Loss of the mitochondrial citrate carrier, Slc25a1/CIC disrupts embryogenesis via 2-Hydroxyglutarate.

Biallelic germline mutations in the SLC25A1 gene lead to combined D/L-2-hydroxyglutaric aciduria (D/L-2HGA), a fatal systemic disease uniquely characterized by the accumulation of both enantiomers of 2-hydroxyglutaric acid (2HG). How SLC25A1 deficiency contributes to D/L-2HGA and the role played by 2HG is unclear and no therapy exists. Both enantiomers act as oncometabolites, but their activities in normal tissues remain understudied. Here we show that mice lacking both SLC25A1 alleles exhibit developmental abnormalities that mirror human D/L-2HGA. SLC25A1 deficient cells undergo premature senescence, suggesting that loss of proliferative capacity underlies the pathogenesis of D/L-2HGA. Remarkably, D- and L-2HG directly induce senescence and treatment of zebrafish embryos with the combination of D- and L-2HG phenocopies SLC25A1 loss, leading to developmental abnormalities in an additive fashion relative to either enantiomer alone. Metabolic analyses further demonstrate that cells with dysfunctional SLC25A1 undergo mitochondrial respiratory deficit and remodeling of the metabolism and we propose several strategies to correct these defects. These results reveal for the first time pathogenic and growth suppressive activities of 2HG in the context of SLC25A1 deficiency and suggest that targeting the 2HG pathway may be beneficial for the treatment of D/L-2HGA.

The Mitochondrial Citrate Carrier SLC25A1/CIC and the Fundamental Role of Citrate in Cancer, Inflammation and Beyond.

The mitochondrial citrate/isocitrate carrier, CIC, has been shown to play an important role in a growing list of human diseases. CIC belongs to a large family of nuclear-encoded mitochondrial transporters that serve the fundamental function of allowing the transit of ions and metabolites through the impermeable mitochondrial membrane. Citrate is central to mitochondrial metabolism and respiration and plays fundamental activities in the cytosol, serving as a metabolic substrate, an allosteric enzymatic regulator and, as the source of Acetyl-Coenzyme A, also as an epigenetic modifier. In this review, we highlight the complexity of the mechanisms of action of this transporter, describing its involvement in human diseases and the therapeutic opportunities for targeting its activity in several pathological conditions.

Inhibition of the mitochondrial citrate carrier, Slc25a1, reverts steatosis, glucose intolerance, and inflammation in preclinical models of NAFLD/NASH.

Nonalcoholic fatty liver disease (NAFLD) and its evolution to inflammatory steatohepatitis (NASH) are the most common causes of chronic liver damage and transplantation that are reaching epidemic proportions due to the upraising incidence of metabolic syndrome, obesity, and diabetes. Currently, there is no approved treatment for NASH. The mitochondrial citrate carrier, Slc25a1, has been proposed to play an important role in lipid metabolism, suggesting a potential role for this protein in the pathogenesis of this disease. Here, we show that Slc25a1 inhibition with a specific inhibitor compound, CTPI-2, halts salient alterations of NASH reverting steatosis, preventing the evolution to steatohepatitis, reducing inflammatory macrophage infiltration in the liver and adipose tissue, while starkly mitigating obesity induced by a high-fat diet. These effects are differentially recapitulated by a global ablation of one copy of the Slc25a1 gene or by a liver-targeted Slc25a1 knockout, which unravel dose-dependent and tissue-specific functions of this protein. Mechanistically, through citrate-dependent activities, Slc25a1 inhibition rewires the lipogenic program, blunts signaling from peroxisome proliferator-activated receptor gamma, a key regulator of glucose and lipid metabolism, and inhibits the expression of gluconeogenic genes. The combination of these activities leads not only to inhibition of lipid anabolic processes, but also to a normalization of hyperglycemia and glucose intolerance as well. In summary, our data show for the first time that Slc25a1 serves as an important player in the pathogenesis of fatty liver disease and thus, provides a potentially exploitable and novel therapeutic target.

Fluctuations in circulating endothelial progenitor cell levels and acute cardiac graft rejection.

