L161982 alleviates collagen-induced arthritis in mice by increasing Treg cells and down-regulating Interleukin-17 and monocyte-chemoattractant protein-1 levels

Augmenting regulatory T cells: new therapeutic strategy for rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic, systemic autoimmune condition marked by inflammation of the joints, degradation of the articular cartilage, and bone resorption. Recent studies found the absolute and relative decreases in circulating regulatory T cells (Tregs) in RA patients. Tregs are a unique type of cells exhibiting immunosuppressive functions, known for expressing the Foxp3 gene. They are instrumental in maintaining immunological tolerance and preventing autoimmunity. Increasing the absolute number and/or enhancing the function of Tregs are effective strategies for treating RA. This article reviews the studies on the mechanisms and targeted therapies related to Tregs in RA, with a view to provide better ideas for the treatment of RA.

Rat resistance to rheumatoid arthritis induction as a function of the early-phase adrenal-pineal crosstalk

Chronic inflammatory diseases are triggered by causal stimuli that might occur long before the appearance of the symptoms. Increasing evidence suggests that these stimuli are necessary but not always sufficient to induce the diseases. The murine model of type II collagen emulsified in Freund's incomplete adjuvant (collagen-induced arthritis) to induce rheumatoid arthritis (RA) follows this pattern as some animals do not develop the chronically inflamed phenotype. Considering that in the immune-pineal axis (IPA) theory adrenal-pineal cross-talk adjusts early phases of inflammatory processes, we investigated whether differences in IPA activation could explain why some animals are resistant (RES) while others develop RA. We observed a similar increase in 6-sulfatoxymelatonin (aMT6s) excretion from day 3 to 13 in both RES and RA animals, followed by a significant decrease in RA animals. This pattern of aMT6s excretion positively correlated with plasma corticosterone (CORT) in RES animals. Additionally, RA animals presented a lower aMT6s/CORT ratio than saline-injected or RES animals. Plasmatic levels of tumour necrosis factor were similar in both groups, but interleukin (IL)-1β and monocyte chemotactic protein 1 (MCP-1) levels were lower in RES compared to RA animals. IL-2 and IL-4 were decreased in RES animals compared to saline-injected animals. The aMT6s/CORT ratio inversely correlated with the paw thickness and the inflammatory score (levels of IL-1β, MCP-1, IL-2 and IL-4 combined). Thus, adrenocortical-pineal positive interaction is an early defence mechanism for avoiding inflammatory chronification. KEY POINTS: Immune-pineal axis imbalance is observed in early-phase rheumatoid arthritis development. Only resistant animals present a positive association between adrenal and pineal hormones. The 6-sulfatoxymelatonin/corticosterone ratio is decreased in animals that develop rheumatoid arthritis. The inflammatory score combining the levels of nocturnal interleukin (IL)-1β, monocyte chemotactic protein 1, IL-2 and IL-4 presents a very strong positive correlation with the size of inflammatory lesion. The 6-sulfatoxymelatonin/corticosterone ratio presents a strong negative correlation with the inflammatory score and paw oedema size.

Cartilage-Sparing Properties of Equine Omega Complete in an Organ Culture Model of Cartilage Inflammation

The purpose of this study was to determine anti-inflammatory and/or chondroprotective effects of Equine Omega Complete (EOC) on cartilage explants stimulated with lipopolysaccharide (LPS). Explants were aseptically prepared from the intercarpal joints of 17 market-weight pigs and placed in culture at 37°C for a total of 120 hours. For the final 96 hours, explants were conditioned with a simulated digestion extract of EOC (0, 36 or 180 μL/mL), and for the final 48 hours explants were stimulated with LPS (0 or 15µg/mL). Media was removed and replaced every 24 hours. Samples from the final 48 hours were analyzed for biomarkers of cartilage inflammation (prostaglandin E₂ [PGE₂] and nitric oxide [NO]) and cartilage structure (glycosaminoglycan [GAG]). At the end of the culture period cartilage explants were stained for an estimate of cell viability. Stimulation of unconditioned explants with LPS significantly increased media concentrations of PGE₂, GAG and NO compared with that from unstimulated explants. LPS stimulation did not significantly affect cell viability. Both concentrations of EOC prevented significant LPS-stimulated cartilage release of GAG without impairing chondrocyte viability. No other effects of treatment were observed. These data provide evidence for a non-cytotoxic, chondroprotective effect of EOC in cartilage. This in vitro experiment supports the use of EOC in protecting against the detrimental effects of inflammation on cartilage structure.

