Inhibition of immune checkpoints prevents injury-induced heterotopic ossification.

Heterotopic ossification (HO), true bone formation in soft tissue, is closely associated with abnormal injury/immune responses. We hypothesized that a key underlying mechanism of HO might be injury-induced dysregulation of immune checkpoint proteins (ICs). We found that the earliest stages of HO are characterized by enhanced infiltration of polarized macrophages into sites of minor injuries in an animal model of HO. The non-specific immune suppressants, Rapamycin and Ebselen, prevented HO providing evidence of the central role of the immune responses. We examined the expression pattern of ICs and found that they are dysregulated in HO lesions. More importantly, loss of function of inhibitory ICs (including PD1, PD-L1, and CD152) markedly inhibited HO, whereas loss of function of stimulatory ICs (including CD40L and OX-40L) facilitated HO. These findings suggest that IC inhibitors may provide a therapeutic approach to prevent or limit the extent of HO.

A KRT16 mutation in the first Chinese pedigree with Pachyonychia congenita and review of the literatures.

BACKGROUND: Pachyonychia congenita (PC), a rare autosomal dominant disorder, is featured by significant hypertrophic nail, palmoplantar keratoderma, and plantar pain. It is caused by the mutation of KRT6A, KRT6B, KRT6C, KRT16, or KRT17. AIMS: To identify the gene mutation caused the PC in a Chinese family. PATIENTS/METHODS: Genomic DNA was extracted from peripheral blood samples of five patients and six healthy individuals. Genomic DNA of three patients was sequenced by whole-exome sequencing (WES). Then, exons 6 of KRT16 of all samples were amplified by polymerase chain reaction (PCR), and PCR products were sequenced to identify potential mutations. RESULTS: We identified the proline substitution mutation p.Leu421Pro (c.1262T>C) in the 2B domain of K16 that is associated with PC in a Chinese family. The same mutation was not found in the six healthy individuals of the family. CONCLUSIONS: The mutation found in this study is the first report in China. So far, 25 mutations in KRT16 have been reportedly associated with PC. Twenty-one mutations are located on exon 1, and four mutations on exon 6.

BMP-dependent, injury-induced stem cell niche as a mechanism of heterotopic ossification.

BACKGROUND: Heterotopic ossification (HO), either acquired (aHO) or hereditary, such as fibrodysplasia ossificans progressiva (FOP), is a serious condition without effective treatment. Understanding of the core process of injury-induced HO is still severely limited. METHODS: Double-pulse thymidine analog labeling was used to explore the distinctive domains evolved in injury-induced lesions in an animal model of HO (Nse-BMP4). Histological studies were performed to see whether a similar zonal pattern is also consistently found in biopsies from patients with aHO and FOP. In vivo clonal analysis with Rainbow mice, genetic loss-of-function studies with diphtheria toxin A (DTA)-mediated depletion and lineage tracing with Zsgreen reporter mice were used to obtain further evidence that Tie2-cre-, Gli1-creERT-, and Glast-creERT-labeled cells contribute to HO as niche-dwelling progenitor/stem cells. Immunohistochemistry was used to test whether vasculature, neurites, macrophages, and mast cells are closely associated with the proposed niche and thus are possible candidate niche supportive cells. Similar methods also were employed to further understand the signaling pathways that regulate the niche and the resultant HO. RESULTS: We found that distinctive domains evolved in injury-induced lesions, including, from outside-in, a mesenchymal stem cell (MSC) niche, a transient domain and an inner differentiated core in an animal model of HO (Nse-BMP4). A similar zonal structure was found in patients with aHO and FOP. In vivo clonal analysis with Rainbow mice and genetic loss-of-function studies with DTA provided evidence that Tie2-cre-, Gli1-creERT-, and Glast-creERT-labeled cells contribute to HO as niche-dwelling progenitor/stem cells; consistently, vasculature, neurites, macrophages, and mast cells are closely associated with the proposed niche and thus are possible candidate niche supportive cells. Further mechanistic study found that BMP and hedgehog (Hh) signaling co-regulate the niche and the resultant HO. CONCLUSIONS: Available data provide evidence of a potential core mechanism in which multiple disease-specific cellular and extracellular molecular elements form a unique local microenvironment, i.e., an injury-induced stem cell niche, which regulates the proliferation and osteogenic differentiation of mesenchymal stem cells (MSCs). The implication for HO is that therapeutic approaches must consider several different disease specific factors as parts of a functional unit, instead of treating one factor at a time.

