Abstract
BackgroundThis study reports the clinical and pathological features of 12 cases of primary Sjogren syndrome (pSS) with renal involvement presenting with proximal tubular dysfunction in a single center, and investigates the possible correlation of ectopic germinal center formation and megalin/cubilin down-expression.MethodClinical and pathological records were reviewed. Immunohistochemistry was carried out to detect megalin, cubilin, CD21 and IL-17 expression.ResultsPatients presented with different degrees of proximal renal tubule lesion and decreased estimated glomerular filtration rate (eGFR). Renal biopsy revealed tubulointerstitial nephritis, with tubular epithelial cell degeneration, tubular atrophy, interstitial inflammation and focal fibrosis. Immunohistochemistry revealed decreased expression of megalin and cubilin, two important multiligand protein receptors on the brush border of proximal tubular epithelial cells. IL-17 secreted by Th17 subtype effector T cells was diffusely detected in the renal proximal tubule, with a negative correlation of IL-17 and megalin expression. In addition, ectopic germinal centers characterized by CD21+ follicular dendritic cells were present in the renal interstitium. In patients with a decreased eGFR, treatment with 4 weeks of glucocorticoid therapy resulted in an improved eGFR in 75% of patients.ConclusionWe report 12 cases of pSS characterized by Fanconi syndrome. The decreased megalin and cubilin expression may contribute to the proximal tubular reabsorption defect, possibly secondary to Th17 infiltration and formation of ectopic germinal centers.
Highlights
This study reports the clinical and pathological features of 12 cases of primary Sjogren syndrome with renal involvement presenting with proximal tubular dysfunction in a single center, and investigates the possible correlation of ectopic germinal center formation and megalin/cubilin down-expression
We describe the presence of ectopic germinal center (EGC) in the renal interstitium, the prevalence of Th17/Interleukin 17 (IL-17) expression, and alterations in megalin and cubilin expression, to investigate their possible correlation
Clinical characteristics From January 1994 to August 2014, 2546 hospitalized patients in Peking Union Medical College Hospital (PUMCH) were diagnosed of primary Sjogren syndrome (pSS), 335 of them presenting with renal manifestation
Summary
This study reports the clinical and pathological features of 12 cases of primary Sjogren syndrome (pSS) with renal involvement presenting with proximal tubular dysfunction in a single center, and investigates the possible correlation of ectopic germinal center formation and megalin/cubilin down-expression. Primary Sjogren syndrome (pSS) is a chronic autoimmune epithelialitis targeting exocrine glands, with possible multisystem involvement [1]. Characteristic pathological changes are focal lymphocytic infiltration around the epithelial ducts and production of autoantibody by hyperactive B cells [2]. Tubulointerstitial nephritis (TIN) as a result of periepithelial inflammation is a predominant feature of pSS, often with evidence of a Ectopic germinal centers (EGCs), nonlymphoid collections of mature B lymphocytes, have been observed in the labial glands of pSS patients, believed to be the result of chronic inflammation [7]. EGCs are suggested to be the site of immune stimulation and have been identified in other autoimmune
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