Post-transcriptional divergence in the regulation of CAT-2A, CAT-2B and iNOS expression by dexamethasone in vascular smooth muscle cells

Expression Profile of Cationic Amino Acid Transporters in Rats with Endotoxin-Induced Uveitis

Purpose. The transcellular arginine transportation via cationic amino acid transporter (CAT) is the rate-limiting step in nitric oxide (NO) synthesis, which is crucial in intraocular inflammation. In this study, CAT isoforms and inducible nitric oxide synthase (iNOS) expression was investigated in endotoxin-induced uveitis (EIU). Methods. EIU was induced in Lewis rats by lipopolysaccharide (LPS) injection. In the treatment group, the rats were injected intraperitoneally with the proteasome inhibitor bortezomib before EIU induction. After 24 hours, leukocyte quantification, NO measurement of the aqueous humor, and histopathological examination were evaluated. The expression of CAT isoforms and iNOS was determined by reverse transcription-polymerase chain reaction, western blotting, and immunofluorescence staining. Nuclear factor-kappa B (NF-κB) binding activity was evaluated by electrophoretic mobility shift assay. The mouse macrophage cell line RAW 264.7 was used to validate the in vivo findings. Results. LPS significantly stimulated iNOS, CAT-2A, and CAT-2B mRNA and protein expression but did not affect CAT-1 in EIU rats and RAW 264.7 cells. Bortezomib attenuated inflammation and inhibited iNOS, CAT-2A, and CAT-2B expression through NF-κB inhibition. Conclusions. CAT-2 and iNOS, but not CAT-1, are specifically involved in EIU. NF-κB is essential in the induction of CAT-2 and iNOS in EIU.

D-Arginine as a neuroprotective amino acid: promising outcomes for neurological diseases

In humans, as in other mammals, endogenous glucocorticoids (GCs) are essential for adapting to physiological life stress. They are also crucial for the healthy development of the fetus. However, when the physiological concentrations of GCs increase over a long period of time, the central nervous system (CNS) is predisposed to the development of psychiatric disorders and neurological diseases. Here, I discuss the strong influence of GCs on the nitric oxide (NO) pathway and the generation of reactive oxygen species (ROS). I also highlight supporting evidence for the neuroprotective actions of d-arginine (d-Arg) against neurotoxicity induced by high levels of GCs in the CNS. Given that d-Arg does not interfere with the immunosuppressive and anti-inflammatory effects of GCs, this might be a novel way of neutralizing the neurotoxic effects of GCs in the CNS without compromising their positive peripheral actions.

Oleanolic acid improves pulmonary morphofunctional parameters in experimental sepsis by modulating oxidative and apoptotic processes

We compared the effects of oleanolic acid (OA) vs. dexamethasone on lung mechanics and histology, inflammation, and apoptosis in lung and distal organs in experimental sepsis. Seventy-eight BALB/c mice were randomly divided into two groups. Sepsis was induced by cecal ligation and puncture, while the control group underwent sham surgery. 1h after surgery, all animals were further randomized to receive saline (SAL), OA and dexamethasone (DEXA) intraperitoneally. Both OA and DEXA improved lung mechanics and histology, which were associated with fewer lung neutrophils and less cell apoptosis in lung, liver, and kidney than SAL. However, only animals in the DEXA group had lower levels of interleukin (IL)-6 and KC (murine analog of IL-8) in bronchoalveolar lavage fluid than SAL animals. Conversely, OA was associated with lower inducible nitric oxide synthase expression and higher superoxide dismutase than DEXA. In the experimental sepsis model employed herein, OA and DEXA reduced lung damage and distal organ apoptosis through distinct anti-inflammatory mechanisms.

Human uraemic serum displays calcific potential in vitro that increases with advancing chronic kidney disease

Vascular calcification (VC) strongly correlates with declining renal function and contributes to the high morbidity and mortality of patients with CKD (chronic kidney disease). It is closely regulated by circulating factors but little is known about the capacity of serum from patients to induce calcification outside the disease setting, which we now define as the calcific potential of serum. We have therefore examined the ability of serum from age- and sex-matched subjects with and without advancing CKD to induce calcification of cultured SMCs (smooth muscle cells). Samples from patients with CKD induced significant calcification compared with controls. More importantly, samples from patients on haemodialysis induced significantly higher calcification than those with moderate or advanced CKD. The calcification induced by the latter two but not those on haemodialysis could be enhanced with calcium chloride and β-GP (β-glycerophosphate). A positive correlation was evident between measured serum creatinine, phosphate, PTH (parathyroid hormone), OPG (osteoprotegerin) and the degree of calcification in vitro. eGFR (estimated glomerular filtration rate), DBP (diastolic blood pressure), haemoglobin and serum albumin correlated negatively. Stepwise multivariate analysis of log-transformed calcific potential data highlighted serum creatinine, albumin and OPG as significant predictors, explaining approximately 50% of the variation. Thus, other regulators, either not investigated or as yet unidentified, may contribute to the calcification potential of serum in vitro. Furthermore, uraemic serum can induce graded calcification outside of the disease milieu that reflects the degree of kidney impairment in vivo. These findings could have important clinical relevance in terms of developing novel diagnostic and/or therapeutic strategies for subjects with CKD.