Potent Neutralizing Antibodies against SARS-CoV-2 Identified by High-Throughput Single-Cell Sequencing of Convalescent Patients' B Cells.

The COVID-19 pandemic urgently needs therapeutic and prophylactic interventions. Here, we report the rapid identification of SARS-CoV-2-neutralizing antibodies by high-throughput single-cell RNA and VDJ sequencing of antigen-enriched B cells from 60 convalescent patients. From 8,558 antigen-binding IgG1+ clonotypes, 14 potent neutralizing antibodies were identified, with the most potent one, BD-368-2, exhibiting an IC50 of 1.2 and 15 ng/mL against pseudotyped and authentic SARS-CoV-2, respectively. BD-368-2 also displayed strong therapeutic and prophylactic efficacy in SARS-CoV-2-infected hACE2-transgenic mice. Additionally, the 3.8 Å cryo-EM structure of a neutralizing antibody in complex with the spike-ectodomain trimer revealed the antibody's epitope overlaps with the ACE2 binding site. Moreover, we demonstrated that SARS-CoV-2-neutralizing antibodies could be directly selected based on similarities of their predicted CDR3H structures to those of SARS-CoV-neutralizing antibodies. Altogether, we showed that human neutralizing antibodies could be efficiently discovered by high-throughput single B cell sequencing in response to pandemic infectious diseases.

Peripheral immune phenotypes and T cell receptor repertoire in pneumocystis pneumonia in HIV-1 infected patients.

BACKGROUND: The host immune response to pneumocystis pneumonia (PCP) involves interactions among immune cell subsets and cytokines. However, the definite pathogenesis and immunological influences of P. jirovecii have not been fully elucidated. METHODS: Mass cytometry and high-throughput sequencing of the T cell receptor (TCR) were used to profile the host immune response to human immunodeficiency virus-1 (HIV-1) and P. jirovecii infection. RESULTS: Our findings demonstrated that patients with PCP showed different immune cell proportions when compared to healthy controls. Changes in cytokines were found after anti-PCP treatment, suggested that cytokines may play an important role in controlling the pathogen. Furthermore, PCP patients showed marked reduction of TCR repertoire diversity. The diversity of TCR repertoire was restored by the anti-PCP treatment. CONCLUSION: In summary, we profiled the composition and characteristics of immune environment in response to HIV-1 and P. jirovecii infection, which may contribute to elucidating host immunity.

Downregulated Gene Expression Spectrum and Immune Responses Changed During the Disease Progression in Patients With COVID-19.

BACKGROUND: The World Health Organization characterizes novel coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), as a pandemic. Here, we investigated the clinical, cytokine levels; T-cell proportion; and related gene expression occurring in patients with COVID-19 on admission and after initial treatment. METHODS: Eleven patients diagnosed with COVID-19 with similar initial treatment regimens were enrolled in the hospital. Plasma cytokine, peripheral T cell proportions, and microfluidic quantitative polymerase chain reaction analyses for gene expression were conducted. RESULTS: Five patients with mild and 6 with severe disease were included. Cough and fever were the primary symptoms in the 11 COVID-19 cases. Older age, higher neutrophil count, and higher C-reactive protein levels were found in severe cases. IL-10 level significantly varied with disease progression and treatment. Decreased T-cell proportions were observed in patients with COVID-19, especially in severe cases, and all were returned to normal in patients with mild disease after initial treatment, but only CD4+ T cells returned to normal in severe cases. The number of differentially expressed genes (DEGs) increased with the disease progression, and decreased after initial treatment. All downregulated DEGs in severe cases mainly involved Th17-cell differentiation, cytokine-mediated signaling pathways, and T-cell activation. After initial treatment in severe cases, MAP2K7 and SOS1 were upregulated relative to that on admission. CONCLUSIONS: Our findings show that a decreased T-cell proportion with downregulated gene expression related to T-cell activation and differentiation occurred in patients with severe COVID-19, which may help to provide effective treatment strategies for COVID-19.

