Scientific research trends

New progress in the study of irritable bowel syndrome

Publishdate:2019-08-29 Views:223

Irritable bowel syndrome (IBS) is a disorder of gastrointestinal function characterized by abdominal pain or discomfort accompanied by changes in defecation habits and / or stool characteristics. Due to the multifactor and complexity of the pathogenesis of IBS, it is difficult to cure, the symptoms exist for a long time or recur. Frequent medical visits seriously affect the quality of life and physical and mental health of patients. To clarify the pathogenesis of IBS and choose the effective treatment are still the main problems. At the 2014 DDW conference, experts and scholars from all over the world discussed the new progress of IBS research from basic to clinical, and are summarized as follows.

1、 IBS epidemiology

The incidence rate of IBS is 9.8% to 12.8%, of which 14% are females, 8.9% are males, and females are more prone to IBS. The main subtype of IBS was constipation type (IBS-C), followed by mixed type (ibs-m, 29.7%), diarrhea type (IBS-D, 14.3%) and atypical type (ibs-u, 18.7%). The age of IBS mainly concentrated in 30~60 years old, and the incidence rate of young and old people was relatively low.

2、 Pathogenesis of IBS

1. Mental psychology and central nervous system abnormality

IBS is a psychosomatic disease, often accompanied by anxiety, depression, neuroticism, somatization disorders, fatigue and sleep disorders. Sayuk and other studies have shown that abusive experiences (such as physical, emotional and sexual) are more common in IBS patients, and are related to more severe IBS symptoms and worse quality of life. The mechanism may be partly mediated by the accompanying anxiety and depression. Jakobsson et al also found that fatigue (such as cognitive, physical and psychological) is more common in IBS, especially in patients with severe IBS symptoms, anxiety and depression. It is further explained that psychologic abnormality plays an important role in the pathogenesis of IBS, which is closely related to the quality of daily life of patients, and is an important factor to aggravate or induce severe IBS symptoms. The abnormal structure and function of the central nervous system is the basis of the abnormal interaction between brain and intestine in IBS, and it is also very important in the aspects of pain generation, emotion processing and emotion regulation. Labus et al confirmed that IBS patients had abnormal brain structure, such as amygdala, anterior cingulate gyrus, inferior callosal gyrus, anterior insular gyrus, orbitofrontal gyrus, orbital sulcus, central anterior sulcus and so on. Female patients were more obvious, and were related to visceral hypersensitivity, suggesting that IBS abnormal brain gut interaction was related to the changed white matter fiber bundle structure. In addition, sayuk et al. Reported that IBS patients showed a unique pattern of brain activation for colorectal expansion, such as the abnormal enhancement of activation in the insular gyrus, median cingulate gyrus, caudate nucleus and other regions. Hong et al. Showed specific changes of brain functional connection in the anterior insular and prefrontal / orbitofrontal cortex of IBS patients through resting brain functional imaging, suggesting that brain dysfunction plays an important role in the pathogenesis of IBS, especially in the areas related to visceral sensation and emotional regulation.

2. Inflammation and infection

The results showed that 3% - 36% of intestinal infection resulted in IBS symptoms, i.e. IBS after infection. Infection and inflammation are important factors in the pathogenesis of IBS. The intestinal mucosa of IBS patients shows low degree of immune activation, such as the increase of mast cell number and activation, T-lymphocyte subtype differentiation and imbalance of pro-inflammatory / anti-inflammatory factors. Moloney et al. Found that cxcr3-a and cxcr3-b were highly expressed in intestinal mucosa biopsy of IBS patients, but no CXCR3 was expressed in normal people. The expression of CXCL10 and CXCL11 in plasma of IBS patients was significantly higher than that of normal people, while CXCR3 was highly expressed in activated T cells, suggesting that abnormal T cell activation was involved in the development of IBS. The differentiation and maturation of peripheral blood mononuclear cells (PBMCs) in intestinal tract can be divided into two stages: M1 (cd11c-cd206) + M2 (cd11c-cd206 + cx3 CR1 +). Schulson et al. Found that compared with normal people, ML cells in patients with IBS decreased, indicating that monocyte / macrophage developed rapidly in the initial stage of maturation. However, compared with normal people, LPS stimulation did not increase the number of M2 cells in IBS The expression of CR1 indicated that there was abnormal immunoregulation.

3. intestinal flora and abnormal metabolism

In recent years, the role of intestinal flora disorders in the development of IBS has been widely concerned. Ghoshal et al. Found that in IBS patients, Lactobacillus, Bifidobacterium and Bacteroides thetaiotamicron decreased, while Pseudomonas aeruginosa increased, in which IBS-D flora disorder was the most obvious, mainly the decrease of Bifidobacterium and the increase of Bacteroides thetaiotamicron. In addition, Choi et al. Found that the colon pH of all subtypes of IBS was significantly reduced and the fermentation was significantly enhanced, especially in the proximal colon, while the small intestine did not change significantly. These results suggest that IBS is closely related to the structural changes and metabolic abnormalities of intestinal flora. Palma et al. Found that after three weeks of fecal transplantation of IBS patients with anxiety / depression to sterile mice, the mice showed anxiety like behavior; fecal transplantation of IBS patients can also affect intestinal function and immune response, such as accelerated intestinal peristalsis, increased intestinal permeability, and increased β - defensin 3 water level in the transplanted mice, further indicating that intestinal flora plays a key role in the pathogenesis of IBS. Rosique et al. Found that Clostridium dausnitzii and its culture supernatant can improve intestinal permeability and visceral hypersensitivity of chronic low-grade inflammation animal model, improve IBS like symptoms, show the effectiveness of probiotics in regulating intestinal function, suggesting that the restoration and reconstruction of normal intestinal flora may be an effective way to treat IBS.

4. Food and IBS

Food factor is one of the important reasons to induce or aggravate IBS symptoms, including: ① food malabsorption, food intolerance and food allergy, and