Adipokines as potential pharmacological targets for immune inflammatory rheumatic diseases: Focus on rheumatoid arthritis, osteoarthritis, and intervertebral disc degeneration.

Adipokines are a heterogeneous group of signalling molecules secreted prevalently by adipose tissue. Initially considered as regulators of energy metabolism and appetite, adipokines have been recognized for their substantial involvement in musculoskeletal disorders, including osteoarthritis, rheumatoid arthritis, and many others. Understanding the role of adipokines in rheumatic inflammatory and autoimmune diseases, as well as in other musculoskeletal diseases such as intervertebral disc degeneration, is crucial for the development of novel therapeutic strategies. Targeting adipokines, or their signalling pathways, may offer new opportunities for the treatment and management of these conditions. By modulating adipokines levels or activity, it may be possible to regulate inflammation, to maintain bone health, and preserve muscle mass, thereby improving the outcomes and quality of life for individuals affected by musculoskeletal diseases. The aim of this review article is to update the reader on the multifaceted role of adipokines in the main rheumatic diseases such as osteoarthritis and rheumatoid arthritis and to unravel the complex interplay among adipokines, cartilage metabolism, bone remodelling and muscles, which will pave the way for innovative therapeutic intervention in the future. For completeness, the role of adipokines in intervertebral disc degeneration will be also addressed.

IL-23 signaling regulation of pro-inflammatory T-cell migration uncovered by phosphoproteomics.

Interleukin 23 (IL-23) triggers pathogenic features in pro-inflammatory, IL-17-secreting T cells (Th17 and Tγδ17) that play a key role in the development of inflammatory diseases. However, the IL-23 signaling cascade remains largely undefined. Here, we used quantitative phosphoproteomics to characterize IL-23 signaling in primary murine Th17 cells. We quantified 6,888 phosphorylation sites in Th17 cells and found 168 phosphorylations regulated upon IL-23 stimulation. IL-23 increased the phosphorylation of the myosin regulatory light chain (RLC), an actomyosin contractibility marker, in Th17 and Tγδ17 cells. IL-23-induced RLC phosphorylation required Janus kinase 2 (JAK2) and Rho-associated protein kinase (ROCK) catalytic activity, and further study of the IL-23/ROCK connection revealed an unexpected role of IL-23 in the migration of Tγδ17 and Th17 cells through ROCK activation. In addition, pharmacological inhibition of ROCK reduced Tγδ17 recruitment to inflamed skin upon challenge with inflammatory agent Imiquimod. This work (i) provides new insights into phosphorylation networks that control Th17 cells, (ii) widely expands the current knowledge on IL-23 signaling, and (iii) contributes to the increasing list of immune cells subsets characterized by global phosphoproteomic approaches.

WISP-2 modulates the induction of inflammatory mediators and cartilage catabolism in chondrocytes.

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-1ß 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-1ß-mediated chondrocyte catabolism, that IL-1ß and WNT/b-catenin signaling pathways are involved in rhWISP-2 protein and IL-1ß effects in human chondrocytes, and that WISP-2 has a regulatory role in attenuating the catabolic effects of IL-1ß 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-1ß in human primary OA chondrocytes in a Wnt/ß-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/ß-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.

Renin-Angiotensin System Blocker in COVID-19. A Single Center Study.