Activation of EGFR-KLF4 positive feedback loop results in acquired resistance to sorafenib in hepatocellular carcinoma.

Sorafenib is the standard first-line systemic chemotherapeutic drugs for advanced hepatocellular carcinoma (HCC), but acquired resistance to sorafenib is frequently observed in clinical practice. In this study, we first produced three sorafenib resistance (SR) HCC cell lines by using two human HCC cell lines (Hep3B and Huh7) and a human primary HCC cell line. We identified that epidermal growth factor receptor (EGFR) and Kruppel-like factor 4 (KLF4) are dramatically increased in the three SR HCC cell lines. Either inhibition of tyrosine kinase activity of EGFR with Erlotinib/Icotinib or inhibition of KLF4 expression with short hairpin RNA recovered the response of three SR HCC cell lines to sorafenib, suggesting the critical roles of EGFR tyrosine kinase and KLF4 on inducing SR. Luciferase activity and chromatin immunoprecipitation assays further determined that KLF4 promoted EGFR expression through inducing its transcription by directly binding to its promoter. EGFR, conversely, could also promote KLF4 expression through inducing its transcription by binding to its promoter in a tyrosine kinase-dependent manner, suggesting that a positive feedback loop formed by EGFR and KLF4 further amplifies their effects on inducing SR. Up to now, our findings that KLF4 induces the development of SR and it cooperates with EGFR to form a positive feedback loop to amplify their SR-inducing abilities have rarely been reported. Our findings bear possible implications for the improvement of the efficacy of sorafenib in HCC.

Mitochondrial DNA mutations accumulated in HIV-1-infected children who have an excellent virological response when exposed to long-term antiretroviral therapy.

Objectives: There is growing concern about mitochondrial DNA (mtDNA) mutations with long-term NRTI exposure in HIV-1 infected children. Methods: Twenty-four HIV-1 infected children who started ART more than 2 years earlier who had an excellent virological response and had not changed their regimen were enrolled retrospectively. Their corresponding PBMCs in 2009 (T1), 2010 (T2) and 2013 (T3) were included. Sequencing of the entire mtDNA using next-generation sequencing revealed the spectrum of mtDNA variants. Results: The trend showed that the number of mtDNA mutations during ART occurred as T1 < T2 < T3 (P = 0.086). Interestingly, the numbers of whole mtDNA mutations at T3 (median 41, range 24-62) were significantly greater than at T1 (34, 25-46, P = 0.029). A positive correlation was found between total mtDNA mutations and treatment time (r = 0.352, P = 0.002). During the observation period, mtDNA mutations more frequently occurred in the D-loop, cytochrome b (CYTB) and 12S rRNA regions. The heteroplasmic ratio of T3 was higher than that of T1 in CYTB and 12S rRNA (P = 0.034 and P = 0.042, respectively). High heteroplasmic population levels were found at nt 263 (A263G, D-loop) and nt 8860 (A8860G, ATPase6). A significant difference in heteroplasmy between T1, T2 and T3 occurred at nt 14783 (T14783C, CYTB, P = 0.048, T3 > T2 > T1). Conclusions: Our findings reveal the spectrum of mtDNA variants in HIV-1-infected children who had an excellent virological response. mtDNA mutations accumulated during ART may play an important role in facilitating the occurrence of mitochondrial dysfunction.

Mitochondrial DNA D-loop AG/TC transition mutation in cortical neurons of mice after long-term exposure to nucleoside analogues.

With the wide application of combined antiretroviral therapy, the prognosis of human immunodeficiency virus (HIV)-1 infected patient has been significantly improved. However, long-term administration of antiretroviral drugs can result in various drug-associated toxicities. Among them, nucleoside analogues were confirmed to inhibit DNA polymerase gamma, resulting in mitochondrial toxicity. Our previous study indicated that long-term exposure of mice to nucleoside analogue could induce mitochondria DNA (mtDNA) loss in cortical neurons. Herein, we further identify mitochondrial toxicity of four nucleoside analogues (zidovudine (AZT), stavudine (D4T), lamivudine (3TC), and didanosine (DDI)) by cloning and sequencing mtDNA D-loop region in mice neurons captured with laser capture microdissection. The results showed that mutation of neuronal mtDNA D-loop sequences increased in mice treated with each of the four nucleoside analogues for 4 months and D4T and DDI induced more severe D-loop lesion than the other two nucleoside analogues. The major type of D-loop point mutations induced by four nucleoside analogues was transition, in particular of "A→G" and "T→C" transition, but the point transition sites were variable. Our findings suggest that long-term exposure to nucleoside analogue can result in mtDNA D-loop region lesion in mouse cortical neurons.

