Cyclin-dependent Kinase 9 as a Potential Target for Anti-TNF-resistant Inflammatory Bowel Disease.

BACKGROUND & AIMS: Resistance to single cytokine blockade, namely anti-tumor necrosis factor (TNF) therapy, is a growing concern for patients with inflammatory bowel disease (IBD). The transcription factor T-bet is a critical regulator of intestinal homeostasis, is genetically linked to mucosal inflammation and controls the expression of multiples genes such as the pro-inflammatory cytokines interferon (IFN)-γ and TNF. Inhibiting T-bet may therefore offer a more attractive prospect for treating IBD but remains challenging to target therapeutically. In this study, we evaluate the effect of targeting the transactivation function of T-bet using inhibitors of P-TEFb (CDK9-cyclin T), a transcriptional elongation factor downstream of T-bet. METHODS: Using an adaptive immune-mediated colitis model, human colonic lymphocytes from patients with IBD and multiple large clinical datasets, we investigate the effect of cyclin-dependent kinase 9 (CDK9) inhibitors on cytokine production and gene expression in colonic CD4+ T cells and link these genetic modules to clinical response in patients with IBD. RESULTS: Systemic CDK9 inhibition led to histological improvement of immune-mediated colitis and was associated with targeted suppression of colonic CD4+ T cell-derived IFN-γ and IL-17A. In colonic lymphocytes from patients with IBD, CDK9 inhibition potently repressed genes responsible for pro-inflammatory signalling, and in particular genes regulated by T-bet. Remarkably, CDK9 inhibition targeted genes that were highly expressed in anti-TNF resistant IBD and that predicted non-response to anti-TNF therapy. CONCLUSION: Collectively, our findings reveal CDK9 as a potential target for anti-TNF-resistant IBD, which has the potential for rapid translation to the clinic.

A Crohn's Disease-associated IL2RA Enhancer Variant Determines the Balance of T Cell Immunity by Regulating Responsiveness to IL-2 Signalling.

BACKGROUND AND AIMS: Differential responsiveness to interleukin [IL]-2 between effector CD4+ T cells [Teff] and regulatory T cells [Treg] is a fundamental mechanism of immunoregulation. The single nucleotide polymorphism [SNP] rs61839660, located within IL2RA [CD25], has been associated with the development of Crohn's disease [CD]. We sought to identify the T cell immune phenotype of IBD patients who carry this SNP. METHODS: Teff and Treg were isolated from individuals homozygous [TT], heterozygous [CT], or wild-type [CC] for the minor allele at rs61839660, and used for phenotyping [flow cytometry, Cytometry Time Of Flight] functional assays or T cell receptor [TCR] sequencing. Phosphorylation of signal transducer and activator of transcription 5 [STAT5] was assessed in response to IL-2, IL-7, and in the presence of basiliximab, a monoclonal antibody directed against CD25. Teff pro-inflammatory cytokine expression levels were assessed by reverse transcription quantitative polymerase chain reaction after IL-2 and/or TCR stimulation. RESULTS: Presence of the minor T allele enhances CD25 expression, leading to increased STAT5 phosphorylation and pro-inflammatory cytokine transcript expression by Teff in response to IL-2 stimulation in vitro. Teff from TT individuals demonstrate a more activated gut homing phenotype. TCR sequencing analysis suggests that TT patients may have a reduced clonal capacity to mount an optimal regulatory T cell response. CONCLUSIONS: rs61839660 regulates the responsiveness of T cells to IL-2 signalling by modulating CD25 expression. As low-dose IL-2 is being trialled as a selective Treg modulator in CD, these findings highlight the potential for adverse effects in patients with this genotype.

ILC1 drive intestinal epithelial and matrix remodelling.

Organoids can shed light on the dynamic interplay between complex tissues and rare cell types within a controlled microenvironment. Here, we develop gut organoid cocultures with type-1 innate lymphoid cells (ILC1) to dissect the impact of their accumulation in inflamed intestines. We demonstrate that murine and human ILC1 secrete transforming growth factor ß1, driving expansion of CD44v6+ epithelial crypts. ILC1 additionally express MMP9 and drive gene signatures indicative of extracellular matrix remodelling. We therefore encapsulated human epithelial-mesenchymal intestinal organoids in MMP-sensitive, synthetic hydrogels designed to form efficient networks at low polymer concentrations. Harnessing this defined system, we demonstrate that ILC1 drive matrix softening and stiffening, which we suggest occurs through balanced matrix degradation and deposition. Our platform enabled us to elucidate previously undescribed interactions between ILC1 and their microenvironment, which suggest that they may exacerbate fibrosis and tumour growth when enriched in inflamed patient tissues.

