Proinflammatory cytokine gene polymorphisms in irritable bowel syndrome

Belgian consensus on irritable bowel syndrome

BACKGROUND

Irritable bowel syndrome (IBS) is characterised by recurrent abdominal pain related to defaecation or associated with altered stool frequency or consistency. Despite its prevalence, major uncertainties in the diagnostic and therapeutic management persist in clinical practice.

METHODS

A Delphi consensus was conducted by 20 experts from Belgium, and consisted of literature review and voting process on 78 statements. Grading of recommendations, assessment, development and evaluation criteria were applied to evaluate the quality of evidence. Consensus was defined as > 80 % agreement.

RESULTS

Consensus was reached for 50 statements. The Belgian consensus agreed as to the multifactorial aetiology of IBS. According to the consensus abdominal discomfort also represents a cardinal symptom, while bloating and abdominal distension often coexist. IBS needs subtyping based on stool pattern. The importance of a positive diagnosis, relying on history and clinical examination is underlined, while additional testing should remain limited, except when alarm features are present. Explanation of IBS represents a crucial part of patient management. Lifestyle modification, spasmolytics and water-solube fibres are considered first-line agents. The low FODMAP diet, selected probiotics, cognitive behavioural therapy and specific treatments targeting diarrhoea and constipation are considered appropriate. There is a consensus to restrict faecal microbiota transplantation and gluten-free diet, while other treatments are strongly discouraged.

CONCLUSIONS

A panel of Belgian gastroenterologists summarised the current evidence on the aetiology, symptoms, diagnosis and treatment of IBS with attention for the specificities of the Belgian healthcare system.

Latest Insights on the Pathogenesis of Irritable Bowel Syndrome

The pathogenesis of irritable bowel syndrome is multifactorial and complex. Our understanding of its pathophysiology has evolved, but remains incompletely understood. Symptoms result from a dysregulation of brain-gut interactions. Evidence has identified alterations in central and peripheral (gut) mechanisms in irritable bowel syndrome and the bidirectional communication between the brain and the gut. Pertinent mechanisms include disturbed gut motility, visceral hypersensitivity, altered mucosal and immune function, altered gut microbiota, and altered central nervous system processing. This review addresses factors that increase the risk of irritable bowel syndrome and the central and peripheral mechanisms thought to underlie its symptoms.

Inflammatory factors, genetic variants, and predisposition for preterm birth

Preterm birth is a major clinical and public health challenge, with a prevalence of 11% worldwide. It is the leading cause of death in children younger than 5 years old and represents 70% of neonatal deaths and 75% of neonatal morbidity. Despite the clinical and public health significance, this condition's etiology is still unclear, and most of the cases are spontaneous. There are several known preterm birth risk factors, including inflammatory diseases and the genetic background, although the underlying molecular mechanisms are far from understood. The present review highlights the research advances on the association between inflammatory-related genes and the increased risk for preterm delivery. The most associated genetic variants are the TNFα rs1800629, the IL1α rs17561, and the IL1RN rs2234663. Moreover, many of the genes discussed in this review are also implicated in pathologies involving inflammatory or autoimmune systems, such as periodontal disease, bowel inflammatory disease, and autoimmune rheumatic diseases. This review presents evidence suggesting a common genetic background to preterm birth, autoimmune and inflammatory diseases susceptibility.

Cytokine-Mediated Crosstalk between Immune Cells and Epithelial Cells in the Gut

Cytokines are small proteins that are secreted by a vast majority of cell types in the gut. They not only establish cell-to-cell interactions and facilitate cellular signaling, but also regulate both innate and adaptive immune responses, thereby playing a central role in genetic, inflammatory, and infectious diseases of the gut. Both, immune cells and gut epithelial cells, play important roles in intestinal disease development. The epithelium is located in between the mucosal immune system and the gut microbiome. It not only establishes an efficient barrier against gut microbes, but it also signals information from the gut lumen and its composition to the immune cell compartment. Communication across the epithelial cell layer also occurs in the other direction. Intestinal epithelial cells respond to immune cell cytokines and their response influences and shapes the microbial community within the gut lumen. Thus, the epithelium should be seen as a translator or a moderator between the microbiota and the mucosal immune system. Proper communication across the epithelium seems to be a key to gut homeostasis. Indeed, current genome-wide association studies for intestinal disorders have identified several disease susceptibility loci, which map cytokine signatures and their related signaling genes. A thorough understanding of this tightly regulated cytokine signaling network is crucial. The main objective of this review was to shed light on how cytokines can orchestrate epithelial functions such as proliferation, cell death, permeability, microbe interaction, and barrier maintenance, thereby safeguarding host health. In addition, cytokine-mediated therapy for inflammation and cancer are discussed.

Ethnic differences in genetic polymorphism associated with irritable bowel syndrome

Genetic polymorphism is associated with irritable bowel syndrome (IBS) in terms of susceptibility and clinical manifestations. Previous studies have shown that genetic polymorphism might play a key role in the onset and progression of IBS by modulating components of its pathogenesis such as the gut-brain axis, gastrointestinal motility, inflammatory activity, and immune status. Although underlying pathophysiological mechanisms have not been fully clarified, the potential ethnic differences that are present in worldwide genetic studies of IBS deserve attention. This review surveyed numerous studies focusing on IBS-associated single nucleotide polymorphisms, and investigated the ethnic disparities revealed by them. The results demonstrate the need for more attention on ethnic factors in IBS-related genetic studies. Taking ethnic backgrounds into accounts and placing emphasis on disparities potentially ascribed to ethnicity could help lay a solid and generalized foundation for transcultural, multi-ethnic, or secondary analyses in IBS, for example, a meta-analysis. Broader genetic studies considering ethnic factors are greatly needed to obtain a better understanding of the pathophysiological mechanisms of IBS and to improve the prevention, intervention, and treatment of this disease.

Silencing interleukin 1α underlies a novel inhibitory role of miR-181c-5p in alleviating low-grade inflammation of rats with irritable bowel syndrome

Irritable bowel syndrome (IBS) is a common disorder of unknown etiology. Studies have found a close relation between IBS and microRNAs (miRNAs), but the study concerning the relationship between IBS and miR-181c-5p in IBS is still blank. Thus, this study aims to explore the role of miR-181c-5p in IBS via interleukin 1α (IL1A). Initially, microarray analysis was used to retrieve the genes related to IBS and to predict miRNAs regulating IL1A gene. IBS model was then established with abdominal withdraw reflection (AWR) and Bristol stool grading in mice measured. Afterwards, the functional role of miR-181c-5p in IBS was determined using the ectopic expression, depletion and reporter assay experiments, as well as miR-181c-5p and IL1A expression detected. Subsequently, expression of tumor necrosis factor-α (TNF-α), interleukin-2 (IL-2), and IL-6 were detected to further determine the effects of miR-181c-5p and IL1A on inflammation in IBS. miR-181c-5p and IL1A might be involved in IBS. miR-181c-5p was found to be decreased while IL1A was increased in IBS rats. In addition, miR-181c-5p could target and inhibit expression of IL1A, and IBS mice exhibited elevated AWR and Bristol stool grading, namely 6 to 7 points (70.4 [38 of 54]). Moreover, with the overexpression of miR-181c-5p or silencing of IL1A, the expression of TNF-α, IL-2, and IL-6 was decreased. Collectively, this study suggested that overexpressed miR-181c-5p could silence IL1A, thus inhibiting low-grade inflammation in IBS rats. miR-181c-5p/IL1A is expected to serve as a novel target for the treatment of IBS.