Discordant patterns of tissue-specific genetic characteristics in the HIV-1 env gene from HIV-associated neurocognitive disorder (HAND) and non-HAND patients.

The genetic evolution of HIV-1 in the central nervous system (CNS) is different from that in peripheral tissues. We analyzed 121 clonal sequences of the V3-V5 regions of the env gene generated from paired cerebrospinal fluid (CSF) and plasma samples from nine chronically infected patients (four with HIV-associated neurocognitive disorder (HAND) and five without HAND). The sequence analysis indicated the significant differences between CSF and plasma was only observed in the C4 region (P = 0.043) in HAND patients. Significant increases in synonymous substitutions (dS) within the V4 region (P = 0.020) and in nonsynonymous substitutions (dN) within the C4 region (P = 0.029) were observed in the CSF-derived sequences. By contrast, CSF-derived sequences from non-HAND patients showed similar levels of diversity; dS and dN as the plasma-derived sequences. Signature differences between the CSF- and plasma-derived sequences were found at 12 amino acid positions for HAND patients and nine positions for non-HAND patients. Interestingly, five sites (positions 388, 396, 397, 404, and 406) that all belong to signature patterns exhibited positive selection pressure in CSF samples, but only site 406 was positively selected in the plasma samples from the HAND patients. Conversely, in the non-HAND patients, there were four sites (positions 397, 404, 432, and 446) showed positive selection pressure in the plasma samples, but only site 446 in the CSF samples. These results suggest that discordant patterns of genetic evolution occur between the tissue-specific HIV-1 quasispecies in the HAND and non-HAND patients. Viral molecular heterogeneity between specific tissues is greater in patients with HAND compared to non-HAND patients.

The mechanism and experimental verification of Ixeris sonchifolia promoting apoptosis of hepatocellular carcinoma based on network pharmacology: Ixeris sonchifolia Induces Hepatocellular Carcinoma Apoptosis via the PI3K/AKT Pathway.

ETHNOPHARMACOLOGICAL RELEVANCE: Ixeris sonchifolia alias Kudiezi, it was named Ixeris sonchifolia (Bunge) Hance, a synonym for Crepidiastrum sonchifolium (Bunge) Pak & Kawano in the https://www.iplant.cn/. And it was first published in J. Linn. Soc., Bot. 13: 108 (1873), which was named Ixeris sonchifolia (Maxim.) Hance in the MPNS (http://mpns.kew.org). As a widely distributed medicinal and edible wild plant, it possesses unique bitter-cold characteristics and constituents with various pharmacological activities. Its main antitumor substances, same as artemisinin and paclitaxel, are classified as terpenoids and have become research foci in recent years. However, its specific biological activity and role in antitumor treatment remain largely unclear. AIM OF THE STUDY: This study aimed to elucidate the molecular targets and potential mechanisms of hepatocellular carcinoma apoptosis induced by Ixeris sonchifolia. MATERIALS AND METHODS: We used network pharmacology methods to analyze and screen the active ingredients and possible underlying mechanisms of Ixeris sonchifolia in treating liver cancer and employed integrative time- and dose-dependent toxicity, transcriptomics, and molecular biology approaches to comprehensively verify the function of Ixeris sonchifolia extract (IsE) in human hepatoblastoma cell (HepG2) apoptosis and its potential mechanism. RESULTS: A total of 169 common targets were screened by network pharmacology, and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that IsE inhibited HepG2 cell activity in a time- and dose-dependent manner. Western blot analysis confirmed that IsE promoted HepG2 cell apoptosis by inhibiting the PI3K/AKT signaling pathway and that the PI3K/AKT inhibitor LY294002 also substantially enhanced IsE-induced apoptosis. The PI3K/AKT signaling pathway exhibited significant differences compared to that in the control group. CONCLUSION: Combining network pharmacology with experimental verification, IsE inhibited mitochondrial function and the PI3K/AKT pathway while inducing hepatoma cell apoptosis. IsE may have promising potential for liver cancer treatment and chemoprevention.

