Sustained aviremia despite anti-retroviral therapy non-adherence in male children after in utero HIV transmission.

After sporadic reports of post-treatment control of HIV in children who initiated combination anti-retroviral therapy (cART) early, we prospectively studied 284 very-early-cART-treated children from KwaZulu-Natal, South Africa, after vertical HIV transmission to assess control of viremia. Eighty-four percent of the children achieved aviremia on cART, but aviremia persisting to 36 or more months was observed in only 32%. We observed that male infants have lower baseline plasma viral loads (P = 0.01). Unexpectedly, a subset (n = 5) of males maintained aviremia despite unscheduled complete discontinuation of cART lasting 3-10 months (n = 4) or intermittent cART adherence during 17-month loss to follow-up (n = 1). We further observed, in vertically transmitted viruses, a negative correlation between type I interferon (IFN-I) resistance and viral replication capacity (VRC) (P < 0.0001) that was markedly stronger for males than for females (r = -0.51 versus r = -0.07 for IFN-α). Although viruses transmitted to male fetuses were more IFN-I sensitive and of higher VRC than those transmitted to females in the full cohort (P < 0.0001 and P = 0.0003, respectively), the viruses transmitted to the five males maintaining cART-free aviremia had significantly lower replication capacity (P < 0.0001). These data suggest that viremic control can occur in some infants with in utero-acquired HIV infection after early cART initiation and may be associated with innate immune sex differences.

Author Correction: Sex-specific innate immune selection of HIV-1 in utero is associated with increased female susceptibility to infection.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Sex-specific innate immune selection of HIV-1 in utero is associated with increased female susceptibility to infection.

Female children and adults typically generate more efficacious immune responses to vaccines and infections than age-matched males, but also suffer greater immunopathology and autoimmune disease. We here describe, in a cohort of > 170 in utero HIV-infected infants from KwaZulu-Natal, South Africa, fetal immune sex differences resulting in a 1.5-2-fold increased female susceptibility to intrauterine HIV infection. Viruses transmitted to females have lower replicative capacity (p = 0.0005) and are more type I interferon-resistant (p = 0.007) than those transmitted to males. Cord blood cells from females of HIV-uninfected sex-discordant twins are more activated (p = 0.01) and more susceptible to HIV infection in vitro (p = 0.03). Sex differences in outcome include superior maintenance of aviraemia among males (p = 0.007) that is not explained by differential antiretroviral therapy adherence. These data demonstrate sex-specific innate immune selection of HIV associated with increased female susceptibility to in utero infection and enhanced functional cure potential among infected males.

Effectiveness of the South African expanded program of immunization against hepatitis B in children infected with human immunodeficiency virus-1 living in a resource-limited setting of Kwazulu-Natal.

Prevalence of Human-Immunodeficiency-Virus/Hepatitis-B-virus (HIV/HBV) coinfection and HBV vaccination response in children are unknown in Kwazulu-Natal. This study included 183 HIV-infected and 108 HIV-uninfected children aged between 5 and 15 years screened for HBV infection and vaccination. HBV infection occurred in 2.1% and 0% of HIV-infected and uninfected children respectively. Serological response to immunization was shown in 15.8% and 61.1% of HIV-infected and uninfected children, respectively (P < 0.001). Even if prevalence of HBV infection was low in these cohorts, HIV-infected children will stay at risk of infection if the vaccine schedule is not adapted. J. Med. Virol. 89:182-185, 2017. © 2016 Wiley Periodicals, Inc.

Role of ATM in bystander signaling between human monocytes and lung adenocarcinoma cells.

