Research report: Liraglutide regulate osteogenesis-resorption via macrophage under compressive stress

Liraglutide, the widely prescribed GLP-1 receptor agonist best known for lowering blood sugar and aiding weight loss, may have a second career waiting in joint medicine. A new cell study from researchers at the Stomatological Hospital of Dalian University, published in Frontiers in Pharmacology, reports that the drug can reverse the bone-destroying effects of mechanical pressure on macrophages, the immune cells that act as gatekeepers of bone metabolism inside joints. The work offers the first molecular map of how liraglutide intervenes in the chain of events that links chronic joint overload to cartilage destruction and bone resorption, the hallmark processes behind osteoarthritis and temporomandibular joint osteoarthritis.

The research team, led by Shuang Liu with co-first authors Runze Kong and Difei Wu, focused on a problem that grows more urgent as populations age. Joints are built to translate mechanical force into healthy tissue turnover: appropriate loading stimulates chondrocyte metabolism and maintains normal bone remodeling. But prolonged abnormal pressure, whether from overuse or internal structural disorders such as disc displacement, disrupts that homeostasis and triggers a cascade of cartilage degeneration, synovial inflammation, and bone resorption.

Osteoarthritis is already one of the leading causes of disability worldwide, and temporomandibular joint osteoarthritis impairs basic functions like chewing and speech. The elderly and obese populations who most commonly take GLP-1 receptor agonists are precisely the groups at highest risk of joint degeneration, making the question of whether these drugs protect joints directly relevant to millions of patients. To model mechanical overload in the laboratory, the researchers built a gravity-loading device using customized smooth glass discs placed on top of monolayers of RAW264.7 macrophages, a murine macrophage cell line.

By varying the thickness of the discs, they generated static pressures of 1, 2, and 3 grams per square centimeter, applied for periods ranging from one to twelve hours. Pressure was calculated from the density and height of the glass according to the formula P = ρh. The team then screened these conditions using CCK-8 viability assays and live/dead staining to find a pressure regime that activated mechanotransduction pathways without simply killing the cells.

The screening revealed a clear dose and time dependence. Cell viability declined with increasing pressure at equivalent time points, dropping sharply between two and four hours; under 2 grams per square centimeter at three hours, viability fell below half of the control level. Yet the majority of cells survived at the four-hour mark, and viability recovered from three hours onward.

Crucially, the molecular readouts peaked in concert at that same time point: the mechanosensitive ion channel Piezo1, the master osteoclast transcription factor NFATc1, and the osteoclast marker enzyme TRAP all reached maximum expression at four hours under 2 grams per square centimeter. The researchers argue that this coordinated, liraglutide-reversible pattern reflects genuine mechanotransduction rather than nonspecific cell injury, which justified selecting 2 grams per square centimeter for four hours as the standard condition for all subsequent experiments. That condition produced a telling picture of what mechanical stress does to macrophages.

Alongside the osteoclastogenic markers, the pressured cells ramped up expression of the pro-inflammatory mediators TNF-α, iNOS, and IL-1β, with IL-1β rising in a time-dependent fashion. The authors interpret this as a dual threat: pressure not only pushes macrophages toward an osteoclast-like fate through Piezo1-mediated calcium influx and NFATc1 activation, but simultaneously creates an inflammatory microenvironment that feeds back to amplify bone resorption. In real joints, macrophages are the most abundant immune cell population, and they sit at the crossroads of mechanical and inflammatory signaling, polarizing toward the pro-inflammatory M1 phenotype and releasing factors that promote osteoclast differentiation.

Elevated TNF-α and IL-1β are readily detected in the synovial fluid of patients with osteoarthritis and temporomandibular joint osteoarthritis, where they degrade cartilage matrix and activate NF-κB in osteoblasts and synovial fibroblasts, driving up RANKL expression and fueling further resorption. Into this pressured environment the researchers introduced liraglutide at a concentration of 250 nanomoles per liter, pretreating the macrophages for four hours before loading. The results split cleanly along the signaling cascade.

Liraglutide did not touch Piezo1 expression, meaning it does not interfere with the cell's ability to sense pressure in the first place. But it markedly suppressed the pressure-induced upregulation of NFATc1 and TRAP at both the mRNA and protein levels, confirmed by quantitative PCR, immunofluorescence staining, and Western blotting. In other words, the drug leaves the mechanical antenna intact but cuts the wire between sensor and effector, intercepting the signal after it has been transduced and blocking the NFATc1-dependent transcriptional program that would otherwise drive osteoclast differentiation.

