Functional consequences of NOD2/CARD15 mutations in Crohn disease

Autophagy and inflammation

Autophagy is a homeostatic mechanism involved in the disposal of damaged organelles, denatured proteins as well as invaded pathogens through a lysosomal degradation pathway. Recently, increasing evidences have demonstrated its role in both innate and adaptive immunity, and thereby influence the pathogenesis of inflammatory diseases. The detection of autophagy machinery facilitated the measurement of autophagy during physiological and pathophysiological processes. Autophagy plays critical roles in inflammation through influencing the development, homeostasis and survival of inflammatory cells, including macrophages, neutrophils and lymphocytes; effecting the transcription, processing and secretion of a number of cytokines, as well as being regulated by cytokines. Recently, autophagy-dependent mechanisms have been studied in the pathogenesis of several inflammatory diseases, including infectious diseases, Crohn’s disease, cystic fibrosis, pulmonary hypertension, chronic obstructive pulmonary diseases and so on. These studies suggested that modulation of autophagy might lead to therapeutic interventions for diseases associated with inflammation. Here we highlight recent advances in investigating the roles of autophagy in inflammation as well as inflammatory diseases.

Association of inflammatory cytokine gene polymorphisms with inflammatory bowel disease in a Moroccan cohort

The purpose of this study was to investigate whether common variants in inflammatory and immune response genes influence inflammatory bowel disease (IBD) risk among Moroccan patients. Using a candidate gene approach, 10 single-nucleotide polymorphisms mapping on six genes (MIF_rs755622, TNFA_rs1800629, IL6_rs2069840, IL6R_rs2228145, IL6ST_rs2228044, IL17A (rs2275913, rs4711998, rs7747909, rs8193036, rs3819024)) were assessed in 510 subjects grouped in 199 IBD and 311 healthy controls. Genotyping was performed with the TaqMan allelic discrimination technology. The results were analyzed using PLINK software. The frequency of allele A for TNFA rs1800629 was significantly higher in ulcerative colitis (UC) patients compared with controls (30.16 vs 16.72%; P=0.0005; odds ratio (OR)=2.15; 95% confidence interval (CI)=1.39-3.32). Statistically significant association to UC was also found under dominant AA+AG vs GG (OR=1.85, 95% CI=1.07-3.21; P=0.02) and recessive models (OR=8.38; 95% CI=2.86-24.53; P=0.0001). In the same way, an association of TNFA rs1800629 variant was observed with IBD under recessive model AA vs AG+GG (OR=4.10; 95% CI=1.56-10.76; P=0.004). No evidence of significant associations was found for the remaining investigated polymorphisms. Our data suggest that TNFA gene promoter polymorphism participates in determining IBD susceptibility in Moroccan patients.

Aerobic and Anaerobic Bacteriology of Hidradenitis Suppurativa: A Study of 22 Cases

INTRODUCTION

Hidradenitis suppurativa (HS) is a chronic inflammatory skin disease of unclear etiology. The role of bacteria in the pathogenesis of disease remains controversial.

MATERIALS AND METHODS

Specimens were obtained from 22 HS patients by direct percutaneous needle aspiration. The collected material was cultured in aerobic and anaerobic conditions, and sensitivity tests were performed.

RESULTS

Of the 22 patients, 32% were culture negative and 68% were culture positive. A total of 16 isolates was obtained, 14 aerobic and 2 anaerobic. Aerobic bacteria were present in 86% of the specimens, whereas only anaerobic bacteria were isolated in 7%. The predominant aerobic species were Proteus mirabilis, Staphylococcus haemolyticus and Staphylococcus lugdunensis. The isolated anaerobic bacteria were Dermacoccus nishinomiyaensis and Propionibacterium granulosum.

CONCLUSION

A variety of aerobic and anaerobic bacteria was isolated from the HS lesions of our patients. In contrast to previous studies, fewer patients were found to be culture positive, and Staphylococcus aureus was isolated in only 1 of them. More studies are necessary to elucidate the controversial role of bacteria in the pathogenesis of HS.

