Increase in production of matrix metalloproteinase 13 by human articular chondrocytes due to stimulation with S100A4: Role of the receptor for advanced glycation end products

Role of microRNA-505 during tumor progression and metastasis

Late diagnosis of cancer in advanced stages due to the lack of screening methods is considered as the main cause of poor prognosis and high mortality rate among these patients. Therefore, it is necessary to investigate the molecular tumor biology in order to introduce biomarkers that can be used in cancer screening programs and early diagnosis. MicroRNAs (miRNAs) have key roles in regulation of the cellular pathophysiological processes. Due to the high stability of miRNAs in body fluids, they are widely used as the non-invasive tumor markers. According to the numerous reports about miR-505 deregulation in a wide range of cancers, we investigated the role of miR-505 during tumor progression. It was shown that miR-505 mainly has the tumor suppressor functions through the regulation of signaling pathways, chromatin remodeling, and cellular metabolism. This review has an effective role in introducing miR-505 as a suitable marker for the early cancer diagnosis.

Osteoarthritis as a Systemic Disease Promoted Prostate Cancer In Vivo and In Vitro

Osteoarthritis (OA) is increasing worldwide, and previous work found that OA increases systemic cartilage oligomeric matrix protein (COMP), which has also been implicated in prostate cancer (PCa). As such, we sought to investigate whether OA augments PCa progression. Cellular proliferation and migration of RM1 murine PCa cells treated with interleukin (IL)-1α, COMP, IL-1α + COMP, or conditioned media from cartilage explants treated with IL-1α (representing OA media) and with inhibitors of COMP were assessed. A validated murine model was used for tumor growth and marker expression analysis. Both proliferation and migration were greater in PCa cells treated with OA media compared to controls (p < 0.001), which was not seen with direct application of the stimulants. Migration and proliferation were not negatively affected when OA media was mixed with downstream and COMP inhibitors compared to controls (p > 0.05 for all). Mice with OA developed tumors 100% of the time, whereas mice without OA only 83.4% (p = 0.478). Tumor weight correlated with OA severity (Pearson correlation = 0.813, p = 0.002). Moreover, tumors from mice with OA demonstrated increased Ki-67 expression compared to controls (mean 24.56% vs. 6.91%, p = 0.004) but no difference in CD31, PSMA, or COMP expression (p > 0.05). OA appears to promote prostate cancer in vitro and in vivo.

S100A4 a classical DAMP as a therapeutic target in fibrosis

Fibrosis regardless of aetiology is characterised by persistently activated myofibroblasts that are contractile and secrete excessive amounts of extracellular matrix molecules that leads to loss of organ function. Damage-Associated Molecular Patterns (DAMPs) are endogenous host-derived molecules that are released from cells dying or under stress that can be triggered by a variety of insults, either chemical or physical, leading to an inflammatory response. Among these DAMPs is S100A4, part of the S100 family of calcium binding proteins that participate in a variety of cellular processes. S100A4 was first described in context of cancer as a pro-metastatic factor. It is now appreciated that aside from its role in cancer promotion, S100A4 is intimately involved in tissue fibrosis. The extracellular form of S100A4 exerts its effects through multiple receptors including Toll-Like Receptor 4 and RAGE to evoke signalling cascades involving downstream mediators facilitating extracellular matrix deposition and myofibroblast generation and can play a role in persistent activation of myofibroblasts. S100A4 may be best understood as an amplifier of inflammatory and fibrotic processes. S100A4 appears critical in systemic sclerosis pathogenesis and blocking the extracellular form of S100A4 in vivo in various animal models of disease mitigates fibrosis and may even reverse established disease. This review appraises S100A4's position as a DAMP and its role in fibrotic conditions and highlight therapeutically targeting this protein to halt fibrosis, suggesting that it is a tractable target.

Beneficial Impact of Eicosapentaenoic Acid on the Adverse Effects Induced by Palmitate and Hyperglycemia on Healthy Rat Chondrocyte

Osteoarthritis (OA) is the most prevalent form of arthritis and a major cause of pain and disability. The pathology of OA involves the whole joint in an inflammatory and degenerative process, especially in articular cartilage. OA may be divided into distinguishable phenotypes including one associated with the metabolic syndrome (MetS) of which dyslipidemia and hyperglycemia have been individually linked to OA. Since their combined role in OA pathogenesis remains to be elucidated, we investigated the chondrocyte response to these metabolic stresses, and determined whether a n-3 polyunsaturated fatty acid (PUFA), i.e., eicosapentaenoic acid (EPA), may preserve chondrocyte functions. Rat chondrocytes were cultured with palmitic acid (PA) and/or EPA in normal or high glucose conditions. The expression of genes encoding proteins found in cartilage matrix (type 2 collagen and aggrecan) or involved in degenerative (metalloproteinases, MMPs) or in inflammatory (cyclooxygenase-2, COX-2 and microsomal prostaglandin E synthase, mPGES) processes was analyzed by qPCR. Prostaglandin E2 (PGE2) release was also evaluated by an enzyme-linked immunosorbent assay. Our data indicated that PA dose-dependently up-regulated the mRNA expression of MMP-3 and -13. PA also induced the expression of COX-2 and mPGES and promoted the synthesis of PGE2. Glucose at high concentrations further increased the chondrocyte response to PA. Interestingly, EPA suppressed the inflammatory effects of PA and glucose, and strongly reduced MMP-13 expression. Among the free fatty acid receptors (FFARs), FFAR4 partly mediated the EPA effects and the activation of FFAR1 markedly reduced the inflammatory effects of PA in high glucose conditions. Our findings demonstrate that dyslipidemia associated with hyperglycemia may contribute to OA pathogenesis and explains why an excess of saturated fatty acids and a low level in n-3 PUFAs may disrupt cartilage homeostasis.

The AGE-RAGE Axis and the Pathophysiology of Multimorbidity in COPD

Chronic obstructive pulmonary disease (COPD) is a disease of the airways and lungs due to an enhanced inflammatory response, commonly caused by cigarette smoking. Patients with COPD are often multimorbid, as they commonly suffer from multiple chronic (inflammatory) conditions. This intensifies the burden of individual diseases, negatively affects quality of life, and complicates disease management. COPD and comorbidities share genetic and lifestyle-related risk factors and pathobiological mechanisms, including chronic inflammation and oxidative stress. The receptor for advanced glycation end products (RAGE) is an important driver of chronic inflammation. Advanced glycation end products (AGEs) are RAGE ligands that accumulate due to aging, inflammation, oxidative stress, and carbohydrate metabolism. AGEs cause further inflammation and oxidative stress through RAGE, but also through RAGE-independent mechanisms. This review describes the complexity of RAGE signaling and the causes of AGE accumulation, followed by a comprehensive overview of alterations reported on AGEs and RAGE in COPD and in important co-morbidities. Furthermore, it describes the mechanisms by which AGEs and RAGE contribute to the pathophysiology of individual disease conditions and how they execute crosstalk between organ systems. A section on therapeutic strategies that target AGEs and RAGE and could alleviate patients from multimorbid conditions using single therapeutics concludes this review.

RAGE Inhibitors for Targeted Therapy of Cancer: A Comprehensive Review

The receptor for advanced glycation end products (RAGE) is a member of the immunoglobulin family that is overexpressed in several cancers. RAGE is highly expressed in the lung, and its expression increases proportionally at the site of inflammation. This receptor can bind a variety of ligands, including advanced glycation end products, high mobility group box 1, S100 proteins, adhesion molecules, complement components, advanced lipoxidation end products, lipopolysaccharides, and other molecules that mediate cellular responses related to acute and chronic inflammation. RAGE serves as an important node for the initiation and stimulation of cell stress and growth signaling mechanisms that promote carcinogenesis, tumor propagation, and metastatic potential. In this review, we discuss different aspects of RAGE and its prominent ligands implicated in cancer pathogenesis and describe current findings that provide insights into the significant role played by RAGE in cancer. Cancer development can be hindered by inhibiting the interaction of RAGE with its ligands, and this could provide an effective strategy for cancer treatment.

