Sterol regulatory element-binding proteins are essential for the metabolic programming of effector T cells and adaptive immunity.

Newly activated CD8(+) T cells reprogram their metabolism to meet the extraordinary biosynthetic demands of clonal expansion; however, the signals that mediate metabolic reprogramming remain poorly defined. Here we demonstrate an essential role for sterol regulatory element-binding proteins (SREBPs) in the acquisition of effector-cell metabolism. Without SREBP signaling, CD8(+) T cells were unable to blast, which resulted in attenuated clonal expansion during viral infection. Mechanistic studies indicated that SREBPs were essential for meeting the heightened lipid requirements of membrane synthesis during blastogenesis. SREBPs were dispensable for homeostatic proliferation, which indicated a context-specific requirement for SREBPs in effector responses. Our studies provide insights into the molecular signals that underlie the metabolic reprogramming of CD8(+) T cells during the transition from quiescence to activation.

Healthcare resource utilization after initiation of sodium-glucose co-transporter-2 inhibitors versus dipeptidyl peptidase-4 inhibitors or other glucose-lowering drugs in Japanese patients with type 2 diabetes.

AIM: To examine healthcare resource utilization in type 2 diabetes (T2D) patients after initiation of sodium-glucose co-transporter-2 inhibitors (SGLT-2is) versus dipeptidyl peptidase-4 inhibitors (DPP-4is) or other glucose-lowering drugs (oGLDs). MATERIALS AND METHODS: A cost-utilization analysis was performed using a nationwide hospital-based administrative claims database (Medical Data Vision) during 2014-2018 in Japan, where universal healthcare coverage is maintained under a single-payer system. Data on T2D patients initiated on either SGLT-2is or oGLDs during the study period (228 514 patients) were extracted and subjected to a 1:1 propensity score-matching analysis (7626 patient pairs for DPP-4is and 28 484 for oGLDs). Direct healthcare resource utilizations and inpatient and outpatient costs were compared. RESULTS: After matching, baseline characteristics were well balanced, including healthcare costs within 3 and 12 months before the index date (standardized difference <5% for all variables), with a mean age of 61.6-64.1 years. While diabetes medication costs were higher in patients initiated with SGLT-2is than in those initiated with DPP-4is or oGLDs, further breakdown of individual cost components showed that SGLT-2is were associated with a lower hospitalization frequency and a shorter total hospital stay (by 213.0 or 204.6 days/100 patient-years compared with DPP-4is or oGLDs, respectively; P < .001). Accordingly, overall mean cumulative cost per patient at the 2.5-year postindex date was lower in patients with SGLT-2is than in those with DPP-4is or oGLDs by $2545 (1384.6-3759.7) and $2330 (1793.1-2882.9), respectively (P < .001). CONCLUSIONS: Our results show the benefits in healthcare resource utilization associated with SGLT-2i use in Japanese T2D patients.

Current trends in diabetes mellitus database research in Japan.

With the widespread use of electronic medical records and administrative claims databases, analytic results from so-called real-world data have become increasingly important in healthcare decision-making. Diabetes mellitus is a heterogeneous condition that involves a broad spectrum of patients. Real-world database studies have been recognised as a powerful tool to understand the impact of current practices on clinical courses and outcomes, such as long-term glucose control, development of microvascular or macro-vascular diseases, and mortality. Diabetes is also a major global health issue and poses a significant social and economic burden worldwide. Therefore, it is critical to understand the epidemiology, clinical course, treatment reality, and long-term outcomes of diabetes to determine realistic solutions to a variety of disease-related issues that we are facing. In the present review, we summarise the healthcare system and large-scale databases currently available in Japan, introduce the results from recent database studies involving Japanese patients with diabetes, and discuss future opportunities and challenges for the use of databases in the management of diabetes.

Impact of body mass index on real-world outcomes of rivaroxaban treatment in Japanese patients with non-valvular atrial fibrillation.

