Explore the vast range of titles available.

Increased osteoclast (OC) differentiation and activity is the critical event that results in bone loss and joint destruction in common pathological bone conditions, such as osteoporosis and rheumatoid arthritis (RA). RANKL and its decoy receptor, osteoprotegerin (OPG), control OC differentiation and activity. However, there is a specific concern of a rebound effect of denosumab discontinuation in treating osteoporosis. TNFα can induce OC differentiation that is independent of the RANKL/RANK system. In this review, we discuss the factors that negatively and positively regulate TNFα induction of OC formation, and the mechanisms involved to inform the design of new anti-resorptive agents for the treatment of bone conditions with enhanced OC formation. Similar to, and being independent of, RANKL, TNFα recruits TNF receptor-associated factors (TRAFs) to sequentially activate transcriptional factors NF-κB p50 and p52, followed by c-Fos, and then NFATc1 to induce OC differentiation. However, induction of OC formation by TNFα alone is very limited, since it also induces many inhibitory proteins, such as TRAF3, p100, IRF8, and RBP-j. TNFα induction of OC differentiation is, however, versatile, and Interleukin-1 or TGFβ1 can enhance TNFα-induced OC formation through a mechanism which is independent of RANKL, TRAF6, and/or NF-κB. However, TNFα polarized macrophages also produce anabolic factors, including insulin such as 6 peptide and Jagged1, to slow down bone loss in the pathological conditions. Thus, the development of novel approaches targeting TNFα signaling should focus on its downstream molecules that do not affect its anabolic effect.

Monascus purpureus is a filamentous fungus renowned for producing bioactive secondary metabolites, including lovastatin and azaphilone pigments. Lovastatin is valued for its cholesterol-lowering properties and cardiovascular benefits, while Monascus pigments exhibit anti-cancer, anti-inflammatory, and antimicrobial activities, underscoring their pharmaceutical and biotechnological relevance. This study evaluated the impact of carbohydrate-derived elicitors—mannan oligosaccharides, oligoguluronate, and oligomannuronate—on the enhancement of pigment and lovastatin production in M. purpureus C322 under submerged fermentation. Elicitors were added at 48 h in shake flasks and 24 h in 2.5 L stirred-tank fermenters. All treatments increased the production of yellow, orange, and red pigments and lovastatin compared to the control, with higher titres upon scale-up. OG led to the highest orange pigment yield (1.2 AU/g CDW in flasks; 1.67 AU/g CDW in fermenters), representing 2.3- and 3.0-fold increases. OM yielded the highest yellow and red pigments (1.24 and 1.35 AU/g CDW in flasks; 1.58 and 1.80 AU/g CDW in fermenters) and the highest lovastatin levels (10.46 and 12.6 mg/g CDW), corresponding to 2.03–3.03-fold improvements. These results highlight the potential of carbohydrate elicitors to stimulate metabolite biosynthesis and facilitate scalable optimisation of fungal fermentation.

Monascus purpureus is a filamentous fungus known for producing pharmaceutically valuable secondary metabolites, including azaphilone pigments and lovastatin. Lovastatin is an HMG-CoA reductase inhibitor widely used to manage hypercholesterolaemia, while Monascus pigments serve as natural colourants with antioxidant and antimicrobial properties. This study evaluated the impact of quorum-sensing molecules (QSMs)—tyrosol (0.3 mM), farnesol (0.2 mM) and linoleic acid (0.4 mM)—on pigment and lovastatin yields in shake flasks and 2.5 L stirred-tank bioreactors. QSMs were introduced 48 h post-inoculation in shake flasks and 24 h in bioreactors. All QSMs increased yellow (OD400), orange (OD470), and red (OD510) pigments and lovastatin concentration relative to the control, with scale-up further enhancing yields. Farnesol produced the most pronounced effect: in flasks, OD400 7.10 (1.86-fold), OD470 8.00 (2.12-fold), OD510 7.80 (2.08-fold), and 74.6 mg/L lovastatin (2.05-fold); in bioreactors, OD400 11.9 (2.06-fold), OD470 15.1 (2.71-fold), OD510 13.7 (2.47-fold), and 97.2 mg/L lovastatin (2.48-fold). This was followed by tyrosol treatment and then linoleic acid. These findings demonstrate that QSMs—particularly farnesol—significantly (p < 0.01) stimulate pigment and lovastatin biosynthesis in M. purpureus. Quorum sensing modulation represents a promising, scalable strategy to optimise fungal fermentation for industrial metabolite production.