Pressure management as an occupational stress risk factor in irritable bowel syndrome: A cross-sectional study

Irritable Bowel Syndrome (IBS) is the most prevalent functional gastrointestinal disorder. Psychosocial stress is one of the pathogenic factors involved in the pathogenesis of IBS. The Pressure Management Indicator (PMI) is a validated questionnaire to analyze all aspects of occupational stress-a model involving sources of pressure, the mechanisms of coping, the personality, and the resulting effects of the interaction between these 3 elements. The purpose of this study was to analyze the association between socio-professional stress effects in IBS, and the relationship of IL-6 levels and salivary cortisol with occupational stress.We conducted a prospective cross-sectional study on 76 patients (39 patients with IBS, diagnosed according to the Rome III criteria and 37 healthy controls) who were investigated using a validated self-administered questionnaire: PMI. The biologic markers of chronic stress were analyzed using salivary cortisol and the immune response with serum interleukin 6 (IL-6).The IBS patients corresponded to the following subtypes: diarrhea-predominant: 22, constipation-predominant: 14 and mixed: 3. All the socio-professional pressure effects variables and scales were statistically significant, in an inversely proportional relation with IBS. Lower scores (poor effects) were found in IBS subjects. The adjusted odds ratios of having IBS versus healthy subjects for the socio-professional pressure effects scales were: 0.81 (95% confidence interval (CI) 0.72-0.88), for satisfaction, 0.85 (95% CI 0.78-0.91) for organization, 0.85 (95% CI 0.79-0.91) for mental wellbeing and 0.8 (95% CI 0.71-0.87) for physical wellbeing (P <.001). Also, the serum IL-6 levels were significantly higher in IBS than in controls (p < 0.001). There was no statistical difference between the salivary levels of cortisol between IBS patients and controls (P = .898).The level of occupational stress was higher in IBS patients compared to healthy subjects (socio-professional stress effects were lower in IBS patients) and correlated with IL-6 levels. Salivary cortisol was not associated with occupational pressure management.

Association of Interleukin-6 and Interleukin-1 Family Gene Polymorphisms in Autoimmune Hepatitis

INTRODUCTION AND AIM

Autoimmune hepatitis (AIH) is an immune-mediated destruction of liver cells, in recognition of interface hepatitis, seropositivity for autoantibodies, and interface hepatitis in histology sections. Hepatocyte destruction in AIH is the direct result of CD4+ T-cell destruction. Yet, Th17 mediated immune attach and a diversity of cytokine networks, including pro-inflammatory cytokines such as Interleukin 1 (IL-1) and Interleukin 6 (IL-6), set the stage for the destructive liver damage.

MATERIAL AND METHOD

Peripheral blood samples from 57 patients, with AIH, recruited from referrals to the main pediatric hospital in Tehran. Single nucleotide polymorphisms for the following cytokines genes, were evaluated through, polymerase chain reaction with sequencespecific primers (PCR-SSP) assay: IL-1a (C/T -889), IL-1α (C/T -511), IL-1β (C/T +3962), IL-1 receptor (IL-1R; C/T Pst-I 1970), IL-1RA (C/T Mspa-I 11100), and IL-6 (C/G -174 and A/G nt565).

RESULTS

Significant higher frequency of genotype AA was detected in patients in IL-6 at position nt565 (15.8% in AIH patients vs. 2.9% in controls, p = 0.003). The haplotype GA of IL-6 at -174 and nt565, was significantly overrepresented in the AIH group, compared to (20.9% of AIH vs. 1.4% in controls p < 0.0001).

CONCLUSION

Results of our study, indicate significant deviation toward high yield IL-6 polymorphisms, in AIH patients. These data could bring new insights in pathophysiology of disease, which could contribute to developing novel treatments for AIH.

Current insights into the innate immune system dysfunction in irritable bowel syndrome

Irritable bowel syndrome (IBS) is a functional bowel disorder associated with abdominal pain and alterations in bowel habits. The presence of IBS greatly impairs patients' quality of life and imposes a high economic burden on the community; thus, there is intense pressure to reveal its elusive pathogenesis. Many etiological mechanisms have been implicated, but the pathophysiology of the syndrome remains unclear. As a result, novel drug development has been slow and no pharmacological intervention is universally accepted. A growing evidence implicates the role of low-grade inflammation and innate immune system dysfunction, although contradictory results have frequently been presented. Mast cells (MC), eosinophils and other key immune cells together with their mediators seem to play an important role, at least in subgroups of IBS patients. Cytokine imbalance in the systematic circulation and in the intestinal mucosa may also characterize IBS presentation. Toll-like receptors and their emerging role in pathogen recognition have also been highlighted recently, as dysregulation has been reported to occur in patients with IBS. This review summarizes the current knowledge regarding the involvement of any immunological alteration in the development of IBS. There is substantial evidence to support innate immune system dysfunction in several IBS phenotypes, but additional studies are required to better clarify the underlying pathogenetic pathways. IBS heterogeneity could potentially be attributed to multiple causes that lead to different disease phenotypes, thus explaining the variability found between study results.

Constipation in patients with myofascial pain syndrome as important aspect for clinical and nutritional treatment: A case-control study

ABSTRACT Objective To identify the occurrence of constipation in patients with myofascial pain syndrome and to correlate these disorders with the clinical and nutritional variables. Methods This report describes a case-control study performed with 98 adults of both sexs, including 49 patients and 49 individuals without pain. The intensity of the reported pain was evaluated using the Pain Visual Analog Scale, which provided a simple and efficient measurement of pain intensity consisting of a 10cm horizontal line with the ends marked “absence of pain” and “worst possible pain”. The occurrence of constipation was evaluated using the Rome III criteria. A multivariate linear regression was proposed to investigate risk factors between the frequency of bowel movements per week and independent variables this study. Results The mean ages of the patients and controls were 45.9 (7.6) years and 41.2 (12.2) years, respectively. The intensity of the reported pain showed a mean of 7.3 (1.6) points. The likelihood of exhibiting constipation was 4.5 times higher in the patients than in the controls (p=0.001). The number of stools per week was negatively correlated with the intensity of the reported pain (r=-0.613, p<0.001). The use of benzodiazepines was negatively correlated with the frequency of bowel movements per week, while the use of muscle relaxants appeared to increase the frequency of defecation when combined with the use of benzodiazepines and adjusted for the intake of fiber, water and sexs (p=0.037). Conclusion Constipation was a frequent nosological entity in this patient population and the persistence of a change in intestinal motility showed a significant correlation with the pain intensity and low water intake. The reduction of the number of stools per week seems to be associated with the use of benzodiazepines.

Interleukin-6 in irritable bowel syndrome: A systematic review and meta-analysis of IL-6 (-G174C) and circulating IL-6 levels

BACKGROUND

Irritable bowel syndrome (IBS) is a common functional gastrointestinal disorder which presents with abdominal pain and alterations of the bowel habits. The pathophysiology of IBS is not well-recognized. Low grade inflammation has been suggested as one of the underlying mechanisms of IBS. Variations in the circulating pro-inflammatory interleukin-6 (IL-6) levels and IL-6 gene polymorphisms have been demonstrated in IBS. However, the results of published studies are not consistent, probably due to their small sample sizes. To address this inconsistency, we conducted the current systematic review and meta-analysis on serum/plasma IL-6 levels and IL-6 (-G174C; rs1800795) gene polymorphism in IBS.

