Table 1.

Klotho (KI) involvement in RA, SLE, SSc.

Autoimmune Disease	Klotho Level/Correlation	References
Rheumatoid Arthritis	Low Kl expression in synovial membrane, synovial fibroblasts	37
	Kl is downregulated in CD4+ cells, compared to healthy controls	44
	Kl positively correlates with CD28 on CD4+ cells	45
	Increased Kl in serum, compared to healthy controls	46
	Kl positively correlates with anti-cyclic citrullinated peptide antibody and rheumatic factor	46
Systemic Lupus Erythematosus	Low Kl in cerebrospinal fluid (CSF) is associated with endothelial dysfunction and neuronal damage	51
	Lower CSF Kl, lower serum anti-Smith antibodies, and higher serum C3 were significant factors for predicting neuropsychiatric SLE	51
	Kl in CSF inversely correlates with granulocyte/macrophage-colony stimulating factor in CSF	51
Systemic Sclerosis	Decreased Kl in serum, compared to healthy controls	59
	Lower Kl in microvascular endothelial cells, compared to healthy controls	66