Radiofrequency ablation plays double role in immunosuppression and activation of PBMCs in recurrent hepatocellular carcinoma.

Background: Radiofrequency ablation (RFA) is the primary curative treatment for hepatocellular carcinoma (HCC) patients who are not eligible for surgery. However, the effects of RFA on the global tumor immune response remain unclear. Method: In this study, we examined the phenotypic and functional changes in peripheral blood mononuclear cells (PBMCs) from recurrent HCC patients who had undergone two RFA treatments using mass cytometry and high-throughput mRNA assays. Results: We observed significant increase in monocytes and decrease in T cell subpopulations three days after the first RFA treatment and three days after the second RFA treatment. The down-regulation of GZMB, GZMH, GZMK, and CD8A, which are involved in the cytotoxic function of T cells, was observed following RFA. Furthermore, the population of CD8 effector and memory T cells (CD8 Teff and CD8 Tem) significantly decreased after RFA. The expression of CD5 and CD161 in various T cell subpopulations also showed significant reductions. Additionally, elevated secretion of VEGF was observed in monocytes, B cells, regulatory T cells (Tregs), and CD4 naive T cells. Conclusion: In recurrent HCC patients, serum components derived from radiofrequency therapy can enhance the antigen-presenting capacity of monocytes. However, they also inhibit the anti-cancer immune response by reducing the population of CD8 effector and memory T cells and suppressing the activation of T cells, as well as down-regulating the expression of CD161 and CD5 in various T cell subpopulations. These tumor-derived components also contribute to an immunosuppressive microenvironment by promoting the secretion of VEGF in monocytes, Tregs, B cells, and CD4 naive T cells.

High levels of divergent HIV-1 quasispecies in patients with neurological opportunistic infections in China.

Despite the fact that the survival of people infected with human immunodeficiency virus (HIV) has improved worldwide because of the increasingly powerful and highly active antiretroviral therapy, opportunistic infections (OIs) of the central nervous system (CNS) remain a serious burden. HIV-1 is capable of entering the CNS through infected peripheral monocytes, but its effect on OIs of CNS remains unclear. In this study, we investigated the characteristics of HIV-1 in acquired immunodeficiency syndrome (AIDS) patients with CNS OIs. A total of 24 patients with CNS OIs and 16 non-CNS OIs (control) cases were selected. These AIDS patients were infected with HIV-1 by paid blood donors in China. HIV-1 loads in plasma and cerebrospinal fluid (CSF) were detected using RT-PCR, and the C2-V5 region of HIV-1 envelope gene was amplified from viral quasispecies isolated from CSF using nested PCR. The CSF HIV-1 load of CNS OIs was higher than that of non-CNS OIs, but plasma HIV-1 load of CNS OIs was not higher than that of non-CNS OIs. The nucleotide sequence of C2-V5 region of the HIV-1 quasispecies isolated from the CSF of CNS OIs had a high diversity, and the HIV-1 quasispecies isolated from the CSF of CNS OIs revealed R5 tropism as 11/25 charge rule. These results suggest that high levels of divergent HIV-1 quasispecies in the CNS probably contribute to opportunistic infections.

Cytokines in CSF correlate with HIV-associated neurocognitive disorders in the post-HAART era in China.