Metformin Prevents or Delays the Development and Progression of Osteoarthritis: New Insight and Mechanism of Action

For over 60 years, metformin has been widely prescribed by physicians to treat type 2 diabetes. Along with more in-depth research on metformin and its molecular mechanism in recent decades, metformin has also been proposed as an effective drug to prevent or delay musculoskeletal disorders, including osteoarthritis (OA). The occurrence and development of OA are deemed to be associated with the impaired mitochondrial functions of articular chondrocytes. Metformin can activate the pathways and expressions of both AMPK and SIRT1 so as to protect the mitochondrial function of chondrocytes, thereby promoting osteoblast production. Moreover, the clinical significance of the metformin combination therapy in preventing OA has also been demonstrated. This review aimed to comprehensively summarize the current research progress on metformin as a proposed drug for OA prevention or treatment.

Protective Effect of Resveratrol on Knee Osteoarthritis and its Molecular Mechanisms: A Recent Review in Preclinical and Clinical Trials

Osteoarthritis (OA) is one of the progressing chronic joint associated with by many complex factors such as age, obesity, and trauma. Knee osteoarthritis (KOA) is the most common type of OA. KOA is characterized by articular cartilage destruction and degeneration, synovial inflammation, and abnormal subchondral bone changes. To date, no practical clinical approach has been able to modify the pathological progression of KOA. Drug therapy is limited to pain control and may lead to serious side effects when taken for a long time. Therefore, searching for safer and more reliable treatments has become necessary. Interestingly, more and more research has focused on natural products, and monomeric compounds derived from natural products have received much attention as drug candidates for KOA treatment. Resveratrol (RES), a natural phenolic compound, has various pharmacological and biological activities, including anti-cancer, anti-apoptotic, and anti-decay. Recently, studies on the effects of RES on maintaining the normal homeostasis of chondrocytes in KOA have received increasing attention, which seems to be attributed to the multi-targeted effects of RES on chondrocyte function. This review summarizes preclinical trials, clinical trials, and emerging tissue engineering studies of RES for KOA and discusses the specific mechanisms by which RES alleviates KOA. A better understanding of the pharmacological role of RES in KOA could provide clinical implications for intervention in the development of KOA.

Macrophage-Secreted S100A4 Supports Breast Cancer Metastasis by Remodeling the Extracellular Matrix in the Premetastatic Niche

Metastasis is the major cause of cancer-related mortalities. A tumor-supportive microenvironment, also known as the premetastatic niche at secondary tumor sites, plays a crucial role in metastasis. Remodeling of the extracellular matrix (ECM) is essential for premetastatic niche formation, especially for circulating tumor cell colonization. However, the underlying molecular mechanism that contributes to this effect remains unclear. Here, we developed a lung metastasis model with 4T1 breast cancer cells and found that the metastasis critically depended on the early recruitment of macrophages to the lung. Disruption of macrophage recruitment reduced fibroblast activation and lung metastasis. Furthermore, we identified the secreted protein S100A4, which is produced by M2 macrophages and participates in fibroblast activation and ECM protein deposition via the ERK signaling pathway. Collectively, these results indicate that recruiting S100A4-expressing inflammatory macrophages plays a vital role in ECM remodeling in the premetastatic niche and may act as a potential therapeutic target for breast cancer lung metastasis.

S100A4 Is a Strong Negative Prognostic Marker and Potential Therapeutic Target in Adenocarcinoma of the Stomach and Esophagus

Deregulated Wnt-signaling is a key mechanism driving metastasis in adenocarcinoma of the gastroesophageal junction and stomach (AGE/S). The oncogene S100A4 was identified as a Wnt-signaling target gene and is known to promote metastasis. In this project, we illuminate the role of S100A4 for metastases development and disease prognosis of AGE/S. Five gastric cancer cell lines were assessed for S100A4 expression. Two cell lines with endogenous high S100A4 expression were used for functional phenotyping including analysis of proliferation and migration after stable S100A4 knock-down. The prognostic value of S100A4 was evaluated by analyzing the S100A4 expression of tissue microarrays with samples of 277 patients with AGE/S. S100A4 knock-down induced lower migration in FLO1 and NCI-N87 cells. Treatment with niclosamide in these cells led to partial inhibition of S100A4 and to reduced migration. Patients with high S100A4 expression showed lower 5-year overall and disease-specific survival. In addition, a larger share of patients in the S100A4 high expressing group suffered from metachronous metastasis. This study identifies S100A4 as a negative prognostic marker for patients with AGE/S. The strong correlation between S100A4 expression, metastases development and patient survival might open opportunities to use S100A4 to improve the prognosis of these patients and as a therapeutic target for intervention in this tumor entity.

S100A4/TCF Complex Transcription Regulation Drives Epithelial-Mesenchymal Transition in Chronic Sinusitis Through Wnt/GSK-3β/β-Catenin Signaling

Epithelial-mesenchymal transition (EMT) is thought to be involved in the tissue remodeling and long-term inflammatory process of chronic sinusitis (CRS), but the driving mechanism is still unclear. Using high-resolution mass spectrometry, we performed a proteomic screen of CRS nasal mucosal tissue to identify differentially expressed proteins. Data are available via ProteomeXchange with identifier PXD030884. Specifically, we identified S100 calcium binding protein A4 (S100A4), an effective factor in inflammation-related diseases, and its downstream protein closely related to tissue fibrosis collagen type I alpha 1 chain (COL1A1), which suggested its involvement in nasal mucosal tissue remodeling. In addition, stimulation of human nasal epithelial cells (HNEpCs) with lipopolysaccharide (LPS) mimicked the inflammatory environment of CRS and showed that S100A4 is involved in regulating EMT and thus accelerating tissue remodeling in the nasal mucosa, both in terms of increased cell motility and overexpression of mesenchymal-type proteins. Additionally, we further investigated the regulation mechanism of S100A4 involved in EMT in CRS. Our research results show that in the inflammatory environment of CRS nasal mucosal epithelial cells, TCF-4 will target to bind to S100A4 and regulate its transcription. The transcription of S100A4 in turn affects the execution of the important signaling pathway in EMT, the Wnt/GSK-3β/β-catenin pathway, through the TCF-4/β-catenin complex. In conclusion, this study confirmed that the expression of S100A4 was significantly increased during the progressive EMT process of CRS mucosal epithelial cells, and revealed that the transcriptional regulation of S100A4 plays an important role in the occurrence and development of EMT. This finding will help us to better understand the pathogenesis behind the remodeling in CRS patients, and identify target molecules for the treatment of CRS.

The potential roles of JAK/STAT signaling in the progression of osteoarthritis

Osteoarthritis (OA) is an age-related chronic progressive degenerative disease that induces persistent pain and disabilities. The development of OA is a complex process, and the risk factors are various, including aging, genetics, trauma and altered biomechanics. Inflammation and immunity play an important role in the pathogenesis of OA. JAK/STAT pathway is one of the most prominent intracellular signaling pathways, regulating cell proliferation, differentiation, and apoptosis. Inflammatory factors can act as the initiators of JAK/STAT pathway, which is implicated in the pathophysiological activity of chondrocyte. In this article, we provide a review on the importance of JAK/STAT pathway in the pathological development of OA. Potentially, JAK/STAT pathway becomes a therapeutic target for managing OA.

