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Wnt-1 inducible signaling pathway protein 2 (WISP-2/CCN5) is a recently identified adipokine that has been described as an important mediator of canonical Wnt activation in adipogenic precursor cells. In osteoarthritis (OA), the most common form of arthritis, chondrocytes exhibit aberrant and increased production of pro-inflammatory mediators and matrix degrading enzymes such as IL-1β and MMP-13. Although recent evidence suggests a role for Wnt signaling in OA physiopathology, little is known about the involvement of WISP-2 in cartilage degradation. In the present study, we determined the expression of WISP-2 in healthy and OA human chondrocytes. WISP-2 expression is modulated along chondrocyte differentiation and downregulated at the onset of hypertrophy by inflammatory mediators. We also investigated the effect of WISP-2 on cartilage catabolism and performed WISP-2 loss-of-function experiments using RNA interference technology in human T/C-28a2 immortalized chondrocytes. We demonstrated that recombinant human WISP-2 protein reduced IL-1β-mediated chondrocyte catabolism, that IL-1β and WNT/b-catenin signaling pathways are involved in rhWISP-2 protein and IL-1β effects in human chondrocytes, and that WISP-2 has a regulatory role in attenuating the catabolic effects of IL-1β in chondrocytes. Gene silencing of WISP-2 increased the induction of the catabolic markers MMP-13 and ADAMTS-5 and the inflammatory mediators IL-6 and IL-8 triggered by IL-1β in human primary OA chondrocytes in a Wnt/β-catenin dependent manner. In conclusion, here we have shown for the first time that WISP-2 may have relevant roles in modulating the turnover of extracellular matrix in the cartilage and that its downregulation may detrimentally alter the inflammatory environment in OA cartilage. We also proved the participation of Wnt/β-catenin signaling pathway in these processes. Thus, targeting WISP-2 might represent a potential therapeutical approach for degenerative and/or inflammatory diseases of musculoskeletal system, such as osteoarthritis., (© 2022. The Author(s), under exclusive licence to United States and Canadian Academy of Pathology.)

