How inflammation changes neuromuscular function and its relevance to symptoms in diverticular disease

Nerve fiber overgrowth in patients with symptomatic diverticular disease

BACKGROUND

Colonic diverticulosis is a common condition in industrialized countries. Up to 25% of patients with diverticula develop symptoms, a condition termed symptomatic uncomplicated diverticular disease (SUDD). The aim of the present study was to characterize neuroimmune interactions and nerve fiber plasticity in the colonic mucosa of patients with diverticula.

METHODS

Controls, patients with diverticulosis and with SUDD were enrolled in the study. Mucosal biopsies were obtained close to diverticula (diverticular region) and in a normal mucosa (distant site), corresponding to sigmoid and descending colon in the controls. Quantitative immunohistochemistry was used to assess mast cells, T cells, macrophages, nerve fibers, and neuronal outgrowth (growth-associated protein 43, GAP43+fibers).

KEY RESULTS

No difference emerged in mast cells and T cells among the three groups. Macrophages were increased in patients with SUDD and diverticulosis as compared to controls. Nerve fibers were enhanced in patients with SUDD and diverticulosis in comparison with controls in the diverticular region. GAP43+ fibers were increased only in patients with SUDD as compared to controls and to patients with diverticulosis in the diverticular region. In patients with SUDD, GAP43 density was increased in the diverticular region compared to distant site. Macrophages close to GAP43+ fibers were increased in the diverticular region of patients with SUDD. Significant correlations were found between GAP43+ fibers and immune cells.

CONCLUSIONS AND INFERENCES

Patients with diverticula are characterized by increased macrophage counts, while nerve fiber sprouting is increased only in the diverticular region of patients with SUDD suggesting a role in symptom generation.

Diverticular Disease in the Elderly

PURPOSE OF REVIEW

While few diseases are limited solely to the elderly, diverticular disease is clearly more prevalent with increasing age and therefore the aim of this review is to focus on the clinical implications of diverticular disease in the elderly.

RECENT FINDINGS

Diverticulitis in the elderly is best managed with an individualized treatment approach including considerations for selective antibiotic usage even in uncomplicated disease. Furthermore, due to the increased prevalence of ischemic colitis in the elderly and the similarities in presentation with diverticular hemorrhage, there needs to be a high index of suspicion and appropriate evaluation for ischemic colitis in patients with hematochezia, particularly if they have abdominal pain. The elderly are a vulnerable population where the index of suspicion for complications of diverticular disease should be high.

Diverticulosis, Symptoms and Colonic Inflammation: A Population-Based Colonoscopy Study

INTRODUCTION

Low-grade chronic inflammation has been suggested to play a role in uncomplicated asymptomatic and symptomatic diverticular disease. However, population-based studies are lacking. We investigated whether community participants with diverticulosis, with or without symptoms, would have colonic inflammation on histology and serology.

METHODS

In a nested case-control study of 254 participants from the population-based colonoscopy (PopCol) study, colonic histological inflammatory markers and serological C-reactive protein levels were analyzed in cases with diverticulosis and controls without diverticulosis. Statistical methods included logistic and linear regression models.

RESULTS

Background variables including age (P = 0.92), sex (P = 1.00), body mass index (P = 0.71), smoking (P = 0.34), and recent antibiotic exposure (P = 0.68) were similar between cases and controls. Cases reported more abdominal pain (P = 0.04) and diarrhea symptoms (mushy and high-frequency stools) than controls (P = 0.01 and P = 0.03, respectively) but were otherwise similar. The median C-reactive protein levels were similar among cases and controls [1.05 mg/L (0.3, 2.7) vs 0.8 (0.4, 2.2), P = 0.53]. There was a trend of increased numbers of cecal lymphoid aggregates in cases vs controls (P = 0.07), but no other associations between diverticulosis and inflammatory markers on histology were found. Similarly, no serological or mucosal inflammation was associated with symptomatic cases of diarrhea or abdominal pain vs asymptomatic controls.

CONCLUSIONS

In a general community sample, both asymptomatic and symptomatic diverticulosis are not associated with colonic mucosal inflammation. Other explanations for symptomatic colonic diverticulosis need to be identified.

Functional neuromuscular impairment in severe intestinal dysmotility

BACKGROUND

Chronic intestinal pseudo-obstruction (CIPO) and enteric dysmotility (ED) are severe intestinal motility disorders usually associated with underlying neuromuscular abnormalities.

OBJECTIVE

To evaluate the in vitro neuromuscular function of patients with severe intestinal motility disorders.