Endocrine regulation and metabolic mechanisms of osteopontin in the development and progression of osteosarcoma, metastasis and prognosis

Osteosarcoma is the most common type of malignant bone tumor, occurring in adolescents and patients over 60. It has a bimodal onset and a poor prognosis, and its development has not yet been fully explained. Osteopontin (OPN) is a high protein consisting of 314 amino acid residues with a negative charge and is involved in many biological activities. OPN is not only an essential part of the regulation of the nervous system and endocrine metabolism of skeletal cells. Still, it is also involved in several other important biological activities, such as the division, transformation, and proliferation of skeletal cells and their associated cells, such as bone tumor cells, including bone marrow mesenchymal stem cells, hematopoietic stem cells, osteoblasts, and osteoclasts. Osteoblasts and osteocytes. Recent studies have shown a strong correlation between OPN and the development and progression of many skeletal diseases, such as osteosarcoma and rheumatoid arthritis. This review aims to understand the mechanisms and advances in the role of OPN as a factor in the development, progression, metastasis, and prognosis of osteosarcoma in an attempt to provide a comprehensive summary of the mechanisms by which OPN regulates osteosarcoma progression and in the hope of contributing to the advancement of osteosarcoma research and clinical treatment.

Current Advances in the Regeneration of Degenerated Articular Cartilage: A Literature Review on Tissue Engineering and Its Recent Clinical Translation

Functional ability is the basis of healthy aging. Articular cartilage degeneration is amongst the most prevalent degenerative conditions that cause adverse impacts on the quality of life; moreover, it represents a key predisposing factor to osteoarthritis (OA). Both the poor capacity of articular cartilage for self-repair and the unsatisfactory outcomes of available clinical interventions make innovative tissue engineering a promising therapeutic strategy for articular cartilage repair. Significant progress was made in this field; however, a marked heterogeneity in the applied biomaterials, biofabrication, and assessments is nowadays evident by the huge number of research studies published to date. Accordingly, this literature review assimilates the most recent advances in cell-based and cell-free tissue engineering of articular cartilage and also focuses on the assessments performed via various in vitro studies, ex vivo models, preclinical in vivo animal models, and clinical studies in order to provide a broad overview of the latest findings and clinical translation in the context of degenerated articular cartilage and OA.

Resveratrol and Curcumin Attenuate Ex Vivo Sugar-Induced Cartilage Glycation, Stiffening, Senescence, and Degeneration

OBJECTIVE

Advanced glycation end-product (AGE) accumulation is implicated in osteoarthritis (OA) pathogenesis in aging and diabetic populations. Here, we develop a representative nonenzymatic glycation-induced OA cartilage explant culture model and investigate the effectiveness of resveratrol, curcumin, and eugenol in inhibiting AGEs and the structural and biological hallmarks of cartilage degeneration.

DESIGN

Bovine cartilage explants were treated with AGE-bovine serum albumin, threose, and ribose to determine the optimal conditions that induce physiological levels of AGEs while maintaining chondrocyte viability. AGE crosslinks, tissue stiffness, cell viability, metabolism and senescence, nitrite release and loss of glycosaminoglycans were assessed. Explants were cotreated with resveratrol, curcumin, or eugenol to evaluate their anti-AGE properties. Blind docking analysis was conducted to estimate binding energies of drugs with collagen II.

RESULTS

Treatment with 100 mM ribose significantly increased AGE crosslink formation and tissue stiffness, resulting in reduced chondrocyte metabolism and enhanced senescence. Blind docking analysis revealed stronger binding energies of both resveratrol and curcumin than ribose, with glycation sites along a human collagen II fragment, indicating their increased likelihood of competitively inhibiting ribose activity. Resveratrol and curcumin, but not eugenol, successfully inhibited AGE crosslink formation and its associated downstream biological response.

CONCLUSIONS

We establish a cartilage explant model of OA that recapitulates several aspects of aged human cartilage. We find that resveratrol and curcumin are effective anti-AGE therapeutics with the potential to decelerate age-related and diabetes-induced OA. This in vitro nonenzymatic glycation-induced model provides a tool for screening OA drugs, to simultaneously evaluate AGE-induced biological and mechanical changes.

Vitamin D Levels Correlate with Metabolic Syndrome Criteria in Algerian Patients: The Ex-vivo Immunomodulatory Effect of α, 25 Dihydroxyvitamin D3

BACKGROUND

Metabolic syndrome (MetS) is a combination of metabolic disorders with increased risks for several diseases, such as cardiovascular diseases and diabetes. It is associated with the presence of various inflammatory molecules. Vitamin D plays an important role in the regulation of metabolism homeostasis.

OBJECTIVE

The main goal of this work is to investigate vitamin D levels among Algerian MetS patients and its possible outcomes on key molecules of the immune response, as well, the immunomodulatory effects of its active metabolite.

METHODS

We evaluated vitamin D status by the electrochemiluminescence method, Nitric Oxide (NO) levels by the Griess method and Matrix Metalloproteinases (MMPs) activities such as MMP-2 and MMP-9 by zymography in plasma of patients and healthy controls (HC). The immunomodulatory effects of the active metabolite of vitamin D (α-25 (OH)2D3) on the production of NO, IL-6, IL-10, TGF- β and s-CTLA-4 were assessed by Griess method and ELISA, in peripheral blood mononuclear cells (PBMCs) of Algerian MetS patients and HC. MMPs activities were also determined ex-vivo, while iNOS expression was assessed by immunofluorescence staining.

RESULTS

Severe vitamin D deficiency was registered in Algerian MetS patients. The deficiency was found to be associated with an elevated in vivo NO production and high MMPs activity. Interestingly, α-25 (OH)2D3 declined the NO/iNOS system and IL-6 production, as well as MMPs activities. However, the ex-vivo production of IL-10, TGF-β increased in response to the treatment. We observed in the same way, the implication of s-CTLA-4 in MetS, which was markedly up-regulated with α-25 (OH)2D3.

CONCLUSION

Our report indicated the relationship between MetS factors and Vitamin D deficiency. The ex-vivo findings emphasize its impact on maintaining regulated immune balance.

Molecular Characteristics of RAGE and Advances in Small-Molecule Inhibitors

Receptor for advanced glycation end-products (RAGE) is a member of the immunoglobulin superfamily. RAGE binds and mediates cellular responses to a range of DAMPs (damage-associated molecular pattern molecules), such as AGEs, HMGB1, and S100/calgranulins, and as an innate immune sensor, can recognize microbial PAMPs (pathogen-associated molecular pattern molecules), including bacterial LPS, bacterial DNA, and viral and parasitic proteins. RAGE and its ligands stimulate the activations of diverse pathways, such as p38MAPK, ERK1/2, Cdc42/Rac, and JNK, and trigger cascades of diverse signaling events that are involved in a wide spectrum of diseases, including diabetes mellitus, inflammatory, vascular and neurodegenerative diseases, atherothrombosis, and cancer. Thus, the targeted inhibition of RAGE or its ligands is considered an important strategy for the treatment of cancer and chronic inflammatory diseases.

Tetracycline use in treating osteoarthritis: a systematic review

BACKGROUND AND AIMS

The purpose of the review was to synthesize the current literature regarding tetracyclines in the treatment of osteoarthritis.

METHODS

Using multiple databases, a systematic review was performed with customized search terms crafted to identify studies examining doxycycline or minocycline in the treatment of osteoarthritis. Results were classified into basic science mechanistic studies, in vivo animal studies, and human clinical trials. A total of 1446 potentially relevant studies were reviewed, and after exclusion criteria were applied, 23 investigations were included in the final analysis.

RESULTS

From 12 basic science mechanistic studies, we report on three main mechanisms by which tetracyclines may exert benefit in osteoarthritis progression: matrix metalloproteinase inhibition, immunomodulation, and nitric oxide synthase inhibition. Seven animal studies showed generally encouraging results. Four articles reported human clinical studies, showing mixed results in the treatment of osteoarthritis, potentially related to the choice of patient population, primary outcomes, and timing of treatment.

CONCLUSION

Tetracyclines have the potential to benefit osteoarthritis patients via multiple mechanisms. Further study is warranted to examine the optimal dose and timing of tetracycline treatment in osteoarthritis.