Background and Purpose: Recombinant human relaxin-2, serelaxin, is being proved as a novel drug with therapeutic efficacy in some cardiovascular diseases, especially heart failure, a disease whose physiopathology and course are firmly correlated with important alterations in cardiac metabolism. The aim of our present work was to investigate changes in the cardiac metabolome following relaxin-2 treatment., Experimental Approach: Sprague-Dawley rats were treated with human recombinant relaxin-2 using osmotic minipumps at a dose of 0.4 mg/kg/day for 2 weeks. Body composition was measured with a nuclear magnetic resonance imaging system seven days after surgery and on the final day of the experiment. The last two days of treatment, respiratory quotient, locomotor activity and energy expenditure were measured with a calorimetric system. The plasma levels of relaxin-2, total cholesterol, high- and low- density lipoproteins (HDL, LDL), triglycerides and the hepatic enzymes glutamic-pyruvic transaminase (GTP) and gamma-glutamyltransferase (GGT) levels were analyzed. The metabolic profiling of both atria from relaxin-2-treated and control rats was carried out using two separate ultra-high performance liquid chromatography (UHPLC)-Time of Flight-MS based platforms analyzing methanol and chloroform/methanol extracts combined with a UHPLC-single quadrupole-MS based platform used to analyze aminoacids and with a methanol/water extract platform that covered polar metabolites. Identified ion features in the methanol extract platform included fatty acids, acyl carnitines, bile acids, monoacylglycerophospholipids, monoetherglycerophospholipids, free sphingoid bases, and oxidized fatty acids. The chloroform / methanol extract platform provided coverage over glycerolipids, cholesterol esters, sphingolipids, diacylglycerophospholipids, and acyl-ether-glycerophospholipids. Gene expression levels of the adipokines adiponectin, leptin and nesfatin-1 in visceral adipose tissue and cardiac gene expression levels of key enzymes of desaturation and elongation of n-6 and n-3 PUFAs were assessed by Real Time-PCR., Key Results: Twenty-eight metabolites out of three hundred sixty-two were significantly altered by human relaxin-2. These included fifteen glycerophospholipids: three phosphatidylethanolamines (PE) and twelve phosphatidylcholines (PC); eight sphingolipids: three ceramides (Cer) and five sphingomyelins (SM); and also five aminoacids and one carboxylic acid. Interestingly, the majority of changes correspond to lipid classes, twelve of them polyunsaturated diacylglycerophosphatidylcholines with long acyl chains, containing mainly docosahexaenoic acid (22:6) and arachidonic acid (20:4). Atrial levels of Elovl5 (Elongation of very long chain fatty acids protein 5), Fads1 (Δ5-fatty acid desaturase) and Fads2 (Δ6-fatty acid desaturase), key enzymes of elongation and desaturation of n-6 and n-3 PUFAs like arachidonic acid and DHA, respectively, were significantly increased by relaxin-2 treatment. Atrial tissues from rats treated with relaxin-2 showed a significant increase in the mRNA levels of Srebf1, a transcription factor that activates the gene expression of Elovl5, Fads1 and Fads2. The treatment with relaxin-2 significantly decreased the visceral fat mRNA expression levels of adiponectin, leptin and nesfatin-1, adipokines known to exert an important influence on the regulation of cardiovascular function., Conclusion and Implications: Serelaxin (human recombinant relaxin-2) treatment induces significant changes in cardiac major components of the membrane lipid bilayer such as glycerophospholipids and sphingolipids, known to have structural roles but also very relevant regulatory effects in cardiac function. Serelaxin induced also modifications in several aminoacids of high influence in cardiac energy metabolism regulation. Our results highlight the need to further understand the role of relaxin-2 in the regulation of cardiac energy metabolism, in the context of the therapeutic strategies for the treatment of cardiometabolic pathologies as heart failure., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Composite hydrogels were obtained by the entrapment of chitosan, pectin or κ-carrageenan within methacrylate-based hydrogels to improve their swelling and the mechanical properties. The results indicated that the water uptake (WU) of κ-carrageenan and chitosan hydrogels were until 3.5 and 2.2 times higher than the WU of the synthetic hydrogel, respectively. The surface morphologies of the hydrogels showed that the pectin and κ-carrageenan favors the formation of larger and more defined pores. The mechanical properties indicated that the pectin increased slightly the mechanical properties and the κ-carrageenan improves the mechanical properties of the synthetic hydrogel reaching up 400 N of compression load. Therefore, the entrapment of κ-carrageenan within synthetic hydrogels improved both the swelling and the mechanical properties. The biocompatibility of the hydrogels was evaluated with in vitro cytotoxicity assays and the results indicated that they could be considered as candidates for biomedical use., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Background/aims: The E74-like factor 3 (ELF3) is an inflammatory mediator that participates in cartilage destruction in osteoarthritis. Leptin and other adipokines negatively impact articular cartilage, triggering catabolic and inflammatory responses in chondrocytes. Here, we investigated whether leptin induces ELF3 expression in chondrocytes and the signaling pathway involved in this process., Methods: We determined mRNA and protein levels of ELF3 by RT-qPCR and Western blotting using cultured human primary chondrocytes and the human T/C-28a2 chondrocyte cell line. Further, we measured luciferase activities of different reporter constructs, and we assessed the contribution of leptin to the induction of ELF3 mRNA by knocking down hLEPR gene expression using siRNA technology., Results: Leptin synergizes with IL-1β in inducing ELF3 expression in chondrocytes. We also found that PI3K, p38, and JAK2 signaling pathways are at play in the leptin-driven induction of ELF3. Moreover, we confirm the participation of NFΚB in the leptin/IL-1β synergistic induction of ELF3., Conclusion: Here we show, for the first time, the regulation of ELF3 expression by leptin, suggesting that this transcription factor likely mediates the inflammatory responses triggered by leptin in articular chondrocytes., (© 2018 The Author(s). Published by S. Karger AG, Basel.)

