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TNF-? has both stimulatory and inhibitory effects on mouse monocyte-derived osteoclastogenesis.

ABSTRACT: Phenotypically different osteoclasts may be generated from different subsets of precursors. To what extent the formation of these osteoclasts is influenced or mediated by the inflammatory cytokine TNF-?, is unknown and was investigated in this study. The osteoclast precursors early blasts (CD31^hi Ly-6C^- ), myeloid blasts (CD31⁺ Ly-6C⁺ ), and monocytes (CD31^- Ly-6C^hi ) were sorted from mouse bone marrow using flow cytometry and cultured with M-CSF and RANKL, with or without TNF-?. Surprisingly, TNF-? prevented the differentiation of TRAcP⁺ osteoclasts generated from monocytes on plastic; an effect not seen with early blasts and myeloid blasts. This inhibitory effect could not be prevented by other cytokines such as IL-1? or IL-6. When monocytes were pre-cultured with M-CSF and RANKL followed by exposure to TNF-?, a stimulatory effect was found. TNF-? also stimulated monocytes' osteoclastogenesis when the cells were seeded on bone. Gene expression analysis showed that when TNF-? was added to monocytes cultured on plastic, RANK, NFATc1, and TRAcP were significantly down-regulated while TNF-?R1 and TNF-?R2 were up-regulated. FACS analysis showed a decreased uptake of fluorescently labeled RANKL in monocyte cultures in the presence of TNF-?, indicating an altered ratio of bound-RANK/unbound-RANK. Our findings suggest a diverse role of TNF-? on monocytes' osteoclastogenesis: it affects the RANK-signaling pathway therefore inhibits osteoclastogenesis when added at the onset of monocyte culturing. This can be prevented when monocytes were pre-cultured with M-CSF and RANKL, which ensures the binding of RANKL to RANK. This could be a mechanism to prevent unfavorable monocyte-derived osteoclast formation away from the bone.

SUBMITTER: Cao Y

PROVIDER: S-EPMC5601245 | biostudies-literature | 2017 Dec

REPOSITORIES: biostudies-literature

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TNF-α has both stimulatory and inhibitory effects on mouse monocyte-derived osteoclastogenesis.

Cao Yixuan Y Jansen Ineke D C IDC Sprangers Sara S de Vries Teun J TJ Everts Vincent V

Journal of cellular physiology 20170717 12

Phenotypically different osteoclasts may be generated from different subsets of precursors. To what extent the formation of these osteoclasts is influenced or mediated by the inflammatory cytokine TNF-α, is unknown and was investigated in this study. The osteoclast precursors early blasts (CD31hi Ly-6C- ), myeloid blasts (CD31+ Ly-6C+ ), and monocytes (CD31- Ly-6Chi ) were sorted from mouse bone marrow using flow cytometry and cul ...[more]

PMID: 28543070

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Project description:Mouse pancreatic islets were used to investigate how muscarinic stimulation influences the cytoplasmic Ca2+ concentration ([Ca2+]i) in insulin-secreting B-cells. In the absence of extracellular Ca2+, acetylcholine (ACh) triggered a transient, concentration-dependent and thapsigargin-inhibited increase in [Ca2+]i. In the presence of extracellular Ca2+ and 15 mM glucose, ACh induced a biphasic rise in [Ca2+]i. The initial, transient phase increased with the concentration of ACh, whereas the second, sustained, phase was higher at low (0.1-1 microM) than at high (> or = 10 microM) concentrations of ACh. Thapsigargin attenuated (did not suppress) the first phase of the [Ca2+]i rise and did not affect the sustained response. This sustained rise was inhibited by omission of extracellular Na+ (which prevents the depolarizing action of ACh) and by D600 or diazoxide (which prevent activation of voltage-dependent Ca2+ channels). During steady-state stimulation, the Ca2+ action potentials in B-cells were stimulated by 1 microM ACh but inhibited by 100 microM ACh. When B-cells were depolarized by 45 mM K+, ACh induced a concentration-dependent, biphasic change in [Ca2+]i, consisting of a first peak rapidly followed by a decrease. Thapsigargin suppressed the peak without affecting the drop in [Ca2+]i. Measurements of 45Ca2+ efflux under similar conditions indicated that ACh decreases Ca2+ influx and slightly increases the efflux. All effects of ACh were blocked by atropine. In conclusion, three mechanisms at least are involved in the biphasic change in [Ca2+]i that muscarinic stimulation exerts in excitable pancreatic B-cells. A mobilization of Ca2+ from the endoplasmic reticulum contributes significantly to the first peak, but little to the steady-state rise in [Ca2+]i. This second phase results from an influx of Ca2+ through voltage-dependent Ca2+ channels activated by a Na(+)-dependent depolarization. However, when high concentrations of ACh are used, Ca2+ influx is attenuated.

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TNF-? has both stimulatory and inhibitory effects on mouse monocyte-derived osteoclastogenesis.

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TNF-α has both stimulatory and inhibitory effects on mouse monocyte-derived osteoclastogenesis.

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