Complement Properdin Determines Disease Activity in MRL/lpr Mice

Evaluation of serum and peritoneal fluid mannose-binding lectin associated serine protease-3, adipsin, properdin, and complement factor-H levels in endometriosis patients

OBJECTIVE

Endometriosis is a chronic disease which has been reported to be associated with distorted immune mechanisms. The alternative pathway is a complement system which plays a role in immune defense. The present study aimed to evaluate whether the level of alternative complement molecules differ in women with endometriosis compared to heathy individuals.

METHODS

A total of 58 women participated in this prospective research. Women with a diagnosis of endometriosis confirmed by laparoscopy (n = 32) were compared to healthy women (n = 26) in terms of serum adipsin, properdin, mannose-binding lectin-associated serine protease-3 and complement factor-H (CFH) levels. The peritoneal fluid samples which were taken during the endometriosis surgery were also analyzed in terms of the complement levels. The clinical and demographic data including the serum CA-125 level and pelvic pain were also analyzed. SPSS version 23.0 was used in statistical analysis.

RESULTS

The serum levels of adipsin and CFH were found to be significantly increased in women with endometriosis (P = 0.027 and P = 0.040, respectively). Serum adipsin level was found to significantly correlate with serum CA-125 level (r = 0.320, P = 0.015), serum CFH level (r = 0.705, P < 0.001), and degree of the pelvic pain complaint (r = 0.326, P = 0.013). A strong, positive correlation was also observed between peritoneal fluid levels of adipsin, and CFH (r = 0.593; P < 0.001).

CONCLUSION

To the best of our knowledge, the present study is the first to evaluate the alternative complement system in women with endometriosis. The current findings may be noteworthy to elucidate the possible role of the key molecules of the alternative pathway in endometriosis pathogenesis.

Vγ6+γδT Cells Participate in Lupus Nephritis in MRL/Lpr Mice

BACKGROUND

γδT cells have been implicated in the pathogenesis of autoimmune diseases. The study aims to investigate the abundance of γδT cells in MRL/lpr mice.

METHODS

MRL/lpr mice were used as lupus models, while C3H/HeJ mice served as normal controls. The abundance of γδT cells in different organs was examined by flow cytometry. Plasma double-stranded DNA antibody levels, blood urea nitrogen, creatinine, and urinary protein levels were measured. Renal histopathology was observed via H&E staining. The correlations between the abundance of γδT cells and lupus manifestations were analyzed.

RESULTS

Compared with C3H/HeJ mice, the number of γδT cells and Vγ6+γδT cell subset in the peripheral blood of MRL/lpr mice was significantly reduced. However, in the kidney, the number of γδT cells and Vγ6+γδT cell subset was significantly increased. Additionally, the number of Vγ6+γδT cells in the kidney was positively correlated with the urinary protein level. The number of IFN-γ+Vγ6+γδT cells in the kidney was positively correlated with urinary protein level.

CONCLUSION

In MRL/lpr mice, it is likely that peripheral γδT cells, especially the Vγ6 subset, infiltrate the kidney and secrete IFN-γ, which contributes to the development of lupus nephritis.

Urinary biomarkers for active Lupus Nephritis that have survived independent validation across cohorts

Most reported biomarkers for lupus nephritis (LN) have not been independently validated across cohorts. Moreover, many of the documented biomarker candidates have been reported to be elevated in LN compared to healthy controls. However, biomarkers that distinguish patients with active LN (ALN) from inactive systemic lupus erythematosus (iSLE) hold significant clinical utility. Hence, our review attempts to identify urine protein biomarkers for LN that have been independently validated across two or more cohorts and exhibit good diagnostic potential for distinguishing ALN from iSLE. PubMed and OVID were screened for studies assessing the diagnostic value of urinary biomarkers in patients with ALN compared to iSLE. Forty peer-reviewed articles were evaluated, encompassing urine biomarker data from 3,411 distinct patients. Of the 32 candidate biomarkers identified, fourteen were repeatedly reported/tested in four or more papers each, namely ALCAM, CCL2 (MCP1), CD163, HAVCR1 (KIM-1), HPGDS, ICAM-1 (CD54), ICAM-2 (CD102), IGFBP-2, LCN2, NCAM-1 (CD56), SELE (E-Selectin), SELL (L-Selectin), TNFSF12 (TWEAK), and VCAM-1, with most exhibiting C-statistics of 0.80 or more across multiple studies when discriminating patients with ALN from iSLE. The 32 reproducibly elevated biomarkers for active LN mapped to nine functional categories. The urinary proteins reported here promise to serve as a liquid biopsy for ALN. Besides representing potential candidates for diagnostic, monitoring, predictive, and prognostic biomarkers in LN, they also provide a window into potential molecular processes within the kidney that may be driving LN. Thus, ongoing advances in proteomics, which offer wider proteome coverage at increased sensitivity, are likely to further reshape our perspective of urinary biomarkers for LN.