Characterizing Innate Lymphoid Cell Phenotype and Function in Human Inflammatory Bowel Disease.

Innate lymphoid cells (ILCs) are emerging as important effectors of innate immunity and play a critical role in maintaining intestinal immune homeostasis. They are tissue-residing immune cells that can be subdivided based on master transcription factor and cytokine expression, bearing striking resemblance to their CD4+ T helper (Th) cell counterparts. ILCs are increasingly recognized as potential mediators of inflammatory bowel disease (IBD) providing a need to explore their functional and phenotypic differences in health vs. disease. In this chapter we outline protocols for the characterization of human ILCs and intracellular cytokine expression using flow cytometry. We include protocols for isolating human peripheral blood and colonic lamina propria mononuclear cells essential for evaluating human IBD specimens.

Regulatory T-cell therapy in Crohn's disease: challenges and advances.

The prevalence of IBD is rising in the Western world. Despite an increasing repertoire of therapeutic targets, a significant proportion of patients suffer chronic morbidity. Studies in mice and humans have highlighted the critical role of regulatory T cells in immune homeostasis, with defects in number and suppressive function of regulatory T cells seen in patients with Crohn's disease. We review the function of regulatory T cells and the pathways by which they exert immune tolerance in the intestinal mucosa. We explore the principles and challenges of manufacturing a cell therapy, and discuss clinical trial evidence to date for their safety and efficacy in human disease, with particular focus on the development of a regulatory T-cell therapy for Crohn's disease.

Definitions for warning signs and signs of severe dengue according to the WHO 2009 classification: Systematic review of literature.

Since warning signs and signs of severe dengue are defined differently between studies, we conducted a systematic review on how researchers defined these signs. We conducted an electronic search in Scopus to identify relevant articles, using key words including dengue, "warning signs," "severe dengue," and "classification." A total of 491 articles were identified through this search strategy and were subsequently screened by 2 independent reviewers for definitions of any of the warning or severe signs in the 2009 WHO dengue classification. We included all original articles published in English after 2009, classifying dengue by the 2009 WHO classification or providing the additional definition or criterion of warning signs and severity (besides the information of 2009 WHO). Analysis of the extracted data from 44 articles showed wide variations among definitions and cutoff values used by physicians to classify patients diagnosed with dengue infection. The establishment of clear definitions for warning signs and severity is essential to prevent unnecessary hospitalization and harmonizing the interpretation and comparability of epidemiological studies dedicated to dengue infection.

Optimal percutaneous coronary intervention in patients with ST-elevation myocardial infarction and multivessel disease: An updated, large-scale systematic review and meta-analysis.

BACKGROUND: Our study aimed to compare three different percutaneous coronary intervention (PCI) approaches: culprit-only (COR) and complete (CR) revascularization - categorizing into immediate (ICR) or staged (SCR). METHODS: We searched 13 databases for randomized controlled trials. Articles were included if they compared at least two strategies. To have more studies in each analysis, an adjusted analysis was performed using person-years to incorporate follow-up durations and obtain pooled rate ratios (RR), with their corresponding 95% confidence interval. RESULTS: Thirteen trials were included with a population of 2830 patients. COR significantly increased major adverse cardiac event (MACE) (adjusted RR 1.67, 95% CI: 1.27-2.19) and repeat revascularization (2.12, 1.67-2.69), which was driven by repeat PCI, without any difference in all-cause mortality and myocardial infarction (MI) compared to CR. When categorizing CR into SCR and ICR, the trend repeated with COR increased MACE (1.99, 1.53-2.6 for ICR), cardiovascular mortality (2.06, 1.07-3.96 for ICR), MI for ICR (1.72, 1.04-2.86), repeat revascularization and repeat PCI for both ICR and SCR. Non-cardiovascular mortality, stroke, nephropathy, re-hospitalization, stent thrombosis and bleeding were similar among all approaches. CONCLUSIONS: In MVD-STEMI patients, CR is better than COR in terms of MACE, cardiovascular mortality, repeat revascularization with no difference in safety outcomes. There was a trend towards to a reduction of cardiovascular mortality and MI in ICR compared to SCR when each matched with COR; even though there is no statistically significant difference between ICR and SCR when compared together.

