Other researchers have reported significantly lower levels of MT1 expression in RA synovial tissue compared with normal healthy tissue, and the finding that siRNAs against MT1 reverse melatonin-mediated inhibition of TNF-α and IL-1β production, confirming that melatonin suppresses TNF-α and IL-1β via the MT1 receptor [20]. Here, IL1B is linked to rheumatoid arthritis.