Background/aims: Oleocanthal (OC), a phenolic compound present in extra virgin olive oil (EVOO), has attracted attention since its discovery for its relevant pharmacological properties in different pathogenic processes, including inflammation. Here, we investigated the involvement of OC in LPS-activated osteoarthritis (OA) human primary chondrocytes., Methods: Human primary chondrocytes were harvested from articular cartilage samples obtained from OA patients. The effects of OC on the viability of chondrocytes were tested by MTT assay. Protein and mRNA expression of several catabolic and pro-inflammatory factors after OC treatment were measured by RT-qPCR and western blot respectively. Moreover, we analysed the NO production by Griess reaction. Finally, several pathways mediators were analysed by western blot., Results: We demonstrated that OC did not have any cytotoxic effect. Oleocanthal inhibited NO production and strongly decreased NOS2 and COX-2 protein and mRNA expression in LPS-activated human primary OA chondrocytes. Interestingly, OC also inhibits MMP-13 and ADAMTS-5. In addition, OC downregulates several pro-inflammatory factors, such as IL-6, IL-8, CCL3, LCN2 and TNF-α induced by LPS in human primary OA chondrocytes. Finally, we demonstrated that OC exerts its effects through the MAPK/P38/NF-kB pathways., Conclusion: These data show that OC is able to block LPS-mediated inflammatory response and MMP-13 and ADAMTS-5 induction in human primary OA chondrocytes via MAPKs/NF-kB pathways, suggesting that OC may be a promising agent for the treatment of inflammation in cartilage and a potential molecule to prevent disease progression by inhibiting metalloproteases and aggrecanases., (© 2018 The Author(s). Published by S. Karger AG, Basel.)

Progranulin is a cysteine-rich secreted protein with diverse pleiotropic actions and participates in several processes, such as inflammation or tumorigenesis. Progranulin was first identified as a growth factor and, recently, it was characterised as an adipokine implicated in obesity, insulin resistance and rheumatic disease. At a central level, progranulin acts as a neurotropic and neuroprotective factor and protects from neural degeneration. In this review, we summarise the most recent research advances concerning the potential role of progranulin as a therapeutic target and biomarker in cancer, neurodegenerative and inflammatory diseases., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Osteoarthritis (OA) is a chronic systemic musculoskeletal disorder involving inflammation, immunity, and metabolic alterations. OA is commonly regarded as non-inflammatory disease; still inflammation is recognized as contributing to the symptoms and progression of OA. New evidence suggests that adipokines are involved in the pathophysiology of OA and might modulate the production of inflammatory mediators including in immune cells. However, the role of immune component in osteoarthritis is still poorly investigated. To gain further insights into the interaction of immune cells in OA and the role of adipokines on these cells, we performed experiments aimed to determine the cytokine profile in activated CD4 + T cells from OA patients. For completeness, we also explored the cross talk between T lymphocytes and chondrocytes in OA by co-culturing human primary chondrocytes with activated CD4 + T cells in two ways: the first by incubating the cells by direct contact (D.C.) or by transwell system. Our results show that the exposure of activated CD4 + T cells to adipokines modulates IL-6, IL-8, and CCL-3 production. In addition, the production of key macromolecules of ECM (aggrecan and collagen-2) and matrix metalloproteinase 13 (MMP-13) in co-cultured chondrocytes with activated CD4 + T cells was altered. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1299-1303, 2017., (© 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.)

Leptin is one of the most relevant factors secreted by adipose tissue and the forerunner of a class of molecules collectively called adipokines. Initially discovered in 1994, its crucial role as a central regulator in energy homeostasis has been largely described during the past 20 years. Once secreted into the circulation, leptin reaches the central and peripheral nervous systems and acts by binding and activating the long form of leptin receptor (LEPR), regulating appetite and food intake, bone mass, basal metabolism, reproductive function and insulin secretion, among other processes. Research on the regulation of different adipose tissues has provided important insights into the intricate network that links nutrition, metabolism and immune homeostasis. The neuroendocrine and immune systems communicate bi-directionally through common ligands and receptors during stress responses and inflammation, and control cellular immune responses in several pathological situations including immune-inflammatory rheumatic diseases. This Review discusses the latest findings regarding the role of leptin in the immune system and metabolism, with particular emphasis on its effect on autoimmune and/or inflammatory rheumatic diseases, such as rheumatoid arthritis and osteoarthritis.