ABSTRACT: Early during the Coronavirus disease 2019 (Covid-19) pandemic, concerns were raised regarding potential adverse outcomes in patients taking angiotensin-converting enzyme inhibitors (ACEIs)/angiotensin receptor blockers (ARBs). These concerns were based on animal studies showing increased ACE-2 expression in mice treated with ACEI/ARB. This is a single-center, retrospective, cohort study of 289 patients diagnosed with 2019 Novel Coronavirus (SARS-CoV-2) hospitalized between March of 2020 and June of 2020. The study was intended to investigate the impact of ACEIs and/or ARBs on in-hospital mortality, intensive care unit (ICU) admission, postadmission hemodialysis requirement, and the need for mechanical ventilation in patients with COVID-19. This cohort of 289 patients included 139 of 289 women (48%) with a mean age of 61 ± 19 years. Patients using ACEIs/ARBs were older (69.68 vs. 57.9 years; P < 0.0001), more likely to have a history of hypertension (97% vs. 36%; P < 0.0001), diabetes mellitus (48% vs. 20.9%; P < 0.0001), chronic heart failure (11.39% vs. 4.29%; P < 0.0512), coronary artery disease (20.25% vs. 7.14%; P < 0.0025), stroke/Transient Ischemic Attack (7.59% vs. 2.38%; P < 0.0761), chronic kidney disease (11.39% vs. 3.33%; P < 0.0167), atrial fibrillation/flutter (18.99% vs. 7.14%; P < 0.0080), and dementia (22.7% vs. 11.4%; P < 0.0233) compared with the nonuser group. There was significantly higher in-hospital mortality in patients using ACEIs/ARBs than nonusers, respectively (32.9% vs. 15.2%; P < 0.0015). However, a multivariate logistics regression analysis performed to adjust for common confounders demonstrated no significant difference in all-cause in-patient mortality (P 0.7141). Admission to ICU, postadmission hemodialysis requirement, and mechanical ventilation showed no significant differences between the 2 groups (P = NS). This study suggests that the use of ACEIs and ARBs in patients with COVID-19 was not found to significantly increase all-cause in-hospital mortality, ICU admissions, and hemodialysis and mechanical ventilation requirements.

Analgesic and antiinflammatory effects of Nigella orientalis L. seeds fixed oil: Pharmacological potentials and molecular mechanisms.

Nigella species have been widely used in traditional medicine. The aim of this study was to evaluate the antiinflammatory and analgesic potentials of Nigella orientalis L. seeds fixed oil (NOO). The acetic acid writhing test and the formaldehyde-induced licking paw were performed to assess the analgesic activity of the oil. The antiinflammatory activity was first evaluated in vitro by the erythrocyte membrane stabilization then in vivo by xylene- and carrageenan-induced ear and paw edema, respectively. To further understand the molecular mechanism of action of the Nigella extract, lipopolysaccharide-activated RAW 264.7 macrophages were used. Nitric oxide (NO) production was measured by Griess reaction and cell viability by MTT assay. The gene and protein expression of inflammatory mediators were assessed by RT-PCR and western blot, respectively. NOO exerted a potent analgesic effect in in vivo models of writhing test and induced edema. The analyzed molecular mechanisms revealed a role for NO and prostaglandins as molecules mediating the pharmacological effects of the extract through a mechanism involving nuclear factor-κB and mitogen-activated protein kinases. This study demonstrates, for the first time, that the fixed oil of N. orientalis has strong antinociceptive and antiinflammatory properties and might be a promising agent for the treatment of certain inflammation-related diseases.

Leptin in Osteoarthritis and Rheumatoid Arthritis: Player or Bystander?

White adipose tissue (WAT) is a specialized tissue whose main function is lipid synthesis and triglyceride storage. It is now considered as an active organ secreting a plethora of hormones and cytokines namely adipokines. Discovered in 1994, leptin has emerged as a key molecule with pleiotropic functions. It is primarily recognized for its role in regulating energy homeostasis and food intake. Currently, further evidence suggests its potent role in reproduction, glucose metabolism, hematopoiesis, and interaction with the immune system. It is implicated in both innate and adaptive immunity, and it is reported to contribute, with other adipokines, in the cross-talking networks involved in the pathogenesis of chronic inflammation and immune-related diseases of the musculo-skeletal system such as osteoarthritis (OA) and rheumatoid arthritis (RA). In this review, we summarize the most recent findings concerning the involvement of leptin in immunity and inflammatory responses in OA and RA.

Monomeric C reactive protein (mCRP) regulates inflammatory responses in human and mouse chondrocytes.