Baicalin promotes extracellular matrix synthesis in chondrocytes via the activation of hypoxia-inducible factor-1α

Chinese herbal extracts are being used increasingly to treat osteoarthritis (OA) in recent years. Baicalin (BA) is an active component of Scutellaria baicalensis Georgi extracts and protects chondrocytes against damage. The aim of the present study was to examine the mechanism of action of BA on chondrocytes from mouse articular cartilage. In total, 44 µM BA and 10 µM hypoxia-inducible-factor-1α (HIF-1α) inhibitor BAY-87-2243 were screened by the [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium] method. Alcian blue and Safran O staining were used to investigate the synthesis of extracellular matrix (ECM) in chondrocytes treated with BA. The expression of HIF-1α and chondrogenic marker genes including SOX9, AGG and Col2α was detected by western blotting or reverse-transcription quantitative (RT-qPCR), the expression of PHD1,2,3 and catabolic genes including ADAMTS5, MMP9 and MMP13 were detected by RT-qPCR. To investigate the effect of BA on the ECM synthesis of chondrocytes, 44 µM BA and 10 µM BAY were chosen for further experimentation. It was confirmed that BA at a concentration of 44 µM could significantly promote the secretion of ECM. The expressions of genes including HIF-1α, SOX9, collagen type 2 (Col2α) and aggrecan (AGG) were elevated following BA pretreatment and decreased by subsequent BAY-87-2243 stimulation for 24 h. Compared with untreated chondrocytes, the expressions of genes including ADAMTS5, MMP9, MMP13, PHD1, PHD2 and PHD3 in chondrocytes treated by BA were downregulated, however, BAY-87-2243 reversed the effect of BA on the genes including ADAMTS5, MMP9, MMP13, PHD1, PHD2 and PHD3 in chondrocytes. The findings of the present study suggest that BA may promote ECM synthesis and marker gene expression in chondrocytes by activating HIF-1α. Therefore, BA may represent a novel clinical drug for OA.

Genetics in Cartilage Lesions: Basic Science and Therapy Approaches

Cartilage lesions have a multifactorial nature, and genetic factors are their strongest determinants. As biochemical and genetic studies have dramatically progressed over the past decade, the molecular basis of cartilage pathologies has become clearer. Several homeostasis abnormalities within cartilaginous tissue have been found, including various structural changes, differential gene expression patterns, as well as altered epigenetic regulation. However, the efficient treatment of cartilage pathologies represents a substantial challenge. Understanding the complex genetic background pertaining to cartilage pathologies is useful primarily in the context of seeking new pathways leading to disease progression as well as in developing new targeted therapies. A technology utilizing gene transfer to deliver therapeutic genes to the site of injury is quickly becoming an emerging approach in cartilage renewal. The goal of this work is to provide an overview of the genetic basis of chondral lesions and the different approaches of the most recent systems exploiting therapeutic gene transfer in cartilage repair. The integration of tissue engineering with viral gene vectors is a novel and active area of research. However, despite promising preclinical data, this therapeutic concept needs to be supported by the growing body of clinical trials.

The S100 calcium-binding protein A4 level is elevated in the lungs of patients with idiopathic pulmonary fibrosis

BACKGROUND

Fibroblast dysfunction is the main pathogenic mechanism of idiopathic pulmonary fibrosis (IPF). S100 calcium-binding protein A4 (S100A4) plays critical roles in the proliferation of fibroblasts and in the development of pulmonary, hepatic, and renal fibrosis. However, the clinical implications of S100A4 in IPF have not been evaluated.

METHODS AND MATERIALS

The S100A4 mRNA and protein levels were measured by real-time PCR and immunoblotting in fibroblasts from IPF patients and controls. The S100A4 level was measured by enzyme-linked immunosorbent assay in bronchoalveolar lavage fluid (BALF) from the normal controls (NCs; n = 33) and from patients with IPF (n = 87), non-specific interstitial pneumonia (NSIP; n = 22), hypersensitivity pneumonitis (HP; n = 19), and sarcoidosis (n = 9). S100A4 localization was evaluated by immunofluorescence staining.

RESULTS

The S100A4 mRNA and protein levels were significantly higher in fibroblasts from IPF patients (n = 14) than in those from controls (n = 10, p < 0.001). The S100A4 protein level in BALF was significantly higher in the IPF (89.25 [49.92-203.02 pg/mL]), NSIP (74.53 [41.88-131.45 pg/mL]), HP (222.36 [104.92-436.92 pg/mL]) and sarcoidosis (101.62 [59.36-300.62 pg/mL]) patients than in the NCs (7.57 [1.31-14.04 pg/mL], p < 0.01, respectively). Cutoff S100A4 levels of 18.85 and 28.88 pg/mL had 87.4% and 87.8% accuracy, respectively, for discriminating IPF and other lung diseases from NCs.

CONCLUSIONS

S100A4 is expressed by α-SMA-positive cells in the interstitium of the IPF patients. S100A4 may participate in the development of IPF, and its protein level may be a candidate diagnostic and therapeutic marker for IPF.

S100A4 is secreted by airway smooth muscle tissues and activates inflammatory signaling pathways via receptors for advanced glycation end products

S100A4 is a low-molecular-mass (12 kDa) EF-hand Ca²⁺-binding S100 protein that is expressed in a broad range of normal tissue and cell types. S100A4 can be secreted from some cells to act in an autocrine or paracrine fashion on target cells and tissues. S100A4 has been reported in the extracellular fluids of subjects with several inflammatory diseases, including asthma. Airway smooth muscle plays a critical role in airway inflammation by synthesizing and secreting inflammatory cytokines. We hypothesized that S100A4 may play an immunomodulatory role in airway smooth muscle. Trachealis smooth muscle tissues were stimulated with recombinant His-S100A4, and the effects on inflammatory responses were evaluated. S100A4 induced the activation of Akt and NF-κB and stimulated eotaxin secretion. It also increased the expression of RAGE and endogenous S100A4 in airway tissues. Stimulation of airway smooth muscle tissues with IL-13 or TNF-α induced the secretion of S100A4 from the tissues and promoted the expression of endogenous receptors for advanced glycation end products (RAGE) and S100A4. The role of RAGE in mediating the responses to S100A4A was evaluated by expressing a mutant nonfunctional RAGE (RAGEΔcyto) in tracheal muscle tissues and by treating tissues with a RAGE inhibitor. S100A4 did not activate NF-κB or Akt in tissues that were expressing RAGEΔcyto or treated with a RAGE inhibitor, indicating that S100A4 mediates its effects by acting on RAGE. Our results demonstrate that inflammatory mediators stimulate the synthesis and secretion of S100A4 in airway smooth muscle tissues and that extracellular S100A4 acts via RAGE to mediate airway smooth muscle inflammation.

Extracellular S100A4 as a key player in fibrotic diseases

Fibrosis is characterized by fibroblast activation, extracellular matrix (ECM) accumulation and infiltration of inflammatory cells that sometimes leads to irreversible organ dysfunction. Considerable evidence now indicates that inflammation plays a critical role in the initiation and progression of organ fibrosis. S100A4 protein, a ubiquitous member of the S100 family, has recently been discovered as a potential factor implicated in fibrotic diseases. S100A4 protein is released at inflammatory site and has a certain biological function to promote cell motility, invasion, ECM remodelling, autophagy and angiogenesis. In addition, extracellular S100A4 is also a potential causation of inflammatory processes and induces the release of cytokines and growth factors under different pathological conditions. Elevated S100A4 level in patients’ serum closely correlates with disease activity in several fibrotic diseases and serves as a useful biomarker for diagnosis and monitoring disease progression. Analyses of knockout mouse models have identified a functional role of extracellular S100A4 protein in fibrotic diseases, suggesting that suppressing its expression, release or function might be a promising therapeutic strategy. This review will focus on the role of extracellular S100A4 as a key regulator of pro‐inflammatory signalling pathways and its relative biological processes involved in the pathogenesis of fibrosis.

