Risk factors for developing renal amyloidosis

As a result of the literature review carried out by the authors, it was revealed that the pathogenesis of autoimmune diathesis, rheumatoid arthritis and rheumatoid nephritis in children has a general immunopathological nature. However, autoimmune diathesis is an important risk factor for the onset and progression of rheumatoid arthritis and the subsequent development of renal amyloidosis based on immunopathological reactions in these patients.

LECT-2 amyloidosis: what do we know?

Amyloidosis is a rare group of diseases characterized by abnormal folding of proteins and extracellular deposition of insoluble fibrils. It can be localized to one organ system or can have systemic involvement. The kidney is the most common organ to be involved in systemic amyloidosis often leading to renal failure and the nephrotic syndrome. The two most common types of renal amyloidosis are immunoglobulin light chain-derived amyloidosis (AL) and reactive amyloidosis (AA). A novel form of amyloidosis (ALECT2) derived from leukocyte chemotactic factor 2 (LECT-2) and primarily involving the kidneys was first described by Benson et al in 2008. The liver was subsequently identified as the second most common organ involved in ALECT2 amyloidosis. LECT-2 is a unique protein that can form amyloid deposits even in its unmutated form. Patients with ALECT2 present with minimal proteinuria in contrast to other forms of amyloidosis especially AL and AA. They may present with slightly elevated serum creatinine. Nephrotic syndrome and hematuria are rare. ALECT2 can be found in association with other types of amyloidosis as well as malignancies or autoimmune diseases. ALECT2 may be confused with amyloidosis associated with light and heavy chain monoclonal gammopathy if the immunofluorescence is positive with anti-light chain and anti-AA sera. The other organs involved are the duodenum, adrenal gland, spleen, prostate, gall bladder, pancreas, small bowel, parathyroid gland, heart, and pulmonary alveolar septa, but consistently uninvolved organs included brain and fibroadipose tissue. A renal biopsy along with characteristic features found on immunohistochemistry and mass spectrometry is diagnostic of ALECT2. ALECT2 should be suspected when all markers for AL and AA are negative. Proper diagnosis of ALECT2 can determine need for supportive care versus more aggressive interventions.

A Pilot Study of Rare Renal Amyloidosis Based on FFPE Proteomics

Renal amyloidosis typically manifests albuminuria, nephrotic-range proteinuria, and ultimately progresses to end-stage renal failure if diagnosed late. Different types of renal amyloidosis have completely different treatments and outcomes. Therefore, amyloidosis typing is essential for disease prognosis, genetic counseling and treatment. Thirty-six distinct proteins currently known to cause amyloidosis that have been described as amyloidogenic precursors, immunohistochemistry (IHC) or immunofluorescence (IF), can be challenging for amyloidosis typing especially in rare or hereditary amyloidosis in clinical practice. We made a pilot study that optimized the proteomics pre-processing procedures for trace renal amyloidosis formalin-fixed paraffin-embedded (FFPE) tissue samples, combined with statistical and bioinformatics analysis to screen out the amyloidosis-related proteins to accurately type or subtype renal amyloidosis in order to achieve individual treatment. A sensitive, specific and reliable FFPE-based proteomics analysis for trace sample manipulation was developed for amyloidosis typing. Our results not only underlined the great promise of traditional proteomics and bioinformatics analysis using FFPE tissues for amyloidosis typing, but also proved that retrospective diagnosis and analysis of previous cases laid a solid foundation for personalized treatment.

Late onset familial Mediterranian fever: a clinical case

Familial Mediterranean fever (FMF) is a rare genetic autosomal recessive disease typical for special ethnic groups, such as Arabs, Greeks, Armenians, Jews, Turks and other ethnicities inhabiting the Mediterranean coast. The characteristic clinical signs and symptoms of the disease are recurrent episodes of fever, associated with polyserositis, in particular, with benign (aseptic) peritonitis. The disease is caused by mutation in the MEFV gene encoding the synthesis of the protein pyrine, which leads to an uncontrolled release of pro-inflammatory cytokines by granulocytes. The criterion for the severe course of the disease is AA-renal amyloidosis associated with an unfavorable prognosis.Here we present a clinical case of classic FMF with high fever and abdominal pain syndrome. A 26-year-old Armenian patient had a sudden attack of fever and severe pain in the right iliac area several months before his first hospital admission. Non-steroid anti-inflammatory drugs and antispasmodics were unable to relieve the symptoms, with the attack ceasing spontaneously after 3 days from the beginning. Thereafter, the attacks recurred 1 to 2 times per month within a year. During hospital stay at the peak of the attack, peritoneal symptoms at abdominal palpation, together with neutrophilic leukocytosis and a significant increase in acute phase parameters of inflammation (C-reactive protein, fibrinogen, erythrocyte sedimentation rate) were found. Based on the characteristics of the complaints, past history, laboratory and instrumental results, we excluded infections, autoimmune and surgical disorders and made a decision to perform genetic testing to detect the MEFV gene mutation. Confirmation of the mutation has led to the definitive diagnosis of FMF. This clinical case is remarkable for its late onset, which is not typical for FMF. As a result, the patient was prescribed continuous therapy with сolchicine. Six months of the follow up have demonstrated a positive trend with no attacks during this period.