METHODS

PubMed was searched in July 2016. Case-control studies on serum/plasma IL-6 levels and IL-6 (-G174C) gene polymorphisms in IBS versus control were retrieved. The quality of studies was evaluated based on the modified Newcastle-Ottawa Scale (NOS) with 0 indicating the lowest and 9 as the highest score. Results were pooled using: (a) the standardized mean difference (SMD) for IL-6 levels which was considered statistically significant when the 0 value was not within the 95% confidence interval (CI), or (b) odds ratio (OR; 95% CI) through converting and pooling the IL-6 (-G174C) genotypes and alleles data into individual 2×2 tables. Heterogeneity was assessed based on I² values; where I²≤50% and I²>50% designated using fixed and random effect models, respectively.

RESULTS

Circulating IL-6 levels are higher in IBS patients compared to controls (SMD: 2.40 [95%CI: 0.53-4.28]; p=0.01). Categorizing data based on IBS subtypes, showed that IL-6 level is significantly higher in diarrhea predominant IBS (IBS-D) compared to control (SMD: 2.62 [95%CI: 0.29-4.95]; p=0.03), while it is comparable in constipation predominant IBS (IBS-C) and alternating IBS (IBS-A) patients with healthy controls. The meta-analysis of IL-6 (-G174C) polymorphism in IBS and based on IBS subtypes showed no difference in the distribution of genotypes or alleles compared to control.

CONCLUSION

The higher IL-6 levels in IBS and more specifically in IBS-D suggests a pro-inflammatory phenotype in these patients, while this phenomenon is not supported by the polymorphism of IL-6 (-G174C). Increased IL-6 in IBS might be an acquired phenomenon or mediated by other genotypes. Any potential association between gene polymorphisms and IL-6 levels in IBS should be tested by assessing both IL-6 levels and IL-6 (-G174C) simultaneously in the same IBS subjects compared to their healthy controls. Categorizing patients based on their circulating IL-6 levels may introduce a new opportunity for personalized anti-inflammatory therapies of IBS.

Influence of TNF-α-308 G/A gene polymorphism on temporomandibular disorder

INTRODUCTION

Tumor necrosis factor alpha (TNF-α) levels are significantly upregulated in the synovial fluid of patients with temporomandibular joint disorder (TMD). The TNF-α influences pain generation and maintenance. Therefore, the aim of this study was to investigate the influence of single nucleotide polymorphism TNFA-308 (rs1800629) on TMD risk and on the pressure pain threshold.

METHODS

The genotypic and allelic frequencies of candidate single nucleotide polymorphisms were compared among 152 TMD patients and 91 sex- and age-matched healthy subjects in the control group using the real-time polymerase chain reaction technique. The pressure pain threshold in the temporomandibular joint, anterior fascicle of the temporal muscle, masseter muscle, and Achilles tendon were recorded with an algometer. After the pressure test, all participants received a complete physical examination, including masticatory muscle evaluation, temporomandibular joint palpation, and assessment of mandibular range of motion.

RESULTS

The TNFA-308 polymorphism is positively associated with TMD. Subjects with TMD had a 2.87 (95% confidence interval, 1.256-6.569) times greater chance of having the GA genotype than did the control group. Rare A-allele homozygotes demonstrated decreased pain sensitivity for the temporomandibular joint and anterior fascicle of the temporal muscle in the pressure pain threshold test compared with ancestral allele homozygotes.

CONCLUSIONS

This study presents an unprecedented association between the TNFA-308 (rs1800629) polymorphism and TMD. Future studies are needed to enlighten the association between TNFA-308 G/A single nucleotide polymorphism and mechanical pain sensitivity.

Malassezia Yeast and Cytokine Gene Polymorphism in Atopic Dermatitis

INTRODUCTION

Atopic Dermatitis (AD) is a recurrent chronic condition associated with microorganism and their interaction with the susceptible host. Malassezia yeast is a known commensal which is thought to provoke the recurrent episodes of symptoms in atopic dermatitis patients. Malassezia immunomodulatory properties along with defective skin barrier in such host, results in disease manifestation. Here, we studied Single Nucleotide Polymorphism (SNP) in IL10 and IFN γ genes of the host and its relation with susceptibility to Malassezia infection.

AIM

To isolate Malassezia yeast from AD patients and compare the genetic susceptibility of the host by correlating the cytokine gene polymorphism with the control subjects.

MATERIALS AND METHODS

Study was conducted from January 2012 to January 2013. It was a prospective observational study done in Department of Microbiology and Department of Dermatology and Venereology in University College of Medical Sciences and GTB Hospital, Delhi. Sample size comprised of 38 cases each of AD. Skin scrapings were used for fungal culture on Sabouraud Dextrose Agar (SDA) and Modified Dixon Agar (MDA) and isolated were identified as per conventional phenotypic methods. Genomic DNA was extracted from blood samples collected from all study subjects. Cytokine genotyping was carried out by Amplification Refractory Mutations System- Polymerase Chain Reaction (ARMS-PCR) with sequence specific primers. Three SNPs (IL10-1082A/G; IL10-819/592C/T; IFN-γ+874A/T) in two cytokine genes were assessed in all the patients and healthy controls.

STATISTICAL ANALYSIS

Chi-Square Test or Fisher's-Exact Test and Bonferroni's correction.

RESULTS

In AD group, Malassezia yeasts were cultured in 24 out of 38 samples and thus the identification rate was 63.1 percent as compared to healthy group, 52.6 percent (20/38). Significant difference in allele, or genotype distribution were observed in IL10-819/592C/T and IFN-γ+874A/T gene polymorphism in AD group.

CONCLUSION

Higher isolation rate in cases as compared to control group highlights the implication of Malassezia in AD. Association between specific cytokine gene polymorphism and clinical outcome was found to be significant in study group. The result of cytokine gene polymorphism in the present study demonstrated susceptibility of host to Malassezia infection.

Pro-inflammatory cytokine single nucleotide polymorphisms in Kawasaki disease

AIM

Kawasaki disease (KD) is a systemic vasculitis of children associated with cardiovascular sequelae. Proinflammatory cytokines play a major role in KD pathogenesis. However, their role is both influenced and modified by regulatory T-cells. IL-1 gene cluster, IL-6 and TNF-α polymorphisms have shown significant associations with some vasculitides. Herein we investigated their role in KD.

METHODS

Fifty-five patients with KD who were randomly selected from referrals to the main pediatric hospital were enrolled in this case-control study. Single nucleotide polymorphisms (SNPs) of the following genes were assessed in patients and 140 healthy subjects as control group: IL-1α at -889 (rs1800587), IL-1β at -511 (rs16944), IL-1β at +3962 (rs1143634), IL-1R at Pst-I 1970 (rs2234650), IL-1RN/A at Mspa-I 11100 (rs315952), TNF-α at -308 (rs1800629), TNF-α at -238, IL-6 at -174 (rs1800795) and IL-6 at +565.

RESULTS

Twenty-one percent of the control group had A allele at TNF-α -238 while only 8% of KD patients had A allele at this position (P = 0.003, OR [95%CI] = 0.32 [0.14-0.71]). Consistently, TNF-α genotype GG at -238 had significant association with KD (OR [95% CI] = 4.31 [1.79-10.73]). Most controls carried the CG genotype at IL-6 -174 (n = 93 [66.9%]) while GG genotype was the most common genotype (n = 27 [49%]) among patients. Carriers of the GG haplotype at TNF-α (-308, -238) were significantly more prevalent among the KD group. No association was found between IL-1 gene cluster, allelic or haplotypic variants and KD.

CONCLUSION

TNF-α GG genotype at -238 and GG haplotype at positions -308 and -238 were associated with KD in an Iranian population.

