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OBJECTIVE: This study was undertaken to characterize kidney and urine antibody-secreting cells (ASCs) from patients with active lupus nephritis, before and after induction therapy. METHODS: We included patients with biopsy-proven active lupus nephritis and performed anti-CD138 staining of kidney biopsy samples to visualize ASCs. We performed single-cell gene expression profiling on sorted ASCs from fresh biopsy samples using multiplex reverse transcriptase-polymerase chain reaction. We used a gene set that allowed for the study of ASC maturation from plasmablasts to long-lived plasma cells. We quantified urine ASCs from untreated patients with lupus nephritis at diagnosis and after 6 months of prospective follow-up during induction therapy. RESULTS: The number of kidney CD138+ ASCs in 46 untreated patients with lupus nephritis was correlated with a low estimated glomerular filtration rate and with tubulointerstitial damage. Most kidney ASCs from 3 untreated patients had a plasmablast molecular signature; in contrast, in 4 patients with refractory lupus nephritis, the kidney ASCs were mainly long-lived plasma cells, representing an ASC transcriptional profile similar to that in the bone marrow of 2 healthy donors. Some urine ASCs with a plasmablast signature were detected in patients with untreated active lupus nephritis. The presence of urine ASCs at 6 months was associated with treatment failure. CONCLUSION: Our results suggest potential for ASC-directed therapy in refractory lupus nephritis.

Objective The Euro-Lupus regimen of low-dose intravenous cyclophosphamide (IV CYC) (cumulative dose of 3 gm) was developed to reduce gonadal toxicity. To address the possibility of a marginal effect on the ovarian reserve, we measured serum titers of anti-Mullerian hormone (AMH) in patients with systemic lupus erythematosus (SLE) treated with the Euro-Lupus regimen and compared them with those measured in patients who were treated with higher doses of IV CYC or were never treated with IV CYC. Methods Serum AMH levels were measured by enzyme-linked immunosorbent assay in a cohort of 155 premenopausal SLE patients; 30 of these patients had been treated with the Euro-Lupus regimen, and 24 had received higher doses of IV CYC. None had received oral CYC. AMH levels were age-adjusted using a slope computed from levels measured across the group of SLE patients who had not been treated with IV CYC. Demographic and clinical data were collected. Results Serum titers of AMH measured in SLE patients treated with the Euro-Lupus IV CYC regimen (median dose 1.46 ng/ml) did not differ from those measured in patients never treated with the cytotoxic drug (median 1.85 ng/ml). As expected, patients given >6 gm of IV CYC had significantly lower serum titers of AMH (median 0.83 ng/ml) compared with those never treated with IV CYC (P = 0.047). Median serum AMH titers did not change before (1.24 ng/ml) and after (2.50 ng/ml) treatment with the Euro-Lupus IV CYC regimen in the subset of patients for whom paired samples could be tested (P = 0.43). Conclusion The Euro-Lupus regimen of low-dose IV CYC does not impact the ovarian reserve of SLE patients and can therefore be proposed as treatment in patients seeking to become pregnant.