PRKDC mutations associated with immunodeficiency, granuloma, and autoimmune regulator-dependent autoimmunity.

BACKGROUND: PRKDC encodes for DNA-dependent protein kinase catalytic subunit (DNA-PKcs), a kinase that forms part of a complex (DNA-dependent protein kinase [DNA-PK]) crucial for DNA double-strand break repair and V(D)J recombination. In mice DNA-PK also interacts with the transcription factor autoimmune regulator (AIRE) to promote central T-cell tolerance. OBJECTIVE: We sought to understand the causes of an inflammatory disease with granuloma and autoimmunity associated with decreasing T- and B-cell counts over time that had been diagnosed in 2 unrelated patients. METHODS: Genetic, molecular, and functional analyses were performed to characterize an inflammatory disease evocative of a combined immunodeficiency. RESULTS: We identified PRKDC mutations in both patients. These patients exhibited a defect in DNA double-strand break repair and V(D)J recombination. Whole-blood mRNA analysis revealed a strong interferon signature. On activation, memory T cells displayed a skewed cytokine response typical of TH2 and TH1 but not TH17. Moreover, mutated DNA-PKcs did not promote AIRE-dependent transcription of peripheral tissue antigens in vitro. The latter defect correlated in vivo with production of anti-calcium-sensing receptor autoantibodies, which are typically found in AIRE-deficient patients. In addition, 9 months after bone marrow transplantation, patient 1 had Hashimoto thyroiditis, suggesting that organ-specific autoimmunity might be linked to nonhematopoietic cells, such as AIRE-expressing thymic epithelial cells. CONCLUSION: Deficiency of DNA-PKcs, a key AIRE partner, can present as an inflammatory disease with organ-specific autoimmunity, suggesting a role for DNA-PKcs in regulating autoimmune responses and maintaining AIRE-dependent tolerance in human subjects.

Modulation of blood T cell polyfunctionality and HVEM/BTLA expression are critical determinants of clinical outcome in anti-PD1-treated metastatic melanoma patients.

The need for reliable biomarkers to predict clinical benefit from anti-PD1 treatment in metastatic melanoma (MM) patients remains unmet. Several parameters have been considered in the tumor environment or the blood, but none has yet achieved sufficient accuracy for routine clinical practice. Whole blood samples from MM patients receiving second-line anti-PD1 treatment (NCT02626065), collected longitudinally, were analyzed by flow cytometry to assess the immune cell subsets absolute numbers, the expression of immune checkpoints or ligands on T cells and the functionality of innate immune cells and T cells. Clinical response was assessed according to Progression-Free Survival (PFS) status at one-year following initiation of anti-PD1 (responders: PFS > 1 year; non-responders: PFS ≤ 1 year). At baseline, several phenotypic and functional alterations in blood immune cells were observed in MM patients compared to healthy donors, but only the proportion of polyfunctional memory CD4+ T cells was associated with response to anti-PD1. Under treatment, a decreased frequency of HVEM on CD4+ and CD8+ T cells after 3 months of treatment identified responding patients, whereas its receptor BTLA was not modulated. Both reduced proportion of CD69-expressing CD4+ and CD8+ T cells and increased number of polyfunctional blood memory T cells after 3 months of treatment were associated with response to anti-PD1. Of upmost importance, the combination of changes of all these markers accurately discriminated between responding and non-responding patients. These results suggest that drugs targeting HVEM/BTLA pathway may be of interest to improve anti-PD1 efficacy.

Allogeneic reaction induces dendritic cell maturation through proinflammatory cytokine secretion.

BACKGROUND: A bone marrow transplantation conditioning regimen is known to activate host dendritic cells (DC), which then become able to initiate graft-versus-host disease (GVHD) by presenting alloantigens. In this article, the authors addressed whether the alloreaction could reciprocally maintain DC in an activation state through secretion of proinflammatory cytokines. METHODS: Skin biopsy specimens from GVHD patients were analyzed for the presence of DC. Supernatants collected from primary major histocompatibility antigen (allogeneic mixed leukocyte reaction [MLR] supernatant [SN]) or secondary minor histocompatibility antigen-mismatched mixed lymphocyte reactions were used to culture cytokine-promoted immature (im) DC. DC phenotype, function, and migration were analyzed. RESULTS: Immunostaining from GVHD skin biopsy specimens showed a deficit of Langerhans cells (LC) in the epidermis but the presence of mature DC in the dermis. Because LC should have recovered in the epidermis by this time, the authors then addressed whether the allogeneic reaction could maintain DC in an activation and migratory state, through secretion of inflammatory cytokines. With this aim, cytokine-mediated imDC were exposed to alloMLR-SN for 2 days. The authors observed that DC increased their expression of CD80, CD86, CD40, and human leukocyte antigen (HLA)-DR and neoexpressed CD83, DC-LAMP/CD208, and CCR7. At the functional level, alloMLR-SN-treated DC lost their ability to capture dextran, improved their allostimulatory capacity, and migrated in response to macrophage inflammatory protein 3beta. Interestingly, SN collected from secondary HLA-identical but minor histocompatibility antigen-mismatched MLR induced almost equivalent DC phenotypic maturation. CONCLUSIONS: The authors' results show that the allogeneic reaction leads to maturation and migration of DC through proinflammatory cytokine secretion. This might contribute to the impairment of LC reconstitution in the skin of patients with GVHD.

Anti-MDR1 siRNA restores chemosensitivity in chemoresistant breast carcinoma and osteosarcoma cell lines.

BACKGROUND: Reversion of chemoresistance by inhibition of P-glycoprotein (P-gp) expression may overcome the chemoresistance observed in many cancer types and may allow for improved therapeutic ratio. We investigated whether siRNA specific for ABCB1 (MDR1) mRNA might restore sensitivity to chemotherapy in tumor cell lines known to overexpress the MDR1 gene. MATERIALS AND METHODS: MDR1-expressing tumor cell lines were transiently transfected with anti-MDR1 silencing RNA (siRNA) before exposure to doxorubicin or methotrexate. The capacity of siRNA to reduce cell proliferation and increase the IC50 of the tested chemotherapies was investigated. RESULTS: siRNA down-regulated MDR1 mRNA expression by 50% in breast carcinoma and osteosarcoma cell lines, and significantly inhibited tumor cell proliferation up to 90% (p<0.01), when co-administered with doxorubicin or methotrexate, despite the known chemoresistance of the cell lines. siRNAs reduced the IC50 of doxorubicin and methotrexate by more than 10-fold (p<0.01). CONCLUSION: These results suggest the potential clinical application of anti-MDR1 siRNA to restore chemosensitivity and possibly improve the therapeutic ratio of these cytotoxic drugs.