Neuroinflammation driven primarily by microglia directly contributes to neuronal death in many neurodegenerative diseases. Classical anti-inflammatory approaches aim to suppress pro-inflammatory mediator production, but exploitation of inflammatory resolution may also be of benefit. A key driver of peripheral inflammatory resolution, formyl peptide receptor 2 (Fpr2), is expressed by microglia, but its therapeutic potential in neurodegeneration remains unclear. Here, we studied whether targeting of Fpr2 could reverse inflammatory microglial activation induced by the potent bacterial inflammogen lipopolysaccharide (LPS). Exposure of murine primary or immortalised BV2 microglia to LPS triggered pro-inflammatory phenotypic change and activation of ROS production, effects significantly attenuated by subsequent treatment with the Fpr2 agonist C43. Mechanistic studies showed C43 to act through p38 MAPK phosphorylation and reduction of LPS-induced NFκB nuclear translocation via prevention of IκBα degradation. Here, we provide proof-of-concept data highlighting Fpr2 as a potential target for control of microglial pro-inflammatory activity, suggesting that it may be a promising therapeutic target for the treatment of neuroinflammatory disease.

Aspirin (ASA) and dexamethasone (DEX) are widely used anti-inflammatory agents yet their mechanism(s) for blocking polymorphonuclear neutrophil (PMN) accumulation at sites of inflammation remains unclear. Here, we report that inhibition of PMN infiltration by ASA and DEX is a property shared by aspirin-triggered lipoxins (ATL) and the glucocorticoid-induced annexin 1 (ANXA1)-derived peptides that are both generated in vivo and act at the lipoxin A 4 receptor (ALXR/FPRL1) to halt PMN diapedesis. These structurally diverse ligands specifically interact directly with recombinant human ALXR demonstrated by specific radioligand binding and function as well as immunoprecipitation of PMN receptors. In addition, the combination of both ATL and ANXA1-derived peptides limited PMN infiltration and reduced production of inflammatory mediators (that is, prostaglandins and chemokines) in vivo . Together, these results indicate functional redundancies in endogenous lipid and peptide anti-inflammatory circuits that are spatially and temporally separate, where both ATL and specific ANXA1-derived peptides act in concert at ALXR to downregulate PMN recruitment to inflammatory loci.

Microglial inflammatory activity is thought to be a major contributor to the pathology of neurodegenerative conditions such as Alzheimer’s disease (AD), and strategies to restrain their behaviour are under active investigation. Classically, anti-inflammatory approaches are aimed at suppressing proinflammatory mediator production, but exploitation of inflammatory resolution, the endogenous process whereby an inflammatory reaction is terminated, has not been fully investigated as a therapeutic approach in AD. In this study, we sought to provide proof-of-principle that the major proresolving actor, formyl peptide receptor 2, Fpr2, could be targeted to reverse microglial activation induced by the AD-associated proinflammatory stimulus, oligomeric β-amyloid (oAβ). The immortalised murine microglial cell line BV2 was employed as a model system to investigate the proresolving effects of the Fpr2 ligand QC1 upon oAβ-induced inflammatory, oxidative, and metabolic behaviour. Cytotoxic behaviour of BV2 cells was assessed through the use of cocultures with retinoic acid-differentiated human SH-SY5Y cells. Stimulation of BV2 cells with oAβ at 100 nM did not induce classical inflammatory marker production but did stimulate production of reactive oxygen species (ROS), an effect that could be reversed by subsequent treatment with the Fpr2 ligand QC1. Further investigation revealed that oAβ-induced ROS production was associated with NADPH oxidase activation and a shift in BV2 cell metabolic phenotype, activating the pentose phosphate pathway and NADPH production, changes that were again reversed by QC1 treatment. Microglial oAβ-stimulated ROS production was sufficient to induce apoptosis of bystander SH-SY5Y cells, an effect that could be prevented by QC1 treatment. In this study, we provide proof-of-concept data that indicate exploitation of the proresolving receptor Fpr2 can reverse damaging oAβ-induced microglial activation. Future strategies that are aimed at restraining neuroinflammation in conditions such as AD should examine proresolving actors as a mechanism to harness the brain’s endogenous healing pathways and limit neuroinflammatory damage.