INTRODUCTION: Endothelial progenitor cells (EPCs) in nontransplant settings have reparative properties. However, their role in heart transplantation (HT) is not well defined. OBJECTIVES: The aim of this study was to prospectively evaluate changes in EPC levels in relation to post­HT rejection. PATIENTS AND METHODS: EPC levels were measured in 27 HT recipients for 6 months after HT. Acute cellular rejection (ACR) or antibody­mediated rejection (AMR) were assessed by right ventricular endomyocardial biopsy. RESULTS: ACR and AMR were observed in 7 (25.9%) and 6 (22.2%) patients, respectively. The ACR status at 1 month post­HT did not differ with respect to EPC immediately post­HT. At 1 month post­HT in patients without ACR or AMR, EPC levels were significantly reduced compared with the measurements immediately post­HT (P <0.001). On further follow­up, EPC levels were similar regardless of the rejection events. Nonetheless, greater changes (coefficient of variation) in EPClog (logarithmic transformation) were associated with the risk of AMR or ACR compared with those without any rejection event (median [lower-upper quartile], 15 [13-18] vs 8 [5-13]; P = 0.02 and 22 [14-26] vs 8 [5-13]; P = 0.01, respectively). The receiver operating characteristic curve showed that the coefficient of variation of EPClog of 12 was the optimal cutoff value for the prediction of rejection (area under the curve = 0.85). Higher levels were associated with greater risk of ACR or AMR (P <0.005). CONCLUSIONS: Early reduction of EPC levels was related to a lower risk of ACR or AMR. Greater changes of EPC­levels during follow­up were associated with a significantly higher risk of rejection.

microRNA expression profile in Smooth Muscle Cells isolated from thoracic aortic aneurysm samples.

PURPOSE: Thoracic aortic aneurysm (TAA) is a cardiovascular disease characterized by increased aortic diameter, treated with surgery and endovascular therapy in order to avoid aortic dissection or rupture. The mechanism of TAA formation has not been thoroughly studied and many factors have been proposed to drive its progression; however strong focus is attributed to modification of smooth muscle cells (SMCs). Latest research indicates, that microRNAs (miRNAs) may play a significant role in TAA development - these are multifunctional molecules consisting of 19-24 nucleotides involved in regulation of the gene expression level related to many biological processes, i.e. cardiovascular disease pathophysiology, immunity or inflammation. MATERIALS AND METHODS: Primary SMCs were isolated from aortic scraps of TAA patients and age- and sex-matched healthy controls. Purity of isolated SMCs was determined by flow cytometry using specific markers: α-SMA, CALP, MHC and VIM. Real-time polymerase chain reaction (RT-PCR) was conducted for miRNA analysis. RESULTS: We established an isolation protocol and investigated the miRNA expression level in SMCs isolated from aneurysmal and non-aneurysmal aortic samples. We identified that let-7 g (0.71-fold, p = 0.01), miR-130a (0.40-fold, p = 0.04), and miR-221 (0.49-fold, p = 0.05) significantly differed between TAA patients and healthy controls. CONCLUSIONS: Further studies are required to improve our understanding of the pathophysiology underlying TAA, which may aid the development of novel, targeted therapies. The pivotal role of miRNAs in the cardiovascular system provides a new perspective on the pathophysiology of thoracic aortic aneurysms.

Effect of a punctal plug on ocular surface disease in patients using topical prostaglandin analogues: a randomized controlled trial.

IMPORTANCE: Ocular surface disease (OSD) is common and can reduce treatment compliance and quality of life. BACKGROUND: To determine whether a punctal plug improves OSD and reduces intraocular pressure (IOP) in patients using prostaglandin analogue monotherapy. DESIGN: Randomized controlled trial. PARTICIPANTS: Sixty eligible subjects aged >18 years with symptomatic OSD from glaucoma clinics were invited to participate. Lacrimal or glaucoma surgery, lid malposition and contact lens wear were exclusion criteria. METHODS: One eye received an inferior punctal plug, leaving the fellow eye as a control. MAIN OUTCOME MEASURES: Ocular surface disease index (OSDI), tear film breakup time (TF-BUT), Oxford cornea score, tear osmolarity and IOP were compared at baseline and 6 weeks by masked investigators. RESULTS: From 60 eligible, 48 (80.0%) participated (mean age 69.6 years; 60.0% female). OSDI reduced following plug insertion (mean difference [MD] 14.5, 95% confidence interval [CI] 5.06-23.94, P < 0.001). Compared to control eyes, in eyes receiving plugs the TF-BUT increased (MD 2.3 s, 95% CI 1.4-3.2, P < 0.001), the Oxford cornea score decreased (MD 0.5, 95% CI 0.3-0.7, P < 0.001), and tear osmolarity decreased (MD 10 mOsm/L, 95% CI 3.5-16.5, P = 0.003). Punctal plugs resulted in a significantly lowered IOP (MD 1.5 mmHg, 95% CI 0.1-2.9, P = 0.032). Sub-group analyses showed similar efficacy regardless of prostaglandin preservative status or lubricant drop use. Plugs were well tolerated but extrusion occurred in 8.5%, and epiphora increased in 6.5% eyes. CONCLUSIONS AND RELEVANCE: Punctal plug insertion improves subjective and objective measures of OSD and results in a reduced IOP in patients with symptomatic ocular surface disease using prostaglandin analogue monotherapy.

