Tamm-Horsfall protein in reflux nephropathy

Area of Science:

• Nephrology
• Immunohistology
• Uropathology

Background:

• Tamm-Horsfall protein (THP) is the primary protein in normal urine.
• Vesicoureteric reflux (VUR) can lead to reflux nephropathy, a form of chronic pyelonephritis.
• The role of THP in the pathogenesis of reflux nephropathy is not fully understood.

Purpose of the Study:

• To investigate the distribution of Tamm-Horsfall protein in the kidneys of pigs with experimentally induced reflux nephropathy.
• To determine if THP deposition in extra-tubular sites or glomeruli is associated with reflux nephropathy.
• To compare the findings with THP distribution in cases of lower urinary tract outflow obstruction.

Main Methods:

• Immunohistological examination of kidney tissue from 70 pigs with unilateral vesicoureteric reflux.
• Induction of reflux nephropathy by inoculation of Escherichia coli strains into the bladder.
• Quantification and localization of Tamm-Horsfall protein deposits.

Main Results:

• Inflammatory changes consistent with reflux nephropathy were observed in 52 pigs.
• Extra-tubular Tamm-Horsfall protein deposits were found in only 26 pigs.
• These deposits were small, increased with inflammation size, and not found in glomeruli; no association with THP reaction was noted.

Conclusions:

• Extra-tubular Tamm-Horsfall protein deposition is not a prominent feature of low-pressure reflux nephropathy.
• Tubular leakage and subsequent glomerular backwash of THP are unlikely to be major contributors to reflux nephropathy pathogenesis.
• The findings differentiate the role of THP in reflux nephropathy from that observed in urinary tract outflow obstruction.