S100A4 promotes hepatocellular carcinogenesis by intensifying fibrosis-associated cancer cell stemness

A cancer-promoting role of fibrogenesis in the liver has long been speculated; however, the molecular mechanisms regarding this phenomenon are largely unknown. We demonstrated in our previous study that macrophage-derived S100A4 promotes liver fibrosis via activation of hepatic stellate cells; however, whether and how S100A4 directly contributes to the development of fibrosis-associated liver cancer remains elusive. High expression of S100A4 in the fibrotic region was observed in human liver tumor tissues which associated with advanced disease severity. Through an established hepatocarcinogenesis model involving apparent liver fibrogenesis, we found that S100A4-deficient mice developed significantly less and smaller liver tumor nodules, with no change in the liver inflammation but decreased liver fibrosis and expression of stem cell markers in hepatocellular carcinoma (HCC) tissues. Mechanistically, S100A4 directly promoted stem cell-associated genes signatures in a way synergistic with its interacting protein, extracellular matrix component collagen I. This process is dependent on the receptor of advanced glycation end products (RAGE) and β-catenin signaling. Furthermore, the liver tumor sphere formation in vitro and tumor growth in vivo were greatly enhanced only when the cancer cells were pretreated with both S100A4 and collagen I. Our work firstly demonstrated a key role of S100A4 in synergy with extracellular matrix in the promotion of hepatocellular carcinoma by affecting the stemness of cancer cells.

Role of S100 proteins in health and disease

The S100 family of proteins contains 25 known members that share a high degree of sequence and structural similarity. However, only a limited number of family members have been characterized in depth, and the roles of other members are likely undervalued. Their importance should not be underestimated however, as S100 family members function to regulate a diverse array of cellular processes including proliferation, differentiation, inflammation, migration and/or invasion, apoptosis, Ca²⁺ homeostasis, and energy metabolism. Here we detail S100 target protein interactions that underpin the mechanistic basis to their function, and discuss potential intervention strategies targeting S100 proteins in both preclinical and clinical situations.

S100A4 promotes the development of lipopolysaccharide-induced mouse endometritis

S100A4 is suggested to be a critical regulator of tumor metastasis, and implicated in progression of inflammation. The aim of this study is to investigate the expression and possible role of S100A4 in endometritis. Using a mouse model of endometritis induced by local injection of lipopolysaccharide (LPS), we found that infection induced recruitment of S100A4-positive cells in the endometrium of wild-type mice. Deficiency of S100A4 reduced uterine pathological reaction and mRNA expression of proinflammatory cytokine IL-1β and TNF-α (P < 0.01), suggesting S100A4 promoted the progression of endometritis. To further explore the potential mechanism, we examined the cellular proliferation and apoptosis in the endometrium. Western blot and immunohistochemical results showed that cell apoptosis in uterus during endometritis, marked by cleaved-Caspase 3 protein, was significantly cut down in S100a4-/- mice; cell proliferation, which was indicated by Ki-67, was also significantly decreased in the inflamed endometrial stroma of S100a4-/- mice. Overall, these results demonstrate that S100A4 promotes the development of LPS-induced endometritis, and it may be related to the process of cell proliferation and apoptosis during the inflammation.

Hyperbaric oxygen inhibits the HMGB1/RAGE signaling pathway by upregulating Mir-107 expression in human osteoarthritic chondrocytes

OBJECTIVE

MicroRNA (miRNA)107 expression is downregulated but high mobility group box 1 (HMGB-1), Toll-like receptors (TLRs), and receptor for advanced glycation end products (RAGE) are upregulated in osteoarthritic (OA) cartilage. We investigated mir-107/HMGB-1 signaling in OA after hyperbaric oxygen (HBO) treatment.

DESIGN

MiR-107 mimic was transfected and the HMGB-1 was analyzed in OA chondrocytes. MiRNA targets were identified using bioinformatics and a luciferase reporter assay. After HBO treatment, the mRNA or protein levels of HMGB-1, RAGE, TLR2, TLR4, and inducible nitric oxide (NO) synthase (iNOS) and phosphorylation of mitogen-activated protein kinase (MAPK) were evaluated. The secreted HMGB-1 and matrix metalloproteases (MMPs) levels were quantified. Finally, we detected the HMGB-1 and iNOS expression in rabbit cartilage defects.

RESULTS

Overexpression of miR-107 suppressed HMGB-1 expression in OA chondrocytes. The 3'UTR of HMGB-1 mRNA contained a 'seed-matched-sequence' for miR-107. MiR-107 was induced by HBO and a marked suppression of HMGB-1 was observed simultaneously in OA chondrocytes. Knockdown of miR-107 upregulated HMGB-1 expression in hyperoxic cells. HBO downregulated the mRNA and protein expression of HMGB-1, RAGE, TLR2, TLR4, and iNOS, and the secretion of HMGB-1. HBO decreased the nuclear translocation of nuclear factor (NF)-κB, downregulated the phosphorylation of MAPK, and significantly decreased the secretion of MMPs. Morphological and immunohistochemical observation demonstrated that HBO markedly enhanced cartilage repair and the area stained positive for HMGB-1 and iNOS tended to be lower in the HBO group.

CONCLUSIONS

HBO inhibits HMGB-1/RAGE signaling related pathways by upregulating miR-107 expression in human OA chondrocytes.

The Multifaceted S100A4 Protein in Cancer and Inflammation

The metastasis-promoting S100A4 protein, a member of the S100 family, has recently been discovered as a potent factor implicated in various inflammation-associated diseases. S100A4 is involved in a range of biological functions such as angiogenesis, cell differentiation, apoptosis, motility, and invasion. Moreover, S100A4 is also a potent trigger of inflammatory processes and induces the release of cytokines and growth factors under different pathological conditions.Indeed, the release of S100A4 upon stress and mainly its pro-inflammatory role emerges as the most decisive activity in disease development, such as rheumatoid arthritis (RA), systemic sclerosis (SSc) allergy, psoriasis, and cancer. In the scope of this review, we will focus on the role of S100A4 as a mediator of pro-inflammatory pathways and its associated biological processes involved in the pathogenesis of various human noncommunicable diseases (NCDs) including cancer.

Cell non-autonomous functions of S100a4 drive fibrotic tendon healing

Identification of pro-regenerative approaches to improve tendon healing is critically important as the fibrotic healing response impairs physical function. In the present study we tested the hypothesis that S100a4 haploinsufficiency or inhibition of S100a4 signaling improves tendon function following acute injury and surgical repair in a murine model. We demonstrate that S100a4 drives fibrotic tendon healing primarily through a cell non-autonomous process, with S100a4 haploinsufficiency promoting regenerative tendon healing. Moreover, inhibition of S100a4 signaling via antagonism of its putative receptor, RAGE, also decreases scar formation. Mechanistically, S100a4 haploinsufficiency decreases myofibroblast and macrophage content at the site of injury, with both cell populations being key drivers of fibrotic progression. Moreover, S100a4-lineage cells become α-SMA+ myofibroblasts, via loss of S100a4 expression. Using a combination of genetic mouse models, small molecule inhibitors and in vitro studies we have defined S100a4 as a novel, promising therapeutic candidate to improve tendon function after acute injury.

Elevated S100A4 in asthmatics and an allergen-induced mouse asthma model

The elevated S100A4 level has been found in some inflammatory diseases. However, the expression and role of S100A4 in asthma is unknown. The expression of S100A4 in induced sputum and plasma from healthy control and asthmatics were assessed by ELISA. Then an allergen-induced asthma mouse model treatment with anti-S100A4 antibody was used to explore the role of S100A4 in the pathogenesis of asthma. The S100A4 levels in sputum not in plasma in asthmatics were significantly increased than those of healthy controls and were negatively correlated with some lung function parameters and were positively correlated with sputum eosinophilia and lymphocyte. The expression of S100A4 in the lung as well as in BALF were also significantly higher in the asthma mouse model and treatment with anti-S100A4 antibody exhibited reductions in inflammatory cell accumulation, inflammatory mediators, and airway hyper-responsiveness. We further showed that LY294002, a specific inhibitor of PI3K, markedly decreased S100A4 expression in lung and S100A4 secretion in BALF in asthmatic mice. In conclusion, these data demonstrated that S100A4 may be involved in the pathogenesis of airway inflammation in asthma.