The anti-inflammatory arm of the effect proved equally concrete. Liraglutide significantly reduced expression of TNF-α, iNOS, and IL-1β, and the protein-level assays showed inhibition of TRAF6, total NF-κB p65, and phosphorylated NF-κB p65. TRAF6 is the adaptor molecule that bridges inflammatory receptors such as toll-like receptors and the IL-1 receptor to the canonical NF-κB pathway; once activated, NF-κB phosphorylates, enters the nucleus, and switches on pro-inflammatory genes.

By reducing both the abundance of the upstream adaptor and the activation of the central transcription factor, liraglutide appears to interfere with this axis at multiple levels. This convergence matters because inflammatory cytokines and osteoclastogenic signals reinforce one another, so damping the inflammatory loop also weakens the pressure-driven push toward bone resorption. The third piece of the puzzle came from an indirect co-culture experiment.

The team collected conditioned medium from the treated macrophages, mixed it with fresh α-MEM at a one-to-one ratio, and used it to culture MC3T3-E1 pre-osteoblasts, which were then pushed through osteogenic induction for up to 21 days with alkaline phosphatase and Alizarin Red S staining to track mineralization. Conditioned medium from liraglutide-treated macrophages significantly upregulated the osteogenic markers BMP2, RUNX2, ALP, and OCN in the pre-osteoblasts, with immunofluorescence confirming enhanced ALP and RUNX2 protein. RUNX2 is the master transcription factor that activates ALP and OCN, while BMP2 acts upstream through the Smad pathway to boost RUNX2 activity.

The authors suggest that by suppressing M1-type inflammatory cytokines, liraglutide may shift macrophage secretory function toward a bone-supportive profile, though they candidly note a caveat: because some liraglutide may remain in the conditioned medium, a direct osteogenic effect of the drug on the pre-osteoblasts cannot be excluded. Taken together, the study portrays liraglutide as a triple-acting agent in the pressured joint: it blocks osteoclastogenesis downstream of mechanosensing, suppresses the TRAF6-NF-κB inflammatory axis, and indirectly promotes bone formation by reshaping what macrophages secrete. The authors frame this as systemic regulation of the coupled osteoclast-osteoblast network rather than three independent effects, since the same inflammatory signals that amplify NFATc1 also suppress the osteogenic side of the balance.

The limitations, however, are stated plainly by the researchers themselves. The entire study rests on cell culture, with no animal validation yet; the in vivo bone metabolic microenvironment involves multiple cell types, cytokine networks, and systemic regulators that a single cell line cannot reproduce. Whether liraglutide acts through the GLP-1 receptor in this context also remains unproven, and would require receptor blocking or silencing experiments to establish.

The team says its next step is to identify an animal model that faithfully simulates abnormal mechanical force-induced joint inflammation and to test the drug's effects and mechanisms in that setting. Even with those caveats, the findings land at an opportune moment. GLP-1 receptor agonists have achieved remarkable clinical success in diabetes and obesity, and accumulating evidence already suggests they carry bone-protective and anti-inflammatory properties partly independent of their metabolic effects, including inhibition of RANKL- and LPS-induced osteoclast differentiation and promotion of osteoblast mineralization in earlier work.

For now, the message is a measured one: in a dish, under precisely calibrated weight, liraglutide taught macrophages to stop breaking bone and start supporting its repair.

Subject of Research: Effects of liraglutide on macrophage-mediated bone metabolism under mechanical compressive stress in vitro

Article Title: Liraglutide regulate osteogenesis-resorption via macrophage under compressive stress

Article References: Kong, R., Wu, D., Men, X., He, Y., Du, Q., & Liu, S. (2026). Liraglutide regulate osteogenesis-resorption via macrophage under compressive stress. Frontiers in Pharmacology, 17, Article 1985291. https://doi.org/10.3389/fphar.2026.1985291

Image Credits: AI Generated

DOI: 10.3389/fphar.2026.1985291

Keywords: liraglutide, GLP-1 receptor agonist, macrophages, osteoclastogenesis, NFATc1, NF-κB, Piezo1, mechanical pressure, osteoarthritis, bone resorption, osteogenesis, inflammation