Clinicopathological characteristics of renal amyloid leukocyte chemotactic factor 2 amyloidosis / 中华肾脏病杂志

ABSTRACT

Objective:To investigate the clinicopathological characteristics of renal leukocyte chemotactic factor 2 amyloidosis (ALECT2).Methods:The patients with renal ALECT2 diagnosed by renal biopsy in Peking University First Hospital, Shanxi Medical University Second Hospital and Shanxi Bethune Hospital from January 2001 to October 2021 were retrospectively enrolled. According to whether the patients had concurrent glomerular diseases, they were classified into two groups isolated ALECT2 group and ALECT2 with concurrent renal diseases group. Clinicopathological data of the two groups were compared. Light microscopy, immunofluorescence and immunoelectron microscopy were applied to investigate pathological characteristics of renal tissues. Mass spectrometry was used to analyze the composition of renal amyloid deposits. Gene sequencing was employed to detect the leukocyte chemotactic factor 2 ( LECT2) gene sequence in peripheral blood of the patients. Results:Sixteen patients with ALECT2 were enrolled in this study and nine of them had concurrent renal diseases. The age of 16 patients was (65.00±8.45) years old. The sex ratio of males to females was 7 to 9. Most of patients were Han ethnicity (15/16). Eight patients came from Shanxi province. Fifteen patients presented with varying degree of proteinuria [2.16(1.07, 4.72) g/24 h]; 5 patients had nephrotic syndrome; 11 patients had renal insufficiency; 12 patients had microscopic hematuria. Part of patients also had hypertension (12/16) and diabetics (6/16). Compared with isolated ALECT2, the ALECT2 group with concurrent renal diseases had a higher proportion of nephrotic syndrome (5/9 vs 0/7, P=0.034). Renal biopsy results showed that all patients (16/16) had amyloid deposits in the interstitium of renal cortex with varying degree of inflammatory cell infiltration and fibrosis, and glomeruli (12/16) and arterioles (14/16) were involved by amyloid deposits. The amyloid deposits were strongly congophilic and immunohistochemistry for LECT2 was positive. By semi-quantitative analysis, the proportions of glomerular and overall amyloid loads in ALECT2 with concurrent renal diseases group were lower than those in isolated ALECT2 group (both P<0.05). Electron microscopy revealed randomly oriented and non-branching fibrils with a diameter of 8-12 nm. The LECT2 peptides were detected by mass spectrometry in renal amyloid deposits of 8 patients, and homozygous G allele of LECT2 was found in 7 patients by gene sequencing. Complete follow-up data of 13 patients showed that 2 patients died, 1 patient developed end-stage renal disease at the time of renal biopsy, and most of the rest patients had stable renal function (8/10). Conclusions:Patients with renal ALECT2 mainly present with proteinuria, along with a high incidence of renal insufficiency, microscopic hematuria, and concurrent renal diseases. The pathologic feature is the preferential deposition of amyloid in renal cortical interstitium.