This sub-analysis of the XAPASS, a prospective, single-arm, observational study, aimed to evaluate relationships between body mass index (BMI) and safety (major bleeding and all-cause mortality) and effectiveness [stroke/non-central nervous system (non-CNS) systemic embolism (SE)/myocardial infarction (MI)] outcomes in Japanese patients with non-valvular atrial fibrillation (NVAF) receiving rivaroxaban. Patients were categorized according to BMI (kg/m2) as underweight (< 18.5), normal weight (18.5 to < 25), overweight (25 to < 30), or obese (≥ 30). In total, 9578 patients with NVAF completed the 1-year follow-up and were evaluated; of these, 7618 patients had baseline BMI data. Overall, 542 (5.7%), 4410 (46.0%), 2167 (22.6%), and 499 (5.2%) patients were underweight, normal weight, overweight, and obese, respectively. Multivariable Cox regression analysis demonstrated that none of the BMI categories were independent predictors of major bleeding whereas being underweight was independently associated with increased all-cause mortality [hazard ratio (HR) 3.56, 95% confidence interval (CI) 2.40-5.26, p < 0.001]. The incidence of stroke/non-CNS SE/MI was higher in patients who were underweight than in those of normal weight (HR 2.11, 95% CI 1.20-3.70, p = 0.009). However, in multivariable analyses, being underweight was not identified as an independent predictor of stroke/non-CNS SE/MI (HR 1.64, 95% CI 0.90-2.99, p = 0.104). In conclusion, the high incidence of thromboembolic events and all-cause mortality in patients who were underweight highlights that thorough evaluation of disease status and comorbidities may be required in this population.

Real-world outcomes of rivaroxaban treatment in elderly Japanese patients with nonvalvular atrial fibrillation.

Direct oral anticoagulants (DOACs), such as rivaroxaban, reduce the risk of stroke and systemic embolism in patients with nonvalvular atrial fibrillation (NVAF). However, it is still unclear whether the stroke reduction benefit outweighs the bleeding risk in elderly Japanese patients with NVAF. The Xarelto Post-Authorization Safety and Effectiveness Study in Japanese Patients with Atrial Fibrillation (XAPASS) was a real-world, prospective observational, post-marketing surveillance study on the safety and effectiveness of rivaroxaban in Japanese clinical practice. This sub-analysis evaluated the clinical outcomes of elderly patients aged ≥ 75 years. At the 1-year follow-up, there were 4,685 (48.91%) and 4,893 (51.09%) patients aged ≥ 75 and < 75 years, respectively. Safety and effectiveness outcomes were compared between patients aged ≥ 75 years and those aged < 75 years, and among 3 elderly sub-populations (age ranges: 75-79, 80-84, and ≥ 85 years). Patients aged ≥ 75 years had higher rates of major bleeding [2.22 vs. 1.35 events per 100 patient-years, hazard ratio (HR) 1.63, 95% confidence interval (CI) 1.17-2.28] and composite of stroke (ischemic or hemorrhagic)/non-central nervous system (non-CNS) systemic embolism (SE)/myocardial infarction (MI) (2.41 vs. 1.21 events per 100 patient-years, HR 1.97, 95% CI 1.40-2.77) compared to patients aged < 75 years. Intracranial hemorrhage rates were < 1 event per 100 patient-years in both groups (0.85 vs. 0.59 events per 100 patient-years, HR 1.43, 95% CI 0.85-2.40). Kaplan-Meier curves of major bleeding and stroke/non-CNS SE/MI showed that no significant differences of cumulative event rates were identified among the 3 elderly sub-populations. Stepwise Cox regression analyses revealed that creatinine clearance (CrCl) (<50 mL/min), hepatic impairment, and hypertension were specific predictors for major bleeding and no specific predictors were found for stroke/non-CNS SE/MI in patients aged ≥ 75 years. In conclusion, safety and effectiveness event rates were higher in patients aged ≥ 75 years compared with those aged < 75 years, yet, no distinct differences were observed among the 3 elderly sub-populations.

Clinical Risk Factors of Thromboembolic and Major Bleeding Events for Patients with Atrial Fibrillation Treated with Rivaroxaban in Japan.

