Cytoskeletal reorganization in osteoclasts to form actin rings is necessary for these cells to attach to bone and resorb bone matrices. We delineated the pathway through which Wnt5a signaling through receptor tyrosine kinase-like orphan receptor 2 (Ror2) promoted the bone-resorbing activity of osteoclasts. Wnt5a binding to Ror2 stimulated Rho, a small GTPase involved in cytoskeletal reorganization. Subsequently, the Rho effector kinase Pkn3 bound to and enhanced the activity of c-Src, a nonreceptor tyrosine kinase that is critical for actin ring formation. Mice with an osteoclast-specific deficiency in () had increased bone mass. Osteoclasts derived from these mice exhibited impaired bone resorption and actin ring formation, defects that were rescued by overexpression of constitutively active RhoA. These osteoclasts also exhibited reduced interaction between c-Src and Pkn3 and reduced c-Src kinase activity. Similar to mice, mice with a global deficiency of () had increased bone mass. The proline-rich region and kinase domain of Pkn3 were required to restore the bone-resorbing activity of osteoclasts derived from mice. Thus, Pkn3 promotes bone resorption downstream of Wnt5a-Ror2-Rho signaling, and this pathway may be a therapeutic target for bone diseases such as osteoporosis, rheumatoid arthritis, and periodontal disease.

The Janus kinases (Jaks) are hubs in the signaling process of more than 50 cytokine or hormone receptors. However, the function of Jak in bone metabolism remains to be elucidated. Here, we showed that the inhibition of Jak1 and/or Jak2 in osteoblast-lineage cells led to impaired osteoclastogenesis due to the reduced expression of receptor activator of nuclear factor-κB ligand (RANKL). Murine calvaria-derived osteoblasts induced differentiation of bone marrow cells into osteoclasts in the presence of 1,25-dihydroxyvitamin D3 (1,25D3) and prostaglandin E2 (PGE2) in vitro. However, treatment with the Jak1/2 inhibitor, baricitinib, markedly inhibited osteoclastogenesis in the co-culture. On the other hand, baricitinib did not inhibit RANKL-induced osteoclast differentiation of bone marrow macrophages. These results indicated that baricitinib acted on osteoblasts, but not on bone marrow macrophages. Baricitinib suppressed 1,25D3 and PGE2-induced up-regulation of RANKL in osteoblasts, but not macrophage colony-stimulating factor expression. Moreover, the addition of recombinant RANKL to co-cultures completely rescued baricitinib-induced impairment of osteoclastogenesis. shRNA-mediated knockdown of Jak1 or Jak2 also suppressed RANKL expression in osteoblasts and inhibited osteoclastogenesis. Finally, cytokine array revealed that 1,25D3 and PGE2 stimulated secretion of interleukin-6 (IL-6), IL-11, and leukemia inhibitory factor in the co-culture. Hence, Jak1 and Jak2 represent novel therapeutic targets for osteoporosis as well as inflammatory bone diseases including rheumatoid arthritis.

Regulatory T-cell (Treg) infiltration can be targeted as a cancer immunotherapy. Here, we describe therapeutic efficacy of this strategy in a canine model of bladder cancer. We used dogs with naturally occurring bladder cancer to study the molecular mechanism of Treg infiltration into bladder cancer tissues and the effect of anti-Treg treatment. Tumorinfiltrating Tregs were evaluated by immunohistochemistry, and their association with prognosis was examined in dogs with bladder cancer. The molecular mechanism of Treg infiltration was explored by RNA sequencing and protein analyses. Murine xenograft experiments and canine studies were used to explore the therapeutic potential of anti-Treg treatment for bladder cancer. We found that tumor-infiltrating Tregs were associated with poor prognosis in dogs bearing spontaneous bladder cancer. Treg infiltration was caused by interaction between the tumor-producing chemokine CCL17 and the receptor CCR4 expressed on Tregs. CCR4 blockade inhibited tumor growth and Treg infiltration into the tissues in a xenograft mouse model. Dogs with spontaneous bladder cancer responded to anti-CCR4 treatment with improved survival and low incidence of clinically relevant toxicities. In human patients with bladder cancer, immunohistochemistry showed that tumor-infiltrating Tregs expressed CCR4. Thus, anti-CCR4 treatment may be a rational approach to test in clinical trials for human patients with bladder cancer.

Intermittent parathyroid hormone (iPTH) treatment induces bone anabolic effects that result in the recovery of osteoporotic bone loss. Human PTH is usually given to osteoporotic patients because it induces osteoblastogenesis. However, the mechanism by which PTH stimulates the expansion of stromal cell populations and their maturation toward the osteoblastic cell lineage has not be elucidated. Mouse genetic lineage tracing revealed that iPTH treatment induced osteoblastic differentiation of bone marrow (BM) mesenchymal stem and progenitor cells (MSPCs), which carried the leptin receptor (LepR)-Cre. Although these findings suggested that part of the PTH-induced bone anabolic action is exerted because of osteoblastic commitment of MSPCs, little is known about the in vivo mechanistic details of these processes. Here, we showed that LepR + MSPCs differentiated into type I collagen (Col1) + mature osteoblasts in response to iPTH treatment. Along with osteoblastogenesis, the number of Col1 + mature osteoblasts increased around the bone surface, although most of them were characterized as quiescent cells. However, the number of LepR-Cre-marked lineage cells in a proliferative state also increased in the vicinity of bone tissue after iPTH treatment. The expression levels of SP7/osterix (Osx) and Col1, which are markers for osteoblasts, were also increased in the LepR + MSPCs population in response to iPTH treatment. In contrast, the expression levels of Cebpb, Pparg, and Zfp467, which are adipocyte markers, decreased in this population. Consistent with these results, iPTH treatment inhibited 5-fluorouracil-or ovariectomy (OVX)-induced LepR + MSPC-derived adipogenesis in BM and increased LepR + MSPC-derived osteoblasts, even under the adipocyte-induced conditions. Treatment of OVX rats with iPTH significantly affected the osteoporotic bone tissue and expansion of the BM adipose tissue. These results indicated that iPTH treatment induced transient proliferation of the LepR + MSPCs and skewed their lineage differentiation from adipocytes toward osteoblasts, resulting in an expanded, quiescent, and mature osteoblast population.