Genetic susceptibility to postherniotomy pain. The influence of polymorphisms in the Mu opioid receptor, TNF-α, GRIK3, GCH1, BDNF and CACNA2D2 genes

BACKGROUND AND AIMS

Despite improvements in surgical technique, 5%-8% of patients undergoing herniorrhaphy still suffer from clinically relevant persistent postherniotomy pain. This is a problem at both individual and society levels. The aim of this study was to determine whether or not a single nucleotide polymorphism in a specific gene contributes to the development of persistent pain after surgery.

METHODS

One hundred individuals with persistent postherniotomy pain, along with 100 without pain matched for age, gender and type of surgery were identified in a previous cohort study on patients operated for groin hernia. All patients underwent a thorough sensory examination and blood samples were collected. DNA was extracted and analysed for single nucleotide polymorphism in the Mu opioid receptor, TNF-α, GRIK3, GCH1, BDNF and CACNA2D2 genes.

RESULTS

Patients with neuropathic pain were found to have a homozygous single nucleotide polymorph in the TNF-α gene significantly more often than pain-free patients (P=0.036, one-tailed test).

CONCLUSIONS

SNP in the TNF-α gene has a significant impact on the risk for developing PPSP.

IMPLICATIONS

The result suggests the involvement of genetic variance in the development of pain and this requires further investigation.

Association of Interleukin-1 Gene Cluster and Interleukin-1 Receptor Polymorphisms With Febrile Seizures

Interleukin-1 (IL-1) plays a key role in inflammation, has an effect on a wide variety of cells, and often leads to tissue destruction. While the ratio between IL-1 and IL-1Ra could influence the development of different diseases of the central nervous system, its gene polymorphisms were investigated in a group of patients with febrile seizures. Ninety patients with febrile seizures were enrolled and compared with 140 controls. The allele and genotype frequency of single nucleotide polymorphisms within the IL-1α, β, IL-1 R and IL-1Ra gene were determined. The frequency of the IL-1Ra/C allele at position Mspa-I 11100 was decreased significantly (P= .002) and the IL-1Ra/T frequency was significantly increased in patients (P= .002). In addition, the CT genotype frequency at the same position was significantly overrepresented in controls compared to patients (P= .001). Certain alleles and genotypes in the IL-1 gene were overrepresented in patients with febrile seizures, which possibly could predispose individuals to this disease.

High-sensitive C-Reactive Protein as a Marker for Inflammation in Irritable Bowel Syndrome

BACKGROUND

Recent studies demonstrated low-grade inflammation in patients with irritable bowel syndrome (IBS). However, these studies have been relatively small and do not enable examination of this factor in different subtypes of IBS and the possibility of confounding effects of comorbidities that may be associated with inflammatory responses.

GOALS

To investigate the association between high-sensitive C-reactive protein (hs-CRP) and the diagnosis of IBS, IBS subtypes, symptoms' severity, and IBS-associated comorbidities.

STUDY

This cross-sectional study uses data from a large matched case-control study of IBS subjects and healthy controls (HC). hs-CRP levels were measured in all subjects. IBS diagnosis was determined by Rome III criteria, negative screening blood tests, and normal colonoscopy. Subjects were evaluated for IBS severity and associated pain and psychological comorbidities.

RESULTS

A total of 242 IBS patients and 244 HC were studied. Median hs-CRP levels in the IBS group were significantly higher than in HC (1.80; interquartile range, 0.7 to 4.04 mg/L vs. 1.20, interquartile range, 0.5 to 2.97 mg/L respectively, P<0.006). Levels were highest in IBS-D patients with greater disease severity. Hs-CRP levels mildly correlated with symptoms severity (r=0.169, P=0.009); this correlation was stronger for the IBS-D patients (r=0.27, P=0.006). IBS was a significant independent predictor (P=0.025) for higher hs-CRP levels, whereas other pain and psychological comorbidities were not.

CONCLUSIONS

Given these observations of cross-sectional differences in hs-CRP between IBS subtypes and severity, independent of pain and comorbidities, more research is needed to explore a possible role of low-grade inflammation in the pathogenesis and/or clinical presentation of IBS.

Lessons learned--resolving the enigma of genetic factors in IBS

IBS is the most prevalent functional gastrointestinal disorder and phenotypically characterized by chronic abdominal discomfort, pain and altered defecation patterns. The pathophysiology of IBS is multifactorial, albeit with a substantial genetic component. To date, studies using various methodologies, ranging from family and twin studies to candidate gene approaches and genome-wide association studies, have identified several genetic variants in the context of IBS. Yet, despite enlarged sample sizes, increased statistical power and meta-analyses in the past 7 years, positive associations are still scarce and/or have not been reproduced. In addition, epigenetic and pharmacogenetic approaches remain in their infancy. A major hurdle is the lack of large homogenized case-control cohorts recruited according to standardized and harmonized criteria. The COST Action BM1106 GENIEUR (GENes in Irritable Bowel Syndrome Research Network EURope) has been established to address these obstacles. In this Review, the (epi)genetic working group of GENIEUR reports on the current state-of-the-art in the field, highlights fundamental flaws and pitfalls in current IBS (epi)genetic research and provides a vision on how to address and improve (epi)genetic approaches in this complex disorder in the future.

Tumor necrosis factor-alpha single nucleotide polymorphisms in juvenile systemic lupus erythematosus

BACKGROUND

Juvenile systemic lupus erythematosus (JSLE) is a multi-system autoimmune disorder of unknown origin. Given the importance of the contribution of pro-inflammatory cytokines, including tumor necrosis factor-alpha (TNF-α), towards the pathogenesis of JSLE, this study was performed to assess TNFA gene polymorphisms in a case-control study.

METHODS

Fifty nine patients with JSLE were enrolled in this study as case group and compared with healthy control subjects. The frequency of alleles, genotypes, and haplotypes of TNFA single-nucleotide polymorphisms (SNPs) at positions -308 and -238 were evaluated, using polymerase chain reaction with sequence-specific primers method.

RESULTS

The G allele at position -238 in TNFA promoter region was significantly more frequent in patients with JSLE than in the healthy controls (P value<0.001), while the frequency of A allele at the same position was significantly lower than controls. Furthermore, a significant positive association for G/G genotype at the same position was detected in patients' group compared with control subjects (P value<0.001). The GA haplotype of TNFA (positions -308, -238) was significantly less frequent in case group than in controls (P value<0.001), while GG was the most frequent haplotype for TNFA in the patient group, compared to controls (P value<0.01).

CONCLUSIONS

Pro-inflammatory cytokine gene polymorphisms may influence susceptibility to JSLE. Particular TNFA gene variants are associated with JSLE and could be used as a genetic marker for susceptibility to JSLE.

Single nucleotide polymorphisms of TNF-Α gene in febrile seizures

Febrile seizures (FS) is the most common seizure disorder during childhood. This study was performed in 78 patients with FS and 137 control subjects to assess polymorphisms of the TNF-α gene at positions -308 and -238, using the polymerase chain reaction and the sequence specific primers method. The highest positive allelic association that made the patients susceptible to FS was seen for TNF-α -238/G (p<0.0001). The GG genotype at TNF-α -238 was significantly higher in the patients with FS, compared to the controls (p=0.0001). Also, GA genotype at the same position was significantly lower in patients than in controls (P=0.0001). The GG haplotype had a significant positive association at TNF-α (308, 238) while GA haplotype showed a negative association (P<0.001). Our data support the idea that TNF-α single-nucleotide polymorphisms play a role in the pathogenesis of FS.

