Histopathology in gastrointestinal neuromuscular diseases: methodological and ontological issues

Intestinal hypomotility in systemic sclerosis: a histological study into the sequence of events

OBJECTIVES

The pathogenesis of intestinal involvement in systemic sclerosis (SSc) is thought to be a sequential process (vascular, neuronal, and consecutive muscular impairment), but understanding of the underlying histological changes and how they translate to symptoms, is still lacking. Therefore, we systematically investigated histological characteristics of SSc in the intestines, compared to controls.

METHODS

Autopsy material from the small bowel and colon was used for histological semiquantitative evaluation of the vasculature, enteric nervous system, interstitial cells of Cajal (ICC), and muscle layers, using a combination of histochemical and immunohistochemical stainings, according to guidelines of the Gastro 2009 International Working Group.

RESULTS

Vascular changes were most frequently encountered, represented by intima fibrosis in both arteries and small vessels, and represented by venous dilatation. Second, generalized fibrosis of the circular muscle layer was significantly more found in SSc patients than in controls. Third, reduction of submucosal nerve fibers and myenteric neurons was shown in the colon of four SSc patients, which may explain severe symptoms of intestinal dysmotility. The density of myenteric ICC network was decreased in the small bowel of SSc patients.

CONCLUSIONS

The postulated sequential processes of intestinal involvement in SSc could not be supported by our histological evaluation. The interpatient diversity suggests that parallel processes occur, explaining the variety of histological features and clinical symptoms. Key Points • Histological analysis showed vascular changes, fibrosis in the muscularis propria, and reduction of the ENS and ICC network in the intestines of SSc patients. • Pathophysiological mechanisms leading to intestinal dysmotility in SSc may be parallel rather than sequential. • The interpatient diversity suggests parallel pathophysiological processes, explaining the variety of histological features and clinical symptoms.

Enteric neuron density correlates with clinical features of severe gut dysmotility

Gastrointestinal (GI) symptoms can originate from severe dysmotility due to enteric neuropathies. Current methods used to demonstrate enteric neuropathies are based mainly on classic qualitative histopathological/immunohistochemical evaluation. This study was designed to identify an objective morphometric method for paraffin-embedded tissue samples to quantify the interganglionic distance between neighboring myenteric ganglia immunoreactive for neuron-specific enolase, as well as the number of myenteric and submucosal neuronal cell bodies/ganglion in jejunal specimens of patients with severe GI dysmotility. Jejunal full-thickness biopsies were collected from 32 patients (22 females; 16-77 yr) with well-characterized severe dysmotility and 8 controls (4 females; 47-73 yr). A symptom questionnaire was filled before surgery. Mann-Whitney U test, Kruskal-Wallis coupled with Dunn's posttest and nonparametric linear regression tests were used for analyzing morphometric data and clinical correlations, respectively. Compared with controls, patients with severe dysmotility exhibited a significant increase in myenteric interganglionic distance (P = 0.0005) along with a decrease in the number of myenteric (P < 0.00001) and submucosal (P < 0.0004) neurons. A 50% reduction in the number of submucosal and myenteric neurons correlated with an increased interganglionic distance and severity of dysmotility. Our study proposes a relatively simple tool that can be applied for quantitative evaluation of paraffin sections from patients with severe dysmotility. The finding of an increased interganglionic distance may aid diagnosis and limit the direct quantitative analysis of neurons per ganglion in patients with an interganglionic distance within the control range.NEW & NOTEWORTHY Enteric neuropathies are challenging conditions characterized by a severe impairment of gut physiology, including motility. An accurate, unambiguous assessment of enteric neurons provided by quantitative analysis of routine paraffin sections may help to define neuropathy-related gut dysmotility. We showed that patients with severe gut dysmotility exhibited an increased interganglionic distance associated with a decreased number of myenteric and submucosal neurons, which correlated with symptoms and clinical manifestations of deranged intestinal motility.

Intestinal involvement in amyloidosis is a sequential process

BACKGROUND

Gastrointestinal amyloidosis causes dysmotility. A comprehensive histological analysis to explain these symptoms is lacking. Therefore, we systematically examined histological features of intestinal dysmotility in patients with AL and AA amyloidosis, compared to controls.