METHODS

Full-thickness intestinal biopsies (16 jejunum and 3 ileum) obtained from patients with CIPO (n = 10) and ED (n = 9) were studied using muscle bath and microelectrode techniques. Control samples (n = 6 ileum and n = 6 jejunum) were used to establish the range of normality.

KEY RESULTS

Fourteen parameters were defined to assess muscle contractility and nerve-muscle interaction: five to evaluate smooth muscle and interstitial cells of Cajal (ICC) and nine to evaluate inhibitory neuromuscular transmission. For each sample, a parameter was scored 0 if the value was inside the normal range or a value of 1 if it was outside. Patients' samples (CIPO/ED) had more abnormal parameters than controls (P < 0.001 for both jejunum and ileum). Functional abnormalities were found to be heterogeneous. The most prevalent abnormality was a decreased purinergic neuromuscular transmission, which was detected in 43.8% of jejunal samples.

CONCLUSIONS AND INFERENCES

Abnormalities of neuromuscular intestinal function are detected in vitro in severe intestinal dysmotility. However, consistent with the heterogeneity of the disease pathophysiology, functional impairment cannot be attributed to a single mechanism. Specifically, defects of purinergic neuromuscular transmission may have an important role in motility disorders of the gastrointestinal tract.

Nitrergic neuro-muscular transmission is up-regulated in patients with diverticulosis

BACKGROUND

Neuro-transmission impairment could be associated to motility changes observed in patients with diverticular disease. Therefore, the objective was to characterize the inhibitory neuro-muscular transmission and gene expression changes of the enteric inhibitory pathways in patients with diverticulosis (DS).

METHODS

Circular muscle strips from sigmoid colon of patients with DS and controls were studied using the organ bath technique to evaluate spontaneous contractility and enteric motor neurons stimulated by electrical field and qRT-PCR to assess the expression of nNOS, iNOS, P2Y1 R and PGP9.5.

KEY RESULTS

Patients with DS presented decreased spontaneous rhythmic contractions (SRC) that were significantly enhanced after incubation with L-NNA (1 mM) and TTX (1 μM), and unaffected by the P2Y1 antagonist MRS2500 (1 μM). Stimulation on enteric motor neurons caused an increased duration of the latency of OFF-contractions in DS group (p < 0.001), antagonized by L-NNA and slightly affected by MRS2500 (1 μM). No differences in the IC50 between controls and DS patients were observed on inhibition of SRC for the NO-donor sodium nitroprusside (SNP) and the preferential P2Y agonist ADPβS. Moreover, nNOS relative expression was also up-regulated 2.3-fold in the DS group (p < 0.05) whereas there was no significant difference in relative expression of iNOS, P2Y1 R and the neuronal marker PGP9.5 between groups.

CONCLUSIONS & INFERENCES

Patients with DS presented an over-expression of nNOS with increased endogenously NO-mediated responses suggesting enhanced NO-release. Up-regulation in the nitrergic pathway in early stages of the disease might play a role in colonic motor disorders associated to diverticular disease.

IL-6 signaling blockade increases inflammation but does not affect muscle function in the mdx mouse

Background

IL-6 is a pleiotropic cytokine that modulates inflammatory responses and plays critical roles in muscle maintenance and remodeling. In the mouse model (mdx) of Duchenne Muscular Dystrophy, IL-6 and muscle inflammation are elevated, which is believed to contribute to the chronic inflammation and failure of muscle regeneration in DMD. The purpose of the current study was to examine the effect of blocking IL-6 signaling on the muscle phenotype including muscle weakness and pathology in the mdx mouse.

Methods

A monoclonal antibody against the IL-6 receptor (IL-6r mAb) that blocks local and systemic IL-6 signaling was administered to mdx and BL-10 mice for 5 weeks and muscle function, histology, and inflammation were examined.

Results

IL-6r mAb treatment increased mdx muscle inflammation including total inflammation score and ICAM-1 positive lumens in muscles. There was no significant improvement in muscle strength nor muscle pathology due to IL-6r mAb treatment in mdx mice.

Conclusions

These results showed that instead of reducing inflammation, IL-6 signaling blockade for 5 weeks caused an increase in muscle inflammation, with no significant change in indices related to muscle regeneration and muscle function. The results suggest a potential anti-inflammatory instead of the original hypothesized pro-inflammatory role of IL-6 signaling in the mdx mice.

Absence of mucosal inflammation in uncomplicated diverticular disease

BACKGROUND

Uncomplicated diverticular disease is a common condition in patients older than 50 years. Symptoms are aspecific and overlapping with those of irritable bowel syndrome. Nowadays, patients are often treated with antinflammatory drugs (5-aminosalicilic acid).

