Pathology and immunology of lupus glomerulonephritis: can we bridge the two?

n-3 polyunsaturated fatty acids and autoimmune-mediated glomerulonephritis

Consumption of n-3 polyunsaturated fatty acids (PUFAs) found in fish oil suppresses inflammatory processes making these fatty acids attractive candidates for both the prevention and amelioration of several organ-specific and systemic autoimmune diseases. Both pre-clinical and clinical studies have been conducted to determine whether fish oils containing the n-3 PUFAs docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) can be used in the prevention and treatment of immunoglobulin A nephropathy (IgAN) and lupus nephritis. In a toxin-induced mouse model that mimics the early stages of IgAN, n-3 PUFA consumption suppresses aberrant interleukin (IL)-6-driven IgA production and mesangial IgA immune complex deposition by impairing phosphorylation of upstream kinases and activation of transcription factors essential for IL-6 gene transcription. n-3 PUFAs can also suppress production of anti-double-stranded DNA IgG antibodies and the resultant development of lupus nephritis in the NZBW F1 mouse and related models. These effects have been linked in part to impaired expression of proinflammatory cytokines and adhesion molecules as well as increases in antioxidant enzymes in kidney and immune organs. Several recent clinical trials have provided compelling evidence that n-3 PUFA supplementation could be useful in treatment of human IgAN and lupus nephritis, although some other studies suggest such supplementation might be without benefit. Future investigations employing genomics/proteomics and novel genetically altered mice should provide further insight into how n-3 PUFAs modulate these diseases as well help to identify clinically relevant biomarkers. The latter could be employed in future well-designed, long-term clinical studies that will resolve current controversies on n-3 PUFA efficacy in autoimmune-mediated glomerulonephritis.

Semiquantitative and semi-automated morphometric evaluation of chronic lesions in renal biopsies

Chronic lesions in renal biopsies are a well recognized prognostic factor for renal diseases, including lupus nephritis. The methods used for assessment of chronic lesions are, however, largely based on semiquantitative evaluation and may lead to poor reproducibility. Interobserver variation is particularly important in lupus nephritis, in which acute and chronic lesions may occur simultaneously. In this study we tested the reproducibility of chronic lesion assessment performed by three pathologists, two with specific training in renal pathology, using 20 renal biopsies and a standard semiquantitative method. In a second experiment, we evaluated the reproducibility of chronic lesion assessment in 33 biopsies of lupus nephritis by the two nephropathologists. The semiquantitative estimated values were compared with those from a previously proposed morphometric method for quantification of chronic lesions in renal biopsies. Although correlations were observed among the estimated values, there was a wide range of variation when semiquantitative methods were used. In particular, activity and chronicity indices of lupus nephritis were poorly reproducible. In contrast, use of a morphometric score, although not eliminating interobserver variability, led to better reproducibility of estimated values than that obtained with semiquantitative methods.