In the current era of highly active antiretroviral therapy (HAART), the incidence of HIV dementia has declined, but the prevalence of HIV-associated neurocognitive disorder (HAND) remains high. HIV-induced systemic and localized inflammation is considered to be one of the mechanisms of HAND. Changes in cytokine levels in the cerebrospinal fluid (CSF) during HIV infection might help to identify HAND. To investigate whether the cytokine profile of the CSF during HIV infection could be used as a biomarker of HAND, we compared cytokine levels in the CSF of HIV-infected cases with and without neurocognitive impairment. Cytokine concentrations in the CSF were measured by quantification bioassays (Luminex xMAP). HIV-infected cases with neurocognitive impairment demonstrated higher levels of interleukin (IL)-8, monocyte chemotactic protein (MCP)-1, induced protein (IP)-10, and granulocyte colony-stimulating factor (G-CSF) in the CSF than those without neurocognitive impairment (G-CSF (p = 0.0003), IL-8 (p = 0.0046), IP-10 (p < 0.0001), and MCP-1 (p < 0.0001)). There was no significant impact of HAART on cytokine levels in the CSF, except for IP-10, which was higher in HAART-treated patients with impaired cognition (p = 0.0182). Findings from this preliminary study suggest that elevated levels of the cytokines IL-8, MCP-1, G-CSF, and IP-10 in the CSF are associated with neurocognitive impairment in HIV infection, and these cytokines likely represent a biomarker profile for HAND.

Recent advances in recurrent hepatocellular carcinoma therapy.

Hepatocellular carcinoma (HCC) is the most prevalent form of primary liver cancer, accounting for 75%-85% of cases. Although treatments are given to cure early-stage HCC, up to 50%-70% of individuals may experience a relapse of the illness in the liver after 5 years. Research on the fundamental treatment modalities for recurrent HCC is moving significantly further. The precise selection of individuals for therapy strategies with established survival advantages is crucial to ensuring better outcomes. These strategies aim to minimize substantial morbidity, support good life quality, and enhance survival for patients with recurrent HCC. For individuals with recurring HCC after curative treatment, no approved therapeutic regimen is currently available. A recent study presented novel approaches, like immunotherapy and antiviral medication, to improve the prognosis of patients with recurring HCC with the apparent lack of data to guide the clinical treatment. The data supporting several neoadjuvant and adjuvant therapies for patients with recurring HCC are outlined in this review. We also discuss the potential for future clinical and translational investigations.

An initial screening for HIV-associated neurocognitive disorders of HIV-1 infected patients in China.

HIV-associated neurocognitive disorders (HAND), characterized by cognitive, motor, and behavioral abnormalities, are common among people living with HIV and AIDS. In combined antiretroviral therapy era in Western countries, nearly 40% of HIV-infected patients continue to suffer from HAND, mainly with mild or asymptomatic cognitive impairment. However, the prevalence and the clinical features of HAND in China are still not well known. In this study, a multi-center cross-sectional study was performed to determine the prevalence and clinical features of HAND in 134 HIV-1 infected patients in China. The International HIV Dementia Scale and a neuropsychological test battery were administered for screening and diagnosis HAND. Subjective complaints, CD4 count and viral loads in both blood plasma and cerebrospinal fluid were correlated with diagnosis of HAND. The results showed that the prevalence of HAND was approximately 37% in these patients. CD4 counts at time of sampling were significant lower in the HAND group than in the non-HAND group. But the distribution of the HAND severity did not differ by CD4 count or viral load. The presence of HAND was associated with cognitive and behavior disorder complaints (4.9- and 4.1-fold higher than those without HAND, respectively). The present data suggest that CD4 count and viral load cannot predict the severity of HAND, although the prevalence of HAND is similar to previous report in these patients. Cognitive and behavioral disorder is major complaint rather than cognitive and motor impairment. A larger prospective study is needed to obtain better estimates of HAND in China.

Corrigendum to "Usnea Acid as Multidrug Resistance (MDR) Reversing Agent against Human Chronic Myelogenous Leukemia K562/ADR Cells via an ROS Dependent Apoptosis".

[This corrects the article DOI: 10.1155/2019/8727935.].