Nucleotide-binding oligomerization domain containing 2: structure, function, and diseases

OBJECTIVES

To systematically review literature about the structure and function of nucleotide-binding oligomerization domain containing 2 (NOD2) and its disease association.

METHODS

The English literature was searched using keywords "NOD2" and "disease". Relevant original and review articles were reviewed.

RESULTS

NOD2 is an intracellular protein and shares similar molecular structure with NOD1, pyrin, and cryopyrin. There are more than 100 NOD2 gene mutations, some of which have been linked to diseases such as Crohn disease, Blau syndrome, and NOD2-associated autoinflammatory disease (NAID). The NOD2 variants located in the leucine-rich repeat (LRR) region are susceptible to Crohn disease, and the variants in the nucleotide-binding domain (NBD) and in between the NBD and LRR are associated with Blau syndrome and NAID, respectively. No disease association with the gene variants has been found in rheumatoid arthritis, systemic lupus erythematosus, ankylosing spondylitis, psoriasis/psoriatic arthritis, adult sarcoidosis, granulomatous polyangiitis, or multiple sclerosis. The potential association of the NOD2 variants with graft-versus-host-disease remains controversial. NOD2 functions mainly through RICK or RIP2 to activate p38 mitogen-activated protein kinases and NF-κB, resulting in inflammatory response, and enhanced autophagic activity. Biologic therapy may be beneficial for NOD2-associated diseases, and new drug development may be realized based upon the signaling pathways.

CONCLUSIONS

NOD2 gene mutations are associated with several diseases, and some of the mutations are of diagnostic value in Blau disease and NAID. To understand the NOD2 function, disease association, and its pathogenesis is important given the ever increasing clinical significance of NOD2.

Non-Jewish Israeli IBD patients have significantly higher glutathione S-transferase GSTT1-null frequency

BACKGROUND

The involvement of oxidant/antioxidant imbalance in the development of inflammatory bowel disease (IBD) is well documented. Two members of the glutathione S-transferase (GST) family of enzymes, GSTM1 and GSTT1, known to take part in cellular protection against electrophiles, demonstrate common deletion variants (termed null) associated with impaired enzyme function.

AIM

To evaluate the effect of GSTM1/GSTT1 genotype on IBD susceptibility in a Israeli cohort and to study the correlation between GSTM1/GSTT1 genotype, smoking status, and a variety of clinical characteristics of IBD.

METHODS

A cohort of 606 Israeli IBD patients (453 with Crohn's disease [CD] and 153 with ulcerative colitis [UC]) and 528 ethnically matched healthy controls were genotyped for the null variants of GSTM1 and GSTT1. In patients, phenotype-genotype correlations were examined.

RESULTS

Ethnic stratification of healthy controls revealed a higher frequency of GSTT1-null in Jewish and Arab Moslem individuals compared to Druze individuals (P < 0.0005), but no difference in GSTM1-null was found. Comparing IBD patients (both CD and UC) to healthy controls revealed a pattern of lower GSTM1-null and higher GSTT1-null frequencies, which reached significance in Arab Moslem patients. No association was found between NOD2/CARD15 mutation carriage and GSTM1/GSTT1 genotype. No statistically significant association was found between GSTT1-null or GSTM1-null, smoking status, and other phenotypes of CD/UC.

CONCLUSIONS

GSTT1-null appears to be associated with IBD, while GSTM1-null appears to be conversely associated with IBD. No association was found between GSTT1-null or GSTM1-null and specific IBD phenotypes.

Hidradenitis suppurativa: a review of cause and treatment

PURPOSE OF REVIEW

Hidradenitis suppurativa is a chronic or relapsing inflammatory cutaneous disorder manifested by recurrent formation of abscesses, fistulating sinus and scarring in the apocrine-gland-bearing skin. This review discusses the different aetiological theories and management opportunities.

