Mitochondrion is known as the energy factory of the cell, which is also a unique mammalian organelle and considered to be evolved from aerobic prokaryotes more than a billion years ago. Mitochondrial DNA, similar to that of its bacterial ancestor’s, consists of a circular loop and contains significant number of unmethylated DNA as CpG islands. The innate immune system plays an important role in the mammalian immune response. Recent research has demonstrated that mitochondrial DNA (mtDNA) activates several innate immune pathways involving TLR9, NLRP3 and STING signaling, which contributes to the signaling platforms and results in effector responses. In addition to facilitating antibacterial immunity and regulating antiviral signaling, mounting evidence suggests that mtDNA contributes to inflammatory diseases following cellular damage and stress. Therefore, in addition to its well-appreciated roles in cellular metabolism and energy production,mtDNA appears to function as a key member in the innate immune system. Here, we highlight the emerging roles of mtDNA in innate immunity.
Animals ; DNA, Mitochondrial ; genetics ; Humans ; Immunity, Innate ; immunology ; Mitochondria ; genetics ; immunology ; Signal Transduction

Objective To study the expressions of anaplastic lymphoma kinase (ALK-1) and cytotoxic proteins in primary systemic anaplastic large cell lymphoma (S-ALCL) and their relationship with clinical outcome. Methods 51 S-ALCL cases were collected from Lymphoma Lab of Peking University Health Science Centre & Peking Children's Hospital. The morphologic characteristics were studied under routine microscope, and essential immunohistochemical stainings were performed and reviewed to confirm the diagnosis of S-ALCL. Immunohistochemical stainings for ALK-1 and cytotoxic proteins (TIA-1 & granzyme B) were performed using standard SP method. Patients related clinical data including follow-up materials were collected. Results Survival time of 44 cases with completely clinical follow up materials ranged from 0.5～66months. 36 out of 51 cases(37 %) was positive for ALK-1 protein. While 20 cases out of 47 S-ALCL cases ( 42.55 % ) positive for granzyme B and 22 out of 28 cases (81.48 %) were positive for TIA-1. The prognosis of patients with ALK-1 protein positive and granzyme B negative expression was better, but TIA-1 expression might have nothing to do with clinical outcome (P＞0.05). In addition, multivariate analysis confirmed that ALK-1 protein expression, granzyme B protein expression and Ann-Arbor stage system were possible for prognosis(P＜0.05), Conclusion Expression of ALK-1 and granzyme B protein expression may serve as two independent prognostic predictors in S-ALCL patients.

Objective: To investigate the clinical features and diagnostic bases of childhood leukoencephalopathy with cerebral calcifications and cysts (LCC). Methods: The clinical data involving manifestations and laboratory examinations of 4 children with LCC admitted to Beijing Children's Hospital Affiliated to Capital Medical University from 2012 to 2017 were retrospectively summarized. Each patient had a follow-up visit ranging from 4 months to 5 years and 9 months after initial examination. Results: Patients consisted of 2 males and 2 females, whose age of onset was respectively 2 years and 9 months, 6 years and 2 months, 7 years and 10 months, and 5 years and 1 month. The main clinical symptoms of these cases included headache, dizziness, partial seizure and claudication, and two of these cases had insidious onset. Cerebral calcifications and cysts with leukoencephalopathy were detected by neuroimaging in all patients. In addition, multifocal microhemorrhages and calcifications were observed by magnetic susceptibility-weighted imaging (SWI) series in 3 patients. Brain biopsy performed on 1 case disclosed a neuronal reduction in the cerebral cortex, loosening of focal white matter, multifocal lymphocyte infiltration, fresh hemorrhages, and gliosis, as well as angiomatous changes of blood vessels with hyalinized thicken-wall, stenotic or occlusive lumina and calcification deposits. The compound heterozygous mutations of n.*10G>A and n.82A>G in SNORD118 were identified in 1 case by target-capture next-generation sequencing. Sanger sequencing verified that the variant n.*10G>A was a novel mutation and it was of paternal-origin, while the variant n.82A>G was of maternal-origin, which had already been reported to be pathogenic to LCC. Follow-up study had shown continued partial seizure in 1 case and remissive claudication in another, while the remaining 2 cases had a relatively favorable outcome without obvious neurological symptoms at present time. Conclusions The clinical manifestations of LCC are nonspecific, and the onset of the disease tends to be insidious. The triad neuroimaging findings of cerebral calcifications, cysts and leukoencephalopathy are essential to the diagnosis of the disease, and the signals of microhemorrhages revealed by SWI series provide another eloquent reference for the diagnosis. As biopsy is invasive and usually unavailable in the early stage, gene assessment, instead of pathological data, should be the gold standard in the diagnosis of LCC.