The inhibition of IL-2/IL-2R gives rise to CD8+ T cell and lymphocyte decrease through JAK1-STAT5 in critical patients with COVID-19 pneumonia.

Although most patients with COVID-19 pneumonia have a good prognosis, some patients develop to severe or critical illness, and the mortality of critical cases is up to 61.5%. However, specific molecular information about immune response in critical patients with COVID-19 is poorly understood. A total of 54 patients were enrolled and divided into three groups, among which 34 were common, 14 were severe, and 6 were critical. The constitution of peripheral blood mononuclear cells (PBMC) in patients was analyzed by CyTOF. The profile of cytokines was examined in plasma of patients using luminex. The IL-2 signaling pathway was investigated in the PBMC of patients by qRT-PCR. The count and percentage of lymphocytes were significantly decreased in critical patients compared to common and severe patients with COVID-19 pneumonia. The count of T cells, B cells, and NK cells was remarkably decreased in critical patients compared to normal controls. The percentage of CD8+ T cells was significantly lower in critical patients than that in common and severe patients with COVID-19 pneumonia. The expression of IL-2R, JAK1, and STAT5 decreased in PBMC of common, severe, and critical patients, but IL-2 level was elevated in severe patients and decreased in critical patients with COVID-19 pneumonia. The decrease of CD8+ T cells in critical patients with COVID-19 pneumonia may be related to the IL-2 signaling pathway. The inhibition of IL-2/IL-2R gives rise to CD8+ T cell and lymphocyte decrease through JAK1-STAT5 in critical patients with COVID-19 pneumonia.

Usnea Acid as Multidrug Resistance (MDR) Reversing Agent against Human Chronic Myelogenous Leukemia K562/ADR Cells via an ROS Dependent Apoptosis.

PURPOSE: Multidrug resistance (MDR) is a major obstacle in chemotherapy of leukemia treatments. In this paper, we investigated Usnea Acid (UA) as MDR reversal agent on hematologic K562/ADR cells via ROS dependent apoptosis. METHODS: CCK8 assay was used to measure cell viability rate of K562/ADR. Intracellular reactive oxygen species (ROS) generation, cell cycle distribution, cell apoptosis were measured with flow cytometry, respectively. Proteins related to apoptosis were measured by Western blot. Intracellular Adriamycin accumulation was observed by confocal microscopy and measured by flow cytometry. RESULTS: In vitro study showed intracellular Adriamycin accumulation was remarkably increased by UA. Cell viability treated with Adr (4 µM) was decreased from 89.8% ± 4.7 to 32% ± 8.9 by combined with UA (4 µM). Adr-induced apoptosis and G1/G0 phase cell cycle arrest were remarkably increased by UA, as well as, intracellular ROS level. However, MDR reversing activity of UA was inhibited by N-acetyl cysteine (NAC), a ROS scavenger. CONCLUSION: These data provide compelling evidence that UA is a promising agent against MDR in leukemia cell line and suggest a promising therapeutic approach for leukemia.

DRAM Is Involved in Regulating Nucleoside Analog-Induced Neuronal Autophagy in a p53-Independent Manner.

The widespread use of combined anti-retroviral therapy (cART) has not decreased the prevalence of HIV-1-associated neurocognitive disorder (HAND), a type of neurodegenerative disease, even though cART effectively inhibits virus colonization in the central nervous system. Therefore, anti-retroviral agents cannot be fully excluded from the pathogenesis of HAND. Our previous study reported that long-term nucleoside analogue (NA) exposure induced mitochondrial toxicity in the cortical neurons of HAND patients and mice, but the exact mechanism of NA-associated neurotoxicity has remained unclear. Alteration of autophagy can result in protein aggregation and the accumulation of dysfunctional organelles, which are hallmarks of some neurodegenerative diseases. In this study, we first found increased autophagy in cortical autopsy specimens of AIDS patients. We then found that a low dose of NAs could stimulate autophagy in primary cultured neurons, while a high dose of NAs could induce only neuronal apoptosis. The level of NA-induced Bcl-2 and Bax expressions determined whether neuronal autophagy or apoptosis occurred. Furthermore, the level of NA-induced neuronal apoptosis correlated with the dysfunction of cellular DNA polymerase gamma. Damage-regulated autophagy modulator (DRAM) overexpression was also involved in NA-induced neuronal autophagy. p53 played a role in the regulation of NA-induced neuronal apoptosis, but its role in NA-associated neuronal autophagy was uncertain. Our results suggest that DRAM is involved in the regulation of NA-induced neuronal autophagy in a p53-independent manner. Further research is needed to investigate the underlying mechanism.

