Constitutive IL-1RA production by modified immune cells protects against IL-1-mediated inflammatory disorders.

Dysregulation of the interleukin-1 (IL-1) pathway leads to immune diseases that can result in chronic tissue and organ inflammation. Although IL-1 blockade has shown promise in ameliorating these symptoms and improving patients' quality of life, there is an urgent need for more effective, long-lasting treatments. We developed a lentivirus (LV)-mediated gene transfer strategy using transplanted autologous hematopoietic stem/progenitor cells (HSPCs) as a source of IL-1 receptor antagonist (IL-1RA) for systemic delivery to tissues and organs. Transplantation of mouse and human HSPCs transduced with an IL-1RA-encoding LV ensured stable IL-1RA production while maintaining the clonogenic and differentiation capacities of HSPCs in vivo. We examined the efficacy of cell-mediated IL-1RA delivery in three models of IL-1-dependent inflammation, for which treatment hindered neutrophil recruitment in an inducible model of gout, prevented systemic and multi-tissue inflammation in a genetic model of cryopyrin-associated periodic syndromes, and reduced disease severity in an experimental autoimmune encephalomyelitis model of multiple sclerosis. Our findings demonstrate HSPC-mediated IL-1RA delivery as a potential therapeutic modality that can be exploited to suppress tissue and organ inflammation in diverse immune-related diseases involving IL-1-driven inflammation.

Gasdermins: New Therapeutic Targets in Host Defense, Inflammatory Diseases, and Cancer.

Gasdermins (GSDMs) are a class of pore-forming proteins related to pyroptosis, a programmed cell death pathway that is induced by a range of inflammatory stimuli. Small-scale GSDM activation and pore formation allow the passive release of cytokines, such as IL-1ß and IL-18, and alarmins, but, whenever numerous GSDM pores are assembled, osmotic lysis and cell death occur. Such GSDM-mediated pyroptosis promotes pathogen clearance and can help restore homeostasis, but recent studies have revealed that dysregulated pyroptosis is at the root of many inflammation-mediated disease conditions. Moreover, new homeostatic functions for gasdermins are beginning to be revealed. Here, we review the newly discovered mechanisms of GSDM activation and their prominent roles in host defense and human diseases associated with chronic inflammation. We also highlight the potential of targeting GSDMs as a new therapeutic approach to combat chronic inflammatory diseases and cancer and how we might overcome the current obstacles to realize this potential.

Lentiviral correction of enzymatic activity restrains macrophage inflammation in adenosine deaminase 2 deficiency.

Adenosine deaminase 2 deficiency (DADA2) is a rare inherited disorder that is caused by autosomal recessive mutations in the ADA2 gene. Clinical manifestations include early-onset lacunar strokes, vasculitis/vasculopathy, systemic inflammation, immunodeficiency, and hematologic defects. Anti-tumor necrosis factor therapy reduces strokes and systemic inflammation. Allogeneic hematopoietic stem/progenitor cell (HSPC) transplantation can ameliorate most disease manifestations, but patients are at risk for complications. Autologous HSPC gene therapy may be an alternative curative option for patients with DADA2. We designed a lentiviral vector encoding ADA2 (LV-ADA2) to genetically correct HSPCs. Lentiviral transduction allowed efficient delivery of the functional ADA2 enzyme into HSPCs from healthy donors. Supranormal ADA2 expression in human and mouse HSPCs did not affect their multipotency and engraftment potential in vivo. The LV-ADA2 induced stable ADA2 expression and corrected the enzymatic defect in HSPCs derived from DADA2 patients. Patients' HSPCs re-expressing ADA2 retained their potential to differentiate into erythroid and myeloid cells. Delivery of ADA2 enzymatic activity in patients' macrophages led to a complete rescue of the exaggerated inflammatory cytokine production. Our data indicate that HSPCs ectopically expressing ADA2 retain their multipotent differentiation ability, leading to functional correction of macrophage defects. Altogether, these findings support the implementation of HSPC gene therapy for DADA2.

Tyrosine Dephosphorylation of ASC Modulates the Activation of the NLRP3 and AIM2 Inflammasomes.

The inflammasome is an intracellular multi-protein complex that orchestrates the release of the pro-inflammatory cytokines IL-1ß and IL-18, and a form of cell death known as pyroptosis. Tyrosine phosphorylation of the inflammasome sensors NLRP3, AIM2, NLRC4, and the adaptor protein, apoptosis-associated speck-like protein (ASC) has previously been demonstrated to be essential in the regulation of the inflammasome. By using the pharmacological protein tyrosine phosphatase (PTPase) inhibitor, phenylarsine oxide (PAO), we have demonstrated that tyrosine dephosphorylation is an essential step for the activation of the NLRP3 and AIM2 inflammasomes in human and murine macrophages. We have also shown that PTPase activity is required for ASC nucleation leading to caspase-1 activation, IL-1ß, and IL-18 processing and release, and cell death. Furthermore, by site-directed mutagenesis of ASC tyrosine residues, we have identified the phosphorylation of tyrosine Y60 and Y137 of ASC as critical for inflammasome assembly and function. Therefore, we report that ASC tyrosine dephosphorylation and phosphorylation are crucial events for inflammasome activation.