Inflammation in osteoarthritis: is it time to dampen the alarm(in) in this debilitating disease?

Osteoarthritis (OA) is the most common joint disease that strongly reduces the quality of life in patients; However, no disease-modifying therapy is available. For a long time, OA was considered a non-inflammatory disease that was the result of 'wear-and-tear' and abnormal mechanics, and therefore many considered the term 'osteoarthritis' a misnomer. However, during the last decades the notion arose that inflammation is not only present in the majority of OA patients but, rather, actively involved in the progression of the disease. Influx of immune cells is observed in the synovium and a plethora of inflammatory mediators is present in tissues and fluids from OA patients. These mediators cause the production of degrading enzymes that break down the cartilage matrix, which is the main hallmark of OA. Alarmins, which belong to the group of danger signals, have been implicated in many inflammatory diseases. They are among the first factors to be released upon cell stress due to, for example, infection, damage and inflammation. They attract and activate cells of the immune system and therefore lie at the base of the inflammatory reaction. In this narrative review, an overview of the history of OA, the evolving concept of inflammation as important factor in the OA pathogenesis, and particularly the central role that alarmins play in the initiation and maintenance of the low-grade inflammatory response in OA, is provided. Moreover, the targeting of alarmins as a promising approach to dampen the inflammation in OA is highlighted.

S100B regulates inflammatory response during osteoarthritis via fibroblast growth factor receptor 1 signaling

The present study aimed to investigate the role of S100B in the inflammation process during osteoarthritis (OA). OA cartilage samples were collected for S100B expression analysis. S100B expression levels were significantly increased in patients with OA compared with the Controls (1.28±0.66 vs. 0.42±0.31; P=0.01) and were determined to be correlated with TNF-α (r=0.42; P=0.04) and IL-1β (r=0.73; P=0.001) expression levels. Orthopedic casting tape was used to immobilize the right knee at 180° extension of adult female New Zealand white rabbits for 4 weeks to establish an OA model. Cartilage specimens from the medial femoral condyle of these rabbits were used for histological confirmation and immunohistochemical analyses, whereas synovial fluid was used in ELISA assays for tumor necrosis factor (TNF)-α and interleukin (IL)-1β expression levels. Human synovial fibroblasts from the knee synovial tissues of normal patients with traumatic injury were transfected with S100B overexpression and knockdown plasmids and subjected to lipopolysaccharide (LPS) stimulation; subsequently, TNF-α and IL-1β expression levels in conditioned medium were determined by ELISA; S100B overexpression and knockdown significantly increased and decreased the TNF-α and IL-1β expression levels, respectively. Increased TNF-α (573.3±15.4 vs. 102.6±8.7 pg) and IL-1β (378.6±7.2 vs. 170.1±5.8 pg) expression levels were detected in OA model rabbits compared with the Control rabbits. Additionally, S100B, fibroblast growth factor (FGF)-1 and FGF receptor (FGFR)-1 mRNA and protein expression levels were increased in OA model rabbits compared with the Control group. FGFR1 knockdown significantly decreased TNF-α and IL-1β expression levels in LPS-stimulated S100B-overexpressing human synovial fibroblasts. S100B is involved in FGFR1 signaling-mediated inflammatory response during OA, which may be considered as a potential therapeutic target.

Chronic hyperglycemia mediated physiological alteration and metabolic distortion leads to organ dysfunction, infection, cancer progression and other pathophysiological consequences: An update on glucose toxicity

Chronic exposure of glucose rich environment creates several physiological and pathophysiological changes. There are several pathways by which hyperglycemia exacerbate its toxic effect on cells, tissues and organ systems. Hyperglycemia can induce oxidative stress, upsurge polyol pathway, activate protein kinase C (PKC), enhance hexosamine biosynthetic pathway (HBP), promote the formation of advanced glycation end-products (AGEs) and finally alters gene expressions. Prolonged hyperglycemic condition leads to severe diabetic condition by damaging the pancreatic β-cell and inducing insulin resistance. Numerous complications have been associated with diabetes, thus it has become a major health issue in the 21st century and has received serious attention. Dysregulation in the cardiovascular and reproductive systems along with nephropathy, retinopathy, neuropathy, diabetic foot ulcer may arise in the advanced stages of diabetes. High glucose level also encourages proliferation of cancer cells, development of osteoarthritis and potentiates a suitable environment for infections. This review culminates how elevated glucose level carries out its toxicity in cells, metabolic distortion along with organ dysfunction and elucidates the complications associated with chronic hyperglycemia.

S100A4+ Macrophages Are Necessary for Pulmonary Fibrosis by Activating Lung Fibroblasts

S100A4, a calcium-binding protein, can promote pulmonary fibrosis via fibroblast activation. Due partly to its various cellular origins, the exact role of S100A4 in the development of lung fibrosis remains elusive. Here, we show that in the bronchoalveolar lavage fluid, numbers of S100A4⁺ macrophages correlated well with S100A4 protein levels and occurrence of idiopathic pulmonary fibrosis (IPF) in patients. A mouse model of bleomycin-induced pulmonary fibrosis demonstrated S100A4⁺ macrophages as main source for extracellular S100A4 in the inflammatory phase. In vitro studies revealed that extracellular S100A4 could activate both mouse and human lung fibroblasts by upregulation of α-SMA and type I collagen, during which sphingosine-1-phosphate (S1P) increased. Inhibiting the S1P receptor subtypes S1P₁/S1P₃ abrogated fibroblast activation. Accordingly, absence or neutralization of S100A4 significantly attenuated bleomycin-induced lung fibrosis in vivo. Importantly, adoptive transfer of S100A4⁺ but not of S100A4⁻ macrophages installed experimental lung injury in S100A4^−/− mice that were otherwise not sensitive to fibrosis induction. Taken together, S100A4 released by macrophages promotes pulmonary fibrosis through activation of lung fibroblasts which is associated with S1P. This suggests that extracellular S100A4 or S100A4⁺ macrophages within the lung as promising targets for early clinical diagnosis or therapy of IPF.

Expression and modulation of S100A4 protein by human mast cells

S100A4 protein is expressed in fibroblasts during tissue remodelling and in cancer stem cells and it induces the metastatic spread of tumor cells. In mast cells (MCs) S100A4 have been found in some pathological conditions, but its function in normal MCs remains to be described. The purpose of this study was to characterize the cellular localization of the S100A4 protein in MCs of human tissues with inflammatory or tumor disorders and, to determine the consequence of reducing its expression in MC response. We found that tissue resident MCs stained positive to S100A4. Both human HMC-1 cell line and resting CD34⁺-derived MCs expressed S100A4, whose levels were differentially modulated upon MC activation. Downregulation of the S100A4 protein resulted in MC growth inhibition, enhanced apoptosis and deregulation of MMP-1 and MMP-10 production. Our results suggest that S100A4 is also playing a role in the MC life cycle and functions.