Significance of IL-1RA Polymorphism in Iranian Patients with Inflammatory Bowel Disease

BACKGROUND AND AIM

Interleukin (IL)-1 family members play an important role in the pathogenesis of inflammatory bowel disease (IBD). There are conflicting results regarding the association of IL-1 gene cluster single nucleotide polymorphisms (SNPs) with IBD and its clinical features. The aim of this study was to examine IL-1α -889 C/T, IL-1β -511 C/T, IL-1β +3962 C/T, IL-1R Pst-I1970 C/T, and IL-1RA Mspa-I11100 C/T SNPs in Iranian patients.

METHODS

In this study, SNPs of IL-1 family members were investigated in 75 patients with IBD (40 CD and 35 UC), using polymerase chain reaction with sequence-specific primers method.

RESULTS

IL-1β -511 CC genotype was significantly less present in UC compared to controls, while IL-1RA Mspa-I11100 CC was significantly associated with both Crohn's disease (CD) and ulcerative colitis (UC). IL-1α -889 TT genotype was more frequently associated with extraintestinal manifestations. A significant association was observed between IL-1β +3962 TT genotype and the disease activity in IBD. IL-1RA Mspa-I11100 CC was significantly less frequent in CD patients who need immunosuppressive therapy. IL-1RA Mspa-I11100 CT was associated with earlier age of onset in IBD, while TT genotype was associated with higher age of onset in IBD.

CONCLUSIONS

IL-1 SNPs seem to be associated with IBD and could affect the disease severity as well.

A meta-analysis of immunogenetic Case-Control Association Studies in irritable bowel syndrome

BACKGROUND

To date, genetic-association studies of single nucleotide polymorphisms (SNP) in selected candidate genes with the symptom phenotype of irritable bowel syndrome (IBS) have typically involved hundreds to 2000 patients. SNPs in immune-related genes, such as cytokine and cytokine receptor encoding genes, have been reported to associate with IBS risk.

METHODS

We conducted two independent case-control studies on 16 SNPs in IL1R1, IL4, IL6, IL8, IL10, IL23R, TNFA, and TNFSF15, one from the UK (194 patients and 92 healthy volunteers) and one from the USA (137 patients and 96 healthy volunteers). The main aim was to examine the relationship between inherited immunological diversity and IBS risk in a meta-analysis which included 12 additional, earlier studies. The meta-analysis comprised a total of 2894 patients (839 IBS-C, 1073 IBS-D, 502 IBS-M), and 3138 healthy volunteers with self-reported Caucasian ancestry.

KEY RESULTS

The association of SNP rs4263839 (TNFSF15) was investigated in four studies and confirmed in the meta-analysis: IBS (OR 1.19, 95% CI 1.08-1.31), and IBS-C (OR 1.24, 95% CI 1.08-1.42). No additional SNPs residing in immunogenes associated with IBS symptom phenotypes.

CONCLUSIONS & INFERENCES

Our meta-analysis could not confirm a major role of most investigated SNPs, but a moderate association between rs4263839 TNFSF15 and IBS, in particular IBS-C. The analysis emphasizes the importance of definition and phenotype homogeneity, adequate study size and representativeness of the patient and control collective.

Genetic polymorphism in pathogenesis of irritable bowel syndrome

Irritable bowel syndrome (IBS) is a complex symptom-based disorder without established biomarkers or putative pathophysiology. IBS is a common functional gastrointestinal disorder which is defined as recurrent abdominal pain or discomfort that has at least two of the following symptoms for 3 d per month in the past 3 mo according to ROME III: relief by defecation, onset associated with a change in stool frequency or onset with change in appearance or form of stool. Recent discoveries revealed genetic polymorphisms in specific cytokines and neuropeptides may possibly influence the frequencies and severity of symptoms, as well as the therapeutic responses in treating IBS patients. This review gives new insights on how genetic determinations influence in clinical manifestations, treatment responses and potential biomarkers of IBS.

A role for the gut microbiota in IBS

The past decade has witnessed an explosion of knowledge regarding the vast microbial community that resides within our intestine-the gut microbiota. The topic has generated great expectations in terms of gaining a better understanding of disorders ranging from IBD to metabolic disorders and obesity. IBS is a condition for which investigators have long been in search of plausible underlying pathogeneses and it is inevitable that altered composition or function of the gut microbiota will be considered as a potential aetiological factor in at least a subset of patients with IBS. This Review describes the evidence implicating the gut microbiota in not only the expression of the intestinal manifestations of IBS, but also the psychiatric morbidity that coexists in up to 80% of patients with IBS. The evidence described herein ranges from proof-of-concept studies in animals to observational studies and clinical trials in humans. The gut microbiota is subject to influences from a diverse range of factors including diet, antibiotic usage, infection and stress. These factors have previously been implicated in the pathophysiology of IBS and further prompt consideration of a role for the gut microbiota in IBS.

Irritable bowel syndrome: A disease still searching for pathogenesis, diagnosis and therapy

Irritable bowel syndrome (IBS) is the most frequently diagnosed functional gastrointestinal disorder in primary and secondary care. It is characterised by abdominal discomfort, pain and changes in bowel habits that can have a serious impact on the patient’s quality of life. The pathophysiology of IBS is not yet completely clear. Genetic, immune, environmental, inflammatory, neurological and psychological factors, in addition to visceral hypersensitivity, can all play an important role, one that most likely involves the complex interactions between the gut and the brain (gut-brain axis). The diagnosis of IBS can only be made on the basis of the symptoms of the Rome III criteria. Because the probability of organic disease in patients fulfilling the IBS criteria is very low, a careful medical history is critical and should pay particular attention to the possible comorbidities. Nevertheless, the severity of the patient’s symptoms or concerns sometimes compels the physician to perform useless and/or expensive diagnostic tests, transforming IBS into a diagnosis of exclusion. The presence of alarming symptoms (fever, weight loss, rectal bleeding, significant changes in blood chemistry), the presence of palpable abdominal masses, any recent onset of symptoms in patient aged over 50 years, the presence of symptoms at night, and a familial history of celiac disease, colorectal cancer and/or inflammatory bowel diseases all warrant investigation. Treatment strategies are based on the nature and severity of the symptoms, the degree of functional impairment of the bowel habits, and the presence of psychosocial disorders. This review examines and discusses the pathophysiological aspects and the diagnostic and therapeutic approaches available for patients with symptoms possibly related to IBS, pointing out controversial issues and the strengths and weaknesses of the current knowledge.

Genetic variants in CDC42 and NXPH1 as susceptibility factors for constipation and diarrhoea predominant irritable bowel syndrome

OBJECTIVE

The complex genetic aetiology underlying irritable bowel syndrome (IBS) needs to be assessed in large-scale genetic studies. Two independent IBS cohorts were genotyped to assess whether genetic variability in immune, neuronal and barrier integrity genes is associated with IBS.

DESIGN

384 single nucleotide polymorphisms (SNPs) covering 270 genes were genotyped in an exploratory cohort (935 IBS patients, 639 controls). 33 SNPs with Puncorrected<0.05 were validated in an independent set of 497 patients and 887 controls. Genotype distributions of single SNPs were assessed using an additive genetic model in IBS and clinical subtypes, IBS-C and IBS-D, both in individual and combined cohorts. Trait anxiety (N=614 patients, 533 controls), lifetime depression (N=654 patients, 533 controls) and mRNA expression in rectal biopsies (N=22 patients, 29 controls) were correlated with SNP genotypes.