AIM

Our purpose was to evaluate the presence of inflammation in the colonic mucosa of patients with symptomatic uncomplicated diverticular disease compared with subjects without diverticula.

METHODS

Endoscopic biopsies of colon from 10 patients with symptomatic uncomplicated diverticular disease and 10 from subjects without diverticula (controls) were taken. Specimens were homogenised and IL2, IL4, IL5, IL8, IL10, IL12p70, IL13, IFN gamma, TNF alfa (searchlight multiplex technique), TGF beta, transglutaminase type 2 and caspase 9 were measured. Histochemistry for transglutaminase type 2 and TUNEL were performed on the histological sections, in addition to morphologic evaluation, as markers of tissue remodelling and apoptosis. For statistical analysis Student's t test and Spearman correlation test were used.

RESULTS

No histological differences were detected between the patients with an uncomplicated diverticular disease and controls. Mean values of mucosal cytokines and of the other tested parameters did not show statistically significant differences between patients with uncomplicated diverticular disease and controls.

CONCLUSIONS

Even if based on a small number of patients, the study demonstrates the absence of inflammation in the mucosa of subjects affected by uncomplicated diverticular disease.

Cigarette smoking and appendectomy: effect on clinical course of diverticulosis

AIM

To investigate the effect of appendectomy and cigarette smoking on the clinical course of diverticulosis.

MATERIALS AND METHODS

A retrospective case-control study of 207 consecutive patients (45.8% male mean age 64.0 years), 150 with asymptomatic diverticulosis, and 57 with acute diverticulitis. Diagnosis of diverticulosis was defined on the basis of clinical and colonoscopic criteria, diverticulitis was defined by means of clinical, colonoscopic and computerised tomography criteria. Logistic regression function was used to define the relationship between the dependent variable (diverticulitis) and several covariates: sex, age, body mass index, smoking habit, and history of appendectomy.

RESULTS

According to the final model, the risk of diverticulitis was 4.94-fold higher (95% confidence interval: 1.98-12.37) in patients with a history of appendectomy with emergency resection, compared to patients not submitted to appendectomy or with a history of elective resection (P < 0.001); and 2.79-fold higher (95% confidence interval: 1.30-5.96) in smokers than in non-smokers (P = 0.008). The effects of the two determinants were found to be independent, thus the cumulative risk of diverticulitis was 13.78-fold higher for smokers with a history of emergency surgical treatment.

CONCLUSION

Smoking and emergency appendectomy are important predictive factors for the clinical course of diverticulosis.

Features and management of colonic diverticular disease

Diverticular disease is one of the most prevalent gastrointestinal conditions to afflict Western populations. Although the majority of patients with diverticulosis remain asymptomatic, about one third will develop symptoms at some point in their lives. Symptomatic diverticular disease can range from chronic mild gastrointestinal distress to acute bouts of diverticulitis complicated by abscess or frank colonic perforation. The mainstay of treatment of symptomatic diverticular disease has long been bowel rest, antibiotics, and pain control, reserving surgery for those with complicated disease. This review discusses the epidemiology, pathophysiology, clinical presentation, and management of the spectrum of diverticular disease, including recent advances in the treatment of chronic diverticular disease.

Diverticular disease is associated with an enteric neuropathy as revealed by morphometric analysis

BACKGROUND

The pathogenesis of diverticular disease (DD) is attributed to several aetiological factors (e.g. age, diet, connective tissue disorders) but also includes distinct intestinal motor abnormalities. Although the enteric nervous system (ENS) is the key-regulator of intestinal motility, data on neuropathological alterations are limited. The study aimed to investigate the ENS by a systematic morphometric analysis.

METHODS

Full-thickness sigmoid specimens obtained from patients with symptomatic DD (n = 27) and controls (n = 27) were processed for conventional histology and immunohistochemistry using anti-HuC/D as pan-neuronal marker. Enteric ganglia, nerve and glial cells were quantified separately in the myenteric, external and internal submucosal plexus compartments.

KEY RESULTS

Compared to controls, patients with DD showed significantly (P < 0.05) (i) reduced neuronal density in all enteric nerve plexus, (ii) decrease of ganglionic nerve cell content in the myenteric plexus, (iii) decreased ganglionic density in the internal submucosal plexus, (iv) reduced glial cell density in the myenteric plexus, (v) decrease of ganglionic glial cell content in the myenteric plexus and increase in submucosal plexus compartments, (vi) increased glia index in all enteric nerve plexus. About 44.4% of patients with DD exhibited myenteric ganglia displaying enteric gliosis.

