Genetic predictors of glucocorticoid response in pediatric patients with inflammatory bowel diseases

Long non-coding RNAs as pathophysiological regulators, therapeutic targets and novel extracellular vesicle biomarkers for the diagnosis of inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic relapsing disease of the gastrointestinal (GI) system that includes two groups, Crohn's disease (CD) and ulcerative colitis (UC). To cope with these two classes of IBD, the investigation of pathogenic mechanisms and the discovery of new diagnostic and therapeutic approaches are crucial. Long non-coding RNAs (lncRNAs) which are non-coding RNAs with a length of longer than 200 nucleotides have indicated significant association with the pathology of IBD and strong potential to be used as accurate biomarkers in diagnosing and predicting responses to the IBD treatment. In the current review, we aim to investigate the role of lncRNAs in the pathology and development of IBD. We first describe recent advances in research on dysregulated lncRNAs in the pathogenesis of IBD from the perspective of epithelial barrier function, intestinal immunity, mitochondrial function, and intestinal autophagy. Then, we highlight the possible translational role of lncRNAs as therapeutic targets, diagnostic biomarkers, and predictors of therapeutic response in colon tissues and plasma samples. Finally, we discuss the potential of extracellular vesicles and their lncRNA cargo in the pathophysiology, diagnosis, and treatment of IBD.

NLRP inflammasomes in health and disease

NLRP inflammasomes are a group of cytosolic multiprotein oligomer pattern recognition receptors (PRRs) involved in the recognition of pathogen-associated molecular patterns (PAMPs) and danger-associated molecular patterns (DAMPs) produced by infected cells. They regulate innate immunity by triggering a protective inflammatory response. However, despite their protective role, aberrant NLPR inflammasome activation and gain-of-function mutations in NLRP sensor proteins are involved in occurrence and enhancement of non-communicating autoimmune, auto-inflammatory, and neurodegenerative diseases. In the last few years, significant advances have been achieved in the understanding of the NLRP inflammasome physiological functions and their molecular mechanisms of activation, as well as therapeutics that target NLRP inflammasome activity in inflammatory diseases. Here, we provide the latest research progress on NLRP inflammasomes, including NLRP1, CARD8, NLRP3, NLRP6, NLRP7, NLRP2, NLRP9, NLRP10, and NLRP12 regarding their structural and assembling features, signaling transduction and molecular activation mechanisms. Importantly, we highlight the mechanisms associated with NLRP inflammasome dysregulation involved in numerous human auto-inflammatory, autoimmune, and neurodegenerative diseases. Overall, we summarize the latest discoveries in NLRP biology, their forming inflammasomes, and their role in health and diseases, and provide therapeutic strategies and perspectives for future studies about NLRP inflammasomes.

Glucocorticoid-Induced Ocular Hypertension and Glaucoma

Glucocorticoid (GC) therapy is indicated in many diseases, including ocular diseases. An important side-effect of GC therapy is GC-induced ocular hypertension (GIOHT), which may cause irreversible blindness known as GC-induced glaucoma (GIG). Here, we reviewed the pathological changes that contribute to GIOHT including in the trabecular meshwork and Schlemm's canal at cellular and molecular levels. We also discussed the clinical aspects of GIOHT/GIG including disease prevalence, risk factors, the type of GCs, the route of GC administration, and management strategies.

Pharmacogenetics-based personalized treatment in patients with inflammatory bowel disease: A review

The development of treatment options has revolutionized the prognosis of inflammatory bowel disease (IBD). However, a particular group of patients still experience therapeutic failure or drug side effects. Although the high inter-patient variability in therapy is associated with clinical factors, including age, disease behavior, and disease duration, they attribute only a small proportion of inter-individual variability. Thus, pharmacogenetics evaluating associations between specific genetic variations and drug responses or side effects have focused on optimizing therapeutic efficacy and minimizing toxicity in IBD treatment. Thiopurine S-methyltransferase (TPMT) and nudix hydrolase 15 (NUDT15) are well-established predictive markers of thiopurine-induced myelosuppression. Low TPMT activity is related to increased 6-thioguanine nucleotide levels, subsequently leading to myelotoxicity. NUDT15 variants are strongly associated with thiopurine-induced early leukopenia in Asians, with a lower incidence of TPMT-deficient allele. The Korean Association for the Study of Intestinal Diseases guidelines recommend pretreatment determination of NUDT15 genotypes, especially in East Asians, and NUDT15 R139C measurement has been approved for clinical use since 2019. Several studies have attempted to identify powerful genetic markers for personalized medicine. In this article, we review the identified pharmacogenetics of currently available drugs, focusing on 5-aminosalicylic acid, glucocorticosteroids, thiopurines, and anti-tumor necrosis factor-alpha agents.

Interaction between the inflammasome and commensal microorganisms in gastrointestinal health and disease

The inflammasome is a cytosolic multiprotein complex that plays a crucial role in inflammation and cell death. The sensor proteins in the inflammasome complex detect various microbial and endogenous stimuli, leading to subsequent caspase activation. The activation of caspases results in the maturation of pro-inflammatory cytokines IL-1β and IL-18 or pyroptosis. Inflammasome dysfunction is associated with the pathogenesis of various diseases, including autoimmune disease and cancer. It appears that the interactions between the gut microbiota and the inflammasome play crucial roles in the gastrointestinal tract. The gut microbiota induces the expression and activation of inflammasome proteins, which contribute to both homeostasis and disease in the gut. Likewise, although controversial, mounting evidence suggests that inflammasome activation can modulate the composition of the gut microbiota, which, in turn, affects disease progression. In this review, we summarize the current concepts and recent insights linking the inflammasome and gut commensal microorganisms. We describe how the reciprocal interaction between the inflammasome and the commensal microbiota relates to physiological and pathophysiological consequences in the host.

Gender May Influence the Immunosuppressive Actions of Prednisone in Young Patients With Inflammatory Bowel Disease

Although the use of glucocorticoids (GC) is well established, the therapeutic response to these agents often shows important interindividual differences, in particular among young patients with inflammatory bowel diseases (IBD). Currently, GC resistance or dependence cannot be predicted by clinical or laboratory findings. The aim of this study was to investigate the association of gender and age with GC efficacy and with the expression of Glucocorticoid-Induced Leucine Zipper (GILZ). One hundred thirty patients (mean age at enrolment 12.6 years, 53 Crohn’s disease, 70 males) were enrolled in this retrospective study. IBD patients with active disease despite prednisone at a daily dose of up to 2 mg/kg over a period of 4 weeks were defined as steroid resistant. Patients who initially responded but relapsed upon dose reduction were considered steroid-dependent. Total RNA was extracted from biopsies of 14 patients (9 males) and the levels of GILZ mRNA were evaluated by real-time PCR. Association between clinical response to prednisone and the considered demographic variables was evaluated using logistic regression models. After 4 weeks of treatment, 112 patients were responders to prednisone and 18 were resistant; at this time-point, resistant patients were older than responders (p=0.032). After 12 weeks, 42, 71 and 12 patients were sensitive, dependent and resistant respectively; at this time-point, females were more prone than males to develop prednisone dependence vs a good response (p=0.028) while age had no effect. Age was associated with response both at 4 and 12 weeks in the subgroups of females: resistant patients were older than sensitive ones at 4 weeks (p=0.02). Likewise, at 12 weeks of therapy, dependent patients resulted older than sensitive ones (p=0.05). No association of age with prednisone response was found in males. In a subgroup of 14 patients (5 females), GILZ mRNA expression in intestinal biopsies was higher in males (p=0.0031). Patients with unfavorable response (7) presented lower GILZ expression at disease onset in comparison to the responder group (p=0.017). Older females with IBD have a higher incidence of prednisone unfavorable response and reduced intestinal expression of the GC pharmacodynamic marker GILZ.

