High-Mobility Group Box Protein 1 Is an Independent Prognostic Marker for All-Cause Mortality in Patients With Dilated Cardiomyopathy.

High-mobility group box protein 1 (HMGB1) is released during tissue damage and activates the innate immune system through toll-like receptor 4. Because mortality in dilated cardiomyopathy (DCM) is associated with activation of the innate immune system, we hypothesized that HMGB1 possesses a prognostic value in estimating mortality in patients with DCM. We determined HMGB1 and N-terminal B-type natriuretic peptide (NT-proBNP) levels in 67 patients with DCM (12 women, mean age 53.6 ± 1.5 years). Kaplan-Meier analyzes revealed that higher levels of HMGB1 and NT-proBNP are related to increased all-cause mortality. Multivariable Cox regression confirmed HMGB1 as a risk factor for mortality in patients with DCM, independent of NT-proBNP, age, and gender (hazard ratio per 1 SD 1.920, 95% confidence interval 1.401 to 2.631, p <0.001). HMGB1 is a promising candidate to estimate the prognosis of patients with DCM.

Myeloid differentiation factor-2 activates monocytes in patients with dilated cardiomyopathy.

Plasma levels of myeloid differentiation factor-2 (MD-2), a co-receptor of toll-like-receptor 4 (TLR4), independently predict mortality in patients with dilated cardiomyopathy (DCM). We tested whether monocyte activation by MD-2 contributes to immune activation and inflammatory status in DCM patients. We found increased MD-2 plasma levels in 25 patients with recent-onset DCM (1250 ± 80.7 ng/ml) compared to 25 age- and gender-matched healthy controls (793.4 ± 52.0 ng/ml; p < 0.001). Monocytes isolated from DCM patients showed a higher expression (141.7 ± 12.4%; p = 0.006 vs. controls) of the MD-2 encoding gene, LY96 and an increased NF-κB-activation. Further, the TLR4-activator lipopolysaccharide (LPS) caused a higher increase in interleukin (IL)-6 in monocytes from DCM patients compared to controls (mean fluorescence intensity: 938.7 ± 151.0 vs. 466.9 ± 51.1; p = 0.005). MD-2 increased IL-6 secretion in a TLR4/NF-κB-dependent manner in monocyte-like THP-1-cells as demonstrated by TLR4-siRNA and NF-κB-inhibition. Since endothelial cells (ECs) are responsible for recruiting monocytes to the site of inflammation, ECs were treated with MD-2 leading to an activation of Akt and increased secretion of monocyte-chemoattractant-protein-1 (MCP-1). Activation of ECs by MD-2 was accompanied by an increased expression of the adhesion molecules CD54, CD106 and CD62E, resulting in an increased monocyte recruitment, which was attenuated by CD54 inhibition. In addition, in murine WT but not LY96-KO bone marrow-derived macrophages LPS increased the amount of CD54 and CD49d/CD29. MD-2 facilitates a pro-inflammatory status of monocytes and EC-mediated monocyte recruitment via TLR4/NF-κB. Elevated MD-2 plasma levels are possibly involved in monocyte-related inflammation-promoting disease progression in DCM. Our results suggest that MD-2 contributes to increasing monocytic inflammatory activity and triggers the recruitment of monocytes to ECs in DCM.

Combined vaccine-immune-checkpoint inhibition constitutes a promising strategy for treatment of dMMR tumors.

BACKGROUND: Mlh1-knock-out-driven mismatch-repair-deficient (dMMR) tumors can be targeted immunologically. By applying therapeutic tumor vaccination, tumor growth is delayed but escape mechanisms evolve, including upregulation of immune-checkpoint molecules (LAG-3, PD-L1). To counteract immune escape, we investigated the therapeutic activity of a combined tumor vaccine-immune-checkpoint inhibitor therapy using α-PD-L1. DESIGN: In this trial, Mlh1-knock-out mice with established gastrointestinal tumors received single or thrice injections of α-PD-L1 monoclonal antibody clone 6E11 (2.5 mg/kg bw, q2w, i.v.) either alone or in combination with the vaccine. Longitudinal flow cytometry and PET/CT imaging studies were followed by ex vivo functional immunological and gene expression assays. RESULTS: 6E11 monotherapy slightly increased median overall survival (mOS: 6.0 weeks vs. control 4.0 weeks). Increasing the number of injections (n = 3) improved therapy outcome (mOS: 9.2 weeks) and was significantly boosted by combining 6E11 with the vaccine (mOS: 19.4 weeks vs. 10.2 weeks vaccine monotherapy). Accompanying PET/CT imaging confirmed treatment-induced tumor growth control, with the strongest inhibition in the combination group. Three mice (30%) achieved a complete remission and showed long-term survival. Decreased levels of circulating splenic and intratumoral myeloid-derived suppressor cells (MDSC) and decreased numbers of immune-checkpoint-expressing splenic T cells (LAG-3, CTLA-4) accompanied therapeutic effects. Gene expression and protein analysis of residual tumors revealed downregulation of PI3K/Akt/Wnt-and TGF-signaling, leading to T cell infiltration, reduced numbers of macrophages, neutrophils and MDSC. CONCLUSIONS: By successful uncoupling of the PD-1/PD-L1 axis, we provide further evidence for the safe and successful application of immunotherapies to combat dMMR-driven malignancies that warrants further investigation.

