ABSTRACT
A male child presented initially well with a mixed nephrotic-nephritic syndrome and was commenced on standard high-dose oral corticosteroids. Clinical deterioration occurred 3 weeks later with rapidly progressing renal dysfunction, seizures and diminished urinary output, requiring renal replacement therapy. Once stabilised, renal biopsy demonstrated mesangial and capillary C3, minimal IgG deposition, with mesangial electron dense deposits felt consistent with postinfectious glomerulonephritis or C3 glomerulopathy. Further investigations identified circulating autoantibody directed against factor H, as a plausible aetiology of the membranoproliferative glomerulonephritis (MPGN). Treatment with rituximab and mycophenolate mofetil was associated with a reduction in antibody titres and a concurrent reduction in proteinuria and normalisation of renal function.Subsequent monitoring of antibody titres prompted further administrations of rituximab, with reduction in titres demonstrated after repeat doses. Atypical presentations or complications of nephrotic syndrome or MPGN should prompt detailed investigations for the cause with consideration of antifactor H antibodies.
Subject(s)
Glomerulonephritis, Membranoproliferative , Glomerulonephritis , Nephrotic Syndrome , Autoantibodies , Child , Female , Glomerulonephritis/drug therapy , Glomerulonephritis/etiology , Glomerulonephritis, Membranoproliferative/pathology , Humans , Male , Nephrotic Syndrome/drug therapy , Nephrotic Syndrome/etiology , Rituximab/therapeutic useABSTRACT
Post-translational modifications are necessary for collagen precursor molecules (procollagens) to acquire final shape and function. However, the mechanism and contribution of collagen modifications that occur outside the endoplasmic reticulum and Golgi are not understood. We discovered that VIPAR, with its partner proteins, regulate sorting of lysyl hydroxylase 3 (LH3, also known as PLOD3) into newly identified post-Golgi collagen IV carriers and that VIPAR-dependent sorting is essential for modification of lysines in multiple collagen types. Identification of structural and functional collagen abnormalities in cells and tissues from patients and murine models of the autosomal recessive multisystem disorder Arthrogryposis, Renal dysfunction and Cholestasis syndrome caused by VIPAR and VPS33B deficiencies confirmed our findings. Thus, regulation of post-Golgi LH3 trafficking is essential for collagen homeostasis and for the development and function of multiple organs and tissues.
