Methotrexate suppresses psoriatic skin inflammation by inhibiting muropeptide transporter SLC46A2 activity.

Cytosolic innate immune sensing is critical for protecting barrier tissues. NOD1 and NOD2 are cytosolic sensors of small peptidoglycan fragments (muropeptides) derived from the bacterial cell wall. These muropeptides enter cells, especially epithelial cells, through unclear mechanisms. We previously implicated SLC46 transporters in muropeptide transport in Drosophila immunity. Here, we focused on Slc46a2, which was highly expressed in mammalian epidermal keratinocytes, and showed that it was critical for the delivery of diaminopimelic acid (DAP)-muropeptides and activation of NOD1 in keratinocytes, whereas the related transporter Slc46a3 was critical for delivering the NOD2 ligand MDP to keratinocytes. In a mouse model, Slc46a2 and Nod1 deficiency strongly suppressed psoriatic inflammation, whereas methotrexate, a commonly used psoriasis therapeutic, inhibited Slc46a2-dependent transport of DAP-muropeptides. Collectively, these studies define SLC46A2 as a transporter of NOD1-activating muropeptides, with critical roles in the skin barrier, and identify this transporter as an important target for anti-inflammatory intervention.

Nanoparticle delivery of innate immune agonists combines with senescence-inducing agents to mediate T cell control of pancreatic cancer.

Pancreatic ductal adenocarcinoma has quickly risen to become the 3rd leading cause of cancer-related death. This is in part due to its fibrotic tumor microenvironment (TME) that contributes to poor vascularization and immune infiltration and subsequent chemo- and immunotherapy failure. Here we investigated an innovative immunotherapy approach combining local delivery of STING and TLR4 innate immune agonists via lipid-based nanoparticles (NPs) co-encapsulation with senescence-inducing RAS-targeted therapies that can remodel the immune suppressive PDAC TME through the senescence-associated secretory phenotype. Treatment of transplanted and autochthonous PDAC mouse models with these regimens led to enhanced uptake of NPs by multiple cell types in the PDAC TME, induction of type I interferon and other pro-inflammatory signaling, increased antigen presentation by tumor cells and antigen presenting cells, and subsequent activation of both innate and adaptive immune responses. This two-pronged approach produced potent T cell-driven and Type I interferon-dependent tumor regressions and long-term survival in preclinical PDAC models. STING and TLR4-mediated Type I interferon signaling were also associated with enhanced NK and CD8+ T cell immunity in human PDAC. Thus, combining localized immune agonist delivery with systemic tumor-targeted therapy can synergize to orchestrate a coordinated innate and adaptive immune assault to overcome immune suppression and activate durable anti-tumor T cell responses against PDAC.

Dual agonist immunostimulatory nanoparticles combine with PD1 blockade for curative neoadjuvant immunotherapy of aggressive cancers.

Lethal cancer is characterized by drug-resistant relapse and metastasis. Here, we evaluate the efficacy of a neoadjuvant therapeutic strategy prior to surgery that combines the immune checkpoint inhibitor anti-PD1 with a powerful immunostimulatory nanoparticle (immuno-NP). Lipid-based immuno-NPs are uniquely designed to co-encapsulate a STING and TLR4 agonist that are functionally synergistic. Efficacy of neoadjuvant combination immunotherapy was assessed in three aggressive murine tumor models, including B16F10 melanoma and 4T1 and D2.A1 breast cancer. Primary splenocytes treated with dual-agonist immuno-NPs produced a 75-fold increased production of interferon ß compared to single-agonist treatments. Systemic delivery facilitated the widespread deposition of immuno-NPs in the perivascular space throughout the tumor mass and their preferential uptake by tumor-resident antigen-presenting cells. Our findings strongly suggested that immuno-NPs, when administered in combination with anti-PD1, harnessed and activated the otherwise "exhausted" CD8+ T cells as key mediators of tumor clearance. Neoadjuvant combination immunotherapy resulted in significant efficacy, curative responses, and protective immunological memory in 71% of good-responding mice bearing B16F10 melanoma tumors and showed similar trends in the two breast cancer models. Finally, this neoadjuvant combination immunotherapy drove the generation of B and T cell de novo epitopes for a comprehensive memory response.