Predicting Outcomes in Pediatric Ulcerative Colitis for Management Optimization: Systematic Review and Consensus Statements From the Pediatric Inflammatory Bowel Disease-Ahead Program

BACKGROUND & AIMS

A better understanding of prognostic factors in ulcerative colitis (UC) could improve patient management and reduce complications. We aimed to identify evidence-based predictors for outcomes in pediatric UC, which may be used to optimize treatment algorithms.

METHODS

Potential outcomes worthy of prediction in UC were determined by surveying 202 experts in pediatric UC. A systematic review of the literature, with selected meta-analysis, was performed to identify studies that investigated predictors for these outcomes. Multiple national and international meetings were held to reach consensus on evidence-based statements.

RESULTS

Consensus was reached on 31 statements regarding predictors of colectomy, acute severe colitis (ASC), chronically active pediatric UC, cancer and mortality. At diagnosis, disease extent (6 studies, N = 627; P = .035), Pediatric Ulcerative Colitis Activity Index score (4 studies, n = 318; P < .001), hemoglobin, hematocrit, and albumin may predict colectomy. In addition, family history of UC (2 studies, n = 557; P = .0004), extraintestinal manifestations (4 studies, n = 526; P = .048), and disease extension over time may predict colectomy, whereas primary sclerosing cholangitis (PSC) may be protective. Acute severe colitis may be predicted by disease severity at onset and hypoalbuminemia. Higher Pediatric Ulcerative Colitis Activity Index score and C-reactive protein on days 3 and 5 of hospital admission predict failure of intravenous steroids. Risk factors for malignancy included concomitant diagnosis of primary sclerosing cholangitis, longstanding colitis (>10 years), male sex, and younger age at diagnosis.

CONCLUSIONS

These evidence-based consensus statements offer predictions to be considered for a personalized medicine approach in treating pediatric UC.

NGS study of glucocorticoid response genes in inflammatory bowel disease patients

INTRODUCTION

Despite intensive research and a long history of glucocorticoids being applied in various clinical areas, they still generate a challenge for personalized medicine by causing resistance or dependence in nearly 50% of patients treated. The objective of the present study was to determine the genetic predictors of variable reactions in inflammatory bowel disease patients to glucocorticoid therapy. Therefore, based on the current knowledge on how glucocorticoids act, we have compiled a panel of 21 genes for variant analysis: NR3C1, NLRP1, IPO13, FKBP5, HSPA4, ABCB1, STIP1, HSP90AA1, IL-1A, IL-1B, IL-2, IL-4, CXCL8, IL-10, NFKBIA, JUN, MIF, TNF, MAPK14, CYP3A4, and CYP3A5.

MATERIAL AND METHODS

These genes were analyzed using the amplicon next-generation sequencing method in a group of 139 diagnosed and clinically characterized inflammatory bowel disease patients with a confirmed glucocorticoid response.

RESULTS

Analysis of all the targeted DNA sequences for the whole patient group indicated 121 different functional variants. After association analyses of 31 selected variants, the polymorphism c.1088A>G in the NR3C1 gene was linked with glucocorticoid resistance (p = 0.002), variant c.241+6A>G of the FKBP5 gene with glucocorticoid sensitivity (p = 0.040), and deletion c.306-7delT in the MAPK14 gene with an adverse therapeutic effect (dependency and resistance, p = 0.041) in ulcerative colitis patients. In Crohn's disease, the change c.2685+49T>C of the ABCB1 gene related to glucocorticoid resistance (p = 0.034).

CONCLUSIONS

Among the 21 analyzed genes, four (NR3C1, FKBP5, MAPK14, and ABCB1) revealed a significant impact on the glucocorticoid treatment response, which could result in valuable pharmacogenetic biomarkers after being confirmed in other populations and in functional studies.

The microbiome and cytosolic innate immune receptors

The discovery of innate immune sensors (pattern recognition receptors, PRRs) has profoundly transformed the notion of innate immunity, in providing a mechanistic basis for host immune interactions with a wealth of environmental signals, leading to a variety of immune-mediated outcomes including instruction and activation of the adaptive immune arm. As part of this growing understanding of host-environmental cross talk, an intimate connection has been unveiled between innate immune sensors and signals perceived from the commensal microbiota, which may be regarded as a hub integrating a variety of environmental cues. Among cytosolic PRRs impacting on host homeostasis by interacting with the commensal microbiota are nucleotide-binding domain, leucine-rich repeat-containing protein receptors (NLRs), together with a number of cytosolic DNA sensors and the family of absent in melanoma (AIM)-like receptors (ALRs). NLR sensors have been a particular focus of research, and some NLRs have emerged as key orchestrators of inflammatory responses and host homeostasis. Some NLRs achieve this through the formation of cytoplasmic multiprotein complexes termed inflammasomes. More recently discovered PRRs include retinoic acid-inducible gene-I (RIG-I)-like receptors (RLRs), cyclic GMP-AMP synthase (cGAS), and STING. In the present review, they summarize recent advancements in knowledge on structure and function of cytosolic PRRs and their roles in host-microbiota cross talk and immune surveillance. In addition, we discuss their relevance for human health and disease and future therapeutic applications involving modulation of their activation and signaling.

The Emerging Role of Noncoding RNAs in Pediatric Inflammatory Bowel Disease

Prevalence of inflammatory bowel disease (IBD), a chronic inflammatory disorder of the gut, has been on the rise in recent years-not only in the adult population but also especially in pediatric patients. Despite the absence of curative treatments, current therapeutic options are able to achieve long-term remission in a significant proportion of cases. To this end, however, there is a need for biomarkers enabling accurate diagnosis, prognosis, and prediction of response to therapies to facilitate a more individualized approach to pediatric IBD patients. In recent years, evidence has continued to evolve concerning noncoding RNAs (ncRNAs) and their roles as integral factors in key immune-related cellular pathways. Specific deregulation patterns of ncRNAs have been linked to pathogenesis of various diseases, including pediatric IBD. In this article, we provide an overview of current knowledge on ncRNAs, their altered expression profiles in pediatric IBD patients, and how these are emerging as potentially valuable clinical biomarkers as we enter an era of personalized medicine.

Double-edged sword of inflammasome genetics in colorectal cancer prognosis

Inflammation is a colorectal cancer (CRC) hallmark. Inflammasome-dependent cytokines IL-1ß and IL-18 can play a beneficial or detrimental role in tumorigenesis depending on cancer type. Variants in inflammasome genes were associated with tumor development and/or outcome, and have been proposed as potential biomarkers for population screening. In this study, 215 CRC patients followed-up for 10 years were examined for 9 polymorphisms in selected inflammasome genes. Multivariate association analysis and survival analysis were performed to evaluate the association between the polymorphisms and CRC prognosis. Variants associated with lower levels of IL-18 (rs1834481, rs5744256), or with increased activation of inflammasome receptors NLRP1 (rs12150220) and NLRP3 (rs35829419) resulted detrimental to CRC prognosis and may be used as prognostic markers.