The response of a cell or tissue to ionizing radiation is mediated by direct damage to cellular components and indirect damage mediated by radiolysis of water. Radiation affects both irradiated cells and the surrounding cells and tissues. The radiation-induced bystander effect is defined by the presence of biological effects in cells that were not themselves in the field of irradiation. To establish the contribution of the bystander effect in the survival of the neighboring cells, lung carcinoma A549 cells were exposed to gamma-irradiation, 2Gy. The medium from the irradiated cells was transferred to non-irradiated A549 cells. Irradiated A549 cells as well as non-irradiated A549 cells cultured in the presence of medium from irradiated cells showed decrease in survival and increase in γ-H2AX and p-ATM foci, indicating a bystander effect. Bystander signaling was also observed between different cell types. Phorbol-12-myristate-13-acetate (PMA)-stimulated and gamma-irradiated U937 (human monocyte) cells induced a bystander response in non-irradiated A549 (lung carcinoma) cells as shown by decreased survival and increased γ-H2AX and p-ATM foci. Non-stimulated and/or irradiated U937 cells did not induce such effects in non-irradiated A549 cells. Since ATM protein was activated in irradiated cells as well as bystander cells, it was of interest to understand its role in bystander effect. Suppression of ATM with siRNA in A549 cells completely inhibited bystander effect in bystander A549 cells. On the other hand suppression of ATM with siRNA in PMA stimulated U937 cells caused only a partial inhibition of bystander effect in bystander A549 cells. These results indicate that apart from ATM, some additional factor may be involved in bystander effect between different cell types.

Differential response of three cell types to dual stress of nitric oxide and radiation.

The perception of toxicity to nitric oxide (NO) and irradiation (IR) by three different cell types has been studied. The three cell types are the macrophage like RAW264.7 cells, EL4 lymphoma cells, and splenocytes, which represent the different components of a tumor. These three cell types respond differently to NO donors (SNP and SNAP) and radiation treatment. The macrophages were found to be most radio-resistant and insensitive to NO donors. The innate resistance of the macrophages was not due to its antioxidant defense system since there was no significant activation of the enzymes (superoxide dismutases, catalase, and glutathione peroxidase) in RAW264.7 cells after NO donor and irradiation. But the cell cycle arrest of the three cell types was different from each other. The EL4 cells were found to arrest in the G2/M phase while the macrophages were found arrested in the G1 phase of the cell cycle. Such specific killing of the tumor cell in response to NO donor while sparing the macrophages can be of immense importance to radiotherapy.

Ionizing radiation induced signaling of DNA damage response molecules in RAW 264.7 and CD4⁺ T cells.

Ionizing radiation (IR) treatment results in activation of several DNA damage response molecules, such as ataxia telangiectasia, mutated (ATM), and DNA-dependent protein kinase (DNAPK) in mammals that are increasingly recognized for their potential roles in the sensing of DNA damage and initiating the subsequent protein kinase cascade. In vitro evidence indicates that both ATM and DNA-PK are responsible for efficient repair of DNA double strand breaks in response to IR exposure. To unravel the role of ATM and DNA-PK, we studied the mRNA and protein levels of ATM, DNA-PK and their downstream substrates in two different cell types after irradiation viz. macrophage like RAW264.7 cells and CD4(+) T cells isolated from mice spleen. Our results show that despite significant increase in phosphorylation of ATM, its mRNA levels continue to remain low after IR exposure in both the cell types. Conversely, the mRNA expression of DNAPK shows a considerable increase immediately after IR exposure. Moreover, no increase in ATM mRNA levels is seen in DNAPK deficit RAW264.7 cells treated with DNAPK siRNA, indicating that ATM does not undergo any change at its transcriptional levels in response to IR treatment. However, in a similar study in CD4(+) T cells, inhibition of DNAPK by siRNA, shows a considerable increase in ATM after IR exposure. Collectively, these results suggest a discrepancy in the role of the ATM and DNA-PK pathways in the cellular response to IR at the mRNA and protein levels in two different cell types.

Role of Rad52 in fractionated irradiation induced signaling in A549 lung adenocarcinoma cells.

The effect of fractionated doses of γ-irradiation (2Gy per fraction over 5 days), as delivered in cancer radiotherapy, was compared with acute doses of 10 and 2Gy, in A549 cells. A549 cells were found to be relatively more radioresistant if the 10Gy dose was delivered as a fractionated regimen. Microarray analysis showed upregulation of DNA repair and cell cycle arrest genes in the cells exposed to fractionated irradiation. There was intense activation of DNA repair pathway-associated genes (DNA-PK, ATM, Rad52, MLH1