Embigin Promotes Prostate Cancer Progression by S100A4-Dependent and-Independent Mechanisms

Embigin, a transmembrane glycoprotein belonging to the immunoglobulin superfamily, is involved in prostate and mammary gland development. As embigin’s roles in cancer remain elusive, we studied its biological functions and interaction with extracellular S100A4 in prostate cancer progression. We found by a pull-down assay that embigin is a novel receptor for S100A4, which is one of the vital cancer microenvironment milleu. Binding of extracellular S100A4 to embigin mediates prostate cancer progression by inhibition of AMPK activity, activation of NF-κB, MMP9 and mTORC1 signaling, and inhibition of autophagy, which increase prostate cancer cell motility. We also found that embigin promotes prostate cancer growth, spheroid- and colony-forming ability, and survival upon chemotherapy independently of S100A4. An in vivo growth mouse model confirmed the importance of embigin and its cytoplasmic tail in mediating prostate tumor growth. Moreover, embigin and p21^WAF1 can be used to predict survival of prostate cancer patients. Our results demonstrated for the first time that the S100A4-embigin/AMPK/mTORC1/p21^WAF1 and NF-κB/MMP9 axis is a vital oncogenic molecular cascade for prostate cancer progression. We proposed that embigin and p21^WAF1 could be used as prognostic biomarkers and a strategy to inhibit S100A4-embigin binding could be a therapeutic approach for prostate cancer patients.

Diabetes escalates knee osteoarthritis in rats: Evidence of adaptive mechanism

Clinical reports on the coexistence of diabetes mellitus (DM) and osteoarthritis (OA) dated back to the 1960 s. Therefore, the study investigated the effects of induced DM and/or knee osteoarthritis (KOA) on known biomarkers in male Wistar rats. Twenty rats of five animals per group were induced with DM and/or knee OA using streptozotocin plus nicotinamide and sodium monoiodoacetate. Afterwards, they were left untreated for four weeks.The results showed that pro-inflammatory and pro-oxidative events were most significantly expressed in D + OA group and least in OA group. In contrast to the other experimental groups, there was a decreased bone formation in DM group.Unexpectedly, there were significant increases in bone and cartilage degradation markers in diabetic group, relative to D + OA group. In conclusion, diabetic-osteoarthritic state is characterised by more altered biochemical profile, relative to what is probable in either disease condition. Nevertheless, this situation remains subject to the influence of endogenous homeostatic mechanisms.

S100A4 promotes colon inflammation and colitis-associated colon tumorigenesis

S100A4 plays important roles in tumor development and metastasis, but its role in regulating inflammation and colitis-associated tumorigenesis has not been well characterized. Here, we report that S100A4 expression was increased in azoxymethane (AOM) and dextran sulfate sodium (DSS) induced colorectal cancer (CRC) in mice. After AOM/DSS treatment, both S100A4-TK mice with the selective depletion of S100A4-expressing cells and S100A4-deficient (S100A4^−/−) mice developed fewer and smaller tumors than wild-type (WT) control littermates. Furthermore, S100A4^−/− mice were resistant to DSS-induced colitis, reduced infiltration of macrophages, and the diminished production of proinflammatory cytokines. Further studies revealed that reduced colon inflammation and colorectal tumor development in S100A4^−/− mice were partly due to the dampening of nuclear factor (NF)-κB activation in macrophages. Furthermore, the administration of a neutralizing S100A4 antibody to WT mice significantly decreased AOM/DSS-induced colon inflammation and tumorigenesis. These results indicate that S100A4 amplifies an inflammatory microenvironment that promotes colon tumorigenesis and provides a promising therapeutic strategy for treatment of inflammatory bowel disease and prevention of colitis-associated colorectal carcinogenesis.

Inducible nitric oxide synthase as a target for osteoarthritis treatment

INTRODUCTION

Inducible nitric oxide synthase (iNOS) is the enzyme responsible for the production of nitric oxide (NO), a major proinflammatory and destructive mediator in osteoarthritis (OA). Areas covered: This is a comprehensive review of the recent literature on the involvement of iNOS in osteoarthritis and its potential to be used as a target for OA treatment. Evidence from in vitro, in vivo and human studies was systematically collected using medical search engines. Preclinical studies have focused on the effect of direct and indirect iNOS inhibitors in both animal and human tissues. Apart from direct inhibitors, common pharmacological agents, herbal and dietary medicines as well as hyperbaric oxygen, low level laser and low intensity pulsed ultrasound have been shown to exhibit a chondroprotective effect by inhibiting the expression of iNOS. Expert opinion: Data support the further investigation of iNOS inhibitors for the treatment of OA in human studies and clinical trials. Indirect iNOS inhibitors such as interleukin 1 inhibitors also need to be studied in greater detail. Finally, human studies need to be conducted on the herbal and dietary medicines and on the non-invasive, non-pharmacological treatments.

Calcitonin and Omega-3 Fatty Acids Exhibit Antagonistic and Non-Additive Effects in Experimental Diabetes

Because optimising therapy for the management of diabetes mellitus remains challenging, the study investigated the effects of salmon calcitonin (Sct) and/or omega-3 fatty acids (N-3 - eicosapentaenoic acid and docosahexaenoic acid-3:2), compared to metformin, on selected biochemical parameters in male Wistar rats, in an experimental model of diabetes. Forty rats were used for this study. They were divided into eight groups of five rats each, which included: Normal control; Diabetic (D) control; D + N-3; D + low dose Sct (Sct. Lw); D + high dose Sct (Sct. Hi); D + N-3 + Sct.Lw; D + N-3 + Sct.Hi; and D + metformin. Diabetes was induced in overnight fasted rats by the administration of streptozotocin (65 mg/kg b.w., i.p.), 15 min after the administration of nicotinamide (110 mg/kg b.w., i.p.). Nine days later, Sct was administered at 2.5 and 5.0 IU/kg b.w./day (i.m.), while N-3 and metformin were administered at 200 and 180 mg/kg b.w./day (p.o.) respectively, for four weeks. Sct, N-3, and metformin significantly reduced total cholesterol, LDL-C, cortisol, c-telopeptide of type 1 collagen, and collagen type 2 alpha-1. The combined administration of Sct and N-3 had more favorable effects on triglyceride and HDL-C than either monotherapy. Unlike metformin and Sct. Hi, N-3 significantly reduced alkaline phosphatase activity. Moreover, N-3 significantly suppressed the hypocalcaemic, hyperglycaemic, and insulin resistance provoking actions of Sct. Furthermore, N-3 contradicted the hepatic glycogen depletion and inhibition of nitric oxide synthesis brought about by Sct. In conclusion, N-3 demonstrated antagonistic and non-additive actions with Sct. Moreover, the effects of the combined administration of Sct and N-3 were comparable to that of metformin; therefore, they might be considered as therapeutic alternatives in diabetes.

Defective interplay between mTORC1 activity and endoplasmic reticulum stress-unfolded protein response in uremic vascular calcification

Vascular calcification increases the risk of cardiovascular disease and death in patients with chronic kidney disease (CKD). Increased activity of mammalian target of rapamycin complex 1 (mTORC1) and endoplasmic reticulum (ER) stress-unfolded protein response (UPR) are independently reported to partake in the pathogenesis of vascular calcification in CKD. However, the association between mTORC1 activity and ER stress-UPR remains unknown. We report here that components of the uremic state [activation of the receptor for advanced glycation end products (RAGE) and hyperphosphatemia] potentiate vascular smooth muscle cell (VSMC) calcification by inducing persistent and exaggerated activity of mTORC1. This gives rise to prolonged and excessive ER stress-UPR as well as attenuated levels of sestrin 1 ( Sesn1) and Sesn3 feeding back to inhibit mTORC1 activity. Activating transcription factor 4 arising from the UPR mediates cell death via expression of CCAAT/enhancer-binding protein (c/EBP) homologous protein (CHOP), impairs the generation of pyrophosphate, a potent inhibitor of mineralization, and potentiates VSMC transdifferentiation to the osteochondrocytic phenotype. Short-term treatment of CKD mice with rapamycin, an inhibitor of mTORC1, or tauroursodeoxycholic acid, a bile acid that restores ER homeostasis, normalized mTORC1 activity, molecular markers of UPR, and calcium content of aortas. Collectively, these data highlight that increased and/or protracted mTORC1 activity arising from the uremic state leads to dysregulated ER stress-UPR and VSMC calcification. Manipulation of the mTORC1-ER stress-UPR pathway opens up new therapeutic strategies for the prevention and treatment of vascular calcification in CKD.