BACKGROUND: It is important to understand the risk of thromboembolism and bleeding in patients with nonvalvular atrial fibrillation (NVAF) receiving direct oral anticoagulants; however, data on risk factors in Japanese patients are limited. METHODS: XAPASS (Xarelto Post-Authorization Safety and Effectiveness Study in Japanese Patients with Atrial Fibrillation) is a prospective observational study examining the safety and effectiveness of rivaroxaban in Japanese real-world clinical practice. We investigated risk factors for stroke/noncentral nervous system systemic embolism (non-CNS SE)/myocardial infarction (MI) and major bleeding using 1-year follow-up data. Associations between baseline characteristics and outcomes were examined by Cox regression analysis. RESULTS: During April 2012-June 2014, 11,308 patients newly started with rivaroxaban treatment were enrolled. Of 9578 patients with 1-year data fixed as of September 2017, 6220 patients who received appropriate dosages of rivaroxaban for their creatinine clearance were included in the present safety outcomes subanalysis, and 6198 were included in the effectiveness outcomes analysis. Stroke/non-CNS SE/MI was observed in 97 of 6198 patients (1.6%, 1.8 events/100 patient-years), and major bleeding occurred in 102 of 6220 patients (1.6%, 1.9 events/100 patient-years). Age greater than or equal to 75 years (hazard ratio [HR]: 2.27; [95% confidence interval (CI): 1.49, 3.47]), prior ischemic stroke/transient ischemic attack (2.08; [1.38, 3.13]), and antiplatelet use (3.23; [1.83, 5.70]) were associated with stroke/non-CNS SE/MI. Creatinine clearance less than 50 mL/min (HR: 1.86; [95% CI: 1.26, 2.75]), diabetes (1.55; [1.02, 2.35]), and antiplatelet use (3.04; [1.70, 5.45]) were associated with major bleeding. CONCLUSIONS: These results would help physicians to assess risks in Japanese patients with NVAF receiving rivaroxaban.

Real-World Outcomes of Rivaroxaban Treatment in Patients with Both Nonvalvular Atrial Fibrillation and a History of Ischemic Stroke/Transient Ischemic Attack.

INTRODUCTION: Prior stroke is a risk factor for stroke and bleeding during anticoagulation in patients with atrial fibrillation (AF). Although rivaroxaban is widely prescribed to reduce their risk of stroke in patients with nonvalvular AF (NVAF), the real-world evidence on rivaroxaban treatment is limited. We aimed to examine the outcomes of rivaroxaban treatment in NVAF patients with prior ischemic stroke/transient ischemic attack (TIA) by using the data of the Xarelto Post-Authorization Safety and Effectiveness Study in Japanese -Patients with AF, a prospective, single-arm, observational study. METHODS: The clinical outcomes of 9,578 patients who completed the 1-year follow-up were evaluated. Safety and effectiveness outcomes were compared between patients with and without prior ischemic stroke/TIA. RESULTS: Among the patients, 2,153 (22.5%) had prior ischemic stroke/TIA. They were significantly older and had lower body weight, lower creatinine clearance, higher CHADS2, CHA2DS2-VASc, and modified HAS-BLED scores as compared to those without prior ischemic stroke/TIA. Any bleeding (9.1 vs. 7.2 events per 100 patient-years), major bleeding (2.3 vs. 1.6 events per 100 patient-years), and stroke/non-central nervous system systemic embolism/myocardial infarction (3.4 vs. 1.3 events per 100 patient-years) were more frequent in patients with prior ischemic stroke/TIA. Stepwise regression analysis suggested that body weight of ≤50 kg and diabetes mellitus were predictive of major bleeding in patients with prior ischemic stroke/TIA. CONCLUSIONS: Safety and effectiveness event rates were higher in patients with prior ischemic stroke/TIA than those without. This might be explained by differences in several risk profiles including age, body weight, renal function, and risk scores such as CHADS2 between the groups. Clinicaltrials.gov: NCT01582737.

Outcomes associated with under-dosing of rivaroxaban for management of non-valvular atrial fibrillation in real-world Japanese clinical settings.