Correlation of elimination fraction area under the curve with total body clearance.

This study attempted to determine the area under the curve ([Formula: see text]), which corresponds to the sum of all elimination processes correlated with the total clearance value. The study attempted to determine the [Formula: see text] based on the coordinates known from classic non-compartmental pharmacokinetics for a single administration of the drug. 318 pharmacokinetics profiles were used for the analysis, obtained from 220 healthy subjects over ten studies. Pharmacokinetic calculations were performed with the use of Phoenix™ WinNonlin(®) 6.3. The leave-one-out (LOO) method was used for model cross-validation. Squared cross-validated correlation coefficient (Q (2)) parameter and the difference between Q (2) and R (2) were calculated as a measure of the internal performance and model predictive ability. A high correlation between the clearance value and [Formula: see text] was demonstrated (R (2) > 0.65). However, only in the case of four studies was it possible to validate the linear model using the leave-one-out validation procedure (R (2) > 0.86). The present study proposed a method of graphical and mathematical determination of the area under the curve for the drug elimination process after a single dose of the drug. Furthermore, the concept of calculating the statistical moments and mean elimination time (MET) only for elimination processes based on [Formula: see text] was presented. The result of this work is also a new method of determining the half-life of elimination phase based on the MET value.

Evaluation of sampling spacing in pharmacokinetic studies using six sigma method.

Key elements of pharmacokinetics (PK) studies include both, the number of sampling points (NSP) as well as the spacing between the sampling points (SSP). Optimization of the SSP is discussed in guidelines of all key regulatory agencies (RA). Those however, provide only very general rules on how to properly distribute the NSPs in proposed PK studies. Here we demonstrate that the six sigma (SX) method can be effectively used to assess the quality of SSPs. We have tested a modified SX method analyzing 466 PK profiles from 16 studies including a total of 368 healthy volunteers. Non-compartmental modeling was used to estimate PK parameters. The arithmetic means of minimum and maximum values of SX obtained for each subject in all studies were 1.97 and 3.83, respectively. The method described here allows comparing quality of studies performed at different centers, even if they cover different chemical entities. We propose that the SX values can be used to assess quality of PK studies, what is consistent with recommendations of the RAs.

Genetic architecture of factors underlying partial resistance to Alternaria leaf blight in carrot.

In most production areas, Alternaria leaf blight (ALB) is recognized as the most common and destructive foliage disease in carrot. To assess the genetic architecture of carrot ALB resistance, two parental coupling maps were developed with similar number of dominant markers (around 70), sizes (around 650 cM), densities (around 9.5 cM), and marker composition. The F(2:3) progenies were evaluated in field and tunnel for two scoring dates. The continuous distribution of the disease severity value indicated that ALB resistance is under polygenic control. Three QTLs regions were found on three linkage groups. Two of them were tunnel or field specific and were detected only at the second screening date suggesting that the expression of these two QTLs regions involved in resistance to Alternaria dauci might depend on environment and delay after infection.

Immunophenotype and cytogenetics of mucinous tubular and spindle cell carcinoma of the kidney.

Mucinous tubular and spindle cell carcinoma (MTSCC) of the kidney is a rare, recently described entity. The authors present three new cases. The histological picture was that of classic MTSCC, with alternating small tubules located in a mucin-containing stroma, and spindle cell areas composed of bland, monomorphic cells. On immunohistochemistry, the tumors were positive for epithelial markers, including CK7 and CK18, vimentin, CD15, AMACR, and neuroendocrine markers, such as NSE and CD57. On FISH analysis we found losses on chromosomes 1 and 8, and gains of chromosomes 7 and 17. This is the first report of this rare entity in Polish medical literature.