MD-2 is a new predictive biomarker in dilated cardiomyopathy and exerts direct effects in isolated cardiomyocytes.

BACKGROUND: Myeloid differentiation factor-2 (MD-2) has been shown to be an important modulator of the innate immune system, but its role in cardiac diseases is unknown. We investigated whether MD-2 plays a role as risk predictor and contributor in dilated cardiomyopathy (DCM). METHODS AND RESULTS: We included 174 patients with reduced left ventricular (LV) ejection fraction (LVEF <45%) due to DCM. Coronary artery disease and severe valvular diseases were excluded in all patients by angiography or echocardiography. Cardiac inflammation, viral infection and MD-2 expression were analyzed from right ventricular endomyocardial biopsies. MD-2 was quantified by ELISA in serum upon first hospital admission. Myocyte contractility and inflammatory response after stimulation with recombinant MD-2 protein were analyzed in isolated rat cardiomyocytes. Median follow-up of the patients was 3.51 years (2.73; 4.48) with 34 deaths. Absolute mortality risk increases in patients displaying a MD-2 serum concentration greater than the median (302 ng/ml) was 23% (P < 0.0001). Age- and sex-adjusted Cox regression analyses demonstrated that mortality risk was highly related to MD-2 concentrations (P < 0.001), but not to age or sex. An increase of 100 ng/ml in the MD-2 level was associated with an absolute mortality risk increase of 50.4%. Receiver operating characteristic (ROC) analyses showed no difference between MD-2 and nterminal-pro brain natriuretic peptide (NT-pro-BNP), while the combination of both MD-2 and NT-pro-BNP resulted in a significantly increased capability of risk prediction when compared to NT-pro-BNP alone (P = 0.014). In-vitro, recombinant MD-2 decreases cell shortening and modulates cytokine activation in isolated cardiomyocytes. CONCLUSION: MD-2 predicts long-term outcome in DCM patients and improves mortality risk prediction capability compared to NT-pro-BNP alone. In addition, MD-2 exerts direct negative inotropic effects on isolated cardiomyocytes in-vitro. Further randomized trials should confirm MD-2 as a diagnostic and therapeutic target.

Transcriptional regulation of urate transportosome member SLC2A9 by nuclear receptor HNF4α.

Renal tubular handling of urate is realized by a network of uptake and efflux transporters, including members of drug transporter families such as solute carrier proteins and ATP-binding cassette transporters. Solute carrier family 2, member 9 (SLC2A9), is one key factor of this so called "urate transportosome." The aim of the present study was to understand the transcriptional regulation of SLC2A9 and to test whether identified factors might contribute to a coordinated transcriptional regulation of the transporters involved in urate handling. In silico analysis and cell-based reporter gene assays identified a hepatocyte nuclear factor (HNF)4α-binding site in the promoter of SLC2A9 isoform 1, whose activity was enhanced by transient HNF4α overexpression, whereas mutation of the binding site diminished activation. HNF4α overexpression induced endogenous SLC2A9 expression in vitro. The in vivo role of HNF4α in the modulation of renal SLC2A9 gene expression was supported by findings of quantitative real-time RT-PCR analyses and chromatin immunoprecipitation assays. Indeed, mRNA expression of SLC2A9 and HNF4α in human kidney samples was significantly correlated. We also showed that in renal clear cell carcinoma, downregulation of HNF4α mRNA and protein expression was associated with a significant decline in expression of the transporter. Taken together, our data suggest that nuclear receptor family member HNF4α contributes to the transcriptional regulation of SLC2A9 isoform 1. Since HNF4α has previously been assumed to be a modulator of several urate transporters, our findings support the notion that there could be a transcriptional network providing synchronized regulation of the functional network of the urate transportosome.