RESULTS

Two SNPs associated independently in the exploratory and validation cohort: rs17837965-CDC42 with IBS-C (ORexploratory=1.59 (1.05 to 1.76); ORvalidation=1.76 (1.03 to 3.01)) and rs2349775-NXPH1 with IBS-D (ORexploratory=1.28 (1.06 to 1.56); ORvalidation=1.42 (1.08 to 1.88)). When combining both cohorts, the association of rs2349775 withstood post hoc correction for multiple testing in the IBS-D subgroup. Additionally, three SNPs in immune-related genes (rs1464510-LPP, rs1881457-IL13, rs2104286-IL2RA), one SNP in a neuronal gene (rs2349775-NXPH1) and two SNPs in epithelial genes (rs245051-SLC26A2, rs17837965-CDC42) were weakly associated with total-IBS (Puncorrected<0.05). At the functional level, rs1881457 increased IL13 mRNA levels, whereas anxiety and depression scores did not correlate with rs2349775-NXPH1.

CONCLUSIONS

Rs2349775 (NXPH1) and rs17837965 (CDC42) were associated with IBS-D and IBS-C, respectively, in two independent cohorts. Further studies are warranted to validate our findings and to determine the mechanisms underlying IBS pathophysiology.

Association of single nucleotide polymorphisms of interleukin-1 family with atopic dermatitis

BACKGROUND

Interleukin-1 (IL-1) seems to have an important role in early reactions towards microbes, while its genetic variability could affect this role in atopic patients who have a distressed immunity towards dermatological infections.

METHODS

Eighty-nine patients with atopic dermatitis (AD), who were referred to a main referral paediatric hospital, were enrolled in this study. Single nucleotide polymorphisms (SNP) of the following IL-1 cluster genes were assessed in this group of patients: IL-1α -889, IL-1β -511, IL-1β +3962, IL-1R Pst-I 1970, and IL-1RA Mspa-I 11100. The results were compared with a group of 140 healthy subjects from the same region.

RESULTS

Fourteen percent of the controls had TT homozygous genotype in IL-1R at position Pst-I 1970, while only 2% of the patients with AD had this genotype (p=0.005, OR: 0.14, 95%CI: 0.02-0.64). The CC homozygous genotype was the most common genotype in IL-1α position -889 and IL-1β at position +3962 in both groups of patients with AD and the controls, while the TC heterozygous genotype was the most common genotype in IL-1β at position -511 and IL-1R at position Pst-I 1970, with no significant difference between the two groups.

CONCLUSIONS

This study showed a significant negative association in the IL-1R Mspa-I 11100 TT homozygous genotype in the patients with AD.

Association of IL6 single nucleotide polymorphisms with febrile seizures

Febrile seizures (FSs) are the most common convulsive event in children. Inflammatory elements and genetics have major roles in their pathogenesis. As of the importance of interleukin-6 (IL-6) in FS, this study was performed to assess IL6 single nucleotide polymorphisms (SNPs) in a group of patients with FS. IL6 gene (-174 and +565) SNPs were studied on genomic DNAs of 90 children with FS, using PCR-SSP method. The results were compared to 139 healthy individuals. The presence of the G allele or the GG genotype at +565 position reduced risk of FS, while the A allele at +565 position of the promoter regions was a constituted risk factor for developing FS. This study could support the idea that IL6 SNPs play a role in the pathogenesis of FS.

Pathogenesis of irritable bowel syndrome--review regarding associated infection and immune activation

There is increasing evidence regarding the role of immune activation in the etiology of irritable bowel syndrome (IBS), which has been mainly been shown in studies investigating mechanisms of postinfectious IBS (PI-IBS). Exposure to intestinal infection induces persistent low-grade systemic and mucosal inflammation, which is characterized by an altered population of circulating cells, mucosal infiltration of immune cells and increased production of various cytokines in IBS patients. Recent studies have also indicated an increased innate immune response in these patients by evaluating expression and activation of Toll-like receptors (TLRs). These findings suggest that immune activation may play a crucial role in the pathogenesis of IBS. In addition, psychological stress has been reported to be one of the factors that induces immune activation. However, it remains unknown whether immune activation in IBS patients is largely dependent on infectious gastroenteritis and/or psychological stress. Additional studies are necessary to understand the precise mechanism of immune activation and its relationship to the development of IBS.

Molecular basis of the irritable bowel syndrome

Irritable bowel syndrome (IBS) is a functional disorder characterized by abdominal pain, discomfort and bloating. The pathophysiology of IBS is poorly understood, but the presence of psychosocial basis is now known. There is an increasing number of publications supporting the role of genetics in IBS. Most of the variations are found in genes associated with the brain-gut axis, revealing the strong correlation of brain-gut axis and IBS. miRNAs, which play critical roles in physiological processes, are not well studied in IBS. However, so far there is found an involvement of alterations in miRNA expression or sequence, in IBS symptoms. IBS phenotype is affected by epigenetic alteration and environment. Changes in DNA and histone methylation are observed in patients who suffered childhood trauma or abuse, resulting in altered gene expression, such as the glucocorticoid receptor gene. Finally, diet is another factor associated with IBS, which may contribute to symptom onset. Certain foods may affect on bacterial metabolism and epigenetic modifications, predisposing to IBS.

Intestinal microbiota and immune function in the pathogenesis of irritable bowel syndrome

The pathophysiology of irritable bowel syndrome (IBS) is believed to involve alterations in the brain-gut axis; however, the etiological triggers and mechanisms by which these changes lead to symptoms of IBS remain poorly understood. Although IBS is often considered a condition without an identified "organic" etiology, emerging evidence suggests that alterations in the gastrointestinal microbiota and altered immune function may play a role in the pathogenesis of the disorder. These recent data suggest a plausible model in which changes in the intestinal microbiota and activation of the enteric immune system may impinge upon the brain-gut axis, causing the alterations in gastrointestinal function and the clinical symptoms observed in patients with IBS. This review summarizes the current evidence for altered intestinal microbiota and immune function in IBS. It discusses the potential etiological role of these factors, suggests an updated conceptual model for the pathogenesis of the disorder, and identifies areas for future research.

Host immune response determines visceral hyperalgesia in a rat model of post-inflammatory irritable bowel syndrome

BACKGROUND

Irritable bowel syndrome (IBS) is associated with visceral hyperalgesia and frequently occurs after a transient gastrointestinal infection. Only a proportion of patients with acute gastroenteritis develop post-infectious IBS suggesting differences in host response to inflammatory stimuli. We aimed to investigate this concept by characterizing visceral sensitivity in two rat strains, following a chemically induced colitis.

METHODS

Colorectal instillation of trinitrobenzenesulfonic acid (TNBS) in aqueous ethanol was used to induce a transient colitis in Lewis and F344 rats. The colitis was characterized semiquantitatively by histology, as well as by quantitative methods using (99m)Tc-leukocytes (radioactive organ assay) and plasma IL-2 and IL-6 levels. Visceromotor response to colorectal distensions was assessed after 2 h and, 5, 14, and 28 days.

RESULTS

The colitis peaked on day 5 and dissipated to no visible mucosal damage on day 14. Cytokines were significantly increased in TNBS-treated rats at 2 h and on day 5. On day 14 cytokines were still significantly enhanced in Lewis but not Fisher rats. Both strains had a highly inflamed to non-inflamed tissue ratio at 3 h after TNBS instillation with increased uptake in Lewis compared to F344 rats. No (99m)Tc-tin-colloid-leukocytes were detected in colon samples on day 28. Visceromotor response was significantly elevated in both strains during the acute colitis (day 5), whereas only Lewis rats developed a post-inflammatory (day 28) visceral hyperalgesia.