Osteoarthritis: Trauma vs Disease

Osteoarthritis (OA) is the most prevalent joint disease characterized by pain and degenerative lesions of the cartilage, subchondral bone, and other joint tissues. The causes of OA remain incompletely understood. Over the years, it has become recognized that OA is a multifactorial disease. In particular, aging and trauma are the main risk factors identified for the development of OA; however, other factors such as genetic predisposition, obesity, inflammation, gender and hormones, or metabolic syndrome contribute to OA development and lead to a more severe outcome. While this disease mainly affects people older than 60 years, OA developed after joint trauma affects all range ages and has a particular impact on young individuals and people who have highest levels of physical activity such as athletes. Traumatic injury to the joint often results in joint instability or intra-articular fractures which lead to posttraumatic osteoarthritis (PTOA). In response to injury, several molecular mechanisms are activated, increasing the production and activation of different factors that contribute to the progression of OA.In this chapter, we have focused on the interactions and contribution of the multiple factors involved in joint destruction and progression of OA. In addition, we overview the main changes and molecular mechanisms related to OA pathogenesis.

Sessile Innate Immune Cells

In this chapter, sessile cells of the innate immune system are briefly introduced. Defined as cells equipped with diverse pattern recognition molecules capable of detecting MAMPs and DAMPs, they encompass cells such as epithelial cells, fibroblasts, vascular cells, chondrocytes, osteoblasts, and adipocytes. Located at the body surfaces, epithelial cells represent the first line of innate immune defense against invading microbial pathogens. They are significant contributors to innate mucosal immunity and generate various antimicrobial defense mechanisms. Also, epithelial cells critically contribute to tissue repair via the phenomenon of re-epithelialization. Fibroblasts operate as classical sentinel cells of the innate immune system dedicated to responding to MAMPs and DAMPs emitted upon any tissue injury. Typically, fibroblasts synthesize most of the extracellular matrix of connective tissues, thereby playing a crucial role in tissue repair processes. Vascular cells of the innate immune system represent an evolutionarily developed first-line defense against any inciting insult hitting the vessel walls from the luminal side including bacteria, viruses, microbial toxins, and chemical noxa such as nicotine. Upon such insults and following recognition of MAMPs and DAMPs, vascular cells react with an innate immune response to create an acute inflammatory milieu in the vessel wall aimed at curing the vascular injury concerned. Chondrocytes, osteoblasts, and osteoclasts represent other vital cells of the skeletal system acting as cells of the innate immune system in its wider sense. These cells mediate injury-promoted DAMP-induced inflammatory and regenerative processes specific for the skeletal systems. Finally, adipocytes are regarded as highly active cells of the innate immune system. As white, brown, and beige adipocytes, they operate as a dynamic metabolic organ that can secrete certain bioactive molecules which have endocrine, paracrine, and autocrine actions.

Role of metastasis-induced protein S100A4 in human non-tumor pathophysiologies

S100A4, an important member of the S100 family of proteins, is best known for its significant role in promoting cancer progression and metastasis. In addition to its expression in tumors, upregulation of S100A4 expression has been associated with various non-tumor pathophysiology processes. However, the mechanisms underlying the role of S100A4 remain unclear. Activated “host” cells (fibroblasts, immunocytes, vascular cells, among others) secrete S100A4 into the extracellular space in various non-tumor human disorders, where it executes its biological functions by interacting with intracellular target proteins. However, the exact molecular mechanisms underlying these interactions in different non-tumor pathophysiologies vary, and S100A4 is likely one of the cross-linking factors that acts as common intrinsic constituents of biological mechanisms. Numerous studies have indicated that the S100A4-mediated epithelial–mesenchymal transition plays a vital role in the occurrence and development of various non-tumor pathophysiologies. Epithelial–mesenchymal transition can be categorized into three general subtypes based on the phenotype and function of the output cells. S100A4 regulates tissue fibrosis associated with the type II epithelial–mesenchymal transition via various signaling pathways. Additionally, S100A4 stimulates fibroblasts to secrete fibronectin and collagen, thus forming the structural components of the extracellular matrix (ECM) and stimulating their deposition in tissues, contributing to the formation of a pro-inflammatory niche. Simultaneously, S100A4 enhances the motility of macrophages, neutrophils, and leukocytes and promotes the recruitment and chemotaxis of these inflammatory cells to regulate inflammation and immune functions. S100A4 also exerts a neuroprotective pro-survival effect on neurons by rescuing them from brain injury and participates in angiogenesis by interacting with other target molecules. In this review, we summarize the role of S100A4 in fibrosis, inflammation, immune response, neuroprotection, angiogenesis, and some common non-tumor diseases as well as its possible involvement in molecular pathways and potential clinical value.

Extracellular matrix alterations in senescent cells and their significance in tissue homeostasis

Normal cells after a defined number of successive divisions or after exposure to genotoxic stresses are becoming senescent, characterized by a permanent growth arrest. In addition, they secrete increased levels of pro-inflammatory and catabolic mediators, collectively termed "senescence-associated secretory phenotype". Furthermore, senescent cells exhibit an altered expression and organization of many extracellular matrix components, leading to specific remodeling of their microenvironment. In this review we present the current knowledge on extracellular matrix alterations associated with cellular senescence and critically discuss certain characteristic examples, highlighting the ambiguous role of senescent cells in the homeostasis of various tissues under both normal and pathologic conditions.

Epigenetic silencing of miR-520c leads to induced S100A4 expression and its mediated colorectal cancer progression

The S100 calcium-binding protein A4 (S100A4) induces epithelial mesenchymal transition, migration, invasion, angiogenesis and metastasis. Its induced expression in several cancer types correlates with poor prognosis. Apart from the functional and transcriptional regulatory aspects of S100A4, its post-transcriptional regulation is not yet clearly elucidated. In this study, we show that microRNAs (miR) miR-505-5p and miR-520c-3p target the 3′-UTR of S100A4 and inhibits its expression and its mediated migration and invasion. 5-Aza treatment significantly increased miR-520c-3p expression and reduced the S100A4 protein amounts. The upstream promoter region of miR-520c is hypermethylated irrespective of the metastasis status of colorectal cancer (CRC) patient tissues and in all analyzed CRC cell lines. Moreover, in a cohort of CRC patient specimen (n = 59), miR-520c-3p was significantly downregulated. miR-520c-3p stably expressing HCT116 cells showed a reduced metastasis formation in livers after implanting in mice spleen. Taken together, our findings demonstrate that S100A4 is post-transcriptionally regulated by tumor suppressor miRs, miR-505c-5p and miR-520c-3p, and particularly miR-520c-3p expression is epigenetically silenced in CRC.

S100A4 contributes to colitis development by increasing the adherence of Citrobacter rodentium in intestinal epithelial cells

S100A4 has been implicated in cancer and several inflammatory diseases, but its role in inflammatory bowel disease has not been well investigated. Here, upon infection with Citrobacter rodentium, a model for enteropathogenic Escherichia coli infection in humans, induced the infiltration of a large number of S100A4⁺ cells into the colon in wild type (WT) mice. Deficiency of S100A4 reduced weight loss, bacterial colonization and colonic pathology. Furthermore, the expression of inflammatory cytokines and the recruitment of macrophages and neutrophils also decreased significantly in S100A4 knock out (S100A4 ^-/-) mice. In vitro, soluble S100A4 directly up-regulated expression of integrin β-1 in intestinal epithelial cells and significantly increased the adherence of C. rodentium to intestinal epithelial cells. Additionally, the effects of S100A4 on the adherence of C. rodentium to epithelial cells could be abolished by a receptor for advanced glycation end products (RAGE)-specific inhibitor (FPS-ZM1). Therefore, these data indicate a novel mechanism for S100A4 that promotes colitis development by enhancing host adhesion and colonization of Citrobacter rodentium through the S100A4-mediated host inflammatory responses.