Table 1.

Summary of the adverse, neutral, and beneficial effects of melatonin in rheumatoid arthritis.

Adverse/Neutral/Beneficial	Sample/Animal Model/Cell Line	Melatonin Level	Effects		References
Adverse	CIA mice		RA		[40]
Adverse	CIA mice (pinealectomy)		Serum anti-CII RA		[41]
Adverse	RA synovial macrophages/myeloid monocytic cells (THP-1)		IL-12 NO		[33]
Adverse	CIA rats		Anti-collagen antibodies IL-1β and IL-6		[32]
Neutral		Treatment with melatonin	Erythrocyte sedimentation rate (ESR) and neopterin		[35]
Neutral	RA patients’ plasma levels				[36]
Beneficial		Treatment with melatonin	MMP-9		[46]
Beneficial	Fibroblast-like synoviocytes (FLS)	Treatment with melatonin	P21/P27 FLS proliferation		[48]
Beneficial	Synovial fibroblasts	Treatment with melatonin	miR-3150a-3p IL-1β and TNF-α		[20]
Beneficial		Treatment with melatonin	TLR/MAPK Nrf2		[15]
Beneficial		Treatment with melatonin	ROS and RNS glutathione and antioxidant enzymes		[28]
Beneficial	Osteoblast cells	Treatment with melatonin	miR-590-3p Apoptosis		[55]