Osteocytes are the most abundant cells in bone, making up roughly ninety percent of all bone cells, and they orchestrate the constant remodeling dialogue between bone formation and bone resorption. When glucocorticoid excess strikes, trabecular bone—the spongy lattice inside vertebrae and the ends of long bones—suffers the most visible early damage. But clinicians have long observed that cortical bone, the compact shell that provides most of the skeleton’s strength, also deteriorates under prolonged steroid exposure, and that this cortical thinning correlates strongly with nonvertebral fractures. The new research provides a mechanistic account of how the cells inside cortical bone are driven to self-destruction and how their demise translates directly into mineral loss from the surrounding matrix.

The investigative team used a well-established mouse model of glucocorticoid-induced osteoporosis, in which animals receive chronic prednisolone or methylprednisolone treatment sufficient to reproduce the human pattern of rapid bone loss. Using histomorphometry, micro-computed tomography, and dynamic bone labeling, they documented substantial cortical porosity, cortical thinning, and loss of mechanical integrity. Strikingly, the loss was accompanied by a marked depletion of osteocytes within the cortical compartment and by empty lacunae—minute cavities that once housed living cells—scattered throughout the cortex. This pattern suggested that osteocyte death itself, rather than merely elevated resorption by the classic bone-dissolving osteoclasts, might be a primary event in the pathology.

To define the mode of osteocyte death, the researchers examined the molecular machinery of necroptosis, a form of regulated necrosis distinguished from apoptosis by its explosive, membrane-rupturing character and its capacity to release intracellular contents that inflame surrounding tissue. Necroptosis is executed by a signaling complex in which receptor-interacting protein kinase 1 and receptor-interacting protein kinase 3 activate the executioner protein mixed lineage kinase domain-like pseudokinase, or MLKL, which oligomerizes and punches holes in the cell membrane. In the steroid-treated mice, the team found robust activation of this pathway specifically in cortical osteocytes: phosphorylated RIPK3 and phosphorylated MLKL accumulated within lacunar cells, while markers of apoptosis were comparatively modest. Genetic or pharmacological interference with the pathway therefore became the decisive test of causality.

When the researchers crossed their glucocorticoid-treated mice with animals lacking functional MLKL, or when they treated mice with a selective RIPK1 kinase inhibitor, the picture changed dramatically. Cortical bone loss was substantially attenuated: cortical thickness was preserved, porosity declined, and biomechanical testing showed that bones retained significantly more of their strength compared with steroid-treated controls carrying intact necroptosis machinery. Osteocyte lacunae remained populated, and the hallmarks of inflammatory cell death faded. Inhibiting apoptosis, by contrast, produced only modest skeletal protection, reinforcing the conclusion that necroptosis is the dominant death program through which glucocorticoids destroy the osteocyte network in cortical bone.

The most provocative element of the study is the mechanism the authors propose for how dying osteocytes cause resorption of the mineral that surrounds them. Under normal physiological conditions, osteocytes can participate in a process called osteocytic osteolysis, in which stressed or starved osteocytes demineralize and degrade their own perilacunar matrix, releasing calcium and remolding their immediate microenvironment. The study demonstrates that necroptotic death converts this finely regulated process into a destructive free-for-all. As necroptotic osteocytes rupture, they release damage-associated molecular patterns and lysosomal enzymes that acidify the perilacunar space and dissolve the adjacent mineralized collagen matrix. In essence, each dying cell excavates the bone around it, generating the microscopic porosity that, when multiplied across millions of lacunae, hollows out the cortex from within.

Supporting this mechanism, the researchers tracked perilacunar remodeling with dynamic imaging and found that steroid exposure dramatically expanded the demineralized halos around individual lacunae, a signature of aggressive osteocytic osteolysis. They also showed that products released from necroptotic osteocytes could recruit and activate osteoclast precursors, coupling the internal excavation to conventional resorption on bone surfaces. This dual mechanism—autolytic matrix degradation by the dying cells themselves followed by secondary osteoclast activation—offers a coherent explanation for the peculiar severity and speed of glucocorticoid-induced cortical loss, which has never been fully accounted for by osteoclast activity alone.

