Microsomal Prostaglandin E Synthase-1 Facilitates an Intercellular Interaction between CD4⁺ T Cells through IL-1β Autocrine Function in Experimental Autoimmune Encephalomyelitis

Improved intratumoral penetration of IL12 immunocytokine enhances the antitumor efficacy

Tumor-targeting antibody (Ab)-fused cytokines, referred to as immunocytokines, are designed to increase antitumor efficacy and reduce toxicity through the tumor-directed delivery of cytokines. However, the poor localization and intratumoral penetration of immunocytokines, especially in solid tumors, pose a challenge to effectively stimulate antitumor immune cells to kill tumor cells within the tumor microenvironment. Here, we investigated the influence of the tumor antigen-binding kinetics of a murine interleukin 12 (mIL12)-based immunocytokine on tumor localization and diffusive intratumoral penetration, and hence the consequent antitumor activity, by activating effector T cells in immunocompetent mice bearing syngeneic colon tumors. Based on tumor-associated antigen HER2-specific Ab Herceptin (HCT)-fused mIL12 carrying one molecule of mIL12 (HCT-mono-mIL12 immunocytokine), we generated a panel of HCT-mono-mIL12 variants with different affinities (K D) mainly varying in their dissociation rates (k off) for HER2. Systemic administration of HCT-mono-mIL12 required an anti-HER2 affinity above a threshold (K D = 130 nM) for selective localization and antitumor activity to HER2-expressing tumors versus HER2-negative tumors. However, the high affinity (K D = 0.54 or 46 nM) due to the slow k off from HER2 antigen limited the depth of intratumoral penetration of HCT-mono-mIL12 and the consequent tumor infiltration of T cells, resulting in inferior antitumor activity compared with that of HCT-mono-mIL12 with moderate affinity of (K D = 130 nM) and a faster k off. The extent of intratumoral penetration of HCT-mono-mIL12 variants was strongly correlated with their tumor infiltration and intratumoral activation of CD4+ and CD8+ T cells to kill tumor cells. Collectively, our results demonstrate that when developing antitumor immunocytokines, tumor antigen-binding kinetics and affinity of the Ab moiety should be optimized to achieve maximal antitumor efficacy.

A Systematic Review on the Role of Arachidonic Acid Pathway in Multiple Sclerosis

BACKGROUND & OBJECTIVE

Multiple sclerosis (MS) is an inflammatory neurodegenerative disease characterized by destruction of oligodendrocytes, immune cell infiltration and demyelination. Inflammation plays a significant role in MS, and the inflammatory mediators such as eicosanoids, leukotrienes, superoxide radicals are involved in pro-inflammatory responses in MS. In this systematic review we tried to define and discuss all the findings of in vivo animal studies and human clinical trials on the potential association between arachidonic acid (AA) pathway and multiple sclerosis.

METHODS

A systematic literature search across Pubmed, Scopus, Embase and Cochrane database was conducted. This systematic review was performed according to PRISMA guidelines.

RESULTS

A total of 146 studies were included, of which 34 were conducted in animals, 58 in humans, and 60 studies reported the role of different compounds that target AA mediators or their corresponding enzymes/ receptors, and can have a therapeutic effect in MS. These results suggest that eicosanoids have significant roles in experimental autoimmune encephalomyelitis (EAE) and MS. The data from animal and human studies elucidated that PGI2, PGF2α, PGD2, isoprostanes, PGE2, PLA2, LTs are increased in MS. PLA2 inhibition modulates the progression of the disease. PGE1 analogues can be a useful option in the treatment of MS.

CONCLUSIONS

All studies reported the beneficial effects of COX and LOX inhibitors in MS. The hybrid compounds, such as COX-2 inhibitors/TP antagonists and 5-LOX inhibitors can be an innovative approach for multiple sclerosis treatment. Future work in MS should shed light in synthesizing new compounds targeting arachidonic acid pathway.

Are we aiming to miss in translational autoimmunity treatments?

Autoimmunity treatments, fruitfully pioneered in mouse models, can be disappointing or result in immunosuppression and opportunistic infections in translational trials. Many possible reasons exist, but one major, overlooked reason may be the treatment timing in relation to circadian oscillations of the immune system. Mice and humans both have immunological circadian clocks and experience the same circulatory oscillations of immune cells with regards to their sleep/wake phases, but have opposite sleep/wake phases with regard to the daylight cycle. Therefore, researchers mainly study mice and potential autoimmunity treatments during the murine sleep/rest phase, which is when pro-inflammatory mediators and more adaptive immune cells are prevalent in the circulation. In translational trials, however, treatment administration happens primarily during a patient's wake/activity phase, during the daytime, which is when more local and acute immune responses are active in the circulation. Therefore, we believe that the most opportune window for autoimmunity treatment may be missed in translational trials. Shifting the timing, and adjusting dosing to target only immune cells that are active at that time, may result in higher success with minimized immunosuppression or toxicities.

