Abstract

FERREIRA, Ana Carina; CARVALHO, Fernanda; SANTOS, Ana Rita  and  NOLASCO, Fernando. Kidney dysfunction in renal amyloidosis: does the complement system play a part in hereditary ATTRV30M and iatrogenic ATTR amyloidosis?. Port J Nephrol Hypert [online]. 2019, vol.33, n.2, pp.91-96. ISSN 0872-0169.  https://doi.org/10.32932/pjnh.2019.07.018.

Introduction and aims: The complement system may play a part in the pathogenesis of amyloid disorders. The primary aim of the study was to analyse the relationship between transthyretin renal amyloidosis (ATTR) and the complement system. The secondary aim was to find potential clinical and morphologic features in ATTR amyloidosis associated with complement activation. Methods: We performed a retrospective cohort observational study in patients with renal amyloidosis submitted to kidney biopsy and complement measurements from January 2005 to June 2016. We compared clinical and laboratory results in different types of amyloidosis using the Kruskal-Wallis or Fisher's exact test. We performed a subgroup analysis in ATTR amyloidosis patients, comparing patients with normal and low complement serum levels in terms of clinical, laboratory, and morphologic characteristics, using the Mann-Whitney test or Fisher's exact test. Results: We included 42 patients in the analysis: 15 patients had ATTR amyloid deposits, 16 AA amyloid deposits and 11 AL amyloid deposits (all AL λ). A total of ten patients presented low C3 (6 ATTR; 3 AL; 1 AA). None of the patients had low C4 serum levels. Of the 15 Caucasian patients with renal ATTR amyloidosis, 6 (40%) presented low C3. Those patients had a higher sclerotic glomeruli number and 5 out of 6 had C3 deposits in immunofluorescence. Discussion: In our study, 40% of patients with renal ATTR amyloidosis showed complement consumption or activation, which led us to suspect that ATTR deposits can lead to systemic activation of the alternative complement pathway. It remains to be elucidated if this activation injures peripheral nerves and the kidney. Conclusions: C3 determinations can prove to be a useful tool for predicting renal involvement and glomerulosclerosis in TTR amyloidosis patients.

Keywords : Amyloidosis; complement system; renal biopsy; transthyretin.

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