C-reactive protein (CRP) is an acute-phase protein that is used as an established biomarker to follow disease severity and progression in a plethora of inflammatory diseases. However, its pathophysiologic mechanisms of action are still poorly defined and remain elusive. CRP, in its pentameric form, exhibits weak anti-inflammatory activity. On the contrary, the monomeric isoform (mCRP) exhibits potent pro-inflammatory properties in endothelial cells, leukocytes, and platelets. So far, no data exists regarding mCRP effects in human or mouse chondrocytes. This work aimed to verify the pathophysiological relevance of mCRP in the etiology and/or progression of osteoarthritis (OA). We investigated the effects of mCRP in cultured human primary chondrocytes and in the chondrogenic ATDC5 mouse cell line. We determined mRNA and protein levels of relevant factors involved in inflammatory responses and the modulation of nitric oxide synthase type II (NOS2), an early inflammatory molecular target. We demonstrate, for the first time, that monomeric C reactive protein increases NOS2, COX2, MMP13, VCAM1, IL-6, IL-8, and LCN2 expression in human and murine chondrocytes. We also demonstrated that NF-kB is a key factor in the intracellular signaling of mCRP-driven induction of pro-inflammatory and catabolic mediators in chondrocytes. We concluded that mCRP exerts a sustained catabolic effect on human and murine chondrocytes, increasing the expression of inflammatory mediators and proteolytic enzymes, which can promote extracellular matrix (ECM) breakdown in healthy and OA cartilage. In addition, our results implicate the NF-kB signaling pathway in catabolic effects mediated by mCRP.

An Update on the Role of Leptin in the Immuno-Metabolism of Cartilage.

Since its discovery in 1994, leptin has been considered as an adipokine with pleiotropic effects. In this review, we summarize the actual information about the impact of this hormone on cartilage metabolism and pathology. Leptin signalling depends on the interaction with leptin receptor LEPR, being the long isoform of the receptor (LEPRb) the one with more efficient intracellular signalling. Chondrocytes express the long isoform of the leptin receptor and in these cells, leptin signalling, alone or in combination with other molecules, induces the expression of pro-inflammatory molecules and cartilage degenerative enzymes. Leptin has been shown to increase the proliferation and activation of immune cells, increasing the severity of immune degenerative cartilage diseases. Leptin expression in serum and synovial fluid are related to degenerative diseases such as osteoarthritis (OA), rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). Inhibition of leptin signalling showed to have protective effects in these diseases showing the key role of leptin in cartilage degeneration.

Pharmacological Extracts and Molecules from Virola Species: Traditional Uses, Phytochemistry, and Biological Activity.

Virola is the largest genus of Myristicaceae in America, comprising about 60 species of medium-sized trees geographically spread from Mexico to southern Brazil. The plant species of this genus have been widely used in folk medicine for the treatment of several ailments, such as rheumatic pain, bronchial asthma, tumors in the joints, intestinal worms, halitosis, ulcers, and multiple infections, due to their pharmacological activity. This review presents an updated and comprehensive summary of Virola species, particularly their ethnomedicinal uses, phytochemistry, and biological activity, to support the safe medicinal use of plant extracts and provide guidance for future research. The Virola spp.'s ethnopharmacology, including in the treatment of stomach pain and gastric ulcers, as well as antimicrobial and tryponosomicidal activities, is attributable to the presence of a myriad of phytoconstituents, such as flavonoids, tannins, phenolic acids, lignans, arylalkanones, and sitosterol. Hence, such species yield potential leads or molecular scaffolds for the development of new pharmaceutical formulations, encouraging the elucidation of not-yet-understood action mechanisms and ascertaining their safety for humans.

The utility of pulmonary function testing in the preoperative risk stratification of patients undergoing transcatheter aortic valve replacement.

BACKGROUND: The role of pulmonary function testing (PFT) as a predictor of clinically relevant endpoints in transcatheter aortic valve replacement (TAVR) is unclear. OBJECTIVE: To determine the utility of PFT in the preoperative risk stratification of patients undergoing TAVR. METHODS: An evaluation of PFT (i.e., FEV1), arterial blood gases (i.e., PO2), the diagnosis of chronic obstructive lung disease (COPD) by the Global Initiative for COPD (GOLD), and the diagnosis of chronic lung disease (CLD) by the Society of Thoracic Surgeons (STS) was performed to determine whether a relationship exists among these parameters and clinically relevant outcomes, including all-cause 30-day and 1-year mortality. RESULTS: A total of 513 patients underwent TAVR between March 2013 and December 2016. Per STS criteria, 269/513 (52%) had CLD with a mean FEV1 of 55.4 ± 12%. Per GOLD criteria, 158/513 (30%) of patients had COPD with a mean FEV1/forced vital capacity of 61.8 ± 8.2%. The severity of CLD was affected by changes in ejection fraction, albumin, creatinine, and B-type natriuretic peptide levels (p = .009, p < .001, p < .001, and p < .001, respectively), whereas the severity of COPD was not affected by these same variables, (p = .302, .079, .137, and .102, respectively). An increased A-a gradient (p = .035), increased PCO2 (p = .016), and decreased PO2 (p = <.001) demonstrated increased risk of 30-day mortality. Neither classification (COPD or CLD), nor PFT changes, showed association with 30-day and 1-year mortality (p = NS). CONCLUSION: This study suggests that isolated abnormalities in spirometry are a poor indicator of clinically relevant outcomes in TAVR. When classified correctly, COPD does not predict clinically relevant postoperative outcomes.