Systematic Understanding of Bioactive Lipids in Neuro-Immune Interactions: Lessons from an Animal Model of Multiple Sclerosis

Bioactive lipids, or lipid mediators, are utilized for intercellular communications. They are rapidly produced in response to various stimuli and exported to extracellular spaces followed by binding to cell surface G protein-coupled receptors (GPCRs) or nuclear receptors. Many drugs targeting lipid signaling such as non-steroidal anti-inflammatory drugs (NSAIDs), prostaglandins, and antagonists for lipid GPCRs are in use. For example, the sphingolipid analog, fingolimod (also known as FTY720), was the first oral disease-modifying therapy (DMT) for relapsing-remitting multiple sclerosis (MS), whose mechanisms of action (MOA) includes sequestration of pathogenic lymphocytes into secondary lymphoid organs, as well as astrocytic modulation, via down-regulation of the sphingosine 1-phosphate (S1P) receptor, S1P₁, by in vivo-phosphorylated fingolimod. Though the cause of MS is still under debate, MS is considered to be an autoimmune demyelinating and neurodegenerative disease. This review summarizes the involvement of bioactive lipids (prostaglandins, leukotrienes, platelet-activating factors, lysophosphatidic acid, and S1P) in MS and the animal model, experimental autoimmune encephalomyelitis (EAE). Genetic ablation, along with pharmacological inhibition, of lipid metabolic enzymes and lipid GPCRs revealed that each bioactive lipid has a unique role in regulating immune and neural functions, including helper T cell (T_H1 and T_H17) differentiation and proliferation, immune cell migration, astrocyte responses, endothelium function, and microglial phagocytosis. A systematic understanding of bioactive lipids in MS and EAE dredges up information about understudied lipid signaling pathways, which should be clarified in the near future to better understand MS pathology and to develop novel DMTs.

Endothelial Microsomal Prostaglandin E Synthetase-1 Upregulates Vascularity and Endothelial Interleukin-1β in Deteriorative Progression of Experimental Autoimmune Encephalomyelitis

Microsomal prostaglandin E synthetase-1 (mPGES-1) is an inducible terminal enzyme for the production of prostaglandin E₂ (PGE₂). In experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis, mPGES-1 is induced in vascular endothelial cells (VECs) around inflammatory foci and facilitates inflammation, demyelination, and paralysis. Therefore, we investigated the role of CD31-positive VECs in mPGES-1-mediated EAE aggravation using immunohistochemical analysis and imaging of wild-type (wt) and mPGES-1-deficient (mPGES-1^-/-) mice. We demonstrated that EAE induction facilitated vascularity in inflammatory lesions in the spinal cord, and this was significantly higher in wt mice than in mPGES-1^-/- mice. In addition, endothelial interleukin-1β (IL-1β) production was significantly higher in wt mice than in mPGES-1^-/- mice. Moreover, endothelial PGE₂ receptors (E-prostanoid (EP) receptors EP1⁻4) were expressed after EAE induction, and IL-1β was induced in EP receptor-positive VECs. Furthermore, IL-1 receptor 1 expression on VECs was increased upon EAE induction. Thus, increased vascularity is one mechanism involved in EAE aggravation induced by mPGES-1. Furthermore, mPGES-1 facilitated the autocrine function of VECs upon EP receptor induction and IL-1β production, modulating mPGES-1 induction in EAE.

Initial effects of inflammation-related cytokines and signaling pathways on the pathogenesis of post-traumatic osteoarthritis

The main pathological change in post-traumatic osteoarthritis (PTOA) is cartilage degeneration, which is closely related to inflammation and oxidative stress. Inflammation can cause degeneration of articular cartilage. Cartilage degeneration can also stimulate the progression of inflammation. It has been found that inflammatory cytokines can participate in the pathological process of cartilage degeneration through multiple signaling pathways, mainly mitogen-activated protein kinase, nuclear transcription factor kappa B, and Wnt–β-catenin signal transduction pathways. This review aimed at exploring the relationship between PTOA and inflammation-related cytokines by introducing the role of proinflammatory cytokines in chondrocyte destruction and extracellular matrix degradation.