METHODS

Autopsy tissue material from small bowel and colon was used for histological (semiquantitative) evaluation of the mucosa, blood vessels, muscular layers, enteric nervous system (ENS) and the interstitial cells of Cajal (ICC), using hematoxylin and eosin, periodic acid Schiff, Elastic von Gieson and Congo red staining, and immunohistochemistry with α-smooth muscle actin, HuC/D, S100 and CD117 antibodies, according to guidelines of the Gastro 2009 International Working Group.

KEY RESULTS

Amyloid deposits were present in the vascular walls of all amyloidosis patients. In the mucosa, amyloid was found in 67% of AA patients. The muscular layers were involved in 64% of amyloidosis patients, most prominent in AA patients, associated with the presence of polyglucosan inclusion bodies, but not with either abnormal α-actin patterns or fibrosis. Amyloid in the muscularis propria surrounding the myenteric plexus was found, but not inside the myenteric plexus. These deposits might be related to loss of the ICC network, but there was no association with decreased neuronal or nerve fiber density.

CONCLUSIONS & INFERENCES

We hypothesize that intestinal dysmotility in amyloidosis patients is a sequential process: amyloid deposition starts in the vasculature, followed by involvement of the muscular layers, ICC loss, and potentially affect the myenteric plexus. This final stage may be accompanied by clinical symptoms of severe intestinal dysmotility.

Pathophysiology, Diagnosis, and Management of Chronic Intestinal Pseudo-Obstruction

Chronic intestinal pseudo-obstruction (CIPO) is a rare disorder characterized by an impairment of coordinated propulsive activity in the gastrointestinal (GI) tract, which clinically mimics mechanical intestinal obstruction. CIPO is the most severe and debilitating form of GI dysmotility. CIPO may be primary or be secondary to pathology at any level of the brain-gut axis as well as systemic disease. The clinical features of CIPO are pleomorphic and largely depend on the site and extent of the segment of the GI tract involved. The diagnostic approach includes the need for investigations to exclude mechanical GI obstruction, screening for causes of secondary CIPO and the identification of the disease phenotype as well as the prompt recognition and treatment of complications such as malnutrition and small intestinal bacterial overgrowth. In managing this disorder, a holistic, multidisciplinary approach is needed with judicious use of pharmacotherapeutic agents. While currently there are no specific therapeutic modalities for CIPO, treatment is largely directed at maintaining adequate nutrition and electrolyte balance and enhancing coordinated GI motility. Surgery should be avoided unless advisable for carefully selected patients and may include stoma formation. This narrative review provides a concise overview of the literature on this rare, severe and complex disorder, and highlights the need and areas for further research to improve both diagnostics and therapeutics.

The enteric nervous system and the musculature of the colon are altered in patients with spina bifida and spinal cord injury

Neurogenic bowel dysfunction occurs in a large percentage of adult patients with spina bifida (SB) and spinal cord injury (SCI), significantly affecting their quality of life. Although bowel motility is autonomously regulated by the enteric nervous system (ENS), disruption of the modulation of the ENS by extrinsic innervation as present in many patients with SB and SCI might lead to motility disorders. In order to gain insight in the pathophysiology, we studied histological changes of the neuromuscular structures in the colon of SB and SCI patients. Archival colon tissue blocks from SB (n = 13) and SCI (n = 34) patients were collected nationwide in The Netherlands and compared with control samples (n = 16). Histological (semiquantitative) evaluation of the ENS, the network of interstitial cells of Cajal (ICC), and the muscularis propria was performed using hematoxylin and eosin, periodic acid Schiff, and elastic von Gieson staining, and immunohistochemistry with antibodies against HuC/D, calretinin, S100, CD117, α-smooth muscle actin, and desmin. Compared to controls, SB and SCI patients showed neuronal loss and decreased nerve fiber density in the myenteric plexus. Lower nerve fiber density was significantly more often found in patients with severe bowel dysfunction. Other major findings were loss of ICCs around the myenteric plexus and fibrosis in the longitudinal muscle layer. Altered histology of the ENS may explain abnormal intestinal motility in SB and SCI patients. Furthermore, loss of myenteric nerve fibers (including enteric glial cells) may play a major role in the development of severe motility complaints.

