Increases in type III collagen gene expression and protein synthesis in patients with inguinal hernias

Abstract

Objective: The aim of this study was to determine if alterations in fibrillar collagen synthesis were associated with the development of inguinal hernias.

Summary background data: Previous work has suggested that alterations in connective tissue accumulation may play a functional role in the development of inguinal hernias. In particular, several investigators have suggested that alterations in collagen synthesis, causally related to connective disorders such as osteogenesis imperfecta, may also be responsible for the inguinal herniation that is markedly increased in such patients. This study was undertaken therefore to study collagen synthesis in patients with inguinal hernia in the absence of any other connective tissue disease.

Methods: Skin fibroblasts from 9 patients with hernias and 15 control individuals were radiolabeled with 3H-proline. Trypsin-chymotrypsin-resistant type I and III collagens were isolated and analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis, and recovery was quantified by laser densitometry. Steady-state levels of alpha 1(I) and alpha 1(III) procollagen mRNAs were also determined by northern and slot-blot hybridization analysis.

Results: The alpha 1(I)/alpha 1(III) collagen ratios were shown to be 6.3 +/- 0.34 in fibroblasts from control individuals and 3.0 +/- 0.25 in fibroblasts from patients with inguinal hernias. This statistically significant difference (p < 0.0001) was caused by an increase in the secretion of alpha 1(III) procollagen from the fibroblasts of patients with hernias. A concomitant increase in the steady-state levels of alpha 1(III) procollagen mRNA was observed in total RNA isolated from the patients' fibroblasts.

Conclusions: A constitutive and systemic increase in type III collagen synthesis may result in reduced collagen fibril assembly in the abdominal wall, eventually leading to the development of herniation. Although it is not yet clear what genetic factors are responsible for the elevation in type III collagen synthesis in patients with hernias, this study represents the first attempt to define individuals with an abnormality in collagen production that may be specifically related to herniation. A clearer understanding of the possible genetic factors that influence the pathophysiology of this disease will be important to improve the treatment of patients in whom inguinal hernias develop.