CONCLUSIONS & INFERENCES

Patients with DD show substantial structural alterations of the ENS mainly characterized by myenteric and submucosal oligo-neuronal hypoganglionosis which may account for intestinal motor abnormalities reported in DD. The morphometric data give evidence that DD is associated with structural alterations of the ENS which may complement established pathogenetic concepts.

The microenvironment in chronic pancreatitis and pancreatic cancer induces neuronal plasticity

BACKGROUND

Pancreatic neuropathy in chronic pancreatitis (CP) and pancreatic cancer (PCa) is characterized by pancreatic neuropathy, i.e. increased neural density and hypertrophy, which are associated with neuropathic pain. To better understand the mechanism of these neuropathic alterations, we aimed at achieving an in-vitro simulation of the intrapancreatic neuroplasticity.

METHODS

Dissociated myenteric plexus (MP) and dorsal root ganglia (DRG) neurons of newborn rats were treated with normal human pancreas (NP), CP or PCa tissue extracts. Furthermore, MP and DRG neurons were cultured in supernatants from different pancreatic cancer cell lines (PCC) and human pancreatic stellate cells (hPSC) obtained from either CP or PCa tissues. For analysis, the neurite density, outgrowth, neuronal branching capacity and perikaryonal size were quantified.

KEY RESULTS

Myenteric plexus and DRG neurons grown in CP and PCa tissue extracts built denser networks than in NP extracts. Both neuronal types showed a strong neurite outgrowth, more complex branching pattern and a somatic hypertrophy in CP and PCa extracts. Pancreatic cancer cell supernatants induced a prominent neurite outgrowth, increased neurite density and perikaryonal hypertrophy in MP and DRG neurons. Supernatants of CP-derived hPSC strongly stimulated neurite outgrowth. Glial density in MP cultures was strikingly increased by PCa tissue extracts.

CONCLUSIONS & INFERENCES

Intrapancreatic microenvironment in CP and PCa induces neuroplastic alterations under in-vitro conditions, leading to increased neural density and hypertrophy. Thus, due to its neurotrophic attributes, the intrapancreatic microenviroment in CP and PCa seems to be a key player in the generation of pancreatic neuropathy and neuroplasticity.

Distinct alterations in colonic morphology and physiology in two rat models of enhanced stress-induced anxiety and depression-like behaviour

Stress and anxiety are important causal and exacerbating factors in functional gastro-intestinal (GI) disorders such as irritable bowel syndrome. Stress affects GI motility, faecal transit and visceral pain sensitivity. Additionally, permeability and function of the gut epithelium, which acts as a barrier between the external environment and the body's internal milieu is altered by stress. However, the effects of an enhanced stress response on colonic morphology require further investigation. We have used two animal models of stress and anxiety, the maternally separated (MS) and Wistar Kyoto (WKY) rats to examine colonic morphology. These rats exhibit increased anxiety behaviours, visceral hypersensitivity and increased stress-induced defecation in the open field arena. At a morphological level, increased mucus secretion and an associated elevation in the number of mucosal goblet cells was observed in the high anxiety rats. Additionally, the mucosal layer was flattened in MS and WKY rats, a finding indicative of mild mucosal damage. Furthermore, the muscular layer of the distal colon in these animals was thickened, an observation that may have implications for faecal transit and visceral pain perception. This study provides evidence of altered colonic function and morphology in two animal models with a heightened response to stress.

Chronic diverticulitis: clinical, radiographic, and pathologic findings

OBJECTIVE

The purpose of our study is to present a series of 14 patients with chronic diverticulitis on barium enema examinations and to correlate the radiographic findings with the clinical and pathologic findings in these patients.

CONCLUSION

Chronic diverticulitis is a distinct pathologic entity characterized by the frequent development of chronic obstructive symptoms and abdominal pain rather than the classic clinical findings of acute sigmoid diverticulitis. Barium enema examinations usually reveal a relatively long segment of circumferential narrowing in the sigmoid colon with a spiculated contour and tapered margins, sometimes associated with retrograde obstruction. Our experience suggests that chronic diverticulitis can often be diagnosed on the basis of the characteristic clinical and radiographic findings in these patients.

Diverticular disease and diverticulitis

Diverticular disease is one of the most prevalent medical conditions to affect Western populations. Symptomatic diverticular disease can range from mild, low-level symptomatology similar to that seen in irritable bowel syndrome to acute bouts of diverticulitis complicated by abscess or frank perforation. This review discusses the epidemiology, pathophysiology, clinical presentation, and management of the spectrum of diverticular disease, including mention of recent advances in the treatment of chronic diverticular disease with aminosalicyclates and probiotics.