Impella to unload the left ventricle in patients undergoing venoarterial extracorporeal membrane oxygenation for cardiogenic shock: A systematic review and meta-analysis.

BACKGROUND AND AIM: Impella is frequently used to unload the left ventricle in patients with cardiogenic shock on venoarterial extracorporeal membrane oxygenation (VA-ECMO). There is limited data regarding the use of this strategy. This study aims to evaluate the safety and efficacy of the said strategy. METHODS: A systematic search for studies comparing Impella plus VA-ECMO (ECVAD) vs VA-ECMO alone was performed using Pubmed, Cochrane Library, and Scopus. Studies meeting inclusion criteria were then used to perform a meta-analysis. RESULTS: Three studies involving 448 patients were included in the final analysis. In total, 117 (26%) patients were female, mean age was 57 years. VA-ECMO was placed in 355 out of 448 (79%) patients, while ECVAD was placed in 93 out of 448 (21%). Death occurred in 49 out of 93 (52.6%) patients on ECVAD and 226 out of 355 (63.6%) on ECMO, relative risk (RR): 0.76, confidence interval (CI), 95% (0.62-0.94) P = .01. Hemolysis was present in 46 (49.4%) patients in the ECVAD vs 67 (18%) in the ECMO group, RR: 2.64, CI, 95% (1.97-3.55) P < .01. Bleeding was present in 42 (45.2.%) patients in the ECVAD group and 135 (38%) in the ECMO group, RR: 1.25, CI, 95% (0.95-1.63) P = .11. CVVHD was used on 31 (33.3%) patients in the ECVAD group while 89 (25%) in the ECMO group, RR 1.35, CI, 95% (0.95-1.91) P = .10. CONCLUSION: This study suggests that the use of Impella as an unloading strategy in patients with VA-ECMO decreased mortality, increased rate of hemolysis, neutral bleeding risk, and similar rates of acute kidney injury requiring CVVHD.

Long-term quality of life in octogenarians and nonagenarians with nonvalvular atrial fibrillation following WATCHMAN™ device implantation.

OBJECTIVES: To assess the impact of WATCHMAN™ on quality of life (QoL) in octogenarians and nonagenarians. BACKGROUND: QoL after WATCHMAN™ device in the elderly remains unknown. METHODS: This is a prospective and retrospective cohort study of patients that underwent WATCHMAN™ implantation in a tertiary cardiovascular center from April 1, 2015 to September 27, 2017. The primary outcome was a prospective assessment of QoL via the SF-12v2 Health Survey (SF-12v2) in those aged ≥80 and ≥90 years. Secondary outcomes include major bleeding, stroke, vascular complications, pericardial effusion, device related thrombus (DRT), prolonged length of stay (LOS), acute kidney injury (AKI), and recurrent hospitalizations. RESULTS: This cohort of 151 patients included 48/151 (32%) females with a mean age of 80 ± 7.7 years. Mean CHA2 DS2 -VASc was 4.38 ± 1.36 and mean HAS-BLED was 3.27 ± 1.17. Octogenarians 65/81(80%) and nonagenarians 16/81(20%) comprised 81/151(54%) of patients (mean age 86 ± 4.3 years) from which 36/65 (55%) octogenarians and 10/16 (63%) nonagenarians completed SF-12v2 evaluation at 22 ± 10 and 30 ± 10-months. Octogenarians demonstrated enhanced physical component scores (PCS), and nonagenarians equal PCS versus the age-adjusted norm (45.43 ± 9.84 versus 38.68 ± 11.04, P = 0.0003, and 41.26 ± 12.36 versus 38.68 ± 11.04, P = 0.6463, respectively). The mental component scores (MCS) of octogenarians and nonagenarians remained comparable (51.80 ± 9.56 and 48.97 ± 9.92 versus 50.06 ± 10.94, respectively, P = 0.4659). No stroke, vascular complications, pericardial effusions, or readmissions related to WATCHMAN™ occurred. No difference among patients <80, ≥80, and ≥90 years was found in major bleeding events, DRT, prolonged LOS, or AKI (P = 0.0569, 0.116, 0.498, and 0.795, respectively). CONCLUSIONS: Octogenarians and nonagenarians experience favorable long-term QoL after WATCHMAN™, with acceptable bleeding risk and low incidence of procedure-related complications.