Wnt signaling in physiological and pathological bone formation.

Wnt signaling, canonical or non-canonical, plays conserved roles in numerous physiological and pathological processes. However, it is well beyond the scope of this review to cover all functional aspects of Wnt signaling in different contexts at reasonable depth; therefore this review intends to cover only the roles of Wnt signaling in bone biology; more specifically, we intend to first update the roles of Wnt signaling in physiological bone process, including in osteogenesis and chondrogenesis, since recent years have witnessed tremendous progressions in this area, and then we seek to extend our understanding to the pathological bone process, especially to the heterotopic ossification (HO), even though the understanding of Wnt signaling in HO has been limited. We then further clarify the potential crosstalking between Wnt and other conserved signaling pathways, including FGF, GPCR and Hif1α pathways. Overall, our goal is to update the progressions, identify the general theme and the knowledge gaps and discuss the potential promising avenue for future applications in HO prevention and treatment.

Gli1-labeled adult mesenchymal stem/progenitor cells and hedgehog signaling contribute to endochondral heterotopic ossification.

Heterotopic ossification (HO), acquired or hereditary, endochondral or intramembranous, is the formation of true bone outside the normal skeleton. Since perivascular Gli1+ progenitors contribute to injury induced organ fibrosis, and CD133 is expressed by a variety of populations of adult stem cells, this study utilized Cre-lox based genetic lineage tracing to test the contribution to endochondral HO of adult stem/progenitor cells that expressed either Gli1 or CD133. We found that both lineages contributed broadly to different normal tissues with distinct patterns, but that only Gli1-creERT labeled stem/progenitor cells contributed to all stages of endochondral HO in a BMP dependent, injury induced, transgenic mouse model. Hedgehog (Hh) signaling was abnormal at endochondral HO lesion sites with increased signaling surrounding the lesion but diminished signaling within it. Thus, local dysregulation of Hh signaling participates in the pathophysiology of endochondral HO. However, unlike a previous report of intramembranous HO, systemic inhibition of Hh signaling was insufficient to prevent the initiation of the endochondral HO process or to treat the existing endochondral HO, suggesting that Hh participates in, but is not essential for endochondral HO in this model. This could potentially reflect the underlying difference between intramembranous and endochondral HO. Nevertheless, identification of this novel stem/precursor cell population as a HO-contributing cell population provides a potential drugable target.

Conserved signaling pathways underlying heterotopic ossification.

Heterotopic ossification (HO), a serious disorder of extra-skeletal bone formation, occurs as a common complication of trauma or in rare genetic disorders. Many conserved signaling pathways have been implicated in HO; however, the exact underlying molecular mechanisms for many forms of HO are still unclear. The emerging picture is that dysregulation of bone morphogenetic protein (BMP) signaling plays a central role in the process, but that other conserved signaling pathways, such as Hedgehog (HH), Wnt/ß-catenin and Fibroblast growth factors (FGF), are also involved, either through cross-talk with BMP signaling or through other independent mechanisms. Deep understanding of the conserved signaling pathways is necessary for the effective prevention and treatment of HO. In this review, we update and integrate recent progress in this area. Hopefully, our discussion will point to novel promising, druggable loci for further translational research and successful clinical applications.

Microenvironmental factors that regulate mesenchymal stem cells: lessons learned from the study of heterotopic ossification.

Bone marrow contains a non-hematopoietic, clonogenic, multipotent population of stromal cells that are later called mesenchymal stem cells (MSC). Similar cells that share many common features with MSC are also found in other organs, which are thought to contribute both to normal tissue regeneration and to pathological processes such as heterotopic ossification (HO), the formation of ectopic bone in soft tissue. Understanding the microenvironmental factors that regulate MSC in vivo is essential both for understanding the biology of the stem cells and for effective translational applications of MSC. Unfortunately, this important aspect has been largely underappreciated. This review tries to raise the attention and highlight this critical issue by updating the relevant literature along with discussions of the key issues in the area.