The clinical implications are considerable. Current management of glucocorticoid-induced osteoporosis relies on calcium and vitamin D supplementation and antiresorptive agents such as bisphosphonates, which dampen osteoclast function but do nothing to protect osteocytes from dying. If necroptosis inhibition shields osteocytes from steroid toxicity in humans as it does in mice, a fundamentally new class of preventive therapy becomes conceivable: drugs that preserve the cellular network inside bone, maintaining the mechanosensory and regulatory functions that keep remodeling balanced, while simultaneously stemming the perilacunar erosion that undermines cortical strength. Inhibitors targeting the RIPK1–RIPK3–MLKL axis are already in clinical development for inflammatory and neurodegenerative diseases, which could accelerate translation into skeletal medicine.

The authors are careful to frame their conclusions within the limits of the model system. Necroptosis is a context-dependent process, and its contribution to bone loss may vary with dose, duration of steroid exposure, age, and species. Human bone biopsies from patients on long-term glucocorticoid therapy will be needed to confirm that the same molecular signature of phosphorylated MLKL and perilacunar demineralization appears in cortical osteocytes in vivo. Nonetheless, the convergence of genetic, pharmacological, and structural evidence in this study provides an unusually complete causal chain, linking a specific cell death program to a specific mode of matrix destruction and to a measurable functional outcome in the skeleton.

Beyond the immediate therapeutic horizon, the work reframes how scientists think about the skeleton’s response to stress. Osteocytes, once viewed as inert placeholders, are now firmly established as the command centers of bone, and their death by necroptosis represents a catastrophic failure of that command infrastructure. The finding that the same cells whose death is triggered by steroid excess then participate in dismantling their own mineralized surroundings blurs the boundary between cell death and bone resorption, suggesting that in disease states the two processes are woven together. For the millions of patients worldwide who depend on glucocorticoids, the study offers a concrete molecular target for keeping their skeletons intact—and a reminder that some of the most important cells in bone are the ones buried deepest inside it.

Subject of Research: Necroptosis of osteocytes as a mechanism of cortical bone resorption in glucocorticoid-induced osteoporosis

Article Title: Osteocyte necroptosis drives cortical bone resorption via osteocytic osteolysis in glucocorticoid-induced osteoporosis

Article References: Osteocyte necroptosis drives cortical bone resorption via osteocytic osteolysis in glucocorticoid-induced osteoporosis. (n.d.). https://doi.org/10.1038/s41420-026-03329-y

Image Credits: AI Generated

DOI: 10.1038/s41420-026-03329-y

Keywords: osteocytes, necroptosis, glucocorticoid-induced osteoporosis, cortical bone, osteocytic osteolysis, MLKL, RIPK3, bone resorption, osteoclasts, perilacunar remodeling, Cell Death Discovery, bone fractures

The new research, conducted at Rabin Medical Center, the largest solid organ transplant center in Israel, and published in Archives of Osteoporosis, followed 39 adults who received teriparatide, a recombinant analogue of human parathyroid hormone, after kidney, lung, or liver transplantation. The investigators report that patients treated with the drug for a median of more than 22 months gained significant bone mineral density at the lumbar spine, femoral neck, and total hip, while clinicians observed acceptable metabolic safety and no episodes of graft rejection during therapy. The findings offer some of the most detailed evidence to date on anabolic osteoporosis treatment in a population that has long been underrepresented in bone research.

The scale of the skeletal problem after transplantation is difficult to overstate. In this cohort, 90 percent of patients had already suffered at least one fragility fracture before starting teriparatide, and 79 percent had multiple broken bones. The immune-suppressing glucocorticoids that nearly all transplant recipients take, at an average dose of around 7 milligrams of prednisone-equivalent per day in this study, directly impair the bone-forming cells called osteoblasts while accelerating bone resorption. Combined with pre-existing organ dysfunction, vitamin D deficiency, and the metabolic upheaval of end-stage organ disease, the result is a skeleton under relentless attack in patients who often cannot tolerate standard therapies.

Teriparatide works differently from the antiresorptive drugs, such as bisphosphonates, that are usually the first line of defense against post-transplant bone loss. Rather than slowing bone breakdown, it stimulates new bone formation by mimicking intermittent pulses of parathyroid hormone, a signal that activates osteoblasts when delivered in daily injections. This anabolic mechanism has made it a first-line option for severe glucocorticoid-induced osteoporosis in the general population. But transplant medicine has harbored a persistent worry: laboratory and clinical studies have suggested that bones in chronic kidney disease and after transplantation may become resistant to parathyroid hormone signaling, a condition linked to adynamic bone disease in which the cellular machinery for building bone falls silent. Skeptics questioned whether an anabolic drug could overcome that resistance.