Aortic stiffening precedes onset of heart failure with preserved ejection fraction in patients with asymptomatic diastolic dysfunction.

BACKGROUND: Identifying which patients with diastolic dysfunction will progress to heart failure with preserved ejection fraction (HFpEF) remains challenging. The goal of this study is to determine whether increased vascular stiffness as identified on 2D transthoracic echocardiography (TTE) serves as a biomarker for the development of HFpEF in patients with diastolic dysfunction. METHODS: The study design is a matched retrospective case-control study. Subjects with diastolic dysfunction were divided into two groups based on whether they had a clinical diagnosis of HFpEF. The two groups were matched based on age, gender, race and body surface area, resulting in 77 matched pairs (n = 154). Data from the first TTE that documented diastolic dysfunction prior to the development of HFpEF was extracted along with baseline demographic and clinical data. Indices of vascular stiffness were measured and compared. A sub-group analysis was performed to compare diabetic subjects in Group 1 (n = 43) to those in Group 2 (n = 21). RESULTS: Group 1 had significantly decreased aortic distensibility as measured on the initial TTE when compared to Group 2 (1.9 ± 1.0 vs. 2.8 ± 1.8 cm2dyne-110-3, p = 0.01). In the diabetic subset, Group 1 had significantly less aortic strain (6.9 ± 3.3 vs. 9.7 ± 5.6%, p = 0.02) and aortic distensibility (1.8 ± 1.0 vs. 3.5 ± 2.6 cm2dyne-110-3, p = 0.02) compared to Group 2. Other indices of vascular stiffness did not differ significantly between groups. CONCLUSIONS: This study demonstrates that increased proximal aortic stiffness is associated with the development of HFpEF in patients with asymptomatic diastolic dysfunction. Larger prospective studies are needed to further investigate this relationship.

Pneumocystis pneumonia complicating immunosuppressive therapy in Crohns disease: A preventable problem?

We report the case of a 76-year-old man who presented with moderate active Crohn's colitis that was refractory to high-dose corticosteroids, mesalazine and 6-mercaptopurine. He subsequently received a trial of infliximab with poor response and was diagnosed with cytomegalovirus (CMV) colitis, improving on antiviral therapy. Three weeks into treatment he developed acute respiratory distress with hypoxaemia and diffuse pulmonary interstitial infiltrates. This was confirmed as Pneumocystis jirovecii on bronchoalveolar lavage. He responded well to treatment with trimethoprim-sulfamethoxazole (TMP-SMX) and was subsequently discharged home. Despite the favourable outcome, our case raises the question of whether chemoprophylaxis against opportunistic infections in immunosuppressed patients with inflammatory bowel disease (IBD) is appropriate. There are currently no recommendations on providing chemoprophylaxis against CMV colitis and so we focus on pneumocystis pneumonia (PCP) where wide debate surrounds the use of prophylactic TMP-SMX in HIV-negative patients. Contrasting approaches to chemoprophylaxis against PCP in IBD likely relates to a lack of clear parameters for defining risk of PCP among patient groups. This must be addressed in order to develop universal guidelines that take into account patient-dependent risk factors. Awareness of the severity of PCP among HIV-negative individuals and the current consensus on PCP prophylaxis in IBD must be raised in order to minimise the risk of PCP and drive research in this controversial area.

Dynamic response of model lipid membranes to ultrasonic radiation force.

Low-intensity ultrasound can modulate action potential firing in neurons in vitro and in vivo. It has been suggested that this effect is mediated by mechanical interactions of ultrasound with neural cell membranes. We investigated whether these proposed interactions could be reproduced for further study in a synthetic lipid bilayer system. We measured the response of protein-free model membranes to low-intensity ultrasound using electrophysiology and laser Doppler vibrometry. We find that ultrasonic radiation force causes oscillation and displacement of lipid membranes, resulting in small (<1%) changes in membrane area and capacitance. Under voltage-clamp, the changes in capacitance manifest as capacitive currents with an exponentially decaying sinusoidal time course. The membrane oscillation can be modeled as a fluid dynamic response to a step change in pressure caused by ultrasonic radiation force, which disrupts the balance of forces between bilayer tension and hydrostatic pressure. We also investigated the origin of the radiation force acting on the bilayer. Part of the radiation force results from the reflection of the ultrasound from the solution/air interface above the bilayer (an effect that is specific to our experimental configuration) but part appears to reflect a direct interaction of ultrasound with the bilayer, related to either acoustic streaming or scattering of sound by the bilayer. Based on these results, we conclude that synthetic lipid bilayers can be used to study the effects of ultrasound on cell membranes and membrane proteins.

