Tubular basement membrane amyloid deposition: is it an indicator of renal progression in light chain amyloidosis?

In light chain amyloidosis (LA), the massive glomerular and vascular amyloid deposition leading to interstitial fibrosis/tubular atrophy (IFTA) is thought to be responsible for renal failure. The amyloid deposition in the interstitium and the tubular basement membrane (TBM) has received less attention in the study of LA. We, therefore, collected clinical and laboratory data on patients diagnosed with LA in our Nephrology Department and studied amyloid deposition in the TBM. Twelve LA patients were diagnosed by renal biopsy during a seven-year period. In 4 of the 12, amyloid deposition could also be detected in the TBM. In our first case of a patient with diabetes mellitus, non-amyloid fibrils resembling 'diabetic fibrillosis' were also seen by electron microscopy. Despite the double damage, IFTA was negligible, blood vessels were unaffected, and the glomerular deposition was segmental. In the other three cases, significant (>50%) IFTA and a severely reduced estimated glomerular filtration rate were already detected at the time of diagnosis and amyloid deposition was also observed in the blood vessels. These findings indicate the importance of TBM amyloid deposition in the progression of renal disease. This may represent a late-stage presentation of the disease with a heavy LC burden.

Ibrutinib-induced acute kidney injury via interstitial nephritis.

The introduction of Bruton's tyrosine kinase inhibitor ibrutinib has made a significant progress in the treatment of chronic lymphocytic leukemia and other B-cell malignancies. Due to the reduction of cytokine release, it is effective in chronic graft-versus-host disease, and its use has also been suggested in autoimmune diseases and in prevention of COVID-19-associated lung damage. Despite this effect on the immune response, we report a severe hypersensitivity reaction in a 76-year-old male patient diagnosed with prolymphocytic leukemia. Four weeks after the ibrutinib start, non-oliguric acute kidney injury with proteinuria and microscopic hematuria developed and that was accompanied by lower limb purpuras and paresthesia. Renal biopsy revealed acute interstitial nephritis. Employing 1 mg/kg methylprednisolone administration, serum creatinine decreased from 365 µmol/L to 125 µmol/L at 11 days and the proteinuria-hematuria as well as the purpura, paresthesia resolved. Three months later at stabile eGFR of 56 ml/min/1.73 m2 methylprednisolone was withdrawn and a rituximab-venetoclax treatment was initiated without side effects. We conclude that despite the beneficial effect on cytokines response in Th1 direction, ibrutinib can cause acute interstitial nephritis. Early detection, discontinuation of ibrutinib, glucocorticoid administration may help to better preserve renal function, thereby lowering the risk of potential subsequent kidney injury.

Relapsing polychondritis with p-ANCA associated vasculitis: Which triggers the other?

Relapsing polychondritis (RP) is a rare autoimmune disease with chronic inflammatory/destructive lesions of the cartilaginous tissues. In one third of the cases it is associated with other autoimmune disorders, mostly with anti-neutrophil cytoplasmic antibody (ANCA) associated vasculitis (AAV). We report three cases of RP with p-ANCA positive AAV. In the first patient RP developed 1.5 years after the onset of AAV. In the others the signs of RP were present before the onset of severe crescent glomerulonephritis. Patients responded well on steroid and cyclophosphamide. In dialysis dependent cases plasmapheresis was also used successfully. During the 2 and 1.5 years of follow up, they were symptom-free, and had stable glomerular filtration rate. The first patient died after four years of follow-up due to the complications of sudden unset pancytopenia, which raises the possibility of associated hemophagocytic syndrome. In the setting of RP or AAV physicians should always be aware of the possibility of sudden or insidious appearance of the other disease.

[Clinical consequence and significance of anti-neutrophil cytoplasmic antibody positivity in anti-glomerular basement membrane disease]. / Antiglomeruláris bazálmembrán betegségben észlelt antineutrofil citoplazmatikus antitest pozitivitás klinikuma, jelentosége.

INTRODUCTION: Patients with renopulmonary syndrome who have both anti-neutrophil cytoplasmic and anti-glomerular basement membrane antibodies have been described since 1989. AIM: The aim of the authors was to analyse the data of "double positive" patients diagnosed in their department, and compare these with previous studies. METHOD: During the last 16 years, 87 anti-neutrophil cytoplasmic antibody positive and 11 anti-glomerular basement membrane antibody positive patients were diagnosed. Four patients with anti-glomerular basement membrane antibodies (36%) had detectable anti-neutrophil cytoplasmic antibodies, 2 patients were positive for anti-myeloperoxidase and 2 patients for anti-proteinase 3. RESULTS: In comparison with patients having anti-glomerular basement membrane antibodies, the double-positive patients were characterized by older age (median of 46 vs. 24 years), lack of male dominance (50% vs. 71%), more frequent presence of previous extrarenal symptoms (50% vs. 0%), and lower anti-glomerular basement membrane antibody levels (<100EU/ml: 100% vs. 29%). The double-positive patients had more favourable 1-year survival (100% vs. 71%), despite their older age and similar treatment regimen (immunosuppression 100% in both groups, plasmapheresis in 75% vs. 86%), but 1-year renal survival was not different (25% vs. 14%). CONCLUSIONS: In agreement with literature data, about one third of patients with anti-glomerular basement membrane antibodies had detectable anti-neutrophil cytoplasmic antibodies, and the coexistence of the two antibodies may have clinical consequences.

Association of ANCA-associated vasculitis-rheumatoid arthritis overlap syndrome in four patients: rituximab may be the right choice?

OBJECTIVES: There have been few reports on the association of rheumatoid arthritis (RA) with anti-neutrophil cytoplasmic antigen (ANCA)-associated systemic vasculitides. METHODS: Here we present four cases of RA overlapping with Wegener's granulomatosis (WG), microscopic polyangiitis (MPA) and Churg-Strauss syndrome (CSS). All these cases had both the diagnosis of RA and that of ANCA-associated vasculitis. RESULTS: After we tried corticosteroids, multiple immunosuppressive drugs, sometimes plasmapheresis, rituximab was introduced to 3 out of 4 cases. Rituximab therapy was found to be effective in these three overlap cases. In the fourth case, rituximab was and will be considered; however, the patient has not given consent. CONCLUSION: To our knowledge, this is the first report on RA+CSS association. Common pathogenic background, such as genetic predisposition and ANCA may account for the development of RA+vasculitis overlaps. In DMARD-refractory cases, such as the ones presented here, biologics, especially rituximab may be highly effective.