Erratum: STING Mediates Lupus via the Activation of Conventional Dendritic Cell Maturation and Plasmacytoid Dendritic Cell Differentiation.

[This corrects the article DOI: 10.1016/j.isci.2020.101530.].

STING Mediates Lupus via the Activation of Conventional Dendritic Cell Maturation and Plasmacytoid Dendritic Cell Differentiation.

Signaling through stimulator of interferon genes (STING) leads to the production of type I interferons (IFN-Is) and inflammatory cytokines. A gain-of-function mutation in STING was identified in an autoinflammatory disease (STING-associated vasculopathy with onset in infancy; SAVI). The expression of cyclic GMP-AMP, DNA-activated cGAS-STING pathway, increased in a proportion of patients with SLE. The STING signaling pathway may be a candidate for targeted therapy in SLE. Here, we demonstrated that disruption of STING signaling ameliorated lupus development in Fcgr2b-deficient mice. Activation of STING promoted maturation of conventional dendritic cells and differentiation of plasmacytoid dendritic cells via LYN interaction and phosphorylation. The inhibition of LYN decreased the differentiation of STING-activated dendritic cells. Adoptive transfer of STING-activated bone marrow-derived dendritic cells into the FCGR2B and STING double-deficiency mice restored lupus phenotypes. These findings provide evidence that the inhibition of STING signaling may be a candidate targeted treatment for a subset of patients with SLE.

Biomarkers for Refractory Lupus Nephritis: A Microarray Study of Kidney Tissue.

The prognosis of severe lupus nephritis (LN) is very different among individual patients. None of the current biomarkers can be used to predict the development of refractory LN. Because kidney histology is the gold standard for diagnosing LN, the authors hypothesize that molecular signatures detected in kidney biopsy tissue may have predictive value in determining the therapeutic response. Sixty-seven patients with biopsy-proven severely active LN by International Society of Nephrology/Renal Pathology Society (ISN/RPS) classification III/IV were recruited. Twenty-three kidney tissue samples were used for RNA microarray analysis, while the remaining 44 samples were used for validation by real-time polymerase chain reaction (PCR) gene expression analysis. From hundreds of differential gene expressions in refractory LN, 12 candidates were selected for validation based on gene expression levels as well as relevant functions. The candidate biomarkers were members of the innate immune response molecules, adhesion molecules, calcium-binding receptors, and paracellular tight junction proteins. S100A8, ANXA13, CLDN19 and FAM46B were identified as the best kidney biomarkers for refractory LN, and COL8A1 was identified as the best marker for early loss of kidney function. These new molecular markers can be used to predict refractory LN and may eventually lead to novel molecular targets for therapy.

Exosomes in urine biomarker discovery.

Nanovesicles present in urine the so-called urinary exosomes have been found to be secreted by every epithelial cell type lining the urinary tract system in human. Urinary exosomes are an appealing source for biomarker discovery as they contain molecular constituents of their cell of origin, including proteins and genetic materials, and they can be isolated in a non-invasive manner. Following the discovery of urinary exosomes in 2004, many studies have been performed using urinary exosomes as a starting material to identify biomarkers in various renal, urogenital, and systemic diseases. Here, we describe the discovery of urinary exosomes and address the issues on the collection, isolation, and normalization of urinary exosomes as well as delineate the systems biology approach to biomarker discovery using urinary exosomes.

APRIL, a proliferation-inducing ligand, as a potential marker of lupus nephritis.

INTRODUCTION: BLyS and APRIL are cytokines from the tumor necrosis factor family which play an important role in systemic lupus erythematosus (SLE). Previous works suggested an association between both molecules and SLE disease activity although their correlation with lupus nephritis is not known. We therefore assessed serum BLyS and APRIL in active lupus nephritis patients. METHODS: Serum samples from active lupus nephritis and at 6 months post-treatment were obtained. Serum levels of BLyS and APRIL (n = 47) as well as renal mRNA expression were measured. Serum levels of both molecules and clinical data (n = 27) were available at 6 months follow-up. All biopsy-proven lupus nephritis patients were treated with similar immunosuppressive drugs. RESULTS: Serum levels of APRIL were associated with proteinuria (Rs = 0.44, P value < 0.01) and degree of histological activity (Rs = 0.34; P value < 0.05) whereas BLyS levels were associated with complement levels (Rs = 0.46; P value < 0.01) and dosage of immunosuppressant. Interestingly, serum APRIL as well as its intrarenal mRNA levels were associated with resistance to treatment. From the receiver operating characteristic (ROC) analysis, high levels (> 4 ng/mL) of serum APRIL predicted treatment failure with a positive predictive value of 93 percent. CONCLUSION: APRIL could be a potential biomarker for predicting difficult-to-treat cases of lupus nephritis.

Decreased renal expression of vascular endothelial growth factor in lupus nephritis is associated with worse prognosis.

Recent studies suggest that vascular endothelial growth factor (VEGF) plays a crucial role in the preservation of renal function and may also serve as a useful biomarker in monitoring the progression of lupus nephritis (LN). Here we sought to correlate intrarenal VEGF expression with renal histopathology and prognosis of LN. Biopsy specimens from 35 patients with Class III or IV LN (ISN/RPS categorization) were found to have lower levels of intrarenal VEGF than those found in biopsy tissue taken from 10 donor kidneys sampled at the time of allograft reperfusion. This reduced amount of VEGF mRNA in the patients with LN negatively correlated with glomerular endocapillary proliferation, crescent formation, and a high histologic activity index but was positively associated with increased numbers of urinary podocytes. The level of intrarenal VEGF mRNA accurately predicted the deterioration of renal function in these patients within 12 months. Our study shows that expression of VEGF in renal tissue may serve as a molecular marker of renal damage and may be a predictive factor for short-term loss of kidney function in patients with LN.