Glucocorticosteroid therapy in inflammatory bowel diseases: From clinical practice to molecular biology

Inflammatory bowel diseases(IBDs),such as ulcerative colitis and Crohn's disease,are chronic pathologies associated with a deregulated immune response in the intestinal mucosa,and they are triggered by environmental factors in genetically susceptible individuals.Exogenous glucocorticoids(GCs)are widely used as anti-inflammatory therapy in IBDs.In the past,patients with moderate or severe states of inflammation received GCs as a first line therapy with an important effectiveness in terms of reduction of the disease activity and the induction of remission.However,this treatment often results in detrimental side effects.This downside drove the development of second generation GCs and more precise(non-systemic)drugdelivery methods.Recent clinical trials show that most of these new treatments have similar effectiveness to first generation GCs with fewer adverse effects.The remaining challenge in successful treatment of IBDs concerns the refractoriness and dependency that some patients encounter during GCs treatment.A deeper understanding of the molecular mechanisms underlying GC response is key to personalizing drug choice for IBDs patients to optimize their response to treatment.In this review,we examine the clinical characteristics of treatment with GCs,followed by an in depth analysis of the proposed molecular mechanisms involved in its resistance and dependence associated with IBDs.This thorough analysis of current clinical and biomedical literature may help guide physicians in determining a course of treatment for IBDs patients and identifies important areas needing further study.

Isoleucine, an Essential Amino Acid, Induces the Expression of Human <i>β</i>Defensin 2 through the Activation of the G-Protein Coupled Receptor-ERK Pathway in the Intestinal Epithelia

Anti-microbial peptides are essential for the intestinal innate immunity that protects the intestinal epithelia from attacks by foreign pathogens. Human β-defensin (HBD) is one of the pivotal anti-microbial peptides that are expressed in the colonic epithelia. This study investigated the effect and the signaling mechanism of inducible β-defensin HBD2 by an essential amino acid, isoleucine (Ile) in colonic epithelial cells. Here we examined the expression level of HBD2 on induction of Ile in epithelial cells, and checked this pathway. HBD2 mRNA was induced by co-incubation with IL-1α and Ile in Caco2 cells, but not by Ile alone. An inhibitor of either ERK or Gi, a subunit of G-proteins, reduced the induction of HBD2 mRNA by Ile. The treatment with Ile also increased the intracellular calcium ion concentration, thus suggesting that the GPCR and ERK signaling pathway mediate the effects of Ile. These results indicate that an essential amino acid, Ile, enhances the expression of an inducible β-defensin, namely HBD2, by IL-1α through the activation of GPCRs and ERK signaling pathway. The administration of Ile may therefore represent a possible option to safely treat intestinal inflammation.

Immune function biomarker QuantiFERON-monitor is associated with infection risk in cirrhotic patients

AIM To investigate whether a novel immune function biomarker Quanti FERON-Monitor(QFM) can identify cirrhotic patients at greatest risk of infection. METHODS Adult cirrhotic patients on the liver transplant waiting list were recruited for this observational cohort study from a tertiary liver transplant referral unit. The immune function biomarker, QFM was performed using the same method as the widely available Quantiferon-gold assay, and measures output in interferon gamma in IU/mL after dual stimulation of the innate and adaptive immune systems. Ninety-one cirrhotic patients were recruited, with 47(52%) transplanted on the day of their QFM. The remaining 44(48%) were monitored for infections until transplant, death, or census date of 1st February 2014.RESULTS Cirrhotic patients express a median QFM significantly lower than healthy controls(94.5 IU/mL vs 423 IU/mL), demonstrating that they are severely immunosuppressed.Several factors including model for end stage liver disease, presence of hepatocellular carcinoma, bilirubin, international normalized ratio and haemoglobin were associated with QFM on univariate analysis. Disease aetiology did not appear to impact QFM. On multivariate analysis, only Child-Pugh score and urea were significantly associated with a patient's immune function as objectively measured by QFM. In the 44 patients who were not transplanted immediately after their blood test and could be monitored for subsequent infection risk, 13(29.5%) experienced a pre-transplant infection a median 20 d(range 2-182) post-test. QFM < 214 IU/mL was associated with HR = 4.1(P = 0.01) for infection. A very low QFM < 30 IU/mL was significantly associated(P = 0.003) with death in three patients who died while awaiting transplantation(HR = 56.6).CONCLUSION QFM is lower in cirrhotics, allowing objective determinations of an individual's unique level of immune dysfunction. Low QFM was associated with increased susceptibility to infection.