Increased protease activated receptors in the colon of patients with Hirschsprung's disease

Postoperative Hirschsprung's associated enterocolitis (HAEC): transition zone as putative histopathological predictive factor

AIMS

Hirschsprung's-associated enterocolitis (HAEC) is the most severe complication of Hirschsprung disease (HD), and its pathogenesis is still unknown. Length of transition zone (TZ) interposed between aganglionic and normal bowel has been poorly explored as predictor for postoperative HAEC (post-HAEC). This study aimed to identify potential predictive factors for post-HAEC, with a particular focus on histopathological findings.

METHODS

Data from Hirschsprung patients treated in a single Italian centre between 2010 and 2022 with a follow-up >6 months were collected. Thorough histopathological examination of the resected bowel was conducted, focusing on length of TZ and aganglionic bowel.The degree of inflammatory changes in ganglionic resected bowel was further obtained. Ultra-long HD, total colonic aganglionosis and ultra-short HD were excluded. Bivariate and multivariate regression analysis were performed.

RESULTS

Thirty-one patients were included; 5 experienced preoperative HAEC (pre-HAEC) and later post-HAEC (16.1%), further 10 patients developed post-HAEC (total post-HAEC 48.38%). Pre-HAEC-history and a TZ<2.25 cm correlated with an early development of post-HAEC. Multivariate analysis identified a TZ<2.25 cm as an independent post-HAEC predictive factor (p=0.0096). Inflammation within the ganglionic zone and a TZ<2.25 cm correlated with higher risk of post-HAEC (p=0.0074, 0.001, respectively). Severe post-HAEC more frequently occurred in patients with pre-HAEC (p=0.011), histological inflammation (p=0.0009) and short TZ (p=0.0015).

CONCLUSIONS

This study suggests that TZ<2.25 cm predicts the risk of post-HAEC. Preoperative clinical and histopathology inflammation may predispose to worst post-HAEC. Readily available histopathological findings might help identifying patients at higher risk for HAEC and implementing prevention strategies.

Therapeutic Effect of Proteinase-Activated Receptor-1 Antagonist on Colitis-Associated Carcinogenesis

BACKGROUND & AIMS

Inflammatory bowel disease is associated with carcinogenesis, which limits the prognosis of the patients. The local expression of proteinases and proteinase-activated receptor 1 (PAR1) increases in inflammatory bowel disease. The present study investigated the therapeutic effects of PAR1 antagonism on colitis-associated carcinogenesis.

METHODS

A colitis-associated carcinogenesis model was prepared in mice by treatment with azoxymethane (AOM) and dextran sulfate sodium (DSS). PAR1 antagonist E5555 was administered in long- and short-term protocol, starting on the day of AOM injection and 1 week after completing AOM/DSS treatment, respectively. The fecal samples were collected for metagenome analysis of gut microbiota. The intestinal myofibroblasts of the Crohn's disease patients were used to elucidate underlying cellular mechanisms. Caco-2 cells were used to investigate a possible source of PAR1 agonist proteinases.

RESULTS

AOM/DSS model showed weight loss, diarrhea, tumor development, inflammation, fibrosis, and increased production of inflammatory cytokines. The β-diversity, but not α-diversity, of microbiota significantly differed between AOM/DSS and control mice. E5555 alleviated these pathological changes and altered the microbiota β-diversity in AOM/DSS mice. The thrombin expression was up-regulated in tumor and non-tumor areas, whereas PAR1 mRNA expression was higher in tumor areas compared with non-tumor areas. E5555 inhibited thrombin-triggered elevation of cytosolic Ca2+ concentration and ERK1/2 phosphorylation, as well as IL6-induced signal transducer and activator of transcription 3 (STAT3) phosphorylation in intestinal myofibroblasts. Caco-2 cell-conditioned medium contained immunoreactive thrombin, which cleaved the recombinant protein containing the extracellular domain of PAR1 at the thrombin cleavage site.

CONCLUSIONS

PAR1 antagonism is proposed to be a novel therapeutic strategy for treatment of inflammatory bowel disease and its associated carcinogenesis.

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.

Expression and clinical implications of PARs in the stenotic tissue of ureteropelvic junction obstruction

Objective

To explore the expression and clinical implications of protease activated receptors (PARs) in the pathogenesis of children with ureteropelvic junction obstruction (UPJO).

Material and methods

Immunohistochemistry was employed to investigate the distribution of PARs in both normal human ureteropelvic junction (UPJ) and cases of UPJO. Furthermore, PAR gene expression levels were assessed using real-time PCR (RT-PCR), and the patients in the UPJO group were stratified according to the Onen grading system. Subsequently, the clinical implications of PARs in UPJO were explored through RT-PCR analysis.