The approved dose of oral anticoagulant rivaroxaban for patients with non-valvular atrial fibrillation (NVAF) in Japan is 15 mg once daily (od) in patients whose creatinine clearance is ≥ 50 mL/min, but recent real-world studies have demonstrated that these patients often received less than the recommended dose due to bleeding concerns. The effect of under-dosing on safety and effectiveness outcomes remains unclear. We used 1-year follow-up data from the XAPASS, a real-world Japanese prospective, single-arm, observational study. Of the 11,308 patients, 6521 patients who completed a 1-year follow-up and had a creatinine clearance ≥ 50 mL/min were included in this sub-analysis. Primary endpoints were any bleeding and a composite of stroke/non-central nervous system systemic embolism (non-CNS SE)/myocardial infarction (MI). Among the 6521 patients, 4185 (64.2%; mean CHADS2 score: 1.8) received the 15 mg od (recommended dose), whereas 2336 (35.8%; mean CHADS2 score: 2.3) received 10 mg od (under-dose). After adjusting for patient characteristics by propensity scoring and inverse probability of treatment weighting, incidence rates of major bleeding were comparable between under-dosed patients and patients who received the recommended dose (1.34 vs. 1.63 events/100 patient-years, p = 0.197), although the incidence rates of stroke/non-CNS SE/MI were higher in under-dosed patients than in those who received the recommended dose (2.15 vs. 1.48 events/100 patient-years, p = 0.009). In Japanese clinical practice, some NVAF patients receive rivaroxaban doses inconsistent with the recommendation. Considering the total clinical benefit, the recommended dose may be preferable in terms of balance of safety and effectiveness.Clinicaltrials.gov NCT01582737.

Gene expression in the Gitr locus is regulated by NF-κB and Foxp3 through an enhancer.

Glucocorticoid-induced TNFR (Gitr) and Ox40, two members of the TNFR superfamily, play important roles in regulating activities of effector and regulatory T cells (Treg). Their gene expression is induced by T cell activation and further upregulated in Foxp3+ Treg. Although the role of Foxp3 as a transcriptional repressor in Treg is well established, the mechanisms underlying Foxp3-mediated transcriptional upregulation remain poorly understood. This transcription factor seems to upregulate expression not only of Gitr and Ox40, but also other genes, including Ctla4, Il35, Cd25, all critical to Treg function. To investigate how Foxp3 achieves such upregulation, we analyzed its activity on Gitr and Ox40 genes located within a 15.1-kb region. We identified an enhancer located downstream of the Gitr gene, and both Gitr and Ox40 promoter activities were shown to be upregulated by the NF-κB-mediated enhancer activity. We also show, using the Gitr promoter, that the enhancer activity was further upregulated in conjunction with Foxp3. Foxp3 appears to stabilize NF-κB p50 binding by anchoring it to the enhancer, thereby enabling local accumulation of transcriptional complexes containing other members of the NF-κB and IκB families. These findings may explain how Foxp3 can activate expression of certain genes while suppressing others.

Liver X receptor and peroxisome proliferator-activated receptor as integrators of lipid homeostasis and immunity.

Lipid metabolism has emerged as an important modulator of innate and adaptive immune cell fate and function. The lipid-activated transcription factors peroxisome proliferator-activated receptor (PPAR) α, ß/δ, γ and liver X receptor (LXR) are members of the nuclear receptor superfamily that have a well-defined role in regulating lipid homeostasis and metabolic diseases. Accumulated evidence over the last decade indicates that PPAR and LXR signaling also influence multiple facets of inflammation and immunity, thereby providing important crosstalk between metabolism and immune system. Herein, we provide a brief introduction to LXR and PPAR biology and review recent discoveries highlighting the importance of PPAR and LXR signaling in the modulation of normal and pathologic states of immunity. We also examine advances in our mechanistic understanding of how nuclear receptors impact immune system function and homeostasis. Finally, we discuss whether LXRs and PPARs could be pharmacologically manipulated to provide novel therapeutic approaches for modulation of the immune system under pathologic inflammation or in the context of allergic and autoimmune disease.

Manifestation of Heart Failure and Chronic Kidney Disease are Associated with Increased Mortality Risk in Early Stages of Type 2 Diabetes Mellitus: Analysis of a Japanese Real-World Hospital Claims Database.

