The PI3Kδ inhibitor parsaclisib ameliorates pathology and reduces autoantibody formation in preclinical models of systemic lupus erythematosus and Sjӧgren's syndrome.

Dysregulation of phosphoinositide 3-kinase δ (PI3Kδ) signaling pathway has been implicated in the pathogenesis of inflammatory and autoimmune diseases. Parsaclisib (INCB050465) represents a potent and selective PI3Kδ inhibitor, which is being clinically investigated for treatment of autoimmune hemolytic anemia and hematological malignancies. We characterized the potential of parsaclisib to ameliorate autoimmune mechanisms implicated in the pathophysiology of systemic lupus erythematosus (SLE) and Sjögren's syndrome (SS). Spontaneous mouse models of SLE and SS were utilized to elucidate the efficacy of orally administered parsaclisib on autoreactive B-cell-mediated antibody-driven disease. Parsaclisib significantly reduced disease symptoms and pathology in three distinct mouse models of SLE. Parsaclisib effectively preserved renal function as measured by glomerular filtration rate, abrogated histopathological evidence of nephritis, modulated discrete immune cell subsets, and decreased anti-dsDNA antibody level. Furthermore, parsaclisib demonstrated efficacy in two spontaneous mouse models of SS. Oral parsaclisib treatment ameliorated the severity of salivary gland inflammation and reduced circulating levels of autoantibodies. Parsaclisib mediated improvement of salivary gland inflammation coincided with reduced B-cell activating cytokine (BAFF) in saliva. Transcriptomic analysis of kidney and salivary gland tissues revealed a downregulation in inflammatory gene expression consistent with PI3Kδ pathway inhibition. Parsaclisib reduced autoreactive B-cells and autoantibody levels, and significantly improved nephritis and salivary gland inflammation. These data provide the scientific rationale for PI3Kδ inhibition as a therapeutic strategy for treatment of B-cell-mediated antibody-driven autoimmune diseases.

Chimeric Antigen Receptors Based on Low Affinity Mutants of FcεRI Re-direct T Cell Specificity to Cells Expressing Membrane IgE.

IgE is the key mediator of allergic responses. Omalizumab, an IgE-specific monoclonal antibody that depletes IgE, is effective for treating severe allergic asthma. The need for frequent administration of the expensive drug, however, limits its applications. Taking advantage of T cell memory, adoptive T cell therapy (ACT) targeting IgE-producing cells has the potential to achieve long-term suppression of IgE and relief of symptoms for severe allergic diseases. The transmembrane form of IgE (mIgE), which is present on all IgE-producing cells, serves as an excellent molecular target for ACT that employs chimeric antigen receptors (CARs). Here, we designed and tested CARs that use the extracellular domain of high affinity IgE receptor, FcεRIα, for mIgE recognition. When expressed on Jurkat T cells, FcεRIα-based CARs mediated robust responses in terms of CD69 upregulation to U266 myeloma cells expressing low levels of mIgE. FcεRIα-based CARs specifically recognized cells expressing mIgE, but not cells with secreted IgE captured through Fcε receptors. CAR+ Jurkat cells did not respond to LAD2 mast cells with secreted IgE bound through FcεRI or Ramos cells with secreted IgE bound through FcεRII. Co-culture of CAR+ Jurkat cells and LAD2 mast cells with IgE bound did not trigger LAD2 cell degranulation. The activity of CAR using wild type FcεRIα for mIgE binding was inhibited by the presence secreted IgE, which likely blocked CAR-mIgE interaction. The activities of CARs using low affinity mutants of FcεRIα, however, tolerated secreted IgE at relatively high concentrations. Moreover, primary human CD8+ T cells expressing a low affinity mutant CAR responded to U266 cells with INFγ production and cytotoxicity despite the presence of secreted IgE. The potency, specificity, and robustness of our CAR design, combined with repaid advances in the safety of ACT, hold promise for novel and highly effective cell-based therapies against severe allergic diseases.

Nanoshell-mediated photothermal therapy can enhance chemotherapy in inflammatory breast cancer cells.

Nanoshell-mediated photothermal therapy (PTT) is currently being investigated as a standalone therapy for the treatment of cancer. The cellular effects of PTT include loss of membrane integrity, so we hypothesized that nanoshell-mediated PTT could potentiate the cytotoxicity of chemotherapy by improving drug accumulation in cancer cells. In this work, we validated our hypothesis using doxorubicin as a model drug and SUM149 inflammatory breast cancer cells as a model cancer subtype. In initial studies, SUM149 cells were exposed to nano-shells and near-infrared light and then stained with ethidium homodimer-1, which is excluded from cells with an intact plasma membrane. The results confirmed that nanoshell-mediated PTT could increase membrane permeability in SUM149 cells. In complementary experiments, SUM149 cells treated with nanoshells, near-infrared light, or a combination of the two to yield low-dose PTT were exposed to fluorescent rhodamine 123. Analyzing rhodamine 123 fluorescence in cells via flow cytometry confirmed that increased membrane permeability caused by PTT could enhance drug accumulation in cells. This was validated using fluorescence microscopy to assess intracellular distribution of doxorubicin. In succeeding experiments, SUM149 cells were exposed to subtherapeutic levels of doxorubicin, low-dose PTT, or a combination of the two treatments to determine whether the additional drug uptake induced by PTT is sufficient to enhance cell death. Analysis revealed minimal loss of viability relative to controls in cells exposed to subtherapeutic levels of doxorubicin, 15% loss of viability in cells exposed to low-dose PTT, and 35% loss of viability in cells exposed to combination therapy. These data indicate that nanoshell-mediated PTT is a viable strategy to potentiate the effects of chemotherapy and warrant further investigation of this approach using other drugs and cancer subtypes.