TENASCIN EXPRESSION MAY REFLECT THE ACTIVITY AND CHRONICITY OF HUMAN-IGA NEPHROPATHY

Background: Tenascin is a large oligomeric glycoprotein component of t he extracellular matrix that increases rapidly after inflammation or i njury, suggesting that it may be an indicator of renal disease activit y. Histological activity and chronicity indices are currently used to evaluate the activity and chronicity of IgA nephropathy. Patients and methods: We investigated whether tenascin staining could be an indicat or of activity or chronicity in patients with IgA nephropathy using im munohistochemical and in situ polymerase chain reaction methods. Immun ostaining for tenascin was done on 58 renal specimens, (51 from IgA ne phropathy patients and 7 from normal kidneys), and the in situ polymer ase chain reaction was performed on 24 renal specimens (21 from IgA ne phropathy patients and 3 from normal kidneys). Results: Tenascin expre ssion 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 tena scin mRNA positivity was correlated with the activity index (r = 0.449 , p = 0.0448). Conclusion: Tenascin expression was similar in the glom eruli and tubulointerstitium, but glomerular staining more closely ref lected the pathological state. Tenascin protein expression may be an i ndicator of chronicity and tenascin mRNA expression may be an indicato r of disease activity in IgA nephropathy.