INTRODUCTION: To assess the initial manifestation of comorbidities and their impact on mortality risk in patients with type 2 diabetes mellitus (T2DM) without a history of cardiovascular or renal complications (i.e., in the early stages of T2DM) compared with patients without T2DM. METHODS: We performed a retrospective cohort study using a Japanese hospital claims database. The incidence rates of comorbidities (chronic kidney disease [CKD], heart failure [HF], myocardial infarction [MI], peripheral arterial disease [PAD], and stroke) and mortality risk were compared between patients with T2DM and age-/sex-matched patients without T2DM (matched 1:2). RESULTS: Among the comorbidities assessed in this study, CKD and/or HF was the most frequent initial manifestation in the patients with T2DM (n = 426,186) with an incidence rate 2.02 times greater than that in matched patients without T2DM (n = 1,018,609). The mortality risk was also greater in patients with T2DM than in patients without T2DM with a hazard ratio of 1.73. In both patients with and without T2DM, the presence of CKD or HF was associated with greater mortality risks compared with the presence of MI, PAD, or stroke. CONCLUSIONS: The high incidence of CKD or HF manifestation can contribute to the augmented mortality risk in patients in the early stages of T2DM compared with patients without T2DM. These findings highlight the importance of early interventions for preventing/treating CKD and HF to improve the prognosis of patients with T2DM.

Changes in Treatment Satisfaction Over 3 Years in Patients With Type 2 Diabetes After Initiating Second-line Treatment.

CONTEXT: J-DISCOVER is a prospective observational cohort study aiming to understand the current management of patients with early-stage type 2 diabetes mellitus (T2DM) in Japan, enrolling patients initiating second-line treatment. OBJECTIVE: The current analysis examined the change in treatment satisfaction during the study period and factors affecting this change among patients in J-DISCOVER. METHODS: We used data from the J-DISCOVER study, in which 1798 patients with T2DM aged ≥ 20 years were enrolled from 142 sites across Japan. Treatment satisfaction was assessed using the Diabetes Treatment Satisfaction Questionnaire (DTSQ). RESULTS: The mean DTSQ treatment satisfaction score increased from 25.9 points at baseline to 27.3 points at 6 months, which was maintained through 36 months. Among the baseline characteristics examined, higher baseline DTSQ treatment satisfaction scores (P < 0.0001), older age (≥ 75 vs < 65 years, P = 0.0096), living alone (P = 0.0356), and type of facility (clinics vs hospitals, P = 0.0044) had a significantly negative impact on the changes in DTSQ treatment satisfaction scores. Improvement in mean glycated hemoglobin (HbA1c) from baseline (7.7%) to 36 months (7.1%) was associated with positive changes in the DTSQ treatment satisfaction score (P = 0.0003). CONCLUSION: Changes in DTSQ treatment satisfaction scores were related to HbA1c improvement, suggesting that the management strategy was appropriately planned for each patient. The results also suggest that the availability of social support for patients with T2DM who are elderly or living alone may be an important factor affecting treatment satisfaction, adherence, and clinical outcomes.

Three-Year Glycaemic Control and Management in Patients with Type 2 Diabetes Initiating Second-Line Treatment in Japan: A Prospective Observational Study, J-DISCOVER.

INTRODUCTION: J-DISCOVER is a prospective, observational cohort study that aimed to understand characteristics, glycaemic control, comorbidities and real-world management of patients with early-stage type 2 diabetes mellitus (T2DM) in Japan, by enrolling patients initiating second-line treatment from both diabetes specialist and non-specialist care settings. METHODS: As part of the global DISCOVER programme, J-DISCOVER enrolled 1798 patients with T2DM aged at least 20 years old from 142 sites across Japan, from September 2014 to December 2015, and followed these patients for 3 years. Glycaemic control, body mass index (BMI), blood pressure, lipid profiles, treatment patterns, and prevalence of CKD and retinopathy were examined from baseline to 6, 12, 24 and 36 months, stratified by class of second-line treatment. RESULTS: At baseline, the median time after T2DM diagnosis was 3.1 years and mean glycated haemoglobin (HbA1c) was 7.7%. The mean individualized HbA1c target was 6.7 ± 0.5%, and 55.3% of patients were set the target of < 7.0%. HbA1c reductions were noted from 6 months and mean HbA1c was 7.1% at 36 months. The proportion of patients with HbA1c < 7.0% increased from 28.8% at baseline to 53.3% at 36 months, and the achievement rate of individualized HbA1c targets increased from 6.1% to 30.3%. Only two cases of severe hypoglycaemia occurred during the study. No major changes in BMI, blood pressure, lipid profile or prescription of antihypertensive or dyslipidaemia medications were observed. The frequencies of screening to detect retinopathy and chronic kidney disease (CKD) were 17.0-21.0% and 14.5-16.0%, respectively, during the follow-up period. The prevalence of CKD, but not retinopathy, increased over the follow-up period. CONCLUSIONS: This study provided an overview of the 3-year management of early-stage T2DM in patients initiating second-line treatment. Contemporary management improved glycaemic control with an acceptable risk-benefit balance, although hurdles remain to sufficient implementation of guideline-recommended treatments in current clinical practice. TRIAL REGISTRATION: ClinicalTrials.gov identifier, NCT02226822.