An innovative avenue for anti-inflammatory therapy is inhibition of neutrophil extravasation by potentiating the action of endogenous anti-inflammatory mediators. The glucocorticoid-inducible protein annexin 1 and derived peptides are effective in inhibiting neutrophil extravasation. Here we tested the hypothesis that an interaction with the receptor for formylated peptide (FPR), so far reported only in vitro, could be the mechanism for this in vivo action. In a model of mouse peritonitis, FPR antagonists abrogated the anti-migratory effects of peptides Ac2-26 and Ac2-12, with a partial reduction in annexin 1 effects. A similar result was obtained in FPR (knock-out) KO mice. Binding of annexin 1 to circulating leukocytes was reduced (>50%) in FPR KO mice. In vitro, annexin binding to peritoneal macrophages was also markedly reduced in FPR KO mice. Finally, evidence of direct annexin 1 binding to murine FPR was obtained with HEK-293 cells transfected with the receptor. Overall, these results indicate a functional role for FPR in the anti-migratory effect of annexin 1 and derived peptides.

In cartilage research bovine articular cartilage is used as an alternative to human tissue. However, animal material is subject to availability and primary cultures undergo senescence, limiting their use. Here we report the immortalization of primary bovine chondrocytes, which could be used as a surrogate for freshly isolated chondrocytes. Chondrocytes were isolated from cartilage explants and immortalized using 1.0 µg/ml benzo[alpha]pyrene. For 3-dimensional culture, chondrocytes were resuspended in 0.5% low-melt agarose at high density (HD) and cultured for 24 h prior to determining changes in expression profile and morphology. A13/BACii chondrocytes acquired a ‘flat’ irregular morphology and a foetal-like cell volume (1,509.59 ± 182.04 µm 3 ). The human cell line C-20/A4 showed a statistically similar volume and length to A13/BACii. Two-dimensional-cultured A13/BACii expressed elevated levels of type I collagen (col1), reduced levels of type II collagen (col2) compared to freshly isolated chondrocytes and an overall col2 to col1 expression ratio (col2:col1) of 0.11 ± 0.01. Upon 3-dimensional encapsulation, there was a significant rise in col2 expression in both A13/BACii and C-20/A4, suggesting a capacity for redifferentiation in both cell lines with a return of col2:col1 values of A13/BACii to values previously observed in primary chondrocytes. A13/BACii chondrocytes expressed aggrecan, matrix metalloproteinase (MMP)-3, MMP-9 and MMP-13, further supporting indications of the differentiated phenotype. Here we report the creation of a novel chondrocytic cell line and demonstrate its strong potential for redifferentiation upon HD 3-dimensional encapsulation, providing an alternative to conventional dedifferentiated cell lines and primary culture.

Neuroinflammation driven primarily by microglia directly contributes to neuronal death in many neurodegenerative diseases. Classical anti-inflammatory approaches aim to suppress pro-inflammatory mediator production, but exploitation of inflammatory resolution, the active endogenous process whereby inflammation is terminated, may also be of benefit. A key driver of peripheral inflammatory resolution, formyl peptide receptors 2/3 (Fpr2/3), is expressed by microglia, but its therapeutic potential in neurodegeneration remains unclear. Here, we sought to provide a proof-of-principle that Fpr2/3 targeting could reverse inflammatory microglial activation induced by the potent bacterial inflammogen lipopolysaccharide (LPS). Stimulation of murine BV2 microglia with LPS triggered release of nitric oxide, TNFα and IL-10, upregulated surface expression of CD38 and CD40 and suppressed CD206, all of which were reduced by subsequent treatment with the Fpr2/3 ligand C43. Cellular exposure to LPS also stimulated NADPH oxidase and mitochondrial derived reactive oxygen species production, effects reversed by C43 treatment. Mechanistic studies showed C43 to act through p38 MAPK phosphorylation and reduction of LPS-induced NFκB nuclear translocation through prevention of IκBα degradation. Here, we provide proof-of-concept data indicating exploitation of the pro-resolving receptor Fpr2/3 as a promising therapeutic strategy in neuroinflammatory conditions. Competing Interest Statement The authors have declared no competing interest.