EDAG-1 promotes proliferation and invasion of human thyroid cancer cells by activating MAPK/Erk and AKT signal pathways.

Erythroid differentiation-associated gene (EDAG) is differentially expressed in normal hematopoietic progenitor/stem cells and a variety of embryonic tissues. High EDAG-1 expression is also found in human thyroid cancer cells and peripheral blood of patients with leukemia, but its functional significance was unclear. Current study aims to further clarify the expression pattern of EDAG-1 and tests its roles in proliferation and invasion of human thyroid cancer cells in vitro and in vivo. To this end, we have performed gain-of-function and loss-of-function studies to clarify how EDAG-1 regulates the proliferation, invasion, and adhesion ability of human thyroid cancer cells SW579cells. We found that overexpression of EDAG-1 promoted the proliferation, invasion, and adhesion of human thyroid cancer cells, whereas silencing of EDAG-1 reversed all these changes and reduced the tumorigenesis risk of nude mice. Mechanistically, we found that overexpression of EDAG-1 activated the MAPK/Erk and AKT signal pathways. These findings provide novel insights of the role of EDAG-1 in thyroid tumors, and may have direct clinical implication.

YL4073 is a potent autophagy-stimulating antitumor agent in an in vivo model of Lewis lung carcinoma.

Cancer cells activate autophagy in response to anticancer therapies. Autophagy induction is a promising therapeutic approach to treat cancer. In a previous study, YL4073 inhibited the growth of liver cancer and induced liver cancer cell apoptosis. Here, we demonstrated the anticancer activity and specific mechanisms of YL4073 in Lewis lung carcinoma LL/2 cells. Our results show that YL4073-induced autophagy was followed by apoptotic cell death. The anticancer and autophagy stimulating efficacy was confirmed by several factors, including the appearance of autophagic vacuoles, formation of acidic vesicular organelles, recruitment of microtubule-associated protein 1 light chain 3 II (LC3-II) to the autophagosomes, conversion and cleavage of LC3-I to LC3-II, upregulation of Beclin 1 expression, and formation of the Atg12-Atg5 conjugate in LL/2 cells after YL4073 treatment for 24 or 48 h. Furthermore, P53 activation and p-histone H3 phosphorylation occurred after cell exposure to YL4073 for 48 h, suggesting that cell apoptosis had occurred. Pharmacological inhibition of autophagy using 3-methyladenine increased cell apoptosis. Molecular level studies revealed that YL4073 inhibited survival signalling by blocking the activation of Akt and mTOR phosphorylation and reduced the expression of p-mTOR downstream targets for phosphorylation, including p70S6K, p-TSC, p-MAPK, and p-AMPK. This suggests that the Akt/mTOR/p70S6K and TSC/MAPK/AMPK pathways are involved in the effects of YL4073 treatment in LL/2 cells. In addition, YL4073 significantly inhibited LL/2 tumor growth and induced apoptosis in vivo. These data suggest that YL4073 has a significant anticancer effect, with a pathway-specific mechanism of autophagy both in vitro and in vivo.

Role of adult hippocampal neurogenesis in persistent pain.

The full role of adult hippocampal neurogenesis (AHN) remains to be determined, yet it is implicated in learning and emotional functions, and is disrupted in negative mood disorders. Recent evidence indicates that AHN is decreased in persistent pain consistent with the idea that chronic pain is a major stressor, associated with negative moods and abnormal memories. Yet, the role of AHN in development of persistent pain has remained unexplored. In this study, we test the influence of AHN in postinjury inflammatory and neuropathic persistent pain-like behaviors by manipulating neurogenesis: pharmacologically through intracerebroventricular infusion of the antimitotic AraC; ablation of AHN by x-irradiation; and using transgenic mice with increased or decreased AHN. Downregulating neurogenesis reversibly diminished or blocked persistent pain; oppositely, upregulating neurogenesis led to prolonged persistent pain. Moreover, we could dissociate negative mood from persistent pain. These results suggest that AHN-mediated hippocampal learning mechanisms are involved in the emergence of persistent pain.

MiR-362-5p promotes the malignancy of chronic myelocytic leukaemia via down-regulation of GADD45α.

