Mapping urinary chemokines in human lupus nephritis: Potentially redundant pathways recruit CD4+ and CD8+ T cells and macrophages.

Renal infiltration of inflammatory cells contributes to the pathogenesis of lupus nephritis (LN). Current knowledge on the recruitment mechanisms relies mainly on findings in rodent models. Here, we assess various chemokine pathways in human LN by comparing urinary chemokine concentrations (in 25 patients with acute LN and in 78 lupus patients without active LN) with the expression of corresponding chemokine receptors on urinary leukocytes (in ten acute LN patients). Nine urinary chemokines were significantly elevated in LN patients and correlated with renal disease activity and urinary cell counts; however, their concentrations displayed considerable interindividual heterogeneity. Analysis of the corresponding receptors revealed abundance of urinary CD8+ T cells for CCR5 and CXCR3, while CD4+ T cells were additionally enriched for CCR1, CCR6 and CXCR6. Urinary Treg showed similar CCR expression, and urinary CD14+ macrophages were enriched for CCR5 expressing cells. In conclusion, cell specific recruitment patterns seem to involve CCR5 and CXCR3 in all cells studied, while CD4+ T-cell subset recruitment is probably much more varied. However, urinary chemokine abundance in active LN is individually variable in our cohort and does not offer a singular chemokine usable as universal biomarker or potential future treatment target.

The cellular signature of urinary immune cells in Lupus nephritis: new insights into potential biomarkers.

INTRODUCTION: Urinary T cells represent a reliable noninvasive biomarker for proliferative Lupus nephritis (LN). Little is known about the presence of T cell subsets, B cells and macrophages in the urine although they may further improve the validity of urinary cellular biomarkers for LN. METHODS: We analyzed contemporaneous blood and urine samples of patients with active LN (n = 19), other Systemic Lupus Erythematosus (SLE) patients (n = 79) and urine samples of patients with diabetic nephropathy (DN; n = 14) and anti-neutrophil cytoplasmatic antibody (ANCA) associated vasculitis (AAV; n = 11) by flow cytometry. RESULTS: Numbers of urinary T cells, B cells and macrophages correlated with disease activity and were significantly higher in the active LN group. Urinary T cells showed excellent distinction of patients with active LN, CD8+ T cells (AUC of ROC = 1.000) and CD4+ T cells (AUC = 0.9969) alike. CD19+ B cells (AUC = 0.7823) and CD14+ macrophages (AUC = 0.9066), as well as the clinical standard proteinuria (AUC = 0.9201), failed to reach these high standards. Patients with DN or AAV also showed increased urinary cell counts, although the CD4/CD8-ratio was significantly lower in SLE compared to in DN (p = 0.0006). Urinary CD4+ T cells of active LN patients proved to be mainly of effector memory phenotype and expressed significantly more CD40L and ki67 than corresponding blood cells. Urinary Treg counts correlated with disease activity. CONCLUSIONS: Despite of detectable urinary cell counts for B cells and macrophages, T cells remain the best urinary cellular biomarker for LN. A low CD4/CD8-ratio seems to be characteristic for LN.

Urinary CD4 T cells identify SLE patients with proliferative lupus nephritis and can be used to monitor treatment response.

OBJECTIVES: Proliferative lupus nephritis (LN) is one of the major concerns in the treatment of systemic lupus erythematosus (SLE). Here we evaluate urinary CD4 T cells as a biomarker of active LN and indicator of treatment response. METHODS: Urinary CD3CD4 T cells were quantified using flow cytometry in 186 urine samples from 147 patients with SLE. Fourteen patients were monitored as follow-up. Thirty-one patients with other nephropathies and 20 healthy volunteers were included as controls. RESULTS: In SLE, urinary CD4 T cell counts ≥800/100 ml were observed exclusively in patients with active LN. Receiver operator characteristic analysis documented clear separation of SLE patients with active and non-active LN (area under the curve 0.9969). All patients with up-to-date kidney biopsy results showing proliferative LN had high urinary CD4 T cell numbers. In patients monitored under therapy, normalisation of urinary CD4 T cell counts indicated lower disease activity and better renal function. In contrast, patients with persistence of, or increase in, urinary T cells displayed worse outcomes. CONCLUSIONS: Urinary CD4 T cells are a highly sensitive and specific marker for detecting proliferative LN in patients with SLE. Furthermore, monitoring urinary CD4 T cells may help to identify treatment responders and treatment failure and enable patient-tailored therapy in the future.