Macrophage release of transforming growth factor beta1 during resolution of monosodium urate monohydrate crystal-induced inflammation.
OBJECTIVE
It has previously been shown that as monocytes differentiate into macrophages, they lose the ability to secrete proinflammatory cytokines in response to monosodium urate monohydrate (MSU) crystals. The purpose of this study was to investigate whether MSU crystals induce macrophages to secrete antiinflammatory factor instead.


METHODS
Human monocyte or macrophage isolates were prepared from samples obtained from healthy volunteer donors either by differentiation of blood monocytes in vitro or by collecting cells from skin blisters during the early or late phase of the dermal inflammatory response to cantharidin. Monocyte or macrophage isolates were then incubated with MSU crystals for 24 hours, and culture supernatants were assayed for candidate antiinflammatory mediators (by enzyme-linked immunosorbent assay) and for the capacity to activate or suppress endothelial cell E-selectin expression and secondary neutrophil recruitment under shear flow.


RESULTS
Analysis of supernatants from in vitro-differentiated macrophages revealed that transforming growth factor beta1 (TGFbeta1) was induced following MSU crystal stimulation (mean +/- SEM 1.50 +/- 0.24 ng/ml/10(6) cells), but there was no evidence of interleukin-10 (IL-10), IL-1 receptor antagonist, or tumor necrosis factor (TNF) receptor p55 release. Macrophage TGFbeta1 significantly suppressed endothelial cell E-selectin expression and secondary neutrophil capture on endothelial monolayers stimulated with supernatants from MSU-treated monocytes. Leukocytes isolated from resolving (40-hour) skin blisters similarly elaborated TGFbeta1 when challenged with MSU crystals (0.66 +/- 1.3 ng/ml/10(5) CD14+ cells). In contrast, cells isolated from acute (16-hour) skin blisters secreted TNFalpha (0.49 +/- 0.08 ng/ml/10(5) CD14+ cells) but no detectable TGFbeta1.


CONCLUSIONS
These data provide further support for the concept that differentiated macrophages play a protective role in the pathophysiology of gout, and they identify macrophage TGFbeta1 as a mediator of paracrine suppression during the resolution phase of inflammation.
Yagnik
Darshna R
DR
Imperial College London, Hammersmith Hospital, London, UK.
Evans
Betsy J
BJ
Florey
Oliver
O
Mason
Justin C
JC
Landis
R Clive
RC
Haskard
Dorian O
DO
D000893:Anti-Inflammatory Agents / Q000378:metabolism*; D001768:Blister / Q000139:chemically induced / Q000378:metabolism*; D002193:Cantharidin; D002478:Cells, Cultured; D003460:Crystallization; D019040:E-Selectin / Q000187:drug effects / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects; D006801:Humans; D007249:Inflammation / Q000139:chemically induced* / Q000378:metabolism*; D007962:Leukocytes / Q000187:drug effects / Q000378:metabolism; D008264:Macrophages / Q000187:drug effects* / Q000378:metabolism*; D009000:Monocytes / Q000187:drug effects / Q000378:metabolism; D013997:Time Factors; D016212:Transforming Growth Factor beta / Q000378:metabolism*; D053773:Transforming Growth Factor beta1; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D014527:Uric Acid / Q000737:chemistry / Q000494:pharmacology*
D000893:Anti-Inflammatory Agents; D019040:E-Selectin; C508960:TGFB1 protein, human; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D014409:Tumor Necrosis Factor-alpha; D014527:Uric Acid; D002193:Cantharidin