Knockdown of USF2 inhibits pyroptosis of podocytes and attenuates kidney injury in lupus nephritis

As an essential factor in the prognosis of Systemic lupus erythematosus (SLE), lupus nephritis (LN) can accelerate the rate at which patients with SLE can transition to chronic kidney disease or even end-stage renal disease (ESRD). Proteinuria due to decreased glomerular filtration rate following podocyte injury is LN's most common clinical manifestation. Podocyte pyroptosis and related inflammatory factors in its process can promote lupus to involve kidney cells and worsen the occurrence and progression of LN, but its regulatory mechanism remains unknown. Accumulating evidence has shown that upstream stimulatory factor 2 (USF2) plays a vital role in the pathophysiology of kidney diseases. In this research, multiple experiments were performed to investigate the role of USF2 in the process of LN. USF2 was abnormally highly expressed in MRL/lpr mice kidney tissues. Renal function impairment and USF2 mRNA levels were positively correlated. Silencing of USF2 in MRL/lpr serum-stimulated cells significantly reduced serum-induced podocyte pyroptosis. USF2 enhanced NLRP3 expression at the transcriptional level. Silencing of USF2 in vivo attenuated kidney injury in MRL/lpr mice, which suggests that USF2 is important for LN development and occurrence.

Exploring urine:serum fractional excretion ratios as potential biomarkers for lupus nephritis

Objectives

The goal of this exploratory study is to determine if urine:serum fractional excretion ratios can outperform the corresponding urinary biomarker proteins in identifying active renal disease in systemic lupus erythematosus (SLE).

Methods

Thirty-six adult SLE patients and twelve healthy controls were examined for serum and urine levels of 8 protein markers, namely ALCAM, calpastatin, hemopexin, peroxiredoxin 6 (PRDX6), platelet factor 4 (PF4), properdin, TFPI and VCAM-1, by ELISA. Fractional excretion of analyzed biomarkers was calculated after normalizing both the urine and serum biomarker levels against creatinine. A further validation cohort of fifty SLE patients was included to validate the initial findings.

Results

The FE ratios of all 8 proteins interrogated outperformed conventional disease activity markers such as anti-dsDNA, C3 and C4 in identifying renal disease activity. All but VCAM-1^FE were superior to the corresponding urine biomarkers levels in differentiating LN activity, exhibiting positive correlation with renal SLEDAI. ALCAM^FE, PF4^FE and properdin^FE ratios exhibited the highest accuracy (AUC>0.9) in distinguishing active LN from inactive SLE. Four of the FE ratios exhibited perfect sensitivity (calpastatin, PRDX6, PF4 and properdin), while ALCAM^FE, PF4^FE and properdin^FE exhibited the highest specificity values for active LN. In addition, several of these novel biomarkers were associated with higher renal pathology activity indices. In the validation cohort ALCAM^FE, PF4^FE and properdin^FE once again exhibited higher accuracy metrics, surpassing corresponding urine and serum biomarkers levels, with ALCAM^FE exhibiting 95% accuracy in distinguishing active LN from inactive SLE.

Conclusions

With most of the tested proteins, urine:serum fractional excretion ratios outperformed corresponding urine and serum protein measurements in identifying active renal involvement in SLE. Hence, this novel class of biomarkers in SLE ought to be systemically evaluated in larger independent cohorts for their diagnostic utility in LN assessment.