Early induction of C/EBPβ expression as a potential marker of steroid responsive colitis

The precise mechanism of hydrocortisone immune regulation in the management of colitis is poorly understood. Whilst not without limitations, its ability to suppress pathology and rapidly improve patient clinical outcome is key. We were interested in identifying early markers of therapeutic responsiveness in order to identify patients’ refractory to therapy. Chronic Th1-driven colitis was induced in AKR/J mice using a parasite infection, Trichuris muris. 35 days post infection, mice were treated with low dose hydrocortisone (2 mg/kg/) i.p. on alternate days. Response to therapy was assessed at a systemic and tissue level day 45 post infection. Histopathology, gene and protein analysis was conducted to determine cytokine and transcriptional profiles. The colonic transcriptional profile in steroid treated mice showed significant upregulation of a small subset of T cell associated genes, in particular C/EBPβ, CD4, IL7R and STAT5a. Despite no change in either transcription or protein production in downstream cytokines IFN γ, TNFα IL-17 and IL-10, hydrocortisone treatment significantly reduced colonic pathology and restored colonic length to naïve levels. As expected, steroid treatment of chronic gut inflammation generated significant immunosuppressive effects characterized by histological improvement. Low dose hydrocortisone induced significant upregulation of a subset of genes associated with T cell maintenance and regulation, including C/EBPβ. These data suggest that enhanced expression of C/EBPβ may be one of a subset of early markers demonstrating an immune regulatory response to hydrocortisone therapy, potentially by stabilization of Treg function. These observations contribute to our understanding of the immune landscape after steroid therapy, providing a potential markers of therapeutic responders and those refractory to hydrocortisone treatment.

Oxidative stress, DNA stability and evoked inflammatory signaling in young celiac patients consuming a gluten-free diet

PURPOSE

Celiac disease (CD) is a multifactorial, autoimmune, gluten-sensitive inflammatory disorder of the small intestine. Taking into account the pathogenesis of CD, a strict gluten-free diet (GFD) is the only treatment able to restore epithelium integrity and eliminate complications. The current study was designed to assess whether the use of a GFD is sufficient for maintaining a correct oxidative/antioxidant balance and ameliorating the evoked inflammatory signaling in young patients with CD.

METHODS

The study covered 80 children, aged between 7 and 18 years, attending the Gastroenterology Service of the Gastroenterology, Hepatology and Child Nutrition Service from the Virgen de las Nieves Hospital in Granada. Children with CD diagnosed were included in the celiac group who followed a strict GFD for 2 years (n = 40) and the control group (n = 40) included healthy children, with negative serological screening. Soluble superoxide dismutase 1 and 2, total antioxidant status, 8-hydroxy-2'-deoxyguanosine, cortisol, melatonin and inflammatory parameters in plasma, 15-F2t-isoprostanes in urine, and DNA breaks in peripheral blood lymphocytes were analysed.

RESULTS

No differences were found in oxidative stress between CD patients and controls; however, IFN-γ, IL-1α, IP-10 and TNF-β were higher in the CD patients. VEGF was also higher than in the control group.

CONCLUSION

The GFD in the CD patients is enough to reduce the oxidative stress; however, in the case of the inflammatory signaling, the initial exposure to gluten prior to stablish the GFD is strong enough to induce an inflammatory state which is maintained (even when consuming the GFD); meanwhile the increase in VEGF recorded in the CD group could be a compensatory mechanism to restore the damaged mucosa and duodenal villous atrophy, due to its role in endothelial activation and generation of new functional and stable vascular networks.

Pharmacogenetics of treatments for inflammatory bowel disease

INTRODUCTION

Inflammatory bowel disease is a chronic inflammation of the gut whose pathogenesis is still unclear. Although no curative therapy is currently available, a number of drugs are used in induction and maintenance therapy; however, for most of these drugs, a high inter-individual variability in response is observed. Among the factors of this variability, genetics plays an important role. Areas covered: This review summarizes the results of pharmacogenetic studies, considering the most important drugs used and in particular aminosalycilates, glucocorticoids, thiopurines, monoclonal antibodies and thalidomide. Most studies used a candidate gene approach, even if significant breakthroughs have been obtained recently from applying genome-wide studies. When available, also investigations considering epigenetics and pharmacogenetic dosing guidelines have been included. Expert opinion: Only for thiopurines, genetic markers identified as predictors of efficacy or adverse events have allowed the development of dosing guidelines. For the other drugs, encouraging results are available and great expectations rely on the study of epigenetics and integration with pharmacokinetic information, especially useful for biologics. However, to improve therapy of IBD patients with these drugs, for implementation in the clinics of pharmacogenetics, informatic clinical decision support systems and training about pharmacogenetics of health providers are needed.

NLRP1 restricts butyrate producing commensals to exacerbate inflammatory bowel disease

Anti-microbial signaling pathways are normally triggered by innate immune receptors when detecting pathogenic microbes to provide protective immunity. Here we show that the inflammasome sensor Nlrp1 aggravates DSS-induced experimental mouse colitis by limiting beneficial, butyrate-producing Clostridiales in the gut. The colitis-protective effects of Nlrp1 deficiency are thus reversed by vancomycin treatment, but recapitulated with butyrate supplementation in wild-type mice. Moreover, an activating mutation in Nlrp1a increases IL-18 and IFNγ production, and decreases colonic butyrate to exacerbate colitis. We also show that, in patients with ulcerative colitis, increased NLRP1 in inflamed regions of the colon is associated with increased IFN-γ. In this context, NLRP1, IL-18 or IFN-γ expression negatively correlates with the abundance of Clostridiales in human rectal mucosal biopsies. Our data identify the NLRP1 inflammasome to be a key negative regulator of protective, butyrate-producing commensals, which therefore promotes inflammatory bowel disease.

SNPs affecting the clinical outcomes of regularly used immunosuppressants

Recent studies have suggested that genomic diversity may play a key role in different clinical outcomes, and the importance of SNPs is becoming increasingly clear. In this article, we summarize the bioactivity of SNPs that may affect the sensitivity to or possibility of drug reactions that occur among the signaling pathways of regularly used immunosuppressants, such as glucocorticoids, azathioprine, tacrolimus, mycophenolate mofetil, cyclophosphamide and methotrexate. The development of bioinformatics, including machine learning models, has enabled prediction of the proper immunosuppressant dosage with minimal adverse drug reactions for patients after organ transplantation or for those with autoimmune diseases. This article provides a theoretical basis for the personalized use of immunosuppressants in the future.

Genetics of Inflammasomes

Mutations in inflammasome genes are responsible for rare monogenic and polygenic autoinflammatory diseases. On the other side, genetic polymorphisms in the same molecules contribute to the development of common multifactorial diseases (i.e., autoimmune diseases, cardiovascular pathologies, cancer). In this chapter we depicted the current knowledge about inflammasome genetics.

The Goldilocks Conundrum: NLR Inflammasome Modulation of Gastrointestinal Inflammation during Inflammatory Bowel Disease

Recent advances have revealed significant insight into inflammatory bowel disease (IBD) pathobiology. Ulcerative colitis and Crohn's disease, the chronic relapsing clinical manifestations of IBD, are complex disorders with genetic and environmental influences. These diseases are associated with the dysregulation of immune tolerance, excessive inflammation, and damage to the epithelial cell barrier. Increasing evidence indicates that pattern recognition receptors, including Toll-like receptors (TLRs) and nucleotide-binding domain and leucine-rich repeat-containing proteins (NLRs), function to maintain immune system homeostasis, modulate the gastrointestinal microbiome, and promote proper intestinal epithelial cell regeneration and repair. New insights have revealed that NLR family members are essential components in maintaining this immune system homeostasis. To date, the vast majority of studies associated with NLRs have focused on family members that form a multiprotein signaling platform called the inflammasome. These signaling complexes are responsible for the cleavage and activation of the potent pleotropic cytokines IL-1β and IL-18, and they facilitate a unique form of cell death defined as pyroptosis. In this review, we summarize the current paradigms associated with NLR inflammasome maintenance of immune system homeostasis in the gastrointestinal system. New concepts related to canonical and noncanonical inflammasome signaling, as well as the implications of classical and alternative inflammasomes in IBD pathogenesis, are also reviewed.