Key Points: E74-like factor 3 (ELF3) is a transcription factor regulated by inflammation in different physio-pathological situations. Lipocalin-2 (LCN2) emerged as a relevant adipokine involved in the regulation of inflammation. In this study we showed for the first time the involvement of ELF3 in the control of LCN2 expression and its cooperation with nuclear factor-κB (NFκB). Our results will help to better understand of the role of ELF3, NFκB and LCN2 in the pathophysiology of articular cartilage., Abstract: E74-like factor 3 (ELF3) is a transcription factor induced by inflammatory cytokines in chondrocytes that increases gene expression of catabolic and inflammatory mediators. Lipocalin 2 (LCN2) is a novel adipokine that negatively impacts articular cartilage, triggering catabolic and inflammatory responses in chondrocytes. Here, we investigated the control of LCN2 gene expression by ELF3 in the context of interleukin 1 (IL-1)-driven inflammatory responses in chondrocytes. The interaction of ELF3 and nuclear factor-κB (NFκB) in modulating LCN2 levels was also explored. LCN2 mRNA and protein levels, as well those of several other ELF3 target genes, were determined by RT-qPCR and Western blotting. Human primary chondrocytes, primary chondrocytes from wild-type and Elf3 knockout mice, and immortalized human T/C-28a2 and murine ATDC5 cell lines were used in in vitro assays. The activities of various gene reporter constructs were evaluated by luciferase assays. Gene overexpression and knockdown were performed using specific expression vectors and siRNA technology, respectively. ELF3 overexpression transactivated the LCN2 promoter and increased the IL-1-induced mRNA and protein levels of LCN2, as well as the mRNA expression of other pro-inflammatory mediators, in human and mouse chondrocytes. We also identified a collaborative loop between ELF3 and NFκB that amplifies the induction of LCN2. Our findings show a novel role for ELF3 and NFκB in the induction of the pro-inflammatory adipokine LCN2, providing additional evidence of the interaction between ELF3 and NFκB in modulating inflammatory responses, and a better understanding of the mechanisms of action of ELF3 in chondrocytes., (© 2016 The Authors. The Journal of Physiology © 2016 The Physiological Society.)

Background: Polychlorinated biphenyls (PCBs) are persistent organic pollutants that bioaccumulate in adipose tissue, disturbing its metabolism and the balance of adipokines, related to obesity. The altering secretion pattern of adipokines from the adipose tissue and the increasing mechanical load in weight-bearing joints presented in obesity condition, are risk factors for osteoarthritis development. The most prevalent rheumatic diseases, osteoarthritis and rheumatoid arthritis, are chronic conditions that target the whole joints, leading to increasing disability and health care cost. The goal of this focused review is to summarize the current knowledge on the role of PCBs in osteoarthritis and rheumatoid arthritis pathogenesis., Search Strategy: A PubMed search was managed using keywords as "rheumatic diseases", "polychlorinated biphenyls", "obesity" and "endocrine disruption"., Main Results of the Review: The incidence of rheumatoid arthritis has been reported to be increased especially in urban areas in industrialized countries, emphasizing the importance of environment in the pathogenesis of rheumatic diseases. Analysis of two cohorts exposed to PCBs food contamination showed high incidence of arthritis. In addition, PCBs in serum correlated positively with the prevalence of self-reported arthritis. Few studies support the hypothesis that osteoarthritis development could be related to PCBs induction of chondrocytes apoptosis., Conclusion: Evidences have emerged for a relationship between PCBs and development of several types of arthritis. Further research is encouraged to determine the correlation between PCBs exposure and the development of rheumatic diseases., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Progranulin (PGRN) is a recently identified adipokine that is supposed to have anti-inflammatory actions. The proinflammatory cytokine interleukin-1β (IL1β) stimulates several mediators of cartilage degradation. Toll like receptor-4 (TLR4) can bind to various damage-associated molecular patterns, leading to inflammatory condition. So far, no data exist of PGRN effects in inflammatory conditions induced by IL1β or lipopolysaccharide (LPS). Here, we investigated the anti-inflammatory potential of PGRN in IL1β- or LPS-induced inflammatory responses of chondrocytes. Human osteoarthritic chondrocytes and ATDC-5 cells were treated with PGRN in presence or not of IL1β or LPS. First, we showed that recombinant PGRN had no effects on cell viability. We present evidence that PGRN expression was increased during the differentiation of ATDC-5 cell line. Moreover, PGRN mRNA and protein expression is increased in cartilage, synovial and infrapatellar fat pad tissue samples from OA patients. PGRN mRNA levels are upregulated under TNFα and IL1β stimulation. Our data showed that PGRN is able to significantly counteract the IL1β-induced expression of NOS2, COX2, MMP13 and VCAM-1. LPS-induced expression of NOS2 is also decreased by PGRN. These effects are mediated, at least in part, through TNFR1. Taken together, our results suggest that PGRN has a clear anti-inflammatory function.

