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.

Patients with metastatic breast cancer leading to CD4+ T cell lymphopaenia have poor outcome.

BACKGROUND: Low lymphocyte count is a prognostic factor in cancer patients including metastatic breast cancer patients (MBC) but the relative role of each lymphocyte subtype is unclear in MBC. METHODS: The impact of lymphocyte subsets was analysed in two prospective MBC patients' cohorts. Cohort A patients (n=103) were included before the first line of chemotherapy and cohort B patients (n=101) were included after at least one line of chemotherapy. Extensive phenotypic analyses were performed on fresh whole blood. Plasma cytokines levels were measured using commercially available Luminex-based multiplex kits. Prognostic value of lymphocyte subsets and circulating cytokines was analysed. RESULTS: In both cohorts, severe lymphopaenia (<0.7 Giga/L) correlated with poor overall survival (OS) (median OS: 6.6 months versus 21.7 months in cohort A and 4.5 versus 9 months in cohort B). CD8(+), CD19(+) and CD56(+) T cell counts had no significant prognostic value for OS. After stratification (≤0.2, [0.20-0.45], >0.45 Giga/L), CD4 lymphopaenia appeared to be correlated with poor OS in both cohorts. Furthermore, severe CD4(+) lymphopaenia (≤0.2 Giga/L) was strongly correlated with poor OS in both cohorts (1.2 months versus 24.9 months in cohort A and 5.7 versus 13.1 months in cohort B). In multivariate analysis, after stratification CD4(+) lymphopaenia appeared to be an independent prognostic factor for OS in both cohorts. CD4(+) lymphopaenia correlated with low plasmatic levels of CCL22 that might directly contribute to CD4(+) lymphopaenia. CONCLUSIONS: CD4(+) lymphopaenia was associated with reduced OS in MBC patients regardless of the chemotherapy line. Decreased levels of plasmatic CCL22 may contribute to CD4(+) lymphopaenia.

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.