Role of the Long Non-Coding RNA Growth Arrest-Specific 5 in Glucocorticoid Response in Children with Inflammatory Bowel Disease

Glucocorticoids (GCs) are widely employed in inflammatory, autoimmune and neoplastic diseases, and, despite the introduction of novel therapies, remain the first-line treatment for inducing remission in inflammatory bowel disease (IBD). Given the high incidence of suboptimal response, associated with a significant number of side-effects, that are particularly severe in paediatric patients, the identification of subjects that are most likely to respond poorly to GCs is extremely important. Recent evidence suggests that the long non-coding RNA (lncRNA) GAS5 could be a potential marker of GC resistance. To address this issue, we evaluated the association between the lncRNA GAS5 and the efficacy of steroids, in terms of inhibition of proliferation, in two cell lines derived from colon and ovarian cancers, to confirm the sensitivity and specificity of these lncRNAs. These cells showed a different sensitivity to GCs and revealed differential expression of GAS5 after treatment. GAS5 was up-regulated in GC-resistant cells and accumulated more in the cytoplasm compared to the nucleus in response to the drug. The functions of GAS5 were assessed by silencing, and we found that GAS5 knock-down reduced the proliferation during GC treatment. Furthermore, for the first time, we measured GAS5 levels in 19 paediatric IBD patients at diagnosis and after the first cycle of GCs, and we demonstrated an up-regulation of the lncRNA in patients with unfavourable steroid response. Our preliminary results indicate that GAS5 could be considered a novel pharmacogenomic marker useful for the personalization of GC therapy.

Mechanisms of NLRP1-Mediated Autoinflammatory Disease in Humans and Mice

NLRP1 was the first NOD-like receptor described to form an inflammasome, recruiting ASC to activate caspase-1, which processes interleukin-1β and interleukin-18 to their active form. A wealth of new genetic information has now redefined our understanding of this innate immune sensor. Specifically, rare loss-of-function variants in the N-terminal pyrin domain indicate that this part of NLRP1 is autoinhibitory and normally acts to prevent a familial autoinflammatory skin disease associated with cancer. In the absence of a ligand to trigger human NLRP1, these mutations have now confirmed the requirement of NLRP1 autolytic cleavage within the FIIND domain, which had previously been implicated in NLRP1 activation. Autolytic cleavage generates a C-terminal fragment of NLRP1 containing the CARD domain which then forms an ASC-dependent inflammasome. The CARD domain as an inflammasome linker is consistent with the observation that under some conditions, particularly for mouse NLRP1, caspase-1 can be engaged directly, and although it is no longer processed, it is still capable of producing mature IL-1β. Additional rare variants in a linker region between the LRR and FIIND domains of NLRP1 also cause autoinflammatory disease in both humans and mice. This new genetic information is likely to provide for more mechanistic insight in the years to come, contributing to our understanding of how NLRP1 functions as an innate immune sensor of infection and predisposes to autoimmune or autoinflammatory diseases.

Pharmacogenetics of inflammatory bowel disease: a focus on Crohn's disease

Crohn's disease is an inflammatory bowel disease showing a high heterogeneity in phenotype and a strong genetic component. The treatment is complex, due to different severity of clinical parameters and to the fact that therapies only permit to control symptoms and to induce remission for short periods. Moreover, all categories of drugs present a great interindividual variability both in terms of efficacy and side effects appearance. For this reason, the identification of specific genomic biomarkers involved in drugs response will be of great clinical utility in order to foresee drug's efficacy and to prevent adverse reactions, permitting a more personalized therapeutic approach. In this review, we focus the attention on the pharmacogenetic studies regarding drugs commonly utilized in Crohn's disease treatment.

Inflammasomes and intestinal inflammation

The inflammasome is a cytosolic multi-protein innate immune rheostat, sensing a variety of endogenous and environmental stimuli, and regulating homeostasis or damage control. In the gastrointestinal tract, inflammasomes orchestrate immune tolerance to microbial and potentially food-related signals or drive the initiation of inflammatory responses to invading pathogens. When inadequately regulated, intestinal inflammasome activation leads to a perpetuated inflammatory response leading to immune pathology and tissue damage. In this review, we present the main features of the predominant types of inflammasomes participating in intestinal homeostasis and inflammation. We then discuss current controversies and open questions related to their functions and implications in disease, highlighting how pathological inflammasome over-activation or impaired function impact gut homeostasis, the microbiome ecosystem, and the propensity to develop gut-associated diseases. Collectively, understanding of the molecular basis of intestinal inflammasome signaling may be translated into clinical manipulation of this fundamental pathway as a potential immune modulatory therapeutic intervention.

Genetic variation in the glucocorticoid pathway involved in interindividual differences in the glucocorticoid treatment

Glucocorticoids (GCs) are widely used for treating asthma, rheumatoid arthritis, nephrotic syndrome, acute lymphoblastic leukemia and other autoimmune diseases. However, in a subgroup of patients, failure to respond to GCs is known as GC resistance or GC insensitivity. This represents an important barrier to effective treatment and a clinical problem requiring an urgent solution. Genetic variation in the GC pathway is a significant factor in interindividual differences in GC treatment. This article reviews the pharmacogenetics of GCs in diverse diseases based on the GC pathway.

Inflammasomes in the Gut Mucosal Homeostasis

Inflammasomes are critical checkpoints in inflammation. The activation of inflammasome can cause a series of inflammatory responses including maturation of interleukin (IL)-1β and IL-18 and a specialized form of cell death called pyroptosis. Since its identification in the early 2000s, inflammasomes have been implicated to play multifaceted roles in varied pathological and physiological conditions, especially in the mucosal compartments including the gut. Maintaining gut mucosal homeostasis has always been a remarkable challenge for the host due to both the vast mucosal surface that is exposed to the outside and the enormous amount of local microbiota. To accomplish this challenge, the host mounts a constant dynamic low-grade inflammatory response (physiological inflammation) in coping with insults of microbes in the intestine. This book chapter aims to summarize the current knowledge of how inflammasomes contribute to gut mucosal homeostasis.

Amelioration of experimental colitis after short-term therapy with glucocorticoid and its relationship to the induction of different regulatory markers

The clinical benefits of short-term therapy with glucocorticoids (GC) in patients with inflammatory bowel disease (IBD) are widely known. However, the effects of this treatment towards the re-establishment of the regulatory network in IBD are not fully explored. We have evaluated the immunological effects of the abbreviated GC therapy in experimental colitis induced by 3% dextran sulphate sodium in C57BL/6 mice. Treatment with GC improved disease outcome, constrained circulating leucocytes and ameliorated intestinal inflammation. The control of the local inflammatory responses involved a reduction in the expression of interferon-γ and interleukin-1β, associated with augmented mRNA levels of peroxisome proliferator-activated receptors (α and γ) in intestine. Furthermore, there was a reduction of CD4⁺ T cells producing interferon-γ, together with an increased frequency of the putative regulatory population of T cells producing interleukin-10, in spleen. These systemic alterations were accompanied by a decrease in the proliferative potential of splenocytes of mice treated in vivo with GC. Notably, treatment with GC also led to an increase in the frequency of the regulatory markers GITR, CTLA-4, PD-1, CD73 and FoxP3, more prominently in spleen. Taken together, our results pointed to a role of GC in the control of leucocyte responsiveness and re-establishment of a regulatory system, which probably contributed to disease control and the restoration of immune balance. Finally, this is the first time that GC treatment was associated with the modulation of a broad number of regulatory markers in an experimental model of colitis.