Real-world outcomes of rivaroxaban treatment in patients with nonvalvular atrial fibrillation and worsening renal function.

BACKGROUND: Rivaroxaban is a direct oral anticoagulant administered to reduce the risk of stroke and systemic embolism in patients with nonvalvular atrial fibrillation (NVAF). The Xarelto Post-Authorization Safety and Effectiveness Study in Japanese Patients with Atrial Fibrillation (XAPASS) was a prospective, observational, post-marketing surveillance study that examined the safety and effectiveness of rivaroxaban in routine clinical practice. This sub-analysis of the XAPASS investigated the outcomes of patients with worsening renal function (WRF). METHODS: The XAPASS included 11,308 patients with NVAF who began treatment with rivaroxaban. Of 9578 patients who completed 1-year follow-up, the 7509 patients, for whom the change in creatinine clearance could be assessed, were included in the present analysis. Patients with WRF were those with a decrease in creatinine clearance of ≥20% from enrollment to any time point; patients with stable renal function (SRF) were those without such a decrease. Outcomes in patients with WRF versus SRF were compared at 1 year. RESULTS: We identified 1229 patients with WRF and 6280 patients with SRF. Patients with WRF were older and had higher mean CHADS2 and modified HAS-BLED scores compared to patients with SRF. The incidence rates of any bleeding (hazard ratio: 1.12; 95% confidence interval: 0.88-1.41), major bleeding (1.20; 0.75-1.90), and the composite endpoint stroke/systemic embolism/myocardial infarction (1.06; 0.65-1.71) were similar between the two groups. CONCLUSIONS: No association between WRF and occurrence of any bleeding, major bleeding, and stroke/systemic embolism/myocardial infarction was observed in patients with AF on rivaroxaban treatment during 1-year follow-up in real-world clinical practice. Clinicaltrials.gov: NCT01582737.

Cytokine Secreting Microparticles Engineer the Fate and the Effector Functions of T-Cells.

T-cell immunotherapy is a promising approach for cancer, infection, and autoimmune diseases. However, significant challenges hamper its therapeutic potential, including insufficient activation, delivery, and clonal expansion of T-cells into the tumor environment. To facilitate T-cell activation and differentiation in vitro, core-shell microparticles are developed for sustained delivery of cytokines. These particles are enriched by heparin to enable a steady release of interleukin-2 (IL-2), the major T-cell growth factor, over 10+ d. The controlled delivery of cytokines is used to steer lineage specification of cultured T-cells. This approach enables differentiation of T-cells into central memory and effector memory subsets. It is shown that the sustained release of stromal cell-derived factor 1α could accelerate T-cell migration. It is demonstrated that CD4+ T-cells could be induced to high concentrations of regulatory T-cells through controlled release of IL-2 and transforming growth factor beta. It is found that CD8+ T-cells that received IL-2 from microparticles are more likely to gain effector functions as compared with traditional administration of IL-2. Culture of T-cells within 3D scaffolds that contain IL-2-secreting microparticles enhances proliferation as compared with traditional, 2D approaches. This yield a new method to control the fate of T-cells and ultimately to new strategies for immune therapy.

Reviewing the impact of lipid synthetic flux on Th17 function.

CD4+ T helper 17 cells (Th17) acquire specific effector functions in response to activation and instructional signals. Accumulating evidence indicates that specific cellular lipid metabolic pathways play essential roles in regulating the differentiation and function of Th17 cells. Mechanistic studies reveal that metabolic fluxes through both the cholesterol and long chain fatty acid biosynthetic pathways are important in controlling RORγ transcriptional activity through their ability to generate lipid ligands of RORγ. Genetic and pharmacologic studies demonstrate that altering the flux through these lipid biosynthetic pathways impacts the generation of IL-17 as well as the balance of Th17 and CD4+ regulatory T cells (Tregs). In this mini-review, we briefly introduce the mechanics of cholesterol and long chain fatty acid biosynthesis. We also discuss the evidence underlying the unique role that these lipid metabolic pathways play in intrinsically regulating the fate and function of Th17 cells under normal and pathogenic conditions.