Nitric oxide (NO) has been considered a catabolic factor that contributes to OA pathology by inducing chondrocytes apoptosis, matrix metalloproteinases synthesis, and pro-inflammatory cytokines expression. Thus, the research on NO regulation in chondrocytes represents a relevant field which needs to be explored in depth. However, to date, only the murine ATDC-5 cell line and primary chondrocytes are well-established cells to study NO production in cartilage tissues. The goal of this study is to determine whether two commonly used human chondrocytic cell lines: SW-1353 and T/C-28a2 cell lines are good models to examine lipopolysaccharide and/or pro-inflammatory cytokine-driven NO release and iNOS expression. To this aim, we carefully examined NO production and iNOS protein expression in human T/C-28a2 and SW-1353 chondrocytes stimulated with LPS and interleukin (IL)-1 alone or in combination. We also use ATDC-5 cells as a positive control for NO production. NO accumulation has been determined by colorimetric Griess reaction, whereas NOS type II expression was determined by Western Blot analysis. Our results clearly demonstrated that neither human T/C-28a2 nor SW-1353 chondrocytes showed a detectable increase in NO production or iNOS expression after bacterial endotoxin or cytokines challenge with IL-1. Our study demonstrated that T/C-28a2 and SW-1353 human cell lines are not suitable for studying NO release and iNOS expression confirming that ATDC5 and human primary cultured chondrocytes are the best in vitro cell system to study the actions derived from this mediator., (© 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.)

Recent studies confer to IL-36α pro-inflammatory properties. However, little is known about the expression and function of IL-36α in cartilage. This study sought to analyze the expression of IL-36α in healthy and OA cartilage. Next, we determined the effects of recombinant IL-36α on catabolism and inflammation in chondrocytes. For completeness, part of the signaling pathway elicited by IL-36α was also explored. IL-36α expression was evaluated by immunohistochemistry and RT-qPCR. Expression of MMP-13, NOS2 and COX-2 was also determined in OA articular chondrocytes treated with recombinant IL-36α. IκB-α and P-p38 was explored by western blot. We observed a low constitutive expression of IL-36α in healthy human chondrocytes. However, OA chondrocytes likely expressed more IL-36α than healthy chondrocytes. In addition, immune cells infiltrated into the joint and PBMCs express higher levels of IL-36α in comparison to chondrocytes. OA chondrocytes, treated with IL-36α, showed significant increase in the expression of MMP-13, NOS2 and COX-2. Finally, IL-36α stimulated cells showed NFκB and p38 MAPK activated pathways. IL-36α acts as a pro-inflammatory cytokine at cartilage level, by increasing the expression of markers of inflammation and cartilage catabolism. Like other members of IL-1 family, IL-36α acts through the activation of NFκB and p38 MAPK pathway.