Molecular Relationships among Obesity, Inflammation and Intervertebral Disc Degeneration: Are Adipokines the Common Link?

Intervertebral disc degeneration (IVDD) is a chronic, expensive, and high-incidence musculoskeletal disorder largely responsible for back/neck and radicular-related pain. It is characterized by progressive degenerative damage of intervertebral tissues along with metabolic alterations of all other vertebral tissues. Despite the high socio-economic impact of IVDD, little is known about its etiology and pathogenesis, and currently, no cure or specific treatments are available. Recent evidence indicates that besides abnormal and excessive mechanical loading, inflammation may be a crucial player in IVDD. Furthermore, obese adipose tissue is characterized by a persistent and low-grade production of systemic pro-inflammatory factors. In this context, chronic low-grade inflammation associated with obesity has been hypothesized as an important contributor to IVDD through different, but still unknown, mechanisms. Adipokines, such as leptin, produced prevalently by white adipose tissues, but also by other cells of mesenchymal origin, particularly cartilage and bone, are cytokine-like hormones involved in important physiologic and pathophysiological processes. Although initially restricted to metabolic functions, adipokines are now viewed as key players of the innate and adaptative immune system and active modulators of the acute and chronic inflammatory response. The goal of this review is to summarize the most recent findings regarding the interrelationships among inflammation, obesity and the pathogenic mechanisms involved in the IVDD, with particular emphasis on the contribution of adipokines and their potential as future therapeutic targets.

Butyrate Modulates Inflammation in Chondrocytes via GPR43 Receptor.

BACKGROUND/AIMS: Osteoarthritis (OA) is a joint degenerative biomechanical disorder involving immunity, metabolic alterations, inflammation, and cartilage degradation, where chondrocytes play a pivotal role. OA has not effective pharmacological treatments and new therapeutic targets are needed. Adipokines contribute to the low-grade systemic inflammation in OA. Here, we explored novel molecular mechanisms of sodium butyrate (BuNa) in modulating inflammation and chemotaxis in chondrocytes, demonstrating the direct involvement of its G protein-coupled receptor (GPR)-43. METHODS: ATDC5 murine chondrocytes were stimulated with interleukin (IL)-1ß, in the presence or not of BuNa, for 24 h. RT-PCR and Western blot analysis was performed to evaluate the expression of inflammatory mediators and structural proteins. RESULTS: Butyrate reduced the expression of canonic pro-inflammatory mediators (Nos2, COX-2, IL-6), pro-inflammatory adipokines (lipocalin-2 and nesfatin-1) and adhesion molecule (VCAM-1 and ICAM-1) in IL-1ß-stimulated chondrocytes, inhibiting several inflammatory signalling pathways (NFκB, MAPKinase, AMPK-α, PI3K/Akt). Butyrate also reduced metalloproteinase production and limited the loss of type II collagen in IL-1ß-inflamed chondrocytes. The chemoattractant effect of butyrate, after different inflammatory challenges, was revealed by increased annexin (AnxA)1 levels and chemokines expression. The chemoattractant and anti-inflammatory activities of butyrate were completely blunted by GPR43 silencing using RNA interference. CONCLUSION: Taken together, our data suggest the potential application of sodium butyrate as a novel candidate in a multi-target approach for the treatment of chondrocyte inflammation and cartilage degenerative process.

Oleocanthal Inhibits Catabolic and Inflammatory Mediators in LPS-Activated Human Primary Osteoarthritis (OA) Chondrocytes Through MAPKs/NF-κB Pathways.