CONCLUSION

Genetically determined host factors account for prolonged immune activation in response to a standardized inflammatory stimulus and are linked to susceptibility for a post-inflammatory visceral hyperalgesia.

Immune activation in irritable bowel syndrome: can neuroimmune interactions explain symptoms?

Irritable bowel syndrome (IBS) is a functional disorder of the gastrointestinal (GI) tract characterized by pain or discomfort from the lower abdominal region, which is associated with altered bowel habit. Despite its prevalence, there is currently a lack of effective treatment options for patients. IBS has long been considered as a neurological condition resulting from alterations in the brain gut axis, but immunological alterations are increasingly reported in IBS patients, consistent with the hypothesis that there is a chronic, but low-grade, immune activation. Mediators released by immune cells act to either dampen or amplify the activity of GI nerves. Release of a number of these mediators correlates with symptoms of IBS, highlighting the importance of interactions between the immune and the nervous systems. Investigation of the role of microbiota in these interactions is in its early stages, but may provide many answers regarding the mechanisms underlying activation of the immune system in IBS. Identifying what the key changes in the GI immune system are in IBS and how these changes modulate viscerosensory nervous function is essential for the development of novel therapies for the underlying disorder.

Investigation of interleukin-10 promoter polymorphisms and interleukin-10 levels in children with irritable bowel syndrome

Background/Aims

The aim of this study was to investigate whether genetic variations at positions -1082, -819, and -592 in the interleukin (IL)-10 promoter affect IL-10 production in children with irritable bowel syndrome (IBS).

Methods

Ninety-four children with IBS and 102 children as healthy controls (HCs) were enrolled. Genomic DNA was extracted, and IL-10 -1082, -819, and -592 polymorphisms were detected by direct sequencing from all participants. Peripheral blood mononuclear cells (PBMCs) from 46 IBS children and 38 HCs were isolated and cultured with and without 5 ng/mL Escherichia coli lipopolysaccharide (LPS). IL-10 levels in the culture supernatants were measured by enzyme-linked immunosorbent assay.

Results

There were no significant differences in the distribution of IL-10 -1082, -819, and -592 polymorphisms or in the allele and haplotype frequencies between IBS children and HCs. PBMCs from children with IBS had significantly lower IL-10 levels after LPS stimulation than PBMCs from HCs (p=0.011); however, LPS-induced IL-10 levels in PBMCs with different genotypes of -819 and -592 polymorphisms were not significantly different between IBS patients and HCs.

Conclusions

Although significantly lower LPS-induced IL-10 production by PBMCs was noted, it is unlikely that IL-10 production was fully genetically determined in our IBS children. ClinicalTrials.gov identifier: NCT01131442.

Effect of repeated Campylobacter jejuni infection on gut flora and mucosal defense in a rat model of post infectious functional and microbial bowel changes

BACKGROUND

Campylobacter jejuni infection is a leading cause of gastroenteritis and post infectious irritable bowel syndrome (PI-IBS). Unanswered questions include the role of cytokines, effects on gut flora, and why IBS is not more prevalent in countries with higher gastroenteritis rates. Therefore, we determined the effects of early and repeat C. jejuni infections on post infectious phenotypes, gut flora, and cytokine levels in a rat model of functional bowel and microbial changes.

METHODS

Sprague-Dawley rats were gavaged with 10(8)  cfu C. jejuni as juveniles and again as adults (J+/A+), as adults only (J-/A+), or vehicle (controls). Stool consistency during acute colonization, post infectious stool wet weight, total bacteria and Methanobrevibacter smithii levels in bowel segments, and ileal cytokines were evaluated.

KEY RESULTS

C. jejuni colonization was longer for first exposures as juveniles (43.4 ± 1.7 days) vs. adults (30.4 ± 3.5 days) (P < 0.01) and shortest for second exposures (10.5 ± 1.7 days, P < 0.05). Small intestinal bacterial overgrowth (SIBO) was more prevalent in J+/A+ (47%) than J-/A+ rats (26%) (P = 0.019), but J-/A+ rats had greater stool consistency alterations (P < 0.01). Ileal β-defensin 2, TLR-4, IL-8, and β-defensin 6 levels were increased in J-/A+ rats and further increased in J+/A+ rats; TNF-α was highest and IL6 lowest in J-/A+ rats. Total bacteria increased, and M. smithii decreased, with successive infections.

CONCLUSIONS & INFERENCES

We conclude that C. jejuni infection results in long-term alterations in small bowel flora, including methanogens. Mucosal defense mediators appear related to the number of infections, but not to SIBO development or the development of functional bowel phenotypes.

Correlation between serum serotonin and endoscopy inflammation scores in patients with ileal pouches

BACKGROUND

Inflammatory and functional complications are common in patients with inflammatory bowel disease (IBD) after restorative proctocolectomy with ileal pouch-anal anastomosis (IPAA). The pathogenesis of these complications remains poorly understood, and there is discrepancy between the clinical symptoms and objective endoscopic inflammation scores in these patients. While serum serotonin level has been reported to be associated with symptoms of irritable bowel syndrome, its association with ileal pouch disorders has not been studied.

AIM

To investigate the association between serum serotonin level and symptoms and endoscopic inflammation in patients with IPAA.

METHODS

A total of 185 consecutive eligible IPAA patients who presented to a specialized Pouchitis Clinic from Jan 2009 to May 2009 were prospectively recruited. Patients were divided into 4 groups: normal pouch, irritable pouch syndrome (IPS), inflammatory pouch disorders (Crohn's disease, acute and chronic pouchitis, and cuffitis), and surgical complications. Serum serotonin level was measured and analyzed for correlation with clinical and endoscopic inflammation scores.

RESULTS

Demographic and clinical variables were evaluated, including age, gender, smoking history, duration of UC, duration of the pouch, and disease category of the pouch. The median fasting serum serotonin level was comparable among the 4 groups: 94.0 ng/ml (interquartile range [IQR], 70.0, 128.1), 89.2 ng/ml (IQR 54.2, 155.9), 90.3 ng/ml (IQR 49.7, 164.1), 77.9 ng/ml (IQR 54.7, 129.0), for normal pouch, irritable pouch, inflammatory pouch disorders, and surgical complication groups, respectively (p=0.91). A significant association between serum serotonin level and the Pouchitis Disease Activity Index (PDAI) endoscopy subscore of the pouch (odds ratio [OR]=1.9, 95% confidence interval [CI]: 1.2, 2.9, p<0.05) and total PDAI endoscopy score (OR=1.8; 95% CI: 1.2, 2.8, p<0.05) in the inflammatory complication group were noted.

CONCLUSIONS

Serum serotonin level appears to correlate with the PDAI endoscopy subscores and total PDAI score in patients with inflammatory complications suggesting that the hormone may be involved in mechanisms of mucosal inflammation. These findings may promote future treatment strategies for patients with pouch inflammation.

Nature and nurture of human pain

Humans are very different when it comes to pain. Some get painful piercings and tattoos; others can not stand even a flu shot. Interindividual variability is one of the main characteristics of human pain on every level including the processing of nociceptive impulses at the periphery, modification of pain signal in the central nervous system, perception of pain, and response to analgesic strategies. As for many other complex behaviors, the sources of this variability come from both nurture (environment) and nature (genes). Here, I will discuss how these factors contribute to human pain separately and via interplay and how epigenetic mechanisms add to the complexity of their effects.