A Stepwise Data Interpretation Process For Renal Amyloidosis Subtyping by LMD-MS

Backgrounds: Systemic amyloidosis is classified according to the deposited amyloid protein, which determines its best therapeutic scheme. The laser microdissection combined with mass spectrometry (LMD-MS) technique is a promising approach for precise subtyping of amyloidosis, however, is hampered by how to interpret the MS data.Objectives: The objective of the present study is to establish a complete data interpretation procedure for LMD-MS based amyloidosis subtyping.Methods: Formalin fixed paraffin-embedded specimens from patients with renal amyloidosis were analyzed by LMD-MS for proteome quantification. Forty-two specimens were used for training the data interpretation procedure, which was validated by another 50 validation specimens. Area under receiver operating curve (AUROC) analysis of amyloid accompanying proteins (APOE, APOA4 and SAMP) for discriminating amyloidosis from non-amyloid nephropathies was performed.Results: A stepwise data interpretation procedure that include or exclude the subtypes group by group was established, in which, involvement of non-immunoglobulin amyloid protein is determined by P-score, involvement of immunoglobulin light chain is determined by variable of λ-κ, and immunoglobulin heavy chain’s participation is judged by H-score. This data interpretation method achieved a 88% accuracy in 50 validation specimens. The amyloid accompanying proteins showed significant quantitative differences between amyloidosis specimens and non-amyloid nephropathies. Each of the single accompanying protein had a AUROC value more than 0.9 for diagnosis of amyloidosis from non-amyloid control, and the averaged value of spectral count of the three accompanying proteins showed the highest AUROC (0.966), indicating it might be an alternative indicator for amyloidosis diagnosis.Conclusions: The proteomic data interpretation procedure for amyloidosis subtyping based on LMD-MS was established successfully, which has high clinical application value.

Effectiveness of Canakinumab Treatment in Colchicine Resistant Familial Mediterranean Fever Cases

Anti-interleukin 1 agents are used successfully in colchicine-resistant or intolerant Familial Mediterranean Fever (FMF) patients. Sixty-five patients with FMF who received canakinumab treatment for at least 6 months due to colchicine resistance or intolerance between 2016 and 2020 in our department were retrospectively analyzed. Canakinumab treatment was given subcutaneously every 4 weeks. After completing monthly canakinumab therapy over 12 months, in patients with complete remission, the dosing interval was extended to every 1.5 months for 6 months, then every 2 months for 6 months, and finally every 3 months for a year. In patients without disease activation, canakinumab treatment was discontinued at the end of 3 years and followed up with colchicine treatment. Patients who had a flare switched to the previous dosing interval. In patients with renal amyloidosis, monthly canakinumab treatment was continued without extending the dose intervals. The mean duration of canakinumab use in our patients was 31.4 ± 10.57 months (6–52 months). The mean age at onset of symptoms was 4.65 ± 3.84 (range, 1–18) years, and the mean age at diagnosis was 5.59 ± 3.9 (range, 4–19) years. Complete remission was achieved in 57 (87.6%) and partial remission in seven (10.7%) patients. One patient was unresponsive to treatment. Canakinumab treatment was discontinued in three patients with complete remission and one patient with drug resistance. Erythrocyte sedimentation rate (ESR) (51.85 ± 15.7 vs. 27.80 ± 13.73 mm/h) and C-reactive protein (CRP) [26 (3-73) vs. 5 (1–48) mg/L] values were compared before and after canakinumab treatment in attack-free periods, a significant decrease was found after canakinumab treatment (p < 0.001, p < 0.001, respectively). Bodyweight Z-scores (respectively −0.80 ± 0.86 vs. −0.49 ± 0.92) were compared, similarly, a statistically significant increase after canakinumab treatment (p < 0.001), but no significant increase in height Z scores (−1.00 ± 0.88 vs. −0.96 ± 0.94) (p = 0.445) was detected. Four patients had FMF-related renal amyloidosis. The decrease in proteinuria with canakinumab treatment was not statistically significant (p = 0.068). Cervical lymphadenitis developed in one and local reactions in two patients. No severe adverse effects requiring discontinuation of canakinumab treatment were observed. Our study showed that canakinumab treatment was highly effective, well-tolerated in pediatric FMF patients, and controlled extension of the canakinumab dose interval was safe.