BACKGROUND: MicroRNAs (miR, miRNAs) play pivotal roles in numerous physiological and pathophysiological contexts. We investigated whether miR-362-5p act as an oncogene in chronic myeloid leukaemia (CML) and aimed to understand its potential underlying mechanisms. METHODS: We compared the miR-362-5p expression levels between CML and non-CML cell lines, and between fresh blood samples from CML patients and normal healthy controls using quantitative real-time PCR (qPCR). Cell counting kit-8 (CCK-8) and Annexin V-FITC/PI analyses were used to measure the effects of miR-362-5p on proliferation and apoptosis, and Transwell assays were used to evaluate migration and invasion. A xenograft model was used to examine in vivo tumourigenicity. The potential target of miR-362-5p was confirmed by a luciferase reporter assay, qPCR and western blotting. Involvement of the JNK1/2 and P38 pathways was investigated by western blotting. RESULTS: miR-362-5p was up-regulated in CML cell lines and fresh blood samples from CML patients, and was associated with Growth arrest and DNA damage-inducible (GADD)45α down-regulation. Inhibition of miR-362-5p simultaneously repressed tumour growth and up-regulated GADD45α expression in a xenograft model. Consistently, the knockdown of GADD45α expression partially neutralized the effects of miR-362-5p inhibition. Furthermore study suggested that GADD45α mediated downstream the effects of miR-362-5p, which might indirectly regulates the activation of the JNK1/2 and P38 signalling pathways. CONCLUSION: miR-362-5p acts as an oncomiR that down-regulates GADD45α, which consequently activates the JNK1/2 and P38 signalling. This finding provides novel insights into CML leukaemogenesis and may help identify new diagnostic and therapeutic targets.

[Effects of Panax notoginseng saponins on proliferation, apoptosis and cell cycle of K562 cells in vitro and the mechanisms].

OBJECTIVE: To investigate the effects of Panax notoginseng saponins (PNS) on the proliferation, apoptosis and cell cycle of K562 cells and explore the molecular mechanisms underlying these effects. METHODS: PNS-induced growth inhibition of K562 cells was detected by MTT assay; the cell apoptosis was evaluated by AO/EB staining and Annexin V-FITC/ PI staining; flow cytometry was used to detect cell cycle changes in the treated cells. The mRNA expressions of the molecules in mTOR signaling pathway were examined by RT-PCR, and the cellular expressions of cleaved caspeas-3, cyclin D1 and major proteins in mTOR signaling pathway were detected using Western blotting. RESULTS: MTT assay showed that treatment with 100-800 µg/mL PNS significantly inhibited the proliferation, promoted the cell apoptosis, and caused cell cycle arrest in G0/G1 phase in K562 cells. Western blotting revealed increased protein expression of cleaved caspase-3 and decreased expression of cyclin D1 in PNS-treated cells, in which the proteins expressions of mTOR, p-mTOR, p-p70S6K and p-4E-BP 1 and the mRNA expression of mTOR were all decreased. CONCLUSION: PNS can inhibit the proliferation, induce apoptosis and cause cell cycle arrest in K562 cells possibly by up-regulating cleaved caspase 3 and down-regulating cyclin D1 and mTOR signaling pathway.

A small molecular agent YL529 inhibits VEGF-D-induced lymphangiogenesis and metastasis in preclinical tumor models in addition to its known antitumor activities.

BACKGROUND: The lymph node metastasis is a key early step of the tumor metastatic process. VEGFD-mediated tumor lymphangiogenesis plays a key role, since down-regulation of p-VEGFR-3 could block the lymph node metastasis. YL529 has been reported to possess potent anti-angiogenesis and antitumor activities; however, its roles in tumor-associated lymphangiogenesis and lymphatic metastasis remain unclear. METHOD: We investigated the effect of YL529 on tumor-associated lymphangiogenesis and lymph node metastasis using in vitro lymph node metastasis models and in vivo subcutaneous tumor models in C57 BL/6 mice. RESULT: We found that YL529 inhibited VEGF-D-induced survival, proliferation and tube-formation of Human Lymphatic Endothelial Cells. Furthermore, in established in vitro and in vivo lymph node metastasis models using VEGF-D-LL/2 cells, YL529 significantly inhibited the tumor-associated lymphangiogenesis and metastasis. At molecular level, YL529 down-regulated p-VEGFR-3, p-JNK and Bax while up-regulated Bcl-2. CONCLUSION: YL529 provided the therapeutic benefits by both direct effects on tumor cells and inhibiting lymphangiogenesis and metastasis via the VEGFR-3 signaling pathway, which may have significant direct clinical implications.