Fibrotic and Vascular Remodelling of Colonic Wall in Patients with Active Ulcerative Colitis

BACKGROUND AND AIMS

Intestinal fibrosis is a complication of inflammatory bowel disease [IBD]. Although fibrostenosis is a rare event in ulcerative colitis [UC], there is evidence that a fibrotic rearrangement of the colon occurs in the later stages. This is a retrospective study aimed at examining the histopathological features of the colonic wall in both short-lasting [SL] and long-lasting [LL] UC.

METHODS

Surgical samples of left colon from non-stenotic SL [≤ 3 years, n = 9] and LL [≥ 10 years, n = 10] UC patients with active disease were compared with control colonic tissues from cancer patients without UC [n = 12] to assess: collagen and elastic fibres by histochemistry; vascular networks [CD31/CD105/nestin] by immunofluorescence; parameters of fibrosis [types I and III collagen, fibronectin, RhoA, alpha-smooth muscle actin [α-SMA], desmin, vimentin], and proliferation [proliferating nuclear antigen [PCNA]] by western blot and/or immunolabelling.

RESULTS

Colonic tissue from both SL-UC and LL-UC showed tunica muscularis thickening and transmural activated neovessels [displaying both proliferating CD105-positive endothelial cells and activated nestin-positive pericytes], as compared with controls. In LL-UC, the increased collagen deposition was associated with an up-regulation of tissue fibrotic markers [collagen I and III, fibronectin, vimentin, RhoA], an enhancement of proliferation [PCNA] and, along with a loss of elastic fibres, a rearrangement of the tunica muscularis towards a fibrotic phenotype.

CONCLUSIONS

A significant transmural fibrotic thickening occurs in colonic tissue from LL-UC, together with a cellular fibrotic switch in the tunica muscularis. A full-thickness angiogenesis is also evident in both SL- and LL-UC with active disease, as compared with controls.

The enteric nervous system in patients with calculous and acalculous gallbladder

BACKGROUND

It is generally thought that gallbladder motility plays a more or less important role in the pathogenesis of gallstones. Some studies have shown that some abnormalities of its intrinsic innervations, but these studies were usually limited to one cell component.

AIMS

We investigated the main cell components of gallbladder intrinsic innervation in patients with and without gallstones.

METHODS

Archival gallbladder specimens from 39 patients, 27 with gallstones (age range 45-69 yrs) and 12 patients without gallstones (age range 39-71 yrs) were obtained. Full thickness sections were obtained from the gallbladder neck and immunohistochemistry was carried out for enteric neurons (neuron-specific enolase and calretinin), enteric glia (S100) and interstitial cells of Cajal (CD117 and CD34); tryptase staining was also done to distinguish the latter from mast cells.

RESULTS

Apart from calretinin-positive neurons, patients with gallstones featured a significant decrease of neurons, enteric glial cells (EGC) and mast cells compared to those without gallstones; interstitial cells of Cajal were extremely few and only found in two patients, one for each group.

CONCLUSIONS

The intrinsic innervations of the gallbladder is abnormal in gallstone patients, and this may contribute to gallstone formation in these subjects.

Neuroenteric Staining as a Tool in the Evaluation of Pediatric Motility Disorders

The diagnosis of enteric neuromuscular disorders has come a long way since the first description of an enteric neuropathic disorder by the Danish physician Harald Hirschsprung in 1886. Advances in specialized enteric histopathological staining techniques have made it possible to identify subtle neuropathies and myopathies that cause intestinal motility disorders, from the common and now better understood and relatively easily diagnosed Hirschsprung's disease to the less common and more severe and not well-characterized chronic idiopathic intestinal pseudoobstruction, which continues to present a diagnostic challenge to the gastroenterologist and histopathologist alike. This article will discuss the common gastrointestinal motility disorders and some of the specialized histological stains, such as the relatively common enzyme stain, acetylcholinesterase, used to diagnose Hirschsprung's disease; advanced tinctorial stains, such as Masson trichrome, which may aid in diagnosis of enteric myopathies causing pseudoobstruction; and immunohistochemical stains such as C-Kit or PG 9.5, which may aid in the diagnosis of enteric neuropathies causing pseudoobstruction.

