Adhesion molecule expression precedes brain damages of lupus-prone mice and correlates with kidney pathology.

Central nervous system (CNS) involvement is a frequent and potentially life-threatening complication in systemic lupus erythematosus (SLE) yet the mechanisms of organ damage remain poorly understood. Upregulation of cellular adhesion molecules in kidney and other organs has been implicated in the expression of inflammation and tissue injury, but the relation between kidney pathology and altered brain function has not been studied. We therefore analyzed the expression of cellular adhesion molecules ICAM-1, VCAM-1, and E-selectin in brains from 6 to 14week old MRL/(lpr), MRL+/+ and C57BL/6 mice by real-time PCR and immunofluorescence. Adhesion molecule expression levels were compared to kidney pathology and adhesion molecule expression in the kidney. We found a significant upregulation of ICAM-1 and E-selectin mRNA in the kidneys from 14week-old MRL/(lpr) mice, which correlated with proteinuria and profound kidney damage. Moreover, despite the absence of marked brain histopathological changes, both ICAM-1 and E-selectin were also upregulated in brain tissue from these animals. There was a strong correlation of adhesion molecule expression levels in the kidney and the brain. Immunofluorescence studies revealed that ICAM-1 and E-selectin upregulation localizes to blood vessel walls, astrocytes related to the blood-brain barrier, and microglial cells. Our data indicate that cellular adhesion molecules in the brain are upregulated without evidence of overt brain damage, and that a strong relation exists with the levels of kidney damage. Therefore, brain involvement, even subclinical, should be presumed when peripheral organs are inflamed.

Atrial fibrillation down-regulates renal neutral endopeptidase expression and induces profibrotic pathways in the kidney.

AIMS: Recent studies suggest that atrial fibrillation (AF) substantially influences microvascular flow in ventricular myocardium. This process may contribute to the occurrence of heart failure in AF. In general, development of heart failure and renal dysfunction go hand-in-hand causing systemic fluid overload and oedema. So far, it is unknown whether AF itself influences renal function. The aim of the present study was to determine the impact of AF on renal gene expression in a closed chest rapid atrial pacing model. METHODS AND RESULTS: A total of 14 pigs were studied. In five pigs, rapid atrial pacing (AT) was performed for 7 h (600 bpm); in five additional animals, rapid atrial pacing was performed in the presence of irbesartan infusion (irbesartan group). Four pigs were instrumented without interventions (sham). After the pacing period, renal expression of collagen I alpha 1 and I alpha 3, transforming growth factor-beta (TGF-beta), neutral endopeptidase (NEP; the main enzyme involved in natriuretic protein metabolism), and atrial natriuretic peptide (ANP) were determined by RT-PCR and immunoblot analysis. Functional in vitro experiments were performed using HEK-293 kidney cells. Renal mRNA expression of NEP was substantially down-regulated during AT (AT: 12.7 +/- 9.3% vs. sham: 100 +/- 43.4%; P < 0.01). Results at the mRNA level were confirmed at the protein level. Irbesartan therapy did not prevent down-regulation of NEP. In contrast, TGF-beta1 mRNA expression was up-regulated (AT: 208.5 +/- 79.3% vs. sham: 100 +/- 34.6% P< 0.05). Collagen and angiotensin II type 1 receptor (AT1R) expression were not significantly altered by AT. HEK-293 cells were used to determine the potential humoral factors involved in down-regulation of NEP. Application of aldosterone, ANP, asymmetric dimethylarginine, and angiotensin peptides failed to cause down-regulation of renal NEP expression in vitro. CONCLUSION: AT reduces NEP expression and stimulates TGF-beta1 signalling in the kidneys. Thus, even brief episodes of AT affect renal gene expression, which may account for structural renal changes and alterations of renal function in the long term.

Mitochondrial dysfunction and redox signaling in atrial tachyarrhythmia.

