The CD6/ALCAM pathway promotes lupus nephritis via T cell-mediated responses

Area of Science:

• Immunology
• Nephrology
• Molecular Biology

Background:

• T cells are critical in the development of lupus nephritis (LN), a kidney complication of systemic lupus erythematosus (SLE).
• The CD6 and activated leukocyte cell adhesion molecule (ALCAM) pathway is implicated in T cell activation and movement.
• Elevated urinary soluble ALCAM (uALCAM) in LN patients suggests this pathway's role in disease pathogenesis.

Purpose of the Study:

• To validate uALCAM as a biomarker for active renal involvement in SLE across diverse populations.
• To investigate the expression of CD6 and ALCAM in kidney tissue from LN patients.
• To evaluate the therapeutic potential of blocking the CD6/ALCAM pathway in preclinical models of lupus and glomerulonephritis.

Main Methods:

• Analysis of urinary ALCAM levels in 1038 SLE patients with LN from five ethnically diverse cohorts.
• Assessment of CD6 and ALCAM expression on kidney cells from LN patients.
• CD6 antibody blockade in murine models of spontaneous lupus and immune-complex glomerulonephritis.

Main Results:

• Urinary ALCAM levels robustly identified active renal disease in SLE patients, independent of ethnicity.
• ALCAM was found on renal structural cells, while CD6 was specific to T cells; both were elevated in LN kidneys.
• CD6 blockade significantly reduced immune cell infiltration, inflammatory markers, and overall disease severity in preclinical models.

Conclusions:

• The CD6/ALCAM pathway plays a significant role in the pathogenesis of lupus nephritis and SLE.
• Urinary ALCAM is a validated, ethnicity-independent biomarker for active renal disease in SLE.
• The CD6/ALCAM pathway represents a promising therapeutic target for lupus nephritis.