Effects of hyperthermic intraoperative peritoneal lavage on intra-abdominal pressure in an experimental model of peritonitis: A randomized, controlled, blinded interventional study.

BACKGROUND: Hyperthermic Intraoperative Peritoneal Lavage (HIPL) is useful for bacterial decontamination and prevention of hypothermia during damage-control surgery (DCS). Little is known about the effect of HIPL on intra-abdominal pressure (IAP) alone or in combination with peritonitis. AIM: To determine the effects of HIPL at graded temperatures on IAP in the context of DCS. MATERIALS AND METHODS: A total of 40 rabbits randomly assigned to aseptic-thermal (AT) and peritonitis-thermal (PT) groups and subgroups underwent HIPL at 40°C, 43°C, 46°C, and 49°C. The AT subgroup assigned 40°C was the control group. HIPL was done with a volume of 100 ml/kg. Hourly IAP measurement by two independent observers who were mutually blinded was done through a peritoneal balloon pouch connected to a manometer for 12 hours. RESULTS: All rabbits in group AT survived for at least 11 hours, while all the rabbits in group PT died between 4 and 8 hours. There was significant IAP rise at 4 hours in all subgroups in comparison with the control (I AT40):III AT46 (P < 0.01), IV AT49 (P < 0.001), V PT40 (P < 0.01), VI PT43 (P < 0.01), VII PT46 (P < 0.001), and P 49 (P < 0.001) except II AT43 ( P = 0.85). Multiple linear regression analysis showed a positive correlation:Coefficient of regression {r = 0.85 (AT) and r = 0.89 (PT)} and coefficient of determination {r2 = 0.73 (AT) and r2 = 0.80 (PT)}. CONCLUSION: Our findings suggest that beyond 3°C above the normal body temperature in this species, HIPL acts synergistically with peritonitis to exacerbate intra-abdominal hypertension and is associated with a shortened survival postoperatively due to abdominal compartment syndrome.

A new mechanism for bile acid diarrhea: defective feedback inhibition of bile acid biosynthesis.

BACKGROUND & AIMS: Primary (idiopathic) bile acid malabsorption (BAM) is a common, yet underrecognized, chronic diarrheal syndrome. Diagnosis is difficult without selenium homocholic acid taurine (SeHCAT) testing. The diarrhea results from excess colonic bile acids, but the pathogenesis is unclear. Fibroblast growth factor 19 (FGF19), produced in the ileum in response to bile acid absorption, regulates hepatic bile acid synthesis. We proposed that FGF19 is involved in bile acid diarrhea and measured its levels in patients with BAM. METHODS: Blood was collected from fasting patients with chronic diarrhea; BAM was diagnosed by SeHCAT. Serum FGF19 was measured by enzyme-linked immunosorbent assay. Serum 7alpha-hydroxy-4-cholesten-3-one (C4) was determined using high-performance liquid chromatography, to quantify bile acid synthesis. Data were compared between patients and subjects without diarrhea (controls). Samples were taken repeatedly after meals from several subjects. RESULTS: The median C4 level was significantly higher in patients with primary BAM than in controls (51 vs 18 ng/mL; P < .0001). The median FGF19 level was significantly lower in patients with BAM (120 vs 231 pg/mL; P < .0005). There was a significant inverse relationship between FGF19 and C4 levels (P < .0004). Low levels of FGF19 were also found in patients with postcholecystectomy and secondary bile acid diarrhea. Abnormal patterns of FGF19 levels were observed throughout the day in some patients with primary BAM. CONCLUSIONS: Patients with BAM have reduced serum FGF19 which may be useful in diagnosis. We propose a mechanism whereby impaired FGF19 feedback inhibition causes excessive bile acid synthesis that exceeds the normal capacity for ileal reabsorption, producing bile acid diarrhea.