Bruton Tyrosine Kinase Inhibition Attenuates Liver Damage in a Mouse Warm Ischemia and Reperfusion Model.

BACKGROUND: Bruton tyrosine kinase (Btk) is a central player in multiple signaling pathways of lymphoid and myeloid cells. Myeloid cells are crucial early effectors in organ ischemia-reperfusion (IR) injury. BTKB66 is a selective, irreversible inhibitor of Btk. In this study, we hypothesized that Btk inhibition would reduce hepatocellular injury in a murine model of liver warm hepatic IR. METHODS: First, BTKB66 was tested in in vitro models of lipopolysaccharide-mediated neutrophil and macrophage activation. Then, to assess its efficacy in vivo, BTKB66 was administered orally to mice for 7 days before subjecting them to 90 minutes of warm hepatic ischemia followed by reperfusion for 6 or 24 hours. Clinical and pathologic features in the livers, including AST, ALT, and a panel of cytokines and chemokines, were examined. RESULTS: BTKB66 potently inhibited lipopolysaccharide-mediated activation of bone marrow-derived neutrophils and macrophages in vitro. It also reduced the severity of IR injury as determined by AST and ALT levels, as well as immune cell infiltrates. BTKB66 significantly decreased hepatic markers of sterile inflammation, such as C-X-C motif chemokine 1, C-X-C motif chemokine 2, and C-X-C motif chemokine 10, in parallel with depression of serum markers of the myeloid cell activation, such as CCL5, CCL11, and C-X-C motif chemokine 5. CONCLUSIONS: BTKB66 treatment ameliorated hepatocellular injury in a well-established model of liver partial warm ischemia and in situ reperfusion. These findings confirm that neutrophil recruitment and activation play an essential role in IR stress, and that targeting Btk activity may provide a useful approach for preventing hepatocellular damage and improving outcomes in liver transplantation.

Modulating Cholesterol Homeostasis to Build a Better T Cell.

There is great interest in discovering targets for in vitro manipulation of autologous T cells that enhance their cytotoxicity against tumor targets as a potent cancer immunotherapy. In a recent Nature paper, Xu and colleagues reveal new insights into the link between cellular cholesterol metabolism and CD8 T cell functions.

Lipids rule: resetting lipid metabolism restores T cell function in systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) is a devastating autoimmune disease characterized by chronic inflammation and systemic destruction of host organs or tissue. A key feature of SLE is T cell dysfunction characterized by hyperresponsive antigen receptor signaling. In this issue of the JCI, McDonald and colleagues provide evidence that homeostasis of a subset of lipids, the glycosphingolipids (GSLs), is severely perturbed in the membranes of T cells from SLE patients. Furthermore, normalization of GSLs restored TCR signaling and ameliorated T cell dysfunction. These data suggest that targeting host metabolism may be an effective means of reinforcing self-tolerance and attenuating autoimmunity.

An essential requirement for the SCAP/SREBP signaling axis to protect cancer cells from lipotoxicity.

The sterol regulatory element-binding proteins (SREBP) are key transcriptional regulators of lipid metabolism and cellular growth. It has been proposed that SREBP signaling regulates cellular growth through its ability to drive lipid biosynthesis. Unexpectedly, we find that loss of SREBP activity inhibits cancer cell growth and viability by uncoupling fatty acid synthesis from desaturation. Integrated lipid profiling and metabolic flux analysis revealed that cancer cells with attenuated SREBP activity maintain long-chain saturated fatty acid synthesis, while losing fatty acid desaturation capacity. We traced this defect to the uncoupling of fatty acid synthase activity from stearoyl-CoA desaturase 1 (SCD1)-mediated desaturation. This deficiency in desaturation drives an imbalance between the saturated and monounsaturated fatty acid pools resulting in severe lipotoxicity. Importantly, replenishing the monounsaturated fatty acid pool restored growth to SREBP-inhibited cells. These studies highlight the importance of fatty acid desaturation in cancer growth and provide a novel mechanistic explanation for the role of SREBPs in cancer metabolism.