RECENT FINDINGS

Current understanding of the pathogenesis suggests that hyperkeratosis of the infundibulum, leading to follicular occlusion of the pilosebaceous unit plays a role. Bacterial infection with staphylococci, Escherichia coli and streptococcus is considered as a secondary event in the pathogenesis. Smoking and obesity are both known as risk factors and are associated with more severe disease course. Recently, more attention has been put into the understanding of the immunopathology of the skin and the results indicate that hidradenitis suppurativa may be considered as an inflammatory disease of unknown cause based on a defect in the hair follicle immunity. The treatments are most appropriately chosen on the basis of disease severity and the existence of any associated risk factors or comorbidities. There are three levels in the management of hidradenitis suppurativa: topical options, systemic options and surgical methods including laser therapy. At each level several treatment principles have shown themselves to be efficient, and may therefore be used either alone or in combination. Therapies are generally effective against microorganisms, inflammation or infundibular hyperkeratosis. Where an antimicrobial therapy is used, the drugs used often have significant additional immunomodulatory effects.

SUMMARY

The recent studies give us a better insight into the pathogenesis of hidradenitis suppurativa and should translate into improved therapies.

A case of concurrent sarcoidosis, aortitis syndrome and Crohn's disease

A 24-year-old man was referred to our hospital due to bilateral hilar lymphadenopathy on chest radiography. He had been under medication for aortitis syndrome and Crohn's disease for 12 years. Surgical biopsy from the anterior segment of the left upper lobe and mediastinal lymph nodes was performed under video-assisted thoracoscopy. Histopathological examination revealed epithelioid cell granulomas without caseous necrosis, compatible with sarcoidosis. Full sequence analysis of the CARD15 gene, which is reportedly related to the formation of granulomatous lesions in Crohn's disease and sarcoidosis revealed no mutation of CARD15 gene. This is the first report of concurrent sarcoidosis, Crohn's disease and aortitis syndrome in an individual.

Infliximab in clinical routine: experience with Crohn's disease and biomarkers of inflammation over 5 years

INTRODUCTION

Infliximab was launched for the treatment of Crohn's disease (CD) in 1999. We set up a follow-up protocol to meticulously study disease development with repeated infusions of infliximab.

AIM

To follow the effects of infliximab treatment on disease activity, blood chemistry, quality of life, plasma nitrite, and titers of Saccharomyces cerevisiae antibodies (ASCA).

METHODS

During 1999-2008, CD patients were monitored for disease activity by Harvey-Bradshaw index, blood chemistry with hemoglobin, albumin, C-reactive protein, platelet count, leukocyte count and creatinine, quality of life by the Short Health Scale, and plasma nitrite. During the first year of treatment, follow-up was done repeatedly before and 1 week after each infusion and thereafter every year before the last infusion for 5 years. ASCA was analyzed by flow cytometry with fluorescein isothiocyanate-labelled antibodies.

RESULTS

A total of 1061 infusions were given to 103 patients; 92 responders and 11 nonresponders. Responders were further monitored and Harvey-Bradshaw index decreased with infusions during the first year of treatment (P < 0.0001), whereas hemoglobin (P < 0.01) and albumin (P <0.001) increased, C-reactive protein (P < 0.01) decreased, platelets (P <0.001) increased, and leukocytes (P< 0.01) decreased. Creatinine was not affected. Short Health Scale (questions analyzed separately) decreased (P < 0.0001), and nitrite (P < 0.001) increased. During the next 4 years the improved values remained stable. Adverse effects were noted among 32% of the patients; local circulatory reactions being most common. No correlation between ASCA titers and inflammatory activity or infliximab treatment was found.

CONCLUSION

Infliximab treatment is highly effective in responders and maintains symptomatic improvement and low inflammatory activity over years in CD patients.