Objectives: Osteoarthritis (OA) is a chronic joint disease, characterized by a progressive loss of articular cartilage. During OA, proinflammatory cytokines, such as interleukin IL-1, induce the expression of matrix metalloproteinases (MMPs) in chondrocytes, contributing thus to the extracellular matrix (ECM) degradation. Members of Serpine family, including plasminogen activator inhibitors have been reported to participate in ECM regulation. The aim of this study was to assess the expression of serpin peptidase inhibitor clade E member 2 (SERPINE2), under basal conditions and in response to increasing doses of IL-1α, in human cultured chondrocytes. We also examined the effects of SERPINE2 on IL-1α-induced MMP-13 expression. For completeness, the signaling pathway involved in this process was also explored., Methods: SERPINE2 mRNA and protein expression were evaluated by RT-qPCR and western blot analysis in human T/C-28a2 cell line and human primary chondrocytes. These cells were treated with human recombinant SERPINE2, alone or in combination with IL-1α. ERK 1/2, NFκB and AP-1 activation were assessed by western blot analysis., Results: Human cultured chondrocytes express SERPINE2 in basal condition. This expression increased in response to IL-1α stimulation. In addition, recombinant SERPINE2 induced a clear inhibition of MMP-13 expression in IL-1α-stimulated chondrocytes. This inhibitory effect is likely regulated through a pathway involving ERK 1/2, NF-κB and AP-1., Conclusions: Taken together, these data demonstrate that SERPINE2 might prevent cartilage catabolism by inhibiting the expression of MMP-13, one of the most relevant collagenases, involved in cartilage breakdown in OA.

Objectives: Emerging data suggest that several metabolic factors, released mainly by white adipose tissue (WAT) and joint tissues, and collectively named adipokines, might have a role in the pathophysiology of OA. Recently, novel adipokines such as SERPINE2, WISP2, GPNMB and ITIH5 have been identified in WAT. The main goal of this study was to analyse the expression of these novel adipokines in synovium, infrapatellar fat pad and chondrocytes and to compare the expression of these molecules in healthy and OA tissues., Methods: Synovial tissues, infrapatellar fat pad and chondrocytes were obtained from 36 OA patients (age 52-85; mean BMI 28.9) who underwent total knee replacement surgery. Healthy synovial tissues and infrapatellar fat pad were obtained from 15 traumatic knee patients (age 23-53; mean BMI 23.5). mRNA and protein expression were determined by qRT-PCR and western blot analysis respectively., Results: All the novel adipokines, matter of our study, are expressed in OA synovium, infrapatellar fat pad and chondrocytes. Moreover, we detected a differential expression of SERPINE2 and ITIH5 in OA synovial tissues as compared to healthy samples. Finally, we also observed an increased expression of WISP2 in OA infrapatellar fat pad in comparison to healthy controls., Conclusions: In this study we demonstrated for the first time the expression of four novel adipokines in different joint tissues and how these molecules are differentially expressed in healthy and OA joint tissues.

Environmental pollutants are known to have adverse effects on human health. However, the link between chemical exposure and osteoarthritis remains little investigated. This study sought to assess in vitro the effect of several non-dioxin-like polychlorinated biphenyls (NDL-PCBs) on chondrocytes viability and apoptosis induction. Murine chondrogenic ATDC-5 cell line and human T/C-28a2 immortalized chondrocytes were exposed to NDL-PCBs 101, 153 and 180. Cell viability was examined using MTT assay. Necrosis was evaluated by LDH assay. Expression of apoptotic related proteins, such as caspase-3, Bcl-2 and Bax was assessed by Western blot analysis. Finally, oxidative stress was evaluated by malondialdehyde (MDA) assay and the Oxidative Stress Index. In vitro exposure to NDL-PCBs caused strong reduction of cell viability in a concentration-dependent manner. Data from LDH assay showed cellular necrosis induction. Caspase-3 activation, as well as, altered Bcl2/Bax ratio and p38 MAP-kinase phosphorylation also suggested apoptosis induction. Finally, MDA levels and Oxidative Stress Index revealed that PCBs drive chondrocyte death via increase of oxidative stress. The viability of murine and human chondrocytes was reduced in presence of PCBs. The activity of PCBs on cell viability is likely to be mediated by complex alterations involving regulation mechanisms of apoptosis, necrosis and oxidative stress., (Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.)

