Goodpasture syndrome: selective removal of anti-alpha 3 (IV) collagen autoantibodies. A potential therapeutic alternative to plasmapheresis.

Anti-alpha 3(IV) collagen autoantibodies have been implicated in the pathogenesis of Goodpasture syndrome, an autoimmune disorder causing glomerulonephritis and pulmonary hemorrhage. Currently treatment involves removal of the entire IgG fraction of plasma by plasmapheresis or adsorption to protein A. The present study shows that the anti-alpha 3(IV)NC1 autoantibodies can be removed from plasma specifically and quantitatively by affinity chromatography utilizing either alpha 3 NC1 domain of bovine type IV collagen or recombinant alpha 3 NC1 domain of human type IV collagen immobilized to agarose beads. This study shows the feasibility of using affinity chromatography, as an alternative to plasmapheresis, to exclusively remove the pathogenic autoantibodies from the plasma of patients with Goodpasture syndrome.

Developmental changes in seminiferous tubule extracellular matrix components of the mouse testis: alpha 3(IV) collagen chain expressed at the initiation of spermatogenesis.

The temporal expression of type IV collagen, laminin, and entactin in the basal laminae of the seminiferous tubule during development of the mouse testis was determined. Northern blot analysis was used to examine changes in testicular mRNA for alpha 1-alpha 5 type IV collagen (IV) chains in mice ranging in age from newborn to adult (60 days). Levels for mRNA alpha 1(IV) and alpha 2(IV) chains were highest in newborns through Day 5 and remained elevated through Day 10, but then sharply declined to adult values by Day 30. In sharp contrast, alpha 3(IV) and alpha 4(IV) chain levels were low in newborns, peaked at Day 10, and then declined to adult values by Day 30. 5(IV) mRNA was elevated in newborns and at Days 5 and 10 before dropping to adult levels by Day 30. Changes in the deposition of alpha 1, alpha 2, and alpha 3(IV) collagen chains, laminin, and entactin into the inner and outer basal laminae of the seminiferous tubule were determined from the beginning of tubule formation (embryonic Day 12.5) through adulthood by immunofluorescence microscopy using polyclonal antibodies for these constituents. The alpha 1 and alpha 2(IV) chains, laminin, and entactin were deposited into the inner basal lamina at embyronic Day 12.5 and into the newly formed outer basal lamina at Day 5 after birth. The alpha 3(IV) chains were deposited into both the inner and outer basal laminae at Day 5. Thus, testicular alpha 1-alpha 3(IV) mRNA levels coincide with the incorporation of detectable collagen chains into the seminiferous basal laminae, suggesting transcriptional control of these alpha (IV) chains. Expression of of the alpha 3(IV) chain coincides with the initiation of spermatogenesis, suggesting a functional role of this chain in spermatogonial proliferation.

Seminiferous tubule basement membrane. Composition and organization of type IV collagen chains, and the linkage of alpha3(IV) and alpha5(IV) chains.

Seminiferous tubule basement membrane (STBM) plays an important role in spermatogenesis. In the present study, the composition and structural organization of type IV collagen of bovine STBM was investigated. STBM was found to be composed of all six alpha-chains of type IV collagen based upon immunocytochemical and biochemical analysis. The content of alpha3(IV) chain (40%) and the alpha4(IV) chain (18%) was substantially higher than in any other basement membrane collagen. The supramolecular structure of the six alpha(IV) chains was investigated using pseudolysin (EC 3.4.24.26) digestion to excise triple-helical molecules, subsequent collagenase digestion to produce NC1 hexamers and antibody affinity chromatography to resolve populations of NC1 hexamers. The hexamers, which reflect specific arrangements of alpha(IV) chains, were characterized for their alpha(IV) chain composition using high performance liquid chromatography, two-dimensional electrophoresis, and immunoblotting with alpha(IV) chain-specific antibodies. Three major hexamer populations were found that represent the classical network of the alpha1(IV) and alpha2(IV) chains and two novel networks, one composed of the alpha1(IV)-alpha6(IV) chains and the other composed of the alpha3(IV)-alpha6(IV) chains. The results establish a structural linkage between the alpha3(IV) and alpha5(IV) chains, suggesting a molecular basis for the conundrum in which mutations in the gene encoding the alpha5(IV) chain cause defective assembly of the alpha3(IV) chain in the glomerular basement membrane of patients with Alport syndrome.