Kidney Histopathology Can Predict Kidney Function in ANCA-Associated Vasculitides with Acute Kidney Injury Treated with Plasma Exchanges

BACKGROUND

Data from the PEXIVAS trial challenged the role of plasma exchange (PLEX) in ANCA-associated vasculitides (AAV). We aimed to describe kidney biopsy from patients with AAV treated with PLEX, evaluate whether histopathologic findings could predict kidney function, and identify which patients would most benefit from PLEX.

METHODS

We performed a multicenter, retrospective study on 188 patients with AAV and AKI treated with PLEX and 237 not treated with PLEX. The primary outcome was mortality or KRT at 12 months (M12).

RESULTS

No significant benefit of PLEX for the primary outcome was found. To identify patients benefitting from PLEX, we developed a model predicting the average treatment effect of PLEX for an individual depending on covariables. Using the prediction model, 223 patients had a better predicted outcome with PLEX than without PLEX, and 177 of them had >5% increased predicted probability with PLEX compared with without PLEX of being alive and free from KRT at M12, which defined the PLEX-recommended group. Risk difference for death or KRT at M12 was significantly lower with PLEX in the PLEX-recommended group (-15.9%; 95% CI, -29.4 to -2.5) compared with the PLEX not recommended group (-4.8%; 95% CI, 14.9 to 5.3). Microscopic polyangiitis, MPO-ANCA, higher serum creatinine, crescentic and sclerotic classes, and higher Brix score were more frequent in the PLEX-recommended group. An easy to use score identified patients who would benefit from PLEX. The average treatment effect of PLEX for those with recommended treatment corresponded to an absolute risk reduction for death or KRT at M12 of 24.6%.

CONCLUSIONS

PLEX was not associated with a better primary outcome in the whole study population, but we identified a subset of patients who could benefit from PLEX. However, these findings must be validated before utilized in clinical decision making.

[Acute immuno-allergic interstitial nephritis after treatment with fluindione. Seven cases]

We report seven cases of patients treated with fluindione, who presented with acute renal failure, associated with clinical features of allergy: poor status, fever, dyspnea, lymphadenopathy and erythroderma. All patients had elevated eosinophil counts. Renal biopsy disclosed in all cases a tubulo-interstitial nephritis with or without granuloma. The responsibility of fluindione, an oral anticoagulant widely used in France could be demonstrated. To our knowledge, there are only three reports of single cases of acute renal failure related to fluindione published so far to date. This serious side effect of fluindione should be recognized.

Renal involvement in POEMS syndrome

We describe a patient with POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy and skin changes) who was found to have renal involvement with particular renal pathological findings. So far, 17 other cases, most of them from Japan, of POEMS syndrome with renal involvement, have been published. Clinical features are variable: acute renal failure with anasarca or moderate chronic renal insufficiency with mild proteinuria. This latter presentation often passes unnoticed. There is no severe hypertension, no microangiopathic hemolytic anemia. Renal biopsy shows prominent glomerular changes which are unusual and distinct from membranoproliferative glomerulonephritis (MPGN) and from glomerular thrombotic microangiopathy (TMA). Mesangial proliferation and thickening of the capillary wall with double contour on light microscopy suggest an MPGN. By immunofluorescent microscopy, no immunoglobulins or complement deposits were found. The occurrence of mesangiolytic lesions has led to the term of "mesangiolytic glomerulonephritis". The presence, on electron microscopy, of lucent subendothelial spaces could indicate TMA. But there are neither thrombi nor arteriolar changes. We are inclined to consider that the microangiopathic lesions are due to chronic injury of glomerular endothelial cells, exacerbated at outbreaks of the disease. Increased production of IL 6 could support the efficacy of corticosteroid therapy, particularly in acute clinical situations.

Renal biopsy in the elderly

314 patients, aged 65 years or older, were biopsied because of a history of renal disease. In 203 patients, glomerular disease was diagnosed with one fourth having systemic disease and the remaining primary glomerulonephritis. 90 patients had tubulointerstitial disease, and 21 patients showed prominent vascular pathology. In a comparison with patients of younger age groups, it appeared that amyloidosis, membranous nephropathy, vasculitis and diabetes had a significantly higher incidence in the elderly. Main glomerular syndromes such as nephrotic syndrome and rapidly progressive glomerulonephritis imply to be managed appropriately. Glomerulosclerosis was found in high frequency, either as an isolated feature or associated with other lesions. Glomerulosclerosis seemed to be ischemic in origin and seems to represent a distinct entity as a cause of pathology in the elderly.

[Study of CD45 isoforms on T CD8 lymphocytes, in the peripheral blood and the graft in patients after kidney transplantation]

We report characterization of CD45 isoforms expressed by CD8+ lymphocytes in peripheral blood and in the graft of 40 kidney transplanted patients who underwent kidney biopsy on the basis of clinical signs suggesting rejection. Standard histological examination of the biopsy fragments and three-color cytofluorimetric analysis of lymphocytes extracted from the same fragments by mechanical and enzymatic treatment were performed simultaneously and compared to the peripheral blood lymphocytes. In 14/40 biopsies where lymphocyte extraction succeeded, the predominant subset was CD8 (CD4/CD8 mean ratio was 0.53). Almost all CD8+ cells were activated: among these CD8+ cells, 55 percent were HLA-DR+, and 68 percent CD45RO+, i.e. of a memory cell type with cytotoxic activity. This situation resembles the in vitro observation made during mitogenic stimulation of lymphocytes by phytohemagglutinin, OKT3 or CML ("culture mixte lymphocytaire"). Beside their evident interest for the diagnosis, these data could be useful for our understanding of the physiopathology of the rejection crisis.