Biomarkers in lupus nephritis

Identification of a circRNA-miRNA-mRNA network to explore the effects of circRNAs on renal injury in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease. At present, the mechanism of non-coding RNA in renal injury in SLE patients is still unclear. A total of 64 DEcircRNAs, 75 DEmiRNAs, and 249 DEmRNAs were identified. We integrated 10 circRNAs, 10 miRNAs, and 88 target mRNAs into a circRNA-miRNA-mRNA network and obtained 9 hub genes (circ-0000006, miR-766-3p, miR-409-3p, miR-339-3p, miR-331-3p, miR-140-3p, miR-186-5p, miR-149-5p, PSME3). The ROC curve results showed that the diagnostic efficiency of 6 hub miRNA was higher than that of has_circ_0000006 and PSEME3. SsGSEA analysis revealed immune cell composition in SLE and control renal tissues, including 3 types of immune cells up-regulated (gamma delta T cell, effector memory CD4 T cell, central memory CD8 T cell) and 4 types down-regulated (memory B cell, mast cell, macrophage, immature dendritic cell, eosinophil) in SLE patients. In addition, PSME3 was negatively correlated with 3 up-regulated immune cells and positively correlated with 4 down-regulated immune cells in SLE patients. Our study provides a deeper understanding of the circRNA-related competing endogenous RNA regulatory mechanism in the renal injury of systemic lupus erythematosus.

Insulin-Like Growth Factor Binding Protein-4 as a Marker of Chronic Lupus Nephritis

Kidney biopsy remains the mainstay of Lupus Nephritis (LN) diagnosis and prognostication. The objective of this study is to identify non-invasive biomarkers that closely parallel renal pathology in LN. Previous reports have demonstrated that serum Insulin-like growth factor binding protein 4 (IGFBP-4) was increased in diabetic nephropathy in both animal models and patients. We proceeded to assess if IGFBP4 could be associated with LN. We performed ELISA using the serum of 86 patients with LN. Normal healthy adults (N = 23) and patients with other glomerular diseases (N = 20) served as controls. Compared to the healthy controls or other glomerular disease controls, serum IGFBP-4 levels were significantly higher in the patients with LN. Serum IGFBP-4 did not correlate well with systemic lupus erythematosus disease activity index (SLEDAI), renal SLEDAI or proteinuria, but it did correlate with estimated glomerular filtration rate (R = 0.609, P < 0.0001). Interestingly, in 18 patients with proliferative LN whose blood samples were obtained at the time of renal biopsy, serum IGFBP-4 levels correlated strongly with the chronicity index of renal pathology (R = 0.713, P < 0.001). IGFBP-4 emerges a potential marker of lupus nephritis, reflective of renal pathology chronicity changes.

High SIPA-1 expression in proximal tubules of human kidneys under pathological conditions

Systemic lupus erythematosus (SLE) and clear cell renal cell carcinoma (CC-RCC) are serious disorders and usually fatal, and always accompanied with pathological changes in the kidney. Signal-induced proliferation-associated protein 1 (SIPA-1) is a Rap1GTPase activating protein (Rap1GAP) expressed in the normal distal and collecting tubules of the murine kidney. Lupus-like autoimmune disease and leukemia have been observed in SIPA-1 deficient mice, suggesting a pathological relevance of SIPA-1 to SLE and carcinoma in human being. The expression pattern of SIPA-1 is as yet undefined and the pathogenesis of these diseases in humans remains elusive. In this study, we used both immunohistochemistry and quantum dot (QD)-based immunofluorescence staining to investigate the expression of SIPA-1 in renal specimens from SLE and CC-RCC patients. MTT assay and Western blotting were employed to evaluate the effects of SIPA-1 overexpression on the proliferation and apoptosis of renal cell lines. Semi-quantitative reverse transcriptase-PCR (RT-PCR) was applied to examine the changes of hypoxia-inducible factor-1α (HIF-1α) mRNA level. Results showed that SIPA-1 was highly expressed in the proximal and collecting tubules of nephrons in SLE patients compared to normal ones, and similar results were obtained in the specimens of CC-RCC patients. Although SIPA-1 overexpression did not affect cellular proliferation and apoptosis of both human 786-O renal cell carcinoma cells and rat NRK-52E renal epithelial cell lines, RT-PCR results showed that HIF-1α mRNA level was down-regulated by SIPA-1 overexpression in 786-O cells. These findings suggest that SIPA-1 may play critical roles in the pathological changes in kidney, and might provide a new biomarker to aid in the diagnosis of SLE and CC-RCC.

Measuring eosinophiluria, urinary eosinophil cationic protein and urinary interleukin-5 in patients with Lupus Nephritis

BACKGROUND

Urine is increasingly becoming an attractive biological fluid in clinical practice due to being an easily obtained, non-invasive sampling method, containing proteins and peptides. The aim of this study was to investigate eosinophiluria, urinary eosinophil cationic protein (uECP) and urinary IL-5 (uIL-5) in patients with Lupus Nephritis.

METHODS

Seventy-four patients with SLE-20 with clinical and laboratory evidence of lupus nephritis (LN group) and 54 without evidence of renal involvement (non-LN group)-were analyzed regarding eosinophiluria, uECP and uIL-5. Eosinophiluria was observed by Hansel's stain, ECP by fluoroenzymeimmunoassay and uIL-5 by quantitative sandwich enzyme immunoassay. Both uECP and urinary IL-5 (uIL-5) were corrected by urinary creatinine. Eosinophiluria and uECP were compared with glomerular erythrocyturia, protein/creatinine ratio (Pr/Cr ratio), serum creatinine, estimated glomerular filtration rate (eGFR), anti-double-stranded DNA (anti-dsDNA), serum levels of complement (C3 and C4), uIL-5/Cr ratio, and SLE disease activity index.