Muramyldipeptide modulates CXCL-8 release of BEAS-2B cells via NOD2

Chronic inflammation and acute exacerbations are pathophysiological features of chronic obstructive pulmonary disease (COPD). An impaired immune response to bacterial pathogens can contribute to both of them. Nucleotide oligomerization domain 2 (NOD2) is an intracellular receptor of innate immunity for muramyldipeptide (MDP). Mutations of the NOD2 gene followed by decreased recognition of MDP are associated with chronic intestinal inflammation and pulmonary complications of patients with allogenic stem cell transplant and sepsis. Our study provides evidence that NOD2, toll-like receptor 4 (TLR4) and the adapter protein receptor-interacting protein 2 (RIP2) are induced by tumor-necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) in the bronchial epithelial cell line BEAS-2B. We also demonstrate that lipopolysaccharide (LPS) can further increase NOD2 transcription in a TNF-alpha and IFN-gamma-induced activation state. In addition, we show that, while MDP fails to enhance CXCL-8 release from otherwise unstimulated BEAS-2B cells, a 12 h prestimulation period with TNF-alpha and IFN-gamma primes the cells for an additional increase of CXCL-8 secretion via induction of NOD2 and RIP2. LPS itself significantly augments CXCL-8 production and co-administration of MDP further increases cytokine secretion. Finally, overexpression of an SNP13 mutant decreased MDP-induced chemokine production in BEAS-2B cells compared with NOD2 wild type overexpression. Taken together, our work indicates that MDP and NOD2 play an important role for CXCL-8 release of BEAS-2B cells following LPS-challenge via synergistic interactions between MDP and LPS.

Heterozygous nucleotide-binding oligomerization domain-2 mutations affect monocyte maturation in Crohn’s disease

AIM: To investigate the function of monocytes in Crohn’s disease (CD) patients and to correlate this with disease-associated nucleotide-binding oligomerization domain-2 (NOD2) gene variants.

METHODS: Monocytes from 47 consecutively referred CD patients and 9 healthy blood donors were cultured with interleukin (IL)-4 and granulocyte-macrophage colony-stimulating factor (GM-CSF), and stimulated with lipopolysaccharide (LPS) or muramyldipeptide (MDP), the putative ligand of NOD2.

RESULTS: We found that monocytes from CD patients differentiated in vitro to mature dendritic cells (DCs), as determined by immunophenotype and morphology. NOD2 genotype was assessed in all subjects, and we observed high CD86 expression on immature and LPS-stimulated DCs in NOD2 mutated CD patients, as compared with wtNOD2 CD patients and controls. By contrast, CD86 expression levels of DCs induced to maturity with MDP derived from NOD2-mutated subjects were comparable to those of normal subjects. The amount of IL-12p70 in patient-cell cultures was larger than in controls after LPS treatment, but not after treatment with MDP.

CONCLUSION: Our results suggest that DCs obtained from patients with mutations in the NOD2 gene display an activated phenotype characterized by high CD86 expression, but have a diminished response to MDP when compared to the terminal differentiation phase. We speculate that the altered differentiation of monocytes might lead to an imbalance between inflammation and the killing ability of monocytes, and may be relevant to the pathogenesis of CD.

Mast cells and nerves tickle in the tummy: implications for inflammatory bowel disease and irritable bowel syndrome

Mast cells are well known as versatile cells capable of releasing and producing a variety of inflammatory mediators upon activation and are often found in close proximity of neurons. In addition, inflammation leads to local activation of neurons resulting in the release neuropeptides, which also play an important immune modulatory role by stimulation of immune cells. In intestinal disorders like inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS), the number of mast cells is known to be much higher than in the normal intestine. Moreover, both these disorders are also reported to be associated with alterations in neuropeptide content and in neural innervation. Mutual association between mast cells and enteric nerves has been demonstrated to be increased in pathophysiological conditions and contribute to spreading and amplification of the response in IBD and IBS. In this review the focus lies on studies appointed to the direct interaction between mast cells and nerves in IBD, IBS, and animal models for these disorders so far.