Detection of muramyl dipeptide-sensing pathway defects in monocytes of patients with Crohn's disease using phospho-specific whole blood flow cytometry

Altered pattern of tumor necrosis factor-alpha production in peripheral blood monocytes from Crohn's disease

AIM

To evaluate the inflammatory state in Crohn’s disease (CD) patients and correlate it with genetic background and microbial spreading.

METHODS

By means of flow cytometry, production of tumor necrosis factor-alpha (TNF-α) was measured in peripheral blood monocytes from patients suffering from CD, ulcerative colitis (UC) and in healthy subjects after stimulation of the NOD2 and TLR pathways. CD patients were genotyped for the three most common NOD2 variants (R702W, G908R and L1007Pfs*2) and basal production of TNF-α was correlated to NOD2 genotype. Also, production of TNF-α was correlated to plasmatic levels of LPS Binding Protein (LBP), soluble (s) CD14 and to the activity state of the disease.

RESULTS

The patients with CD were characterized by a significantly higher monocyte basal expression of TNF-α compared with healthy subjects and UC patients, and after stimulation with Pam₃CSK₄ (ligand of TLR2/1) and MDP-L18 (ligand of NOD2) this difference was maintained, while other microbial stimuli (LPS, ligand of TLR4 and PolyI:C, ligand of TLR3) induced massive activation in CD monocytes as well as in UC and in healthy control cells. There was no significant difference in the production of TNF-α between patients who carried CD-associated heterozygous or homozygous variants in NOD2 and patients with wild type NOD2 genotype. Although serum LBP levels have been shown to correlate positively with the state of activity of the disease, TNF-α production did not show a clear correlation with either LBP or sCD14 levels in plasma. Moreover, no clear correlation was seen between TNF-α production and activity indices in either CD or UC.

CONCLUSION

Peripheral monocytes from CD express higher basal and stimulated TNF-α than controls, regardless of NOD2 genotype and without a clear correlation with disease activity.

Dysbiotic gut microbiome: A key element of Crohn's disease

Since the first publication on "regional ileitis", the relevance of this chronic inflammatory disease condition termed finally as Crohn's disease is continuously increasing. Although we are beginning to comprehend certain aspects of its pathogenesis, many facets remain unexplored. Host's gut microbiota is involved in a wide range of physiological and pathological processes including immune system development, and pathogen regulation. Further, the microbiome is thought to play a key role in Crohn's disease. The presence of Crohn's-associated variants of NOD2 and ATG16L genes appears to be associated not only with alterations of mucosal barrier functions, and bacterial killing, but the gut microbiota, as well, reflecting a potential relationship between the host's genotype and intestinal dysbiosis, involved in disease etiology. This review aims to characterize some exciting new aspect of Crohn's disease pathology, focusing mainly on the role of intestinal microbes, and their interplay with the immune system of the host.

Constitutive STAT3 Phosphorylation in Circulating CD4+ T Lymphocytes Associates with Disease Activity and Treatment Response in Recent-Onset Rheumatoid Arthritis

The aim of the present study was to examine constitutive signal transducer and activator of transcription 3 (STAT3) phosphorylation in circulating leukocytes as a candidate biomarker in rheumatoid arthritis (RA). 25 patients with recent-onset, untreated RA provided samples for whole blood flow cytometric determination of intracellular STAT3 phosphorylation, expressed as relative fluorescence units. The occurrence of constitutive STAT3 phosphorylation was evaluated by determining proportion of STAT3-phosphorylated cells among different leukocyte subtypes. Plasma levels of interleukin (IL)-6, IL-17 and IL-21 were measured by immunoassay, radiographs of hands and feet were examined and disease activity score (DAS28) was determined. Biomarkers were restudied and treatment response (according to European League Against Rheumatism) was determined after 12 months of treatment with disease-modifying antirheumatic drugs. At baseline, constitutive phosphorylation of STAT3 occurred in CD4⁺ T cells of 14 (56%) patients, CD8⁺ T cells of 13 (52%) patients, in CD19⁺ B cells of 7 (28%) patients, and in CD14⁺ monocytes of 12 (48%) patients. STAT3 phosphorylation levels of CD4⁺ T cells associated with DAS28, and those of all leukocyte subtypes studied associated with erosive disease. The presence of constitutive STAT3 phosphorylation in CD4⁺ T lymphocytes, pSTAT3 fluorescence intensity of CD4⁺ and CD8⁺ T cells and C-reactive protein (CRP) levels at baseline associated with good treatment response. In conclusion, constitutive STAT3 phosphorylation in circulating CD4⁺ T cells is common in recent-onset untreated RA and associates with good treatment response in patients characterized by high disease activity and the presence of systemic inflammation.

Immuno-genomic profiling of patients with inflammatory bowel disease: a systematic review of genetic and functional in vivo studies of implicated genes

BACKGROUND

Over the last 2 decades, there has been an ever-expanding catalog of genetic variants implicated in inflammatory bowel disease (IBD) through genome-wide association studies and next generation sequencing. In this article, we highlight the remarkable developments in understanding the genetic and immunological basis of IBD. The main objective of the study was to perform a systematic review of published literature detailing functional/immunological studies in patients known to harbor genetic variations in the implicated genes.

METHODS

A panel of 71 candidate genes implicated in IBD was prioritized using 5 network connectivity in silico methods. An electronic search using MEDLINE and EMBASE from 1996 to February 2014 for each of the selected genes was conducted. Only studies describing genotyped IBD cohorts with concurrent in vivo functional studies were included.

RESULTS

Between the reviewers, a total of 35,142 potentially eligible publications were identified. Only 8 genes had publications meeting the inclusion criteria. A total of 67 studies were identified across the selected genes. The NOD2 gene had the most number with 41 studies followed by IL-10 with 11 eligible studies. A meta-analysis was not practical given the heterogeneity of the study design and the number of implicated genes with diverse immunological and physiological functions.

CONCLUSIONS

There is a clear lack of functional studies in humans to assess the in vivo impact of the various genetic variants implicated. A collaborative approach merging genomics and functional studies will help to unravel the obscure mechanisms involved in IBD.