Mitochondrial DNA D­loop lesions with the enhancement of DNA repair contribute to gastrointestinal cancer progression.

Gastrointestinal cancer (GIC) is a worldwide public health problem with a high mortality rate. Mitochondrial DNA (mtDNA) mutations in the displacement loop (D­loop) region are quite common in various types of primary human cancers; however, their role in the pathogenesis of GIC is controversial. In the present study, tumor and para­tumor tissues were selected from 18 patients with gastric cancer (GC), 21 patients with colon cancer (CC) and 30 patients with rectal cancer (RC). The mtDNA D­loop was analyzed by sequencing and reverse transcription­quantitative polymerase chain reaction. Furthermore, DNA oxidative damage and DNA repair functioning were detected by immunohistochemistry. The results demonstrated that increased mtDNA deletion was not evident in GIC; however, significant DNA oxidative damage was significant in RC by detecting 8­hydroxyguanine expression. In addition, over­activated DNA repair was identified in CC and RC through the detection of 8­oxo­20­deoxyguanosine glycosylase 1 expression. The mtDNA D­loop had a specific mutation hotspot region, and the level of mtDNA D­loop mutations was correlated with the progression of the GIC. The mutations of the mtDNA D­loop were primarily homoplasmic in GIC and often transitioned at pyrimidine sites. Mitochondrial microsatellite instability, including the formation of poly­cytidine stretches, was common in GIC. These results demonstrate the occurrence of mtDNA D­loop mutations in GIC in Chinese patients and support the correlation of these mutations with carcinoma progression. Over­activated DNA repair function possibly repairs the GIC mtDNA lesions.

Nucleoside reverse transcriptase inhibitors induced hepatocellular mitochondrial DNA lesions and compensatory enhancement of mitochondrial function and DNA repair.

Nucleoside reverse transcriptase inhibitors (NRTIs) are the backbone of combined antiretroviral therapy (cART) and are widely used in anti-human immunodeficiency virus (HIV) therapy. Long-term administration of NRTIs can result in mitochondrial dysfunction in certain HIV-1-infected patients. However, NRTI-associated liver mitochondrial toxicity is not well known. Herein, the liver autopsy of acquired immune deficiency syndrome (AIDS) patients and the liver tissues of mice with 12 months of NRTI exposure were used to identify NRTI-associated liver toxicity with immunofluorescence, quantitative real-time polymerase chain reaction (qPCR), Amplex red and horseradish peroxidase, and cloning and sequencing. Laser capture microdissection was used to capture hepatocytes from liver tissues. We observed DNA oxidative damage and mitochondrial DNA (mtDNA) loss in the livers of AIDS patients, and cART patients had higher DNA oxidative damage and lower DNA repair function in liver tissues than non-cART patients. We also observed liver oxidative damage, increased DNA repair and mtDNA loss in mice with exposure to four different NRTIs for 12 months, and hepatocytes had no more mtDNA loss than liver tissues. Although NRTIs could induce mitochondrial hydrogen peroxide production, increased mitochondrial oxygen consumption was found with a Clark-type electrode. The captured hepatocytes had greater diversity in their mtDNA D-loop, dehydrogenase subunit1 (ND1) and ND4 than the controls. Long-term NRTI exposure induced single nucleotide variation in hepatocellular mtDNA D-loop, ND1 and ND4. Our findings indicate that NRTIs can induce liver mtDNA lesions, but simultaneously enhance mitochondrial function and mtDNA repair.