Accumulating evidence links calcium-overload and oxidative stress to atrial remodeling during atrial fibrillation (AF). Furthermore, atrial remodeling appears to increase atrial thrombogeneity, characterized by increased expression of adhesion molecules. The aim of this study was to assess mitochondrial dysfunction and oxidative stress-activated signal transduction (nuclear factor-kappaB [NF-kappa B], lectin-like oxidized low-density lipoprotein receptor [LOX-1], intercellular adhesion molecule-1 [ICAM-1], and hemeoxgenase-1 [HO-1]) in atrial tissue during AF. Ex vivo atrial tissue from patients with and without AF and, additionally, rapid pacing of human atrial tissue slices were used to study mitochondrial structure by electron microscopy and mitochondrial respiration. Furthermore, quantitative reverse transcription polymerase chain reaction (RT-PCR), immunoblot analyses, gel-shift assays, and enzyme-linked immunosorbent assay (ELISA) were applied to measure nuclear amounts of NF-kappa B target gene expression. Using ex vivo atrial tissue samples from patients with AF we demonstrated oxidative stress and impaired mitochondrial structure and respiration, which was accompanied by nuclear accumulation of NF-kappa B and elevated expression levels of the adhesion molecule ICAM-1 and the oxidative stress-induced markers HO-1 and LOX-1. All these changes were reproduced by rapid pacing for 24 hours of human atrial tissue slices. Furthermore, the blockade of calcium inward current with verapamil effectively prevented both the mitochondrial changes and the activation of NF-kappa B signaling and target gene expression. The latter appeared also diminished by the antioxidants apocynin and resveratrol (an inhibitor of NF-kappa B), or the angiotensin II receptor type 1 antagonist, olmesartan. This study demonstrates that calcium inward current via L-type calcium channels contributes to oxidative stress and increased expression of oxidative stress markers and adhesion molecules during cardiac tachyarrhythmia.

Thiol-inducing and immunoregulatory effects of flavonoids in peripheral blood mononuclear cells from patients with end-stage diabetic nephropathy.

The cellular thiol status and its relationship to T-cell activation and cytokine synthesis of mononuclear cells was investigated in patients with end-stage diabetic nephropathy (ESDN) undergoing dialysis treatment. The functional effects of thiol repair by in vitro and in vivo treatment with flavonoids were elucidated. The thiol status of peripheral blood lymphocytes from 30 ESDN patients on hemodialysis and healthy controls was determined by flow cytometry. T-cell activation in response to pokeweed mitogen was analyzed by CD69 expression; cytokines were determined in cell culture supernatants. In result, compared to age-matched healthy subjects, a significant thiol deficiency in ESDN patients was obvious. The lowered total intracellular thiol levels correlated directly to a significant diminished T-cell activation and an elevated synthesis of TNF-alpha in the patient group. The treatment with flavonoids led to a restoration of the thiol status within 72 h in vitro and in vivo. This effect showed a biphasic kinetic that first utilized cell surface thiols and secondly intracellular thiols. In parallel, the T-cell activation was improved substantially along with a significant decrease in TNF-alpha release. These data provide the rational for clinical trials using flavonoids in ESDN to normalize immunoregulatory defects via restoration of the cellular thiol status.

Ambulatory treatment with intravenous norepinephrine in a patient with end stage renal disease and generalized AA amyloidosis.

A 35-year-old man with juvenile rheumatoid arthritis and generalized AA amyloidosis of 10 years duration developed end stage renal failure. Following appendectomy, the patient experienced progressive circulatory failure which required IV treatment with norepinephrine. All attempts to discontinue IV norepinephrine failed, each leading to recurrent life-threatening hypotension. Finally, a central venous port with a portable mechanical infusion pump system was implanted supplying a continuous norepinephrine infusion. The patient then became independently mobile and could be discharged. For three months, the patient was monitored as an outpatient and treated by ambulatory intermittent hemofiltration. Finally, the patient suffered from a hemorrhagic infarction of the small bowel due to postoperative adhesions and died shortly after surgery. At autopsy, advanced generalized AA amyloidosis was found. Amyloid deposits had almost entirely replaced the cortex and the medulla of the adrenal glands. It can be speculated that the requirement of exogenous norepinephrine may be in part due to an adrenal insufficiency whereas it was initially considered as being only related to cardiac involvement. A continuous ambulatory treatment with catecholamines could be a possible treatment - at least temporarily - in amyloid cases in which all other attempts have failed to prevent chronic life-threatening hypotension.