The new data argue that, in many patients, it can. Among the subset of participants with paired bone density scans taken at the start and end of therapy, lumbar spine bone mineral density rose by an average of 11 percent, femoral neck density by 8 percent, and total hip density by 11 percent, gains that the authors note are comparable to responses reported in non-transplant populations and exceed what antiresorptive drugs typically achieve in transplant recipients. Statistically, the increases reached significance at all three skeletal sites. Treatment was started a median of 36 months after transplantation, once graft function and immunosuppressive regimens had often stabilized, and continued for a median of 22.3 months, a longer exposure than in most previous reports.

Fracture outcomes, though limited by small numbers, added a reassuring note. Six patients broke bones after starting teriparatide, but only two of those fractures occurred while the drug was actively being taken; the other four happened months to years after treatment had stopped. Given that nearly every participant entered the study with an already shattered fracture history, the apparent stabilization of fracture incidence during therapy is clinically meaningful, even though the retrospective design and small sample size prevented the study from formally demonstrating fracture reduction.

Safety, particularly for the transplanted organ itself, was a central question. Kidney function, measured by estimated glomerular filtration rate, declined modestly during the first six months of therapy, from an average of 73 to 64 milliliters per minute per 1.73 square meters, and then stabilized through the remainder of treatment and follow-up. Crucially, a contemporaneous matched group of transplant recipients who never took teriparatide showed a broadly similar decline over the same period, suggesting the change reflected the natural course of post-transplant kidney function rather than a drug effect. No patient progressed to end-stage kidney disease or required dialysis, and metabolic complications were rare: a single case of hypercalcemia, which resolved when the drug was stopped, and no cases of significant hypercalciuria despite most patients taking calcium and vitamin D supplements.

The study’s authors are careful to frame these results within the limits of a single-center, retrospective design. Patients were not randomly assigned; teriparatide was reserved for those with the most severe disease, often after failure of or intolerance to bisphosphonates, a selection reinforced by national reimbursement criteria in Israel. The matched control group was used only to contextualize kidney function trends, not to compare treatment effects, and causality cannot be inferred. Yet the very severity of the treated cohort strengthens the clinical signal: these were patients whose skeletons had already failed, and they still built substantial new bone. Only one randomized trial has previously tested teriparatide after transplantation, a short six-month study in kidney recipients begun during the intense immunosuppression of early recovery, which found no density gains but did prevent bone loss compared with placebo.

By including lung and liver recipients alongside kidney patients, the new study extends the evidence base to populations for which no dedicated osteoporosis treatment guidelines exist, in contrast to the organ-specific guidelines published for heart, kidney, and liver transplant care. The results align with recent observational work showing that teriparatide outperformed alendronate in renal transplant recipients and produced meaningful density gains in patients with low bone turnover, and they add histological and clinical weight to case reports of improved bone formation in heart transplant patients. Taken together, the picture emerging is that skeletal resistance to parathyroid hormone after transplantation, while a real phenomenon, is not an insurmountable barrier when therapy is timed after graft stabilization and sustained for nearly two years.

For clinicians, the message is one of selective optimism rather than blanket prescription. Teriparatide is expensive, requires daily injections, and carries a limited treatment duration, so it is unlikely to become a universal post-transplant remedy. But for the growing population of transplant survivors with severe osteoporosis, prior fractures, and few remaining options, the study suggests a viable path: an anabolic window that can rebuild what immunosuppression has torn down, administered with routine monitoring of calcium and kidney function. The authors call for prospective trials to define the optimal timing, duration, and sequencing of anabolic therapy after transplantation, questions that will only grow more urgent as transplant medicine continues to extend survival and shifts its focus toward the long-term quality of the lives it saves.

Subject of Research: Teriparatide treatment of severe osteoporosis in solid organ transplant recipients

Article Title: Teriparatide treatment of osteoporosis in solid organ transplant recipients—a single-center experience

Article References: Diker Cohen, T., Shraga-Slutzky, I., Kaminer, K., Gorshtein, A., Dotan, I., & Tsvetov, G. (2026). Teriparatide treatment of osteoporosis in solid organ transplant recipients—a single-center experience. Archives of Osteoporosis, 21(1), Article 136. https://doi.org/10.1007/s11657-026-01751-4

Image Credits: AI Generated

DOI: 10.1007/s11657-026-01751-4

Keywords: teriparatide, osteoporosis, solid organ transplantation, bone mineral density, fragility fractures, glucocorticoid-induced osteoporosis, anabolic therapy, kidney transplant, lung transplant, liver transplant, kidney function, transplant immunosuppression