Levels of gastrin-releasing peptide and substance P in synovial fluid and serum correlate with levels of cytokines in rheumatoid arthritis

Table 1 Cytokine and neuropeptide concentrations in synovial fluid

Substance	Early RA (pg/ml)	Long-standing RA (pg/ml)	P	Controls (pg/ml)
Cytokine
TNF-α	8.0^a	7.0^c	ns	nm
	(1.0–47)	(1.0–24)
IL-6	5100^b	3100^d	<0.05	nd^f
	(4500–8000)	(1300–3900)
MCP-1	1200^b	1500^d	ns	620^f
	(810–1800)	(1200–3000)
Neuropeptide
BN/GRP	31^a	17^c	<0.05	nd^g
	(21–39)	(7.0–23)
CGRP	580^b	450^d	ns	nd^f
	(160–1500)	(230–960)
NPY	190^b	260^e	ns	180^f
	(65–320)	(170–500)
SP	48^a	58^c	ns	nd^g
	(36–80)	(42–77)
VIP	150^b	300^d	ns	nm
	(40–200)	(55–630)

Concentrations were measured by ELISA and RIA in synovial fluid from the knee joints of patients with RA and in healthy control subjects. Values are medians (and Q₁–Q₃). P relates to long-standing RA versus early RA (Mann–Whitney test). ^an = 7; ^bn = 6; ^cn = 28; ^dn = 23; ^en = 25; ^fn = 2; ^gn = 10. BN/GRP, bombesin/gastrin-releasing peptide; CGRP, calcitonin-gene-related peptide; MCP-1, monocyte chemoattractant protein-1; nd, not detectable; nm, not measured; NPY, neuropeptide Y; ns, not significant; RA, rheumatoid arthritis; SP, substance P; TNF, tumour necrosis factor; VIP, vasoactive intestinal peptide.

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