The impact of genetic factors on response to glucocorticoids therapy in IBD

Glucocorticosteroids (GCs) are used for many years as first-line drugs for the achievement of remission in exacerbations of inflammatory bowel disease (IBD). However, close to 20% of patients are resistant to GCs, and 40% of patients become dependent on GCs. The challenge of today's personalized medicine is the anticipation of the steroid therapy effects even before the initiation of treatment. As several studies show, individually variable response to GCs in population has a genetic background and may depend on gene variability encoding proteins involved in the function and metabolism of GCs. To those genes belong: NR3C1--responsible for the synthesis of GC receptor (GR); Hsp90, HSP70, STIP1, FKB5--genes of GR protein complex; ABCB1 and IPO13 coding glycoprotein p170; and importin 13--involved in GCs transport; IL1A, IL1B, IL2, IL4, IL8, IL10, TNF, and MIF--genes of the epithelial pro-inflammatory factors synthesis, which excessive activation causes steroid resistance as well as CYP3A4 and CYP3A5--encoding GCs biotransformation enzymes. This work systematizes and sums up the state of current knowledge in the field of pharmacogenetics as well as expectations for the future in the realm of individualized medicine in IBD patients treated with GC drugs.

Update on pathogenesis and predictors of response of therapeutic strategies used in inflammatory bowel disease

The search for biomarkers that characterize specific aspects of inflammatory bowel disease (IBD), has received substantial interest in the past years and is moving forward rapidly with the help of modern technologies. Nevertheless, there is a direct demand to identify adequate biomarkers for predicting and evaluating therapeutic response to different therapies. In this subset, pharmacogenetics deserves more attention as part of the endeavor to provide personalized medicine. The ultimate goal in this area is the adjustment of medication for a patient’s specific genetic background and thereby to improve drug efficacy and safety rates. The aim of the following review is to utilize the latest knowledge on immunopathogenesis of IBD and update the findings on the field of Immunology and Genetics, to evaluate the response to the different therapies. In the present article, more than 400 publications were reviewed but finally 287 included based on design, reproducibility (or expectancy to be reproducible and translationable into humans) or already measured in humans. A few tests have shown clinical applicability. Other, i.e., genetic associations for the different therapies in IBD have not yet shown consistent or robust results. In the close future it is anticipated that this, cellular and genetic material, as well as the determination of biomarkers will be implemented in an integrated molecular diagnostic and prognostic approach to manage IBD patients.

Glucocorticoid pharmacogenetics in pediatric idiopathic nephrotic syndrome

Idiopathic nephrotic syndrome represents the most common type of primary glomerular disease in children: glucocorticoids (GCs) are the first-line therapy, even if considerable interindividual differences in their efficacy and side effects have been reported. Immunosuppressive and anti-inflammatory effects of these drugs are mainly due to the GC-mediated transcription regulation of pro- and anti-inflammatory genes. This mechanism of action is the result of a complex multistep pathway that involves the glucocorticoid receptor and several other proteins, encoded by polymorphic genes. Aim of this review is to highlight the current knowledge on genetic variants that could affect GC response, particularly focusing on children with idiopathic nephrotic syndrome.

Polymorphisms in the canine glucocorticoid receptor alpha gene (NR3C1α)

Corticosteroids are one of the most extensively used class of therapeutic agents in dogs. In human patients, response to corticosteroid therapy has been correlated with the presence of certain polymorphisms of the glucocorticoid receptor gene (NR3C1). Depending on the polymorphism present, patients may show either increased sensitivity to glucocorticoid-induced adverse effects or resistance to their therapeutic effects. Because response to corticosteroid therapy in dogs can also be variable and unpredictable, we hypothesized that genetic variability exists in the canine NR3C1 gene. The aim of this study was to sequence the coding regions of the canine NR3C1 gene in a representative sample of dogs. Samples from 97 dogs from four previously identified genetic groupings of domestic breeds (Asian/Ancient, Herding, Hunting, and Mastiff) were sequenced and evaluated. Four exons contained polymorphisms and four exons showed no variation from the reference sequence. A total of six single nucleotide polymorphisms (SNPs) were identified including four synonymous SNPs and two nonsynonymous SNPs (c.811A>T and c.2111T>C). No dogs were homozygous for either variant allele, while 23 dogs were heterozygous for the c.811A>T allele and 2 were heterozygous for c.2111T>C allele. The amino acid changes caused by c.811A>T (serine to cysteine) and c.2111T>C (isoleucine to threonine) were both predicted by in silico analysis to be 'probably damaging' to structure and function of the resulting protein. We conclude that NR3C1 polymorphisms occur in dogs and may cause individual variation in response to corticosteroid therapy.

Metabolic dysfunction in lymphocytes promotes postoperative morbidity

Perioperative lymphopenia has been linked with an increased risk of postoperative infectious complications, but the mechanisms remain unclear. We tested the hypothesis that bioenergetic dysfunction is an important mechanism underlying lymphopenia, impaired functionality and infectious complications. In two cohorts of patients (61-82 years old) undergoing orthopaedic joint replacement (n=417 and 328, respectively), we confirmed prospectively that preoperative lymphopenia (≤1.3 x 10(9)·l(-1); <20% white cell count; prevalence 15-18%) was associated with infectious complications (relative risk 1.5 (95% confidence interval 1.1-2.0); P=0.008) and prolonged hospital stay. Lymphocyte respirometry, mitochondrial bioenergetics and function were assessed (n=93 patients). Postoperative lymphocytes showed a median 43% fall (range: 26-65%; P=0.029; n=13 patients) in spare respiratory capacity, the extra capacity available to produce energy in response to stress. This was accompanied by reduced glycolytic capacity. A similar hypometabolic phenotype was observed in lymphocytes sampled preoperatively from chronically lymphopenic patients (n=21). This hypometabolic phenotype was associated with functional lymphocyte impairment including reduced T-cell proliferation, lower intracellular cytokine production and excess apoptosis induced by a range of common stressors. Glucocorticoids, which are ubiquitously elevated for a prolonged period postoperatively, generated increased levels of mitochondrial reactive oxygen species, activated caspase-1 and mature interleukin (IL)-1β in human lymphocytes, suggesting inflammasome activation. mRNA transcription of the NLRP1 inflammasome was increased in lymphocytes postoperatively. Genetic ablation of the murine NLRP3 inflammasome failed to prevent glucocorticoid-induced lymphocyte apoptosis and caspase-1 activity, but increased NLRP1 protein expression. Our findings suggest that the hypometabolic phenotype observed in chronically lymphopenic patients and/or acquired postoperatively increases the risk of postoperative infection through glucocorticoid activation of caspase-1 via the NLRP1 inflammasome.

The NLRP1 inflammasome attenuates colitis and colitis-associated tumorigenesis

Nucleotide-binding domain and leucine-rich repeat (NLR) proteins are a diverse family of pattern recognition receptors that are essential mediators of inflammation and host defense in the gastrointestinal system. Recent studies have identified a subgroup of inflammasome forming NLRs that modulate the mucosal immune response during inflammatory bowel disease (IBD) and colitis associated tumorigenesis. To better elucidate the contribution of NLR family members in IBD and cancer, we conducted a retrospective analysis of gene expression metadata from human patients. These data revealed that NLRP1, an inflammasome forming NLR, was significantly dysregulated in IBD and colon cancer. To better characterize the function of NLRP1 in disease pathogenesis, we used Nlrp1b(-/-) mice in colitis and colitis-associated cancer models. In this paper, we report that NLRP1 attenuates gastrointestinal inflammation and tumorigenesis. Nlrp1b(-/-) mice demonstrated significant increases in morbidity, inflammation, and tumorigenesis compared with wild-type animals. Similar to data previously reported for related inflammasome forming NLRs, the increased inflammation and tumor burden was correlated with attenuated levels of IL-1β and IL-18. Further mechanistic studies using bone marrow reconstitution experiments revealed that the increased disease pathogenesis in the Nlrp1b(-/-) mice was associated with nonhematopoietic-derived cells and suggests that NLRP1 functions in the colon epithelial cell compartment to attenuate tumorigenesis. Taken together, these data identify NLRP1 as an essential mediator of the host immune response during IBD and cancer. These findings are consistent with a model whereby multiple NLR inflammasomes attenuate disease pathobiology through modulating IL-1β and IL-18 levels in the colon.

