), and inflammation index in hematologic tests, such as neutrophil proportion (adjusted OR = 1.09, 95% CI: 1.05-1.33, p < 0.05) and CRP (adjusted OR = 2.13, 95% CI: 1.01-3.27, p < 0.05) were associated with increased risk for perforated HD.

CONCLUSION

Clinical Hirschsprung disease-associated enterocolitis (HAEC) highly correlated with perforated HD. Timely treatment of HAEC should be appropriate therapeutic approaches to prevent perforated HD.

Interstitial cells of Cajal and human colon motility in health and disease

Our understanding of human colonic motility, and autonomic reflexes that generate motor patterns, has increased markedly through high-resolution manometry. Details of the motor patterns are emerging related to frequency and propagation characteristics that allow linkage to interstitial cells of Cajal (ICC) networks. In studies on colonic motor dysfunction requiring surgery, ICC are almost always abnormal or significantly reduced. However, there are still gaps in our knowledge about the role of ICC in the control of colonic motility and there is little understanding of a mechanistic link between ICC abnormalities and colonic motor dysfunction. This review will outline the various ICC networks in the human colon and their proven and likely associations with the enteric and extrinsic autonomic nervous systems. Based on our extensive knowledge of the role of ICC in the control of gastrointestinal motility of animal models and the human stomach and small intestine, we propose how ICC networks are underlying the motor patterns of the human colon. The role of ICC will be reviewed in the autonomic neural reflexes that evoke essential motor patterns for transit and defecation. Mechanisms underlying ICC injury, maintenance, and repair will be discussed. Hypotheses are formulated as to how ICC dysfunction can lead to motor abnormalities in slow transit constipation, chronic idiopathic pseudo-obstruction, Hirschsprung's disease, fecal incontinence, diverticular disease, and inflammatory conditions. Recent studies on ICC repair after injury hold promise for future therapies.