Tenascin expression may reflect the activity and chronicity of human IgA nephropathy

Tenascin is a large oligomeric glycoprotein component of the extracellular matrix that increases rapidly after inflammation or injury, suggesting that it may be an indicator of renal disease activity. Histological activity and chronicity indices are currently used to evaluate the activity and chronicity of IgA nephrophathy.

We investigated whether tenascin staining could be an indicator of activity or chronicity in patients with IgA nephropathy using immunohistochemical and in situ polymerase chain reaction methods. Immunostaining for tenascin was done on 58 renal specimens, (51 from IgA nephropathy patients and 7 from normal kidneys), and the in situ polymerase chain reaction was performed on 24 renal specimens (21 from IgA nephropathy patients and 3 from normal kidneys).

Tenascin expression in the glomeruli was correlated with tenascin expression in the tubulointerstitium (protein; r = 0.386, p = 0.0063, mRNA; r = 0.510, p = 0.0225). Tenascin protein staining in the glomeruli was correlated with the chronicity index (r = 0.506, p = 0.0003), and glomerular tenascin mRNA positivity was correlated with the activity index (r = 0.449, p = 0.0448).

Tenascin expression was similar in the glomeruli and tubulointerstitium, but glomerular staining more closely reflected the pathological state. Tenascin protein expression may be an indicator of chronicity and tenascin mRNA expression may be an indicator of disease activity in IgA nephropathy.