RESULTS

Patients of the LN group had higher eosinophiluria, uECP, uECP/Cr ratio levels, and uIL-5 than patients of the non-LN group (p<0.001 for all). These variables showed a statistically significant correlation with glomerular erythrocyturia, casts, Pr/Cr ratio, serum creatinine, eGFR, anti-dsDNA, uIL-5/Cr, and SLE disease activity index (all p<0.05).

CONCLUSION

These results provide evidence of increased urinary eosinophils, ECP and IL-5 in patients with SLE and LN; uECP/Cr ratio showed better correlation with markers of renal function and SLE disease activity.

Correlation between Doppler parameters and renal cortical fibrosis in lupus nephritis: a preliminary observation

To assess the relationship between renal Doppler parameters and renal cortical fibrosis in lupus nephritis (LN), we retrospectively reviewed 24 patients with LN underwent both renal color Doppler sonography and renal biopsy. The angle-corrected Doppler parameters, including peak systolic velocity (PSV), end diastolic velocity (EDV) and resistive index (RI) at the main and interlobar renal arteries were measured. The Doppler parameters and PSV and EDV ratios of the interlobar artery to main renal artery were compared with histopathologic analysis of the kidney biopsy specimen. On the basis of renal cortical fibrosis, the 24 cases of LN were divided into two groups: mild (6%-25%) renal cortex fibrosis (n = 13) and moderate (26%-50%) renal cortex fibrosis (n = 11). An independent-samples two tailed t test was used to statistically analyze the differences in PSV, EDV and RI between the two groups. Receiver operating characteristic was analyzed for assessing the accuracy of interlobar artery PSV and EDV in predicting moderate renal cortical fibrosis. In our result, both PSV and EDV in moderate renal cortex fibrosis were lower than that in mild renal cortex fibrosis. There were statistically significant differences in PSV and EDV at the interlobar artery, EDV and RI at the main renal artery, and PSV and EDV ratios of the interlobar artery to main renal artery between the two groups (all p < 0.05). The area under receiver operating characteristic curves of PSV and EDV for predicting >26% renal cortical fibrosis was 0.96 and 0.90, respectively. The optimal cutoff values for differentiating >26% renal cortical fibrosis from those <25% were PSV 30 cm/s (sensitivity = 0.92; specificity = 1) and EDV 13 cm/s (sensitivity = 0.77; specificity = 1). Therefore, the values of PSV and EDV at the interlobar artery can potentially be used as hemodynamic indicators of renal cortical fibrosis, which may non-invasively assist in monitoring the progression of renal cortical fibrosis in LN, especially in patients with contraindications to renal biopsy.

Expression of human tumor necrosis factor-like weak inducer of apoptosis in patients with systemic lupus erythematosus

The aim of this study was to compare the mRNA and serum expression of tumor necrosis factor (TNF)-like weak inducer of apoptosis (TWEAK) in patients with systemic lupus erythematosus (SLE) and healthy controls. Sixty-two SLE patients and 15 healthy controls were recruited in the study. TWEAK messenger RNA (mRNA) expression in peripheral blood mononuclear cells (PBMCs) from 33 of 62 patients was detected by relative quantification RT-PCR. TWEAK concentrations in the sera of all 62 patients were measured by ELISA. TWEAK mRNA expressions in PBMCs were decreased in SLE patients compared with healthy controls. Lower TWEAK mRNA expression was also found in the active SLE patients when compared to inactive ones. However, there was no significant difference between patients with lupus nephritis (LN) and those without. The level of serum TWEAK (sTWEAK) in SLE patients was increased when compared to healthy controls. In addition, the sTWEAK level was higher in SLE patients with vasculitis than those without vasculitis, and so was in comparison between patients with and without headache. Nevertheless, no significant differences were found between active SLE patients and inactive patients, or between LN patients and non-LN SLE patients. In this study, patients with SLE express low levels of TWEAK mRNA but high levels of sTWEAK. Additionally, sTWEAK level was associated with several clinical manifestations of SLE, indicating that TWEAK may play a complex role in SLE.

IFN-α mediates the development of autoimmunity both by direct tissue toxicity and through immune cell recruitment mechanisms

IFN-α is known to play a key role in autoimmunity, but the mechanisms are uncertain. Although the induction of autoimmunity by IFN-α is consistent with primarily immunomodulatory effects, the high frequency of nonautoimmune inflammation suggests other mechanisms. We used thyroiditis as a model to dissect these possibilities. IFN-α treatment of cultured thyrocytes increased expression of thyroid differentiation markers, thyroglobulin, thyroid-stimulating hormone receptor, thyroid peroxidase, and sodium iodide transporter. RNAseq analysis demonstrated that pathways of Ag presentation, pattern recognition receptors, and cytokines/chemokines were also stimulated. These changes were associated with markedly increased nonapoptotic thyroid cell death, suggesting direct toxicity. To corroborate these in vitro findings, we created transgenic mice with thyroid-specific overexpression of IFN-α under control of the thyroglobulin promoter. Transgenic mice developed marked inflammatory thyroid destruction associated with immune cell infiltration of thyroid and surrounding tissues leading to profound hypothyroidism, findings consistent with our in vitro results. In addition, transgenic mice thyroids showed upregulation of pathways similar to those observed in cultured thyrocytes. In particular, expression of granzyme B, CXCL10, a subset of the tripartite motif-containing family, and other genes involved in recruitment of bystander cytotoxic immune responses were increased. Pathways associated with apoptosis and autophagy were not induced. Taken together, our data demonstrate that the induction of tissue inflammation and autoimmunity by IFN-α involves direct tissue toxic effects as well as provocation of destructive bystander immune responses.