Polymorphisms in the glucocorticoid receptor gene and in the glucocorticoid-induced transcript 1 gene are associated with disease activity and response to glucocorticoid bridging therapy in rheumatoid arthritis

Glucocorticoids (GC) are widely used in rheumatoid arthritis (RA). Ongoing active disease due to GC resistance may unfavorably influence long-term disease outcome in RA. We studied the association between the presence of glucocorticoid receptor (GR) and glucocorticoid-induced transcript 1 (GLCCI1) gene polymorphisms, which modulate GC sensitivity, and baseline disease activity score (DAS) and efficacy of GC bridging therapy in RA. We prospectively studied in vivo GC sensitivity in 138 patients with recent-onset or longstanding RA. In vivo GC sensitivity was expressed as the relative decrease in DAS following 2 weeks of standardized GC therapy. All patients were genotyped for the GR polymorphisms BclI (rs41423247), N363S (rs6195), 9β (rs6198), ER22/23EK (rs6189 + rs6190), and the GLCCI1 variant rs37972 and subsequently divided in groups carrying a polymorphism associated with increased GC sensitivity (BclI-G allele, N363S-G allele, GLCCI1-C allele) or decreased GC sensitivity (9β-G allele, ER22/23EK-A/A allele, GLCCI1-T allele). Differences in baseline DAS and relative decrease in DAS in the different genotype groups were analyzed using analysis of covariance and linear regression. Baseline DAS was higher in patients who carried polymorphisms of the GR and GLCCI1 genes associated with decreased GC sensitivity. GLCCI1 genotype, but not GR genotypes, was associated with improvement in DAS in male patients with RA. The GLCCI1 gene minor allele (rs37972) may be associated with less efficient GC bridging therapy in male RA patients. Carriers of the BclI-G, N363S-G, or GLCCI1-C alleles had lower levels of baseline disease activity, suggesting a role for the GLCCI1 and GR gene in regulation of GC sensitivity to endogenously produced cortisol.

Contribution of MDR1 gene polymorphisms on IBD predisposition and response to glucocorticoids in IBD in a Chinese population

OBJECTIVE

The cornerstone of conventional treatment for inflammatory bowel disease (IBD) is glucocorticoid (GC). Single nucleotide polymorphisms (SNPs) of genes such as multidrug resistance 1 (MDR1) are related to patient's response to GC, and MDR1 polymorphisms are associated with susceptibility to IBD in Caucasians. We aimed to investigate whether the polymorphisms of five genes including MDR1 influence the response to GC in Chinese patients and the relationship between MDR1 and IBD susceptibility.

METHODS

SNPs were selected and genotyped in 156 IBD patients treated with GC and 223 healthy controls. Patients were evaluated and classified as GC-dependent, GC-resistant or responsive to GC after treatment.

RESULTS

The CC genotypes of rs1128503 and rs1045642 in MDR1 gene were more frequent in Crohn's disease (CD) patients who were GC-dependent than in those responsive to GC (odds ratio [OR] 6.583, 95% confidence interval [CI] 1.760-24.628, P = 0.019 and OR 3.873, 95% CI 1.578-9.506, P = 0.009, respectively). The G allele of MDR1 rs2032582 was less frequent among CD patients than in controls (OR 0.668, 95% CI 0.484-0.921, P = 0.014). G allele carriers were also less likely to develop non-stricturing and non-penetrating CD (OR 0.661, 95% CI 0.462-0.946, P = 0.023) and ileocolonic CD (OR 0.669, 95% CI 0.472-0.948, P = 0.024).

CONCLUSIONS

Polymorphisms of MDR1 are associated with patient's GC response and a predisposition to CD in Chinese population. Further studies are needed to elucidate the role of MDR1 polymorphisms in IBD and that as genetic markers for GC response.

Emerging significance of NLRs in inflammatory bowel disease

Pattern recognition receptors are essential mediators of host defense and inflammation in the gastrointestinal system. Recent data have revealed that toll-like receptors and nucleotide-binding domain and leucine-rich repeat-containing proteins (NLRs) function to maintain homeostasis between the host microbiome and mucosal immunity. The NLR proteins are a diverse class of cytoplasmic pattern recognition receptors. In humans, only about half of the identified NLRs have been adequately characterized. The majority of well-characterized NLRs participate in the formation of a multiprotein complex, termed the inflammasome, which is responsible for the maturation of interleukin-1β and interleukin-18. However, recent observations have also uncovered the presence of a novel subgroup of NLRs that function as positive or negative regulators of inflammation through modulating critical signaling pathways, including NF-κB. Dysregulation of specific NLRs from both proinflammatory and inhibitory subgroups have been associated with the development of inflammatory bowel disease (IBD) in genetically susceptible human populations. Our own preliminary retrospective data mining efforts have identified a diverse range of NLRs that are significantly altered at the messenger RNA level in colons from patients with IBD. Likewise, studies using genetically modified mouse strains have revealed that multiple NLR family members have the potential to dramatically modulate the immune response during IBD. Targeting NLR signaling represents a promising and novel therapeutic strategy. However, significant effort is necessary to translate the current understanding of NLR biology into effective therapies.

Classical and recent advances in the treatment of inflammatory bowel diseases

Crohn's disease (CD) and ulcerative colitis (UC) are intestinal disorders that comprise the inflammatory bowel diseases (IBD). These disorders have a significant effect on the quality of life of affected patients and the increasing number of IBD cases worldwide is a growing concern. Because of the overall burden of IBD and its multifactorial etiology, efforts have been made to improve the medical management of these inflammatory conditions. The classical therapeutic strategies aim to control the exacerbated host immune response with aminosalicylates, antibiotics, corticosteroids, thiopurines, methotrexate and anti-tumor necrosis factor (TNF) biological agents. Although successful in the treatment of several CD or UC conditions, these drugs have limited effectiveness, and variable responses may culminate in unpredictable outcomes. The ideal therapy should reduce inflammation without inducing immunosuppression, and remains a challenge to health care personnel. Recently, a number of additional approaches to IBD therapy, such as new target molecules for biological agents and cellular therapy, have shown promising results. A deeper understanding of IBD pathogenesis and the availability of novel therapies are needed to improve therapeutic success. This review describes the overall key features of therapies currently employed in clinical practice as well as novel and future alternative IBD treatment methods.

Current aspects of vitiligo genetics

Vitiligo is a common acquired depigmentation disorder of the skin manifested by the presence of white macules. The disease occurs at a frequency of approximately 1–4% of the world population. Currently, the most popular theory of vitiligo development is a multifactorial hypothesis according to which genetic conditions predispose vitiligo macules to occur as a result of specific environmental factors. According to the genetic hypothesis, vitiligo inheritance is multigenic. Genetic studies conducted so far concern patients with non-segmental vitiligo. There are three basic techniques of genetic studies: candidate gene association studies, genomewide linkage studies and genome-wide association studies (GWAS). The GWAS are the “gold standard” for detecting susceptibility genes. Up to now, approximately 36 convincing non-segmental vitiligo susceptibility loci have been identified. Approximately 90% of them encode immunoregulatory proteins, while approximately 10% encode melanocyte proteins. The existence of various associations between vitiligo and other autoimmune diseases may provide new knowledge on the causes of many disorders. Examples include the inverse relationship between vitiligo and melanoma and association of vitiligo with other autoimmune diseases. The main goal of all researches is to find new, optimal therapeutic strategies for vitiligo and other autoimmune diseases.

