Phospholipid derived mediators and glomerulonephritis

Lipoxin A(4) activates alveolar epithelial sodium channel, Na,K-ATPase, and increases alveolar fluid clearance

Edema fluid resorption is critical for gas exchange, and both alveolar epithelial sodium channel (ENaC) and Na,K-ATPase are accredited with key roles in the resolution of pulmonary edema. Alveolar fluid clearance (AFC) was measured in in situ ventilated lungs by instilling isosmolar 5% BSA solution with Evans Blue-labeled albumin tracer (5 ml/kg) and measuring the change in Evans Blue-labeled albumin concentration over time. Treatment with lipoxin A4 and lipoxin receptor agonist (5(S), 6(R)-7-trihydroxymethyl 17 heptanoate) significantly stimulated AFC in oleic acid (OA)-induced lung injury, with the outcome of decreased pulmonary edema. Lipoxin A4 and 5(S), 6(R)-7-trihydroxymethyl 17 heptanoate not only up-regulated the ENaC α and ENaC γ subunits protein expression, but also increased Na,K-ATPase α1 subunit protein expression and Na,K-ATPase activity in lung tissues. There was no significant difference of intracellular cAMP level between the lipoxin A4 treatment and OA group. However, the intracellular cGMP level was significantly decreased after lipoxin A4 treatment. The beneficial effects of lipoxin A4 were abrogated by butoxycarbonyl-Phe-Leu-Phe-Leu-Ph (lipoxin A4 receptor antagonist) in OA-induced lung injury. In primary rat alveolar type II epithelial cells stimulated with LPS, lipoxin A4 increased ENaC α and ENaC γ subunits protein expression and Na,K-ATPase activity. Lipoxin A4 stimulated AFC through activation of alveolar epithelial ENaC and Na,K-ATPase.

Rationales for treating IgA nephropathies

An outline is given of the pathophysiology of IgA nephropathy (IgA) in order to emphasize the role of eicosanoids, angiotensin II, and reactive oxygen species. ACE inhibitors and early corticosteroid usage are prime therapies. Tonsillectomy is to be considered, certainly for individual cases. It is logical that other components of a cocktail could be (i) thromboxane antagonists, (ii) leukotriene antagonists, or (iii) PAF antagonist. In theory there should be benefit from antioxidants. Fish oils have not come up to expectation. PDGF aptamers look promising for the prevention of mesangial cell proliferation. Heparins are not used in the way that they could be. Various other agents could help reduce decline.

Cellular biology of glomerulosclerosis

The burgeoning literature on glomerulosclerosis makes frequent review of the literature necessary. At this stage, the key processes involved have surely been defined. It is now appropriate to make deductions about possible therapies and to plan experiments and trials.