The role of PGE2 and EP receptors on lung's immune and structural cells; possibilities for future asthma therapy

Asthma is the most common airway chronic disease with treatments aimed mainly to control the symptoms. Adrenergic receptor agonists, corticosteroids and anti-leukotrienes have been used for decades, and the development of more targeted asthma treatments, known as biological therapies, were only recently established. However, due to the complexity of asthma and the limited efficacy as well as the side effects of available treatments, there is an urgent need for a new generation of asthma therapies. The anti-inflammatory and bronchodilatory effects of prostaglandin E2 in asthma are promising, yet complicated by undesirable side effects, such as cough and airway irritation. In this review, we summarize the most important literature on the role of all four E prostanoid (EP) receptors on the lung's immune and structural cells to further dissect the relevance of EP2/EP4 receptors as potential targets for future asthma therapy.

Prostaglandin E2 directly inhibits the conversion of inducible regulatory T cells through EP2 and EP4 receptors via antagonizing TGF-β signalling

Regulatory T (Treg) cells are essential for control of inflammatory processes by suppressing effector T-cell functions. The actions of PGE2 on the development and function of Treg cells, particularly under inflammatory conditions, are debated. In this study, we employed pharmacological and genetic approaches to examine whether PGE2  had a direct action on T cells to modulate de novo differentiation of Treg cells. We found that TGF-β-induced Foxp3 expression and iTreg cell differentiation in vitro is markedly inhibited by PGE2 , which was mediated by the receptors EP2 and EP4. Mechanistically, PGE2 -EP2/EP4 signalling interrupts TGF-β signalling during iTreg differentiation. Moreover, EP4 deficiency in T cells impaired iTreg cell differentiation in vivo. Thus, our results demonstrate that PGE2 negatively regulates iTreg cell differentiation through a direct action on T cells, highlighting the potential for selectively targeting the PGE2 -EP2/EP4 pathway to control T cell-mediated inflammation.

Molecular biochemical aspects of salt (sodium chloride) in inflammation and immune response with reference to hypertension and type 2 diabetes mellitus

Obesity, insulin resistance, type 2 diabetes mellitus (T2DM) and hypertension (HTN) are common that are associated with low-grade systemic inflammation. Diet, genetic factors, inflammation, and immunocytes and their cytokines play a role in their pathobiology. But the exact role of sodium, potassium, magnesium and other minerals, trace elements and vitamins in the pathogenesis of HTN and T2DM is not known. Recent studies showed that sodium and potassium can modulate oxidative stress, inflammation, alter the autonomic nervous system and induce dysfunction of the innate and adaptive immune responses in addition to their action on renin-angiotensin-aldosterone system. These actions of sodium, potassium and magnesium and other minerals, trace elements and vitamins are likely to be secondary to their action on pro-inflammatory cytokines IL-6, TNF-α and IL-17 and metabolism of essential fatty acids that may account for their involvement in the pathobiology of insulin resistance, T2DM, HTN and autoimmune diseases.

Role of CCL2/CCR2 axis in the immunopathogenesis of rheumatoid arthritis: Latest evidence and therapeutic approaches

Evidence suggests that uncontrolled immune system responses and their components play a significant role in developing rheumatoid arthritis (RA), which is considered an autoimmune disease (AD). Among immune system mediators, cytokines and chemokines are involved in numerous physiological and pathological processes. CCL2 or monocyte chemoattractant protein-1 (MCP-1) is known as a CC chemokine that can induce the locomotion and recruitment of monocytes and macrophages to the site of injury. When CCL2 binds to its receptors, the most important of which is CCR2, various signaling pathways are triggered, eventually leading to various immunological events such as inflammation. This chemokine also participates in several events involved in RA pathogenesis, such as osteoclastogenesis, migration of effector T cells to the RA synovium tissue, and angiogenesis. In this review article, the role of the CCL2/CCR2 axis in RA pathogenesis and the immunotherapy opportunities based on CCL2/CCR2 axis targeting has been discussed based on existing investigations.