Results

Immunofluorescence showed robust PAR2 expression in the control group compared with the UPJO group. The results of RT-PCR analysis revealed a significant decrease in the relative mRNA expression of PAR2 in the UPJO group compared to the control group. Notably, the relative RNA expression of PAR1 was significantly lower in the Onen-4 group compared to the control group. Furthermore, the relative mRNA expression of PAR2 exhibited a statistically significant difference among the Onen-3 group, Onen-4 group, and control group.

Conclusions

PARs are widely distributed throughout the SIP syncytium of the UPJ and play a role in maintaining smooth muscle cells (SMCs) membrane potential by interacting with interstitial cells of Cajal (ICCs), as well as platelet-derived growth factor receptor alpha-positive cells (PDGFR α+ cells). The decreased expression of PAR1 suggests a higher preoperative Onen grade in UPJO patients. Furthermore, the downregulation of PAR2 effects at the UPJ may be involved in the loss of inhibitory neuromuscular transmission, disrupting the rhythmic peristalsis of the UPJ.

Decreased Incidence of Hirschsprung-Associated Enterocolitis During COVID-19 Across United States Children's Hospitals

BACKGROUND

The Coronavirus Disease 2019 pandemic provided a natural experiment to study the effect of social distancing on the risk of developing Hirschsprung's Associated Enterocolitis (HAEC).

METHODS

Using the Pediatric Health Information System (PHIS), a retrospective cohort study of children (<18 years) with Hirschsprung's Disease (HSCR) across 47 United States children's hospitals was performed. The primary outcome was HAEC admissions per 10,000 patient-days. The exposure (COVID-19) was defined as April 2020-December 2021. The unexposed (historical control) period was April 2018-December 2019. Secondary outcomes included sepsis, bowel perforation, intensive care unit (ICU) admission, mortality, and length of stay.

RESULTS

Overall, we included 5707 patients with HSCR during the study period. There were 984 and 834 HAEC admissions during the pre-pandemic and pandemic periods, respectively (2.6 vs. 1.9 HAEC admissions per 10,000 patient-days, incident rate ratio [95% confidence interval]: 0.74 [0.67, 0.81], p < 0.001). Compared to pre-pandemic, those with HAEC during the pandemic were younger (median [IQR]: 566 [162, 1430] days pandemic vs. 746 [259, 1609] days pre-pandemic, p < 0.001) and more likely to live in the lowest quartile of median household income zip codes (24% pandemic vs. 19% pre-pandemic, p = 0.02). There were no significant differences in rates of sepsis (6.1% pandemic vs. 6.1% pre-pandemic, p > 0.9), bowel perforation (1.3% pandemic vs. 1.2% pre-pandemic, p = 0.8), ICU admissions (9.6% pandemic vs. 12% pre-pandemic, p = 0.2), mortality (0.5% pandemic vs. 0.6% pre-pandemic, p = 0.8), or length of stay (median [interquartile range]: 4 [(Pastor et al., 2009; Gosain and Brinkman, 2015) 2,112,11 days pandemic vs. 5 [(Pastor et al., 2009; Tang et al., 2020) 2,102,10 days pre-pandemic, p = 0.4).

CONCLUSIONS

The COVID-19 pandemic was associated with significantly decreased incidence of HAEC admissions across US children's hospitals. Possible etiologies such as social distancing should be explored.

LEVEL OF EVIDENCE

II.

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.

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.

Protease-activated receptors in health and disease

Proteases are signaling molecules that specifically control cellular functions by cleaving protease-activated receptors (PARs). The four known PARs are members of the large family of G protein-coupled receptors. These transmembrane receptors control most physiological and pathological processes and are the target of a large proportion of therapeutic drugs. Signaling proteases include enzymes from the circulation; from immune, inflammatory epithelial, and cancer cells; as well as from commensal and pathogenic bacteria. Advances in our understanding of the structure and function of PARs provide insights into how diverse proteases activate these receptors to regulate physiological and pathological processes in most tissues and organ systems. The realization that proteases and PARs are key mediators of disease, coupled with advances in understanding the atomic level structure of PARs and their mechanisms of signaling in subcellular microdomains, has spurred the development of antagonists, some of which have advanced to the clinic. Herein we review the discovery, structure, and function of this receptor system, highlight the contribution of PARs to homeostatic control, and discuss the potential of PAR antagonists for the treatment of major diseases.