Cytokine gene polymorphisms are associated with irritable bowel syndrome: a systematic review and meta-analysis

BACKGROUND

Low-grade inflammation has been increasingly implicated in the pathophysiology of irritable bowel syndrome (IBS). Imbalances of pro- and anti-inflammatory cytokines and polymorphisms in cytokine genes have been reported in IBS; however, these findings have not been consistently observed. This may be due to small sample sizes and differences in ethnicities. Therefore, we performed a meta-analysis on the studies that investigated cytokine gene polymorphisms in IBS patients compared to healthy controls.

METHODS

A PubMed and EMBASE search was performed, and cytokine gene polymorphisms, which had been investigated in at least two case-control studies, were evaluated. Pooled odds ratios (OR) for the genotypes were calculated using random- or fixed-effects models.

KEY RESULTS

Five studies that investigated interleukin-10 (IL-10; -1082 G/A), transforming growth factor-β1 (TGF-β1; +869 T/C and +915 G/C) and tumor necrosis factor (TNF; -308 G/A) polymorphisms in IBS patients and controls were included. High producer IL-10 (-1082 G/G; OR: 0.64 [95% CI: 0.48-0.87]) was significantly associated with a decreased risk of IBS. The intermediate producer TGF-β1 (+915 G/C) genotype showed a tendency toward decreasing the risk of IBS. No associations were found between TNF (-308 G/A) genotypes and IBS in the whole meta-analysis although an analysis of Asian studies revealed an association between TNF (-308 G/A and G/G) genotypes and IBS (OR: 0.50 [95% CI: 0.29-0.85]), and 1.82 [95% CI: 1.08-3.07], respectively).

CONCLUSIONS & INFERENCES

This meta-analysis indicates a role for IL-10 polymorphisms in IBS in general and TNF in Asian populations. Whether or not gene polymorphisms are associated with alterations in cytokine levels leading to functional effects at the level of the gut needs further investigation.

Findings related to IL-8 and IL-10 gene polymorphisms in a Mexican patient population with irritable bowel syndrome infected with Blastocystis

The intestinal protozoan parasite Blastocystis is one of the most common parasites worldwide in humans and, although its ability to cause human disease has been questioned, some reports have demonstrated that this microorganism is associated to the development of irritable bowel syndrome (IBS) and to a proinflammatory response, in which the expression of some cytokines is unregulated. Since inflammatory cytokine gene polymorphisms might have a role in the pathophysiology of IBS, we assessed the role of single nucleotide polymorphisms (SNPs) for interleukin (IL)-8 and IL-10, in previously collected DNA samples from IBS patients and controls, with or without Blastocystis infection. IL-8+396(G) and IL-10-1082 (A) alleles (p=0.0437 and p=0.0267, respectively), as well as their homozygous (p<0.0001 and p=0.0039, respectively) and IL-8+781(CT) (p=0.0248) genotypes were significantly overrepresented in patients with IBS in comparison with controls. IL-8+396(GG) genotype was relevant because it was associated to IBS (p<0.0001), to Blastocystis (p=0.0025), and to IBS–Blastocystis (p=0.0272). In the latter binomial association, this genotype presented a high contribution (etiological fraction =0.452) and a risk >fourfold to develop IBS. IL-8+781 (T) and IL-10-592 (C) alleles were also associated to Blastocystis and to IBS–Blastocystis, respectively (p=0.0448 and p=0.0166). Our results suggest that some IL-8 and IL-10 SNPs could change individual susceptibility increasing the relative risk in the development of IBS in Blastocystis carriers.

Associations between pro- and anti-inflammatory cytokine genes and breast pain in women prior to breast cancer surgery

The purposes of this study were to determine the occurrence rate for preoperative breast pain; describe the characteristics of this pain; evaluate for differences in demographic and clinical characteristics; and evaluate for variations in pro- and anti-inflammatory cytokine genes between women who did and did not report pain. Patients (n = 398) were recruited prior to surgery and completed self-report questionnaires on a number of pain characteristics. Genotyping was done using a custom genotyping array. Women (28.2%) who reported breast pain were significantly younger (P < .001); more likely to be nonwhite (P = .032); reported significantly lower Karnofsky Performance Status scores (P = .008); were less likely to be postmenopausal (P = .012); and had undergone significantly more biopsies (P = .006). Carriers of the minor allele for a single nucleotide polymorphism in interleukin (IL)1-receptor 1 (IL1R1) (rs2110726) were less likely to report breast pain prior to surgery (P = .007). Carriers of the minor allele for a single nucleotide polymorphism in IL13 (rs1295686) were more likely to report breast pain prior to surgery (P = .019). Findings suggest that breast pain occurs in over a quarter of women who are about to undergo breast cancer surgery. Based on phenotypic and genotypic characteristics found, inflammatory mechanisms contribute to preoperative breast pain.

PERSPECTIVE

In women with breast cancer, preoperative pain may be associated with increases in inflammatory responses associated with an increased number of biopsies. In addition, differences in cytokine genes may contribute to this preoperative breast pain.

Salmeterol attenuates the inflammatory response in asthma and decreases the pro-inflammatory cytokine secretion of dendritic cells

Salmeterol is a long-acting β2-agonist that activates adenylate cyclase, causing long-lasting bronchodilation and has been used for many years to control asthma. However, little information is available about the immunoregulatory effects of salmeterol. We found that salmeterol decreases the production of pro-inflammatory cytokines in a model of allergen-challenged mice that expressed tumor-necrosis factor-alpha, interleukin-1 and interleukin-6. Dendritic cells (DCs) are antigen-presenting cells and act as sentinels in the airway. We found that salmeterol (10(-5) mol/l) reduced the inflammation caused by lipopolysaccharide (0.1 µg/ml) in activated murine bone marrow-derived DCs. Moreover, western blots demonstrated that this protective effect was mediated partially by inhibiting signaling through the nuclear factor-kappa B (NF-κB), mitogen-activated protein kinase (MAPK) pathways and dramatically decreased levels of p-ERK. We suggest that salmeterol regulates the inflammation of allergen-induced asthma by modulating DCs. In conclusion, we provide evidence that DCs are the target immune cells responsible for the action of salmeterol against asthma.

Excess risk of temporomandibular disorder associated with cigarette smoking in young adults

Evidence suggests that the effect of cigarette smoking on chronic pain is stronger in younger than older adults. This case-control study investigated whether age modified an effect of smoking on temporomandibular disorder (TMD) in 299 females aged 18 to 60 years. It also investigated the extent to which this relationship was explained by psychological profile, inflammatory response, and allergy. Cases were defined using the Research Diagnostic Criteria for Temporomandibular Disorders based on clinical examination. Psychological profile was evaluated using standardized instruments. Inflammatory response was evaluated with 11 cytokines isolated in plasma. History of allergy conditions was self-reported. Odds ratios (ORs) for the effect of smoking were calculated using binary logistic regression. Stratified analyses and the likelihood ratio test examined effect modification by smoking. Compared with nonsmokers, ever smokers aged <30 years had higher odds of TMD (OR = 4.14, 95% CI: 1.57, 11.35) than older adults (OR = 1.23, 95% CI: .55, 2.78) (P (effect modification) = .038). Adjustment for psychological profile, cytokines, and history of allergy-like conditions attenuated the effect by 45% to statistical nonsignificance. The main finding was reproduced with secondary analyses of 2 nationally representative surveys of adults conducted in the US and Australia.

PERSPECTIVE

This study showed that smoking was associated with TMD risk in females, but only in young adulthood. It replicated this finding in 2 nationally representative surveys of females in the US and Australia. Findings may alert clinicians to recognize that smoking is a concern for TMD in younger female patients.