Activation of the NF-κB pathway as a mechanism of alcohol enhanced progression and metastasis of human hepatocellular carcinoma.

BACKGROUND: Hepatocellular carcinoma (HCC), the most common form of primary liver cancer, is the third leading cause of cancer-related death in human. Alcohol is a known risk factor for HCC. However it is still unclear whether and how alcohol enhances the progression and metastasis of existing HCC. METHODS AND RESULTS: We first retrospectively investigated 52 HCC patients (24 alcohol-drinkers and 28 non-drinkers), and found a positive correlation between alcohol consumption and advanced Tumor-Node-Metastasis (TNM) stages, higher vessel invasion and poorer prognosis. In vitro and in vivo experiments further indicated that alcohol promoted the progression and migration/invasion of HCC. Specifically, in a 3-D tumor/endothelial co-culture system, we found that alcohol enhanced the migration/invasion of HepG2 cells and increased tumor angiogenesis. Consistently, higher expression of VEGF, MCP-1 and NF-κB was observed in HCC tissues of alcohol-drinkers. Alcohol induced the accumulation of intracellular reactive oxygen species (ROS) and the activation of NF-κB signaling in HepG2 cells. Conversely, blockage of alcohol-mediated ROS accumulation and NF-κB signaling inhibited alcohol-induced expression of VEGF and MCP-1, the tumor growth, angiogenesis and metastasis. CONCLUSION: This study suggested that chronic moderate alcohol consumption may promote the progression and metastasis of HCC; the oncogenic effect may be at least partially mediated by the ROS accumulation and NF-ĸB-dependent VEGF and MCP-1 up-regulation.

Balancing Innate Immunity and Inflammatory State via Modulation of Neutrophil Function: A Novel Strategy to Fight Sepsis.

Sepsis and SIRS (systemic inflammatory response syndrome) belong to a severe disease complex characterized by infection and/or a whole-body inflammatory state. There is a growing body of evidence that neutrophils are actively involved in sepsis and are responsible for both release of cytokines and phagocytosis of pathogens. The neutrophil level is mainly regulated by G-CSF, a cytokine and drug, which is widely used in the septic patient with neutropenia. This review will briefly summarize the role of neutrophils and the therapeutic effect of G-CSF in sepsis. We further suggest that targeting neutrophil function to modulate the balance between innate immunity and inflammatory injury could be a worthwhile therapeutic strategy for sepsis.

Mesenchymal stem cells overexpressing Ihh promote bone repair.

BACKGROUND: Indian hedgehog (Ihh) signaling pathway is known to play key roles in various aspects of normal endochondral bone development. This study tested the potential roles of high Ihh signaling in the context of injury-induced bone regeneration. METHODS: A rabbit tibia defect model was established to test the effects of the implant of Ihh/mesenchymal stem cells (MSCs)/scaffold complex. Computed tomography (CT), gross observation, and standard histological and immunohistological techniques were used to evaluate the effectiveness of the treatment. In vitro studies with MSCs and C3H10T1/2 cells were also employed to further understand the cellular and molecular mechanisms. RESULTS: We found that the implanted Ihh/MSCs/scaffold complex promoted bone repair. Consistently, in vitro study found that Ihh induced the upregulation of chondrocytic, osteogenic, and vascular cell markers, both in C3H10T1/2 cells and MSCs. CONCLUSIONS: Our study has demonstrated that high Ihh signaling in a complex with MSCs enhanced bone regeneration effectively in a clinically relevant acute injury model. Even though the exact underlying mechanisms are still far from clear, our primary data suggested that enhanced chondrogenesis, osteogenesis, and angiogenesis of MSCs at least partially contribute to the process. This study not only has implications for basic research of MSCs and Ihh signaling pathway but also points to the possibility of direct application of this specific paradigm to clinical bone repair.