Comparison of clinical outcomes after total transanal and laparoscopic assisted endorectal pull-through in patients with rectosigmoid Hirschsprung disease

BACKGROUND

Total transanal (TERPT) and laparoscopic endorectal pull-through (LERPT) are the most common procedures to treat rectosigmoid Hirschsprung's disease (HD). Since few studies have compared the two methods, we aimed to assess clinical outcomes after TERPT and LERPT in this cross-sectional study.

METHODS AND PATIENTS

All patients with rectosigmoid HD operated with TERPT and LERPT between 2001 and 2018 were eligible. Peri-operative data were registered from patients' records, and bowel function was assessed according to the Krickenbeck classification.

RESULTS

91/97 (94%) patients were included; 46 operated with TERPT and 45 with LERPT. Bowel function was assessed in 80 patients at median seven (4-17) years. There was no difference in functional outcome between the procedures. Unplanned procedures under general anesthesia were frequent; 28% after TERPT and 49% after LERPT (p = 0.04). 11% of TERPT and 29% of LERPT patients got botulinum toxin injections (p = 0.03). In the TERPT group, patients operated in the neonatal period had poorer outcome (78%) than those operated later (24%) (p = 0.005). No difference in operative time, length of hospital stay, and rate of early and late complications was found between the procedures.

CONCLUSION

There was no difference in long-term bowel function in patients with rectosigmoid HD operated with TERPT or LERPT. More LERPT patients had an unplanned procedure under general anesthesia, mostly due to obstructive symptoms.

LEVEL OF EVIDENCE

III.

Prevalence of Hirschsprung-associated enterocolitis in patients with Hirschsprung disease

PURPOSE

Hirschsprung's associated enterocolitis (HAEC) is a complication of Hirschsprung's Disease (HD) with considerable morbidity and mortality. The variability in presentation leads to a wide variety of the reported prevalence pre-and postoperatively. This systematic review aimed to clarify the prevalence of HAEC in short-(S-HD), long (L-HD), TCA and the type of operation used.

METHODS

A systematic literature-based search for relevant cohorts was performed using Pubmed/Medline, Cochrane Library from its inception to May 2021. Studies reporting on pre-and postoperative enterocolitis, segment length, and surgical procedure (Soave, Swenson, Duhamel) were included. Pooled prevalence and subgroup analysis have been calculated for pre-and postoperative HAEC.

RESULTS

4738 articles were identified from the literature search, among which 57 studies, including 9744 preoperative and 8568 postoperative patients, were included. The groups were sorted by length of the aganglionic segment for further analysis. The pooled prevalence for preoperative HAEC was 18.3% for all types, 15.2% for S-HD and 26.1% for TCA. The pooled prevalence for postoperative HAEC was in total 18.2% for all segment lengths and used techniques. Subgroup analysis showed no significant difference in the occurrence of postoperative enterocolitis between the three techniques.

CONCLUSION

The prevalence of preoperative HAEC increases with segment length. However, pooled data suggest that the postoperative risk for developing HAEC, independently of the employed method and segment length, is comparable to the preoperative risk.

Altered expression of AKT1 and P38A in the colons of patients with Hirschsprung's disease

PURPOSE

Hirschsprung's disease (HSCR) is a functional obstruction of the gastrointestinal tract due to the congenital absence of enteric ganglion cells. The proto-oncogene RET is one of the primary genes implicated in the aetiology of HSCR. We designed this study to investigate the expression of 10 RET regulatory network genes in the colons of patients with HSCR.

METHODS

HSCR tissue specimens (n = 28) were collected at the time of pull-through surgery. qPCR analysis was applied to compare the expression levels of 10 genes in the RET regulatory network. Western blot analysis was performed to quantify the protein expression. Immunohistochemistry was performed to determine the localization of AKT1 and P38A in HSCR colon tissue.

RESULTS

AKT1 (p = 0.015) and P38A (p = 0.039) were both significantly downregulated in the aganglionic segment compared to those in the ganglionic segment in HSCR patients (n = 28). Western blot analysis revealed the decreasing protein expression of AKT1 and P38A in the aganglionic segment compared to ganglionic segment and control colon tissues (p < 0.05). Immunohistochemistry staining revealed that both AKT1 and P38A were localized in the colonic mucosa and were significantly decreased in the aganglionic segment.

CONCLUSION

To our knowledge, we report for the first time the expression of RET regulatory network genes in the colons of patients with HSCR. The markedly decreased expression of AKT1 and P38A suggested a possible role in HSCR pathogenesis.