Colonic motility in ulcerative colitis

BACKGROUND

Inflammatory conditions affecting the gut may cause motility disturbances, and ulcerative colitis - one of the main disorders among the inflammatory bowel diseases - may display abnormal colonic motility.

AIM

To review the abnormalities of the large bowel in ulcerative colitis, by considering the motility, laboratory (in vitro) and pathological studies dealing with this topic.

METHODS

A comprehensive online search of Medline and the Science Citation Index was carried out.

RESULTS

Patients with ulcerative colitis frequently display colonic motor abnormalities, including lack of contractility, an increase of propulsive contractile waves, an excessive production of nitric oxide, vasoactive intestinal polypeptide nerves, interleukin 1 beta, neurotensin, tachykinins levels and the weaker action of substance P, likely related to a neuromuscular dysfunction due to the inflammatory process.

CONCLUSIONS

A better understanding of the pathophysiological grounds of altered colonic motility in ulcerative colitis may lead to a more in-depth knowledge of the accompanying symptoms and to better and more targeted therapeutic approaches.

Understanding and treating refractory constipation

Chronic constipation is a frequently encountered disorder in clinical practice. Most constipated patients benefit from standard medical approaches. However, current therapies may fail in a proportion of patients. These patients deserve better evaluation and thorough investigations before their labeling as refractory to treatment. Indeed, several cases of apparent refractoriness are actually due to misconceptions about constipation, poor basal evaluation (inability to recognize secondary causes of constipation, use of constipating drugs) or inadequate therapeutic regimens. After a careful re-evaluation that takes into account the above factors, a certain percentage of patients can be defined as being actually resistant to first-line medical treatments. These subjects should firstly undergo specific diagnostic examination to ascertain the subtype of constipation. The subsequent therapeutic approach should be then tailored according to their underlying dysfunction. Slow transit patients could benefit from a more robust medical treatment, based on stimulant laxatives (or their combination with osmotic laxatives, particularly over the short-term), enterokinetics (such as prucalopride) or secretagogues (such as lubiprostone or linaclotide). Patients complaining of obstructed defecation are less likely to show a response to medical treatment and might benefit from biofeedback, when available. When all medical treatments prove to be unsatisfactory, other approaches may be attempted in selected patients (sacral neuromodulation, local injection of botulinum toxin, anterograde continence enemas), although with largely unpredictable outcomes. A further although irreversible step is surgery (subtotal colectomy with ileorectal anastomosis or stapled transanal rectal resection), which may confer some benefit to a few patients with refractoriness to medical treatments.

A review of the phytochemistry and pharmacological activities of raphani semen

The dried ripe seed of Raphanus sativus L., commonly known as radish seed (or Raphani Semen), is used as traditional Chinese medicine (TCM) to treat constipation, chronic tracheitis, and hypertension. The major active compounds in Raphani Semen are alkaloids, glucosinolates, brassinosteroids, and flavonoids. Fatty acids are its main nutritional contents. Raphani Semen has been demonstrated to have beneficial effects on hypertension, obesity, diabetes mellitus, constipation, and cough. So far, there is no report about the adverse/toxic effects of this herb on humans. However, Raphani Semen processed by roasting was reported to exhibit some adverse effects on mice. Additionally, erucic acid, the main fatty acid in Raphani Semen, was shown to enhance the toxicity of doxorubicin. Thus, Raphani Semen has a potential risk of causing toxicity and drug interaction. In summary, Raphani Semen is a valuable TCM herb with multiple pharmacological effects. More studies on Raphani Semen could help better understand its pharmacological mechanisms so as to provide clear scientific evidence to explain its traditional uses, to identify its therapeutic potential on other diseases, and to understand its possible harmful effects.