Fenoprofen-induced membranous glomerulonephritis

Loss of MTX2 causes mandibuloacral dysplasia and links mitochondrial dysfunction to altered nuclear morphology

Mandibuloacral dysplasia syndromes are mainly due to recessive LMNA or ZMPSTE24 mutations, with cardinal nuclear morphological abnormalities and dysfunction. We report five homozygous null mutations in MTX2, encoding Metaxin-2 (MTX2), an outer mitochondrial membrane protein, in patients presenting with a severe laminopathy-like mandibuloacral dysplasia characterized by growth retardation, bone resorption, arterial calcification, renal glomerulosclerosis and severe hypertension. Loss of MTX2 in patients' primary fibroblasts leads to loss of Metaxin-1 (MTX1) and mitochondrial dysfunction, including network fragmentation and oxidative phosphorylation impairment. Furthermore, patients' fibroblasts are resistant to induced apoptosis, leading to increased cell senescence and mitophagy and reduced proliferation. Interestingly, secondary nuclear morphological defects are observed in both MTX2-mutant fibroblasts and mtx-2-depleted C. elegans. We thus report the identification of a severe premature aging syndrome revealing an unsuspected link between mitochondrial composition and function and nuclear morphology, establishing a pathophysiological link with premature aging laminopathies and likely explaining common clinical features.

Glomerular, tubular and interstitial nephritis associated with non-steroidal antiinflammatory drugs. Evidence of a common mechanism

AIMS

To study the mechanisms behind NSAID-associated nephropathy.

METHODS

Analysis of published case reports satisfying strict criteria for NSAID nephropathy.

RESULTS

Ninety-seven cases with acute nephritis (AN; 19 patients), minimal change nephropathy (MC; 38 patients), membranous glomerulonephritis (MGN; 19 patients), focal sclerosis (FS; 13 patients) and other glomerulonephritis subgroups (8 patients) were identified. Hypersensitivity reactions were seen in all groups, most often in AN. Proteinuria was more severe in MC and FS than in MGN and unrelated to amount of glomerular deposits. The mean NSAID treatment time was 1.7 months in AN, 8.2 months in MC and 39 months in MGN and associated with amount of glomerular deposits, fusion of podocytes and proteinuria, and inversely associated with hypersensitivity, interstitial damage and renal failure. Rheumatic diseases were common in MGN. At follow-up 68 of 72 patients who had discontinued NSAID treatment had improved, 57 with normal renal function.

CONCLUSIONS

NSAID nephropathy may be caused by hypersensitivity. The reaction is milder than in drug-induced acute tubulointerstitial nephritis, probably because the offending drug inhibits the inflammatory reaction it has started itself. Heavy proteinuria is probably due to lymphokines produced as a result of the immunological response. If the allergic reaction is strong, AN is produced rapidly with severe renal failure but little proteinuria; if it is less violent, immunocompetent cells may develop to produce lymphokines and proteinuria. Immune complexes may be formed eventually, secondary to the increased glomerular permeability, more easily in patients with a hyperactive immune system and with little consequence for renal function.