Extra-virgin olive oil (EVOO), a principal component of the Mediterranean diet (Med diet), is one of the most ancient known foods and has long been associated with health benefits. Many phenolic compounds extracted from Olea europea L. have attracted attention since their discovery. Among these phenolic constituents, oleocanthal has recently emerged as a potential therapeutic molecule for different diseases, showing relevant pharmacological properties in various pathogenic processes, including inflammation, cancers and neurodegenerative diseases. Here, we discuss and summarize the most recent pharmacological evidence for the medical relevance of oleocanthal, focusing our attention on its anti-inflammatory and chemotherapeutic roles., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Lipocalin-2 (LCN2), also known as neutrophil gelatinase-associated lipocalin (NGAL), is a secreted glycoprotein that belongs to a group of transporters of small lipophilic molecules in circulation. LCN2 has been recently characterized as an adipose-derived cytokine. This adipokine is believed to bind small substances, such as steroids and lipopolysaccharides, and has been reported to have roles in the induction of apoptosis in hematopoietic cells, transport of fatty acids and iron, modulation of inflammation, and metabolic homeostasis. Recently, LCN2 has emerged as a useful biomarker and rheumatic diseases. This review provides an overview of LCN2 in inflammation, immunity, and metabolism.

Until the discovery of leptin 20 years ago, adipose tissue was considered only as a fat storage organ, involved in the regulation of energy homeostasis. At present, it is well known that adipokines, being leptin the forerunner of this superfamily, may act in different biological processes, including inflammation and immunity. In this review, we have explored the recent evidence about the relationship between leptin and immune system, summarizing the most important findings related to the involvement of leptin in both innate and adaptive immune response.

Introduction: Over the past 20 years, the idea that white adipose tissue (WAT) is simply an energy depot organ has been radically changed. Indeed, present understanding suggests WAT to be an endocrine organ capable of producing and secreting a wide variety of proteins termed adipokines. These adipokines appear to be relevant factors involved in a number of different functions, including metabolism, immune response, inflammation and bone metabolism., Areas Covered: In this review, the authors focus on the effects of several adipose tissue-derived factors in bone pathophysiology. They also consider how the modification of the adipokine network could potentially lead to promising treatment options for bone diseases., Expert Opinion: There are currently substantial developments being made in the understanding of the interplay between bone metabolism and the metabolic system. These insights could potentially lead to the development of new treatment strategies and interventions with the aim of successful outcomes in many people affected by bone disorders. Specifically, future research should look into the intimate mechanisms regulating peripheral and central activity of adipokines as it has potential for novel drug discovery.

Nesfatin-1 is a recently discovered satiety-inducing adipokine identified in hypothalamic regions that regulates energy balance. So far, no data exist on NUCB2/nesfatin-1 localization in human and murine chondrocytes. Here, we therefore investigated NUCB2/nesfatin-1 gene and protein expression in human and murine chondrocytes and the effect of nesfatin-1 on pro-inflammatory cytokines expression. Peptide localization was performed by laser confocal microscopy, NUCB2 mRNA expression was studied by RT-PCR and protein secretion was measured by XMap technology and Western blot analysis. First, we demonstrated cytoplasmic localization of NUCB2/nesfatin-1 peptide in both human and murine chondrocytes. We present evidence that both mRNA and protein expression of NUCB2 were increased during the differentiation of ATDC5 murine chondrocyte cell line. Furthermore, we demonstrated that nesfatin-1 induces IL-6 and MIP-1α mRNA expression and protein secretion in ATDC-5 cells challenged with IL-1, and also increases COX-2 mRNA expression in these cells. Finally, nesfatin-1 provoked a clear induction of pro-inflammatory agents, such as COX-2, IL-8, IL-6, and MIP-1α in human primary chondrocytes from OA patients., (© 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.)