Oral tacrolimus for pediatric steroid-resistant ulcerative colitis

BACKGROUND

Ulcerative colitis (UC) occurring during childhood is generally extensive and is associated with severe flares that may require intravenous steroid treatment. In cases of corticosteroid resistance is necessary to introduce a second-line treatment to avoid or delay surgery.

AIMS

To describe the efficacy and safety of oral tacrolimus for the treatment of severe steroid-resistant UC.

METHODS

We performed a retrospective study that included all patients under age 18 suffering from severe steroid-resistant UC treated with oral tacrolimus during the period January 1998 to October 2012 and with a follow-up period after treatment of 24 months or more.

RESULTS

A total of ten patients were included. The age at baseline was 9.4±4.9 years, and the time from diagnosis was 1.3 months (IQR, 1-5.7). Seven of the patients were in their first flare of disease. All of them received an oral dose of 0.12 mg/kg/day of tacrolimus divided in two doses. Trough plasma levels of tacrolimus were maintained between 4 and 13 ng/ml. Response was seen in 5/10 patients at 12 months, colectomy was eventually performed in 60% of patients during the follow-up period.

CONCLUSIONS

Tacrolimus is useful in inducing remission in patients with severe steroid-resistant UC, preventing or delaying colectomy, and allowing the patient and family to prepare for a probable surgery. Tacrolimus may also be used as a treatment bridge for corticosteroid-dependent patients until the new maintenance therapy takes effect.

MicroRNAs as tools to predict glucocorticoid response in inflammatory bowel diseases

In spite of the introduction in therapy of highly effective biological agents, glucocorticoids (GCs) are still employed to induce remission in moderate to severe inflammatory bowel diseases (IBD), but considerable inter-individual differences in their efficacy and side effects have been reported. The effectiveness of these drugs is indeed very variable and side effects, particularly severe in pediatric patients, are common and often unpredictable: the understanding of the complex gene regulation mediated by GCs could shed light on the causes of this variability. In this context, microRNAs (miRNAs) represent a new and promising field of research. miRNAs are small non-coding RNA molecules that suppress gene expression at post-transcriptional level, and are fine-tuning regulators of diverse biological processes, including the development and function of the immune system, apoptosis, metabolism and inflammation. Emerging data have implicated the deregulated expression of certain miRNA networks in the pathogenesis of autoimmune and inflammatory diseases, such as IBD. There is a great interest in the identification of the role of miRNAs in the modulation of pharmacological response; however, the association between miRNA and GC response in patients with IBD has not yet been evaluated in a prospective clinical study. The identification of miRNAs differently expressed as a consequence of GC treatment in comparison to diagnosis, represents an important innovative approach that could be translated into clinical practice. In this review we highlight the altered regulation of proteins involved in GC molecular mechanism by miRNAs, and their potential role as molecular markers useful for predicting in advance GC response.

NLRP1 haplotypes associated with vitiligo and autoimmunity increase interleukin-1β processing via the NLRP1 inflammasome

Nuclear localization leucine-rich-repeat protein 1 (NLRP1) is a key regulator of the innate immune system, particularly in the skin where, in response to molecular triggers such as pathogen-associated or damage-associated molecular patterns, the NLRP1 inflammasome promotes caspase-1-dependent processing of bioactive interleukin-1β (IL-1β), resulting in IL-1β secretion and downstream inflammatory responses. NLRP1 is genetically associated with risk of several autoimmune diseases including generalized vitiligo, Addison disease, type 1 diabetes, rheumatoid arthritis, and others. Here we identify a repertoire of variation in NLRP1 by deep DNA resequencing. Predicted functional variations in NLRP1 reside in several common high-risk haplotypes that differ from the reference by multiple nonsynonymous substitutions. The haplotypes that are high risk for disease share two substitutions, L155H and M1184V, and are inherited largely intact due to extensive linkage disequilibrium across the region. Functionally, we found that peripheral blood monocytes from healthy subjects homozygous for the predominant high-risk haplotype 2A processed significantly greater (P < 0.0001) amounts of the IL-1β precursor to mature bioactive IL-1β under basal (resting) conditions and in response to Toll-like receptor (TLR) agonists (TLR2 and TLR4) compared with monocytes from subjects homozygous for the reference haplotype 1. The increase in basal release was 1.8-fold greater in haplotype 2A monocytes, and these differences between the two haplotypes were consistently observed three times over a 3-mo period; no differences were observed for IL-1α or TNFα. NLRP1 RNA and protein levels were not altered by the predominant high-risk haplotype, indicating that altered function of the corresponding multivariant NLRP1 polypeptide predisposes to autoimmune diseases by activation of the NLRP1 inflammasome.

Glucocorticoid receptor gene polymorphisms and glucocorticoid resistance in inflammatory bowel disease: a meta-analysis

BACKGROUND

Studies investigating the associations between glucocorticoid receptor gene polymorphisms and glucocorticoid resistance in inflammatory bowel disease report conflicting results.

AIMS

We conducted a meta-analysis to assess the possible association between the three most commonly investigated glucocorticoid receptor gene (ER22/23EK, N363S, and BclI) polymorphisms and glucocorticoid resistance in inflammatory bowel disease.

METHODS

Articles evaluating the effect of ER22/23EK, N363S, and BclI gene polymorphism on glucocorticoid resistance in inflammatory bowel disease were identified from 1950 to February 2012. After extraction of relevant data, meta-analyses were performed to assess the association between glucocorticoid receptor gene polymorphisms and glucocorticoid resistance in inflammatory bowel disease.

RESULTS

A total of five eligible studies with 942 cases were included. Our analysis showed that ER22/23EK polymorphisms were not associated with glucocorticoid resistance in inflammatory bowel disease [GG versus GA + AA: odds ratio (OR) = 0.58, 95 % confidence interval (CI) 0.16-2.08]. In N363S polymorphisms, AG + GG allele showed no significant effect on glucocorticoid resistance in inflammatory bowel disease compared with AA allele (OR = 1.19, 95 % CI 0.33-4.30). In BclI polymorphisms, there was also no association of CG + GG allele with glucocorticoid resistance (CC versus CG + GG: OR = 1.22, 95 % CI 0.70-2.13). For Crohn's disease (CD) and ulcerative colitis (UC), no statistically significant associations between these three single-nucleotide polymorphisms (SNPs) and glucocorticoid resistance were found. The shape of the funnel plot did not detect publication bias.

CONCLUSIONS

The current meta-analysis found no evidence that glucocorticoid receptor gene polymorphisms (ER22/23EK, N363S, and BclI) are associated with glucocorticoid resistance in inflammatory bowel disease treatment. However, this meta-analysis is underpowered for relatively large effect sizes in some SNPs. More well-designed cohort studies should be conducted to fully characterize such an association.

The use of biologic agents in pediatric inflammatory bowel disease

PURPOSE OF REVIEW

Therapeutic options and approaches in inflammatory bowel disease (IBD) continue to evolve. This review will summarize the recent studies of treatment strategies, efficacy, safety and outcome of biological agents in the treatment of children with Crohn's disease and ulcerative colitis.

RECENT FINDINGS

Although there has been little recent change in the number of biologicals easily available for the treatment of children, usage has broadened in pediatric IBD and new treatment strategies have emerged. The use of biologicals in refractory pediatric ulcerative colitis is now accepted, with evidence supporting their potential for maintenance therapy. In pediatric Crohn's disease, scheduled treatment regimens have shown superiority to episodic treatment. Although the 'top-down' approach with early use of biologicals produces superior remission rates in adults, there is still little evidence in children. Concomitant immunosuppression appears to reduce immunogenicity and improve therapeutic control, but there are added risks for infection and malignancy.

