Disease modifying antirheumatic drugs (DMARDs) have improved the prognosis of autoimmune inflammatory arthritides but a large fraction of patients display partial or nonresponsiveness to front-line DMARDs. Here, an immunoregulatory approach based on sustained joint-localized release of all-trans retinoic acid (ATRA), which modulates local immune activation and enhances disease-protective T cells and leads to systemic disease control is reported. ATRA imprints a unique chromatin landscape in T cells, which is associated with an enhancement in the differentiation of naïve T cells into anti-inflammatory regulatory T cells (T reg ) and suppression of T reg destabilization. Sustained release poly-(lactic-co-glycolic) acid (PLGA)-based biodegradable microparticles encapsulating ATRA (PLGA-ATRA MP) are retained in arthritic mouse joints after intra-articular (IA) injection. IA PLGA-ATRA MP enhance migratory T reg which in turn reduce inflammation and modify disease in injected and uninjected joints, a phenotype that is also reproduced by IA injection of T reg . PLGA-ATRA MP reduce proteoglycan loss and bone erosions in the SKG and collagen-induced arthritis mouse models of autoimmune arthritis. Strikingly, systemic disease modulation by PLGA-ATRA MP is not associated with generalized immune suppression. PLGA-ATRA MP have the potential to be developed as a disease modifying agent for autoimmune arthritis.

Lipids constitute a diverse class of molecular regulators with ubiquitous physiological roles in sustaining life. These carbon‐rich compounds are primarily sourced from exogenous sources and may be used directly as structural cellular building blocks or as a substrate for generating signaling mediators to regulate cell behavior. In both of these roles, lipids play a key role in both immune activation and suppression, leading to inflammation and resolution, respectively. The simple yet elegant structural properties of lipids encompassing size, hydrophobicity, and molecular weight enable unique biodistribution profiles that facilitate preferential accumulation in target tissues to modulate relevant immune cell subsets. Thus, the structural and functional properties of lipids can be leveraged to generate new materials as pharmacological agents for potently modulating the immune system. Here, we discuss the properties of three classes of lipids: polyunsaturated fatty acids, short‐chain fatty acids, and lipid adjuvants. We describe their immunoregulatory functions in modulating disease pathogenesis in preclinical models and in human clinical trials. We conclude with an outlook on harnessing the diverse and potent immune modulating properties of lipids for immunoregulation.

No abstract

Inflammation, an essential cytokine-mediated process for generating a neutralising immune response against pathogens, is generally protective. However, aberrant or excessive production of proinflammatory cytokines is associated with uncontrolled local and systemic inflammation, resulting in cell death and often irreversible tissue damage. Uncontrolled inflammation can manifest over timescales spanning hours to years and is primarily dependent on the triggering event. Rapid and potentially lethal increases in cytokine production, or ‘cytokine storm’, develops in hours to days, and is associated with cancer cell-based immunotherapies, such as chimeric antigen receptor T-cell therapy. On the other hand, some bacterial and viral infections with high microbial replication or highly potent antigens elicit immune responses that result in supraphysiological systemic cytokine concentrations, which manifest over days to weeks. Immune dysregulation in autoimmune diseases can lead to chronic cytokine-mediated tissue damage spanning months to years, which often occurs episodically. Upregulation of IL-1, IL-6, IFN-γ, TNF, and granulocyte macrophage colony-stimulating factor frequently coincides with cytokine storm, sepsis, and autoimmune disease. Inhibition of proinflammatory molecules via antagonist monoclonal antibodies has improved clinical outcomes, but the complexity of the underlying immune dysregulation results in high variability. Rather than a ‘one size fits all’ treatment approach, an identification of disease endotypes may permit the development of effective therapeutic strategies that address the contributors of disease progression. Here, the authors present a literature review of the cytokine-associated aetiology of acute and chronic cytokine-mediated tissue damage, describe successes and challenges in developing clinical treatments, and highlight advancements in preclinical therapeutic strategies for mitigating pathological cytokine production.

Immune Engineering In article number 2202720, Nunzio Bottini, Nisarg J. Shah, and co‐workers report the development of microparticles as a new potential therapy for autoimmune arthritis. When injected in inflamed joints, the microparticles slowly biodegrade and release an immunomodulatory agent that strengthens disease‐protective immune cells. In mouse models of disease, the treatment approach protects joints from damage systemically while avoiding generalized immunosuppression.