Objective Coatomer subunit alpha (COPA) syndrome, also known as autoinflammatory interstitial lung, joint, and kidney disease, is caused by heterozygous mutations in COPA. We identified a novel COPA variant in 4 patients in one family. We undertook this study to elucidate whether and how the variant causes manifestations of COPA syndrome by studying these 4 patients and by analyzing results from a gene‐targeted mouse model. Methods We performed whole‐exome sequencing in 7 family members and measured the type I interferon (IFN) signature of the peripheral blood cells. We analyzed the effects of COPA variants in in vitro experiments and in Copa mutant mice that were generated. Results We identified a heterozygous variant of COPA (c.725T>G, p.Val242Gly) in the 4 affected members of the family. The IFN score was high in the members carrying the variant. In vitro analysis revealed that COPA V242G, as well as the previously reported disease‐causing variants, augmented stimulator of interferon genes (STING)–induced type I IFN promoter activities. CopaV242G/+ mice manifested interstitial lung disease and STING‐dependent elevation of IFN‐stimulated gene expression. In CopaV242G/+ dendritic cells, the STING pathway was not constitutively activated but was hyperactivated upon stimulation, leading to increased type I IFN production. Conclusion V242G, a novel COPA variant, was found in 4 patients from one family. In gene‐targeted mice with the V242G variant, interstitial lung disease was recapitulated and augmented responses of the STING pathway, leading to an increase in type I IFN production, were demonstrated.

Loss of body weight is a common (and the most serious) sequela after gastrectomy. It impairs quality of life, increases various diseases including infection, and may affect long-term survival. Ghrelin, an intrinsic ligand of the growth hormone secretagogue receptor, was discovered in the stomach in 1999. In addition to growth hormone secretion, ghrelin has pleiotropic functions including appetite stimulation, increasing bowel movement and absorption, and anti-inflammatory reactions. In consequence, ghrelin comprehensively leads positive energy balance and weight gain. The fundic gland of the stomach produces the majority of ghrelin, and plasma ghrelin declines to 10-30 % of the preoperative level after total gastrectomy and 50-70 % after distal gastrectomy. Although plasma ghrelin is never restored after total gastrectomy, it gradually recovers to the preoperative level within a few years after distal gastrectomy. Chronic gastritis due to Helicobacter pylori infection and vagotomy are additional factors that perturb the ghrelin secretion of gastric cancer patients after gastrectomy. A randomized clinical trial that revealed that recombinant ghrelin administration successfully increased both food intake and appetite, and ameliorated weight loss after total gastrectomy. Ghrelin administration could thus be a promising strategy to transiently improve the nutritional status of patients who who have undergone gastrectomy, but its effect in the long term remains unclear. Further studies are warranted to elucidate the mechanism of ghrelin and to create and evaluate the analogs that could be administered orally or subcutaneously.

This randomized prospective study aimed to evaluate the clinical outcome of denosumab treatment alone and in combination with teriparatide in treatment-naive postmenopausal Japanese female patients with osteoporosis. Thirty patients were randomly assigned to two groups: (1) denosumab group (denosumab alone, n=13); and (2) combination group (denosumab+teriparatide, n=17). Serum bone-specific alkaline phosphatase (BAP), serum tartrate-resistant acid phosphatase (TRACP)-5b, urinary cross-linked N-terminal telopeptides of type I collagen (NTX), and bone mineral density (BMD) of L1–4 lumbar vertebrae (L-BMD) and bilateral total hips (H-BMD) were determined at the first visit and at various time points up to 24 months post-treatment to determine percentage changes. Serum TRACP-5b and urinary NTX were equally suppressed in both groups and maintained at low levels, with slight increases at 12, 18 and 24 months. BAP was significantly decreased in both groups from 4 to 24 months, with significant differences between the groups at 4, 8 and 15 months (P<0.05). L-BMD was significantly increased at most time points in both groups, with a significant difference between the combination group and denosumab group at 24 months (17.2% increase versus 9.6% increase; P<0.05). There was no significant difference in H-BMD between the two groups, although the levels tended to be higher in the combination group than in the denosumab group (9.5% increase versus 5.6% increase). These findings suggest that denosumab+teriparatide combination therapy may represent an important treatment for primary osteoporotic patients at high risk of vertebral fracture.

Post-SUVmax is more useful for predicting survival of patients with esophageal cancer who undergo neoadjuvant therapy followed by surgery, although both SUVmax-DR and post-SUVmax equally correlate with pathological response.