SUMMARY

Biologicals now form an integral part of the treatment algorithm in childhood IBD and their use is likely to increase. Treatment regimens, particularly those involving concomitant immunosuppressants, need to take account of the perceptions of risk.

Have genomic discoveries in inflammatory bowel disease translated into clinical progress?

Inflammatory bowel disease (IBD) is a heterogeneous disease that can be challenging to diagnose and manage. As a result, significant efforts have been made in attempting to identify clinical, genomic, and serologic markers of disease that can aid in patient assessment and treatment. Recent genomic discoveries have the potential to change clinical practice by identifying those susceptible to IBD, predict natural history and guide choice of therapy. Panels of genetic and genomic markers are more likely to emerge as clinical tools, as opposed to individual allelic variants. Serology and biomarkers are already being used and guiding management but await integration with genomic panels before achieving their maximal potential. This article reviews the current state of IBD genetics and evolving molecular approaches that may have potential clinical impact.

Association between BclI polymorphism in the NR3C1 gene and in vitro individual variations in lymphocyte responses to methylprednisolone

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

In vitro lymphocyte steroid sensitivity has been suggested as a useful tool to predict in vivo response to glucocorticoid treatment in different inflammatory chronic diseases. A correlation between genetic polymorphisms and clinical response to glucocorticoids has been demonstrated in these patients.

WHAT THIS STUDY ADDS

The BclI polymorphism in the glucocorticoid receptor (NR3C1) gene is associated with higher methylprednisolone potency in vitro. The combined evaluation of the in vitro sensitivity to methylprednisolone and BclI polymorphism could represent an aid for physicians to adjust therapy a priori. AIM To evaluate the association between the in vitro sensitivity of peripheral blood mononuclear cells (PBMCs) to methylprednisolone (MP) and the presence of genetic polymorphisms involved in glucocorticoid (GC) response.

METHODS

In vitro MP inhibition of the proliferation of lymphocytes stimulated with concanavalin A was determined. Non linear regression of dose-response data was performed computing the MP concentration required to reduce proliferation to 50% (IC(50) ). The maximum inhibition achievable at the highest MP concentration (I(max) ) was also calculated. Moreover, the Taqman technique was used to analyze the BclI polymorphism in the NR3C1 gene and the Leu155His polymorphism in the NALP1 gene.

RESULTS

A significant association between the BclI mutated genotype and an increased in vitro sensitivity to GCs was observed.

CONCLUSIONS

The a priori evaluation of the BclI polymorphism, associated with a lymphocyte proliferation assay, could represent a useful diagnostic tool for the optimization of steroid treatment.

Diagnostic profiles determined by the C.A.R.T procedure: IBD patients and fatigue

Fatigue is common in IBD. It remains a complex phenomenon with primary factors related to the disease and secondary factors (depression, anxiety, sleep disturbances, pain) whose respective importance and organization are difficult to determine. By using the C.A.R.T. procedure, the diagnostic variables of 108 IBD-related fatigue patients were determined globally, according to their sex and the clinical activity of their disease. Results underline the diversity of diagnostic profiles in which psychological variables have significant influence. It is important to consider fatigue according to profiles that best illustrate its complexity and allow for identifying better potentially remediable factors.

Six decades of vitiligo genetics: genome-wide studies provide insights into autoimmune pathogenesis

Generalized vitiligo (GV) is a complex disease in which patchy depigmentation results from autoimmune loss of melanocytes from affected regions. Genetic analyses of GV span six decades, with the goal of understanding biological mechanisms and elucidating pathways that underlie the disease. The earliest studies attempted to describe the mode of inheritance and genetic epidemiology. Early genetic association studies of biological candidate genes resulted in some successes, principally HLA and PTPN22, but in hindsight many such reports now seem to be false-positives. Later, genome-wide linkage studies of multiplex GV families identified NLRP1 and XBP1, which appear to be valid GV susceptibility genes that control key aspects of immune regulation. Recently, the application of genome-wide association studies to analysis of GV has produced a rich yield of validated GV susceptibility genes that encode components of biological pathways reaching from immune cells to the melanocyte. These genes and pathways provide insights into underlying pathogenetic mechanisms and possible triggers of GV, establish relationships to other autoimmune diseases, and may provide clues to potential new approaches to GV treatment and perhaps even prevention. These results thus validate the hopes and efforts of the early investigators who first attempted to comprehend the genetic basis of vitiligo.

Recent progress in the genetics of generalized vitiligo

Vitiligo is an acquired disease characterized principally by patchy depigmentation of skin and overlying hair. Generalized vitiligo (GV), the predominant form of the disorder, results from autoimmune loss of melanocytes from affected regions. GV is a "complex trait", inherited in a non-Mendelian polygenic, multifactorial manner. GV is epidemiologically associated with other autoimmune diseases, both in GV patients and in their close relatives, suggesting that shared genes underlie susceptibility to this group of diseases. Early candidate gene association studies yielded a few successes, such as PTPN22, but most such reports now appear to be false-positives. Subsequent genomewide linkage studies identified NLRP1 and XBP1, apparent true GV susceptibility genes involved in immune regulation, and recent genome-wide association studies (GWAS) of GV in Caucasian and Chinese populations have yielded a large number of additional validated GV susceptibility genes. Together, these genes highlight biological systems and pathways that reach from the immune cells to the melanocyte, and provide insights into both disease pathogenesis and potential new targets for both treatment and even prevention of GV and other autoimmune diseases in genetically susceptible individuals.

Molecular mechanism of glucocorticoid resistance in inflammatory bowel disease

Natural and synthetic glucocorticoids (GCs) are widely employed in a number of inflammatory, autoimmune and neoplastic diseases, and, despite the introduction of novel therapies, remain the first-line treatment for inducing remission in moderate to severe active Crohn’s disease and ulcerative colitis. Despite their extensive therapeutic use and the proven effectiveness, considerable clinical evidence of wide inter-individual differences in GC efficacy among patients has been reported, in particular when these agents are used in inflammatory diseases. In recent years, a detailed knowledge of the GC mechanism of action and of the genetic variants affecting GC activity at the molecular level has arisen from several studies. GCs interact with their cytoplasmic receptor, and are able to repress inflammatory gene expression through several distinct mechanisms. The glucocorticoid receptor (GR) is therefore crucial for the effects of these agents: mutations in the GR gene (NR3C1, nuclear receptor subfamily 3, group C, member 1) are the primary cause of a rare, inherited form of GC resistance; in addition, several polymorphisms of this gene have been described and associated with GC response and toxicity. However, the GR is not self-standing in the cell and the receptor-mediated functions are the result of a complex interplay of GR and many other cellular partners. The latter comprise several chaperonins of the large cooperative hetero-oligomeric complex that binds the hormone-free GR in the cytosol, and several factors involved in the transcriptional machinery and chromatin remodeling, that are critical for the hormonal control of target genes transcription in the nucleus. Furthermore, variants in the principal effectors of GCs (e.g. cytokines and their regulators) have also to be taken into account for a comprehensive evaluation of the variability in GC response. Polymorphisms in genes involved in the transport and/or metabolism of these hormones have also been suggested as other possible candidates of interest that could play a role in the observed inter-individual differences in efficacy and toxicity. The best-characterized example is the drug efflux pump P-glycoprotein, a membrane transporter that extrudes GCs from cells, thereby lowering their intracellular concentration. This protein is encoded by the ABCB1/MDR1 gene; this gene presents different known polymorphic sites that can influence its expression and function. This editorial reviews the current knowledge on this topic and underlines the role of genetics in predicting GC clinical response. The ambitious goal of pharmacogenomic studies is to adapt therapies to a patient’s specific genetic background, thus improving on efficacy and safety rates.