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.

E74-Like Factor (ELF3) and Leptin, a Novel Loop Between Obesity and Inflammation Perpetuating a Pro-Catabolic State in Cartilage.

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-1ß 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-1ß 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.

E74-like factor 3 and nuclear factor-κB regulate lipocalin-2 expression in chondrocytes.

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.

The potential of lipocalin-2/NGAL as biomarker for inflammatory and metabolic diseases.

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.

High Diversity of Bradyrhizobial Species Fix Nitrogen with Woody Legume Spartocytisus supranubius in a High Mountain Ecosystem.

The symbiosis between rhizobia and legumes is of pivotal importance in nitrogen-poor ecosystems. Furthermore, as it is a specific process (most legumes only establish a symbiosis with certain rhizobia), it is of great interest to know which rhizobia are able to nodulate key legumes in a specific habitat. This study describes the diversity of the rhizobia that are able to nodulate the shrub legume Spartocytisus supranubius in the harsh environmental conditions of the high mountain ecosystem of Teide National Park (Tenerife). The diversity of microsymbionts nodulating S. supranubius was estimated from a phylogenetic analysis of root nodule bacteria isolated from soils at three selected locations in the park. The results showed that a high diversity of species of Bradyrhizobium and two symbiovars can nodulate this legume. Phylogenies of ribosomal and housekeeping genes showed these strains distributed into three main clusters and a few isolates on separate branches. These clusters consist of strains representing three new phylogenetic lineages of the genus Bradyrhizobium. Two of these lineages belong to the B. japonicum superclade, which we refer to as B. canariense-like and B. hipponense-like, as the type strains of these species are the closest species to our isolates. The third main group was clustered within the B. elkanii superclade and is referred to as B. algeriense-like as B. algeriense is its closest species. This is the first time that bradyrhizobia of the B. elkanii superclade have been reported for the canarian genista. Furthermore, our results suggest that these three main groups might belong to potential new species of the genus Bradyrhizobium. Analysis of the soil physicochemical properties of the three study sites showed some significant differences in several parameters, which, however, did not have a major influence on the distribution of bradyrhizobial genotypes at the different locations. The B. algeriense-like group had a more restrictive distribution pattern, while the other two lineages were detected in all of the soils. This suggests that the microsymbionts are well adapted to the harsh environmental conditions of Teide National Park.

Monomeric CRP regulates inflammatory responses in human intervertebral disc cells.

CRP is an acute-phase protein that is used as a biomarker to follow severity and progression in infectious and inflammatory diseases. Its pathophysiological mechanisms of action are still poorly defined. CRP in its pentameric form exhibits weak anti-inflammatory activity. The monomeric isoform (mCRP) exerts potent proinflammatory properties in chondrocytes, endothelial cells, and leucocytes. No data exist regarding mCRP effects in human intervertebral disc (IVD) cells. This work aimed to verify the pathophysiological relevance of mCRP in the aetiology and/or progression of IVD degeneration. We investigated the effects of mCRP and the signalling pathways that are involved in cultured human primary annulus fibrosus (AF) cells and in the human nucleus pulposus (NP) immortalized cell line HNPSV-1. We determined messenger RNA (mRNA) and protein levels of relevant factors involved in inflammatory responses, by quantitative real-time polymerase chain reaction (RT-qPCR) and western blot. We also studied the presence of mCRP in human AF and NP tissues by immunohistochemistry. We demonstrated that mCRP increases nitric oxide synthase 2 (NOS2), cyclooxygenase 2 (COX2), matrix metalloproteinase 13 (MMP13), vascular cell adhesion molecule 1 (VCAM1), interleukin (IL)-6, IL-8, and Lipocalin 2 (LCN2) expression in human AF and NP cells. We also showed that nuclear factor-κß (NF-κß), extracellular signal-regulated kinase 1/2 (ERK1/2), and phosphoinositide 3-kinase (PI3K) are at play in the intracellular signalling of mCRP. Finally, we demonstrated the presence of mCRP in human AF and NP tissues. Our results indicate, for the first time, that mCRP can be localized in IVD tissues, where it triggers a proinflammatory and catabolic state in degenerative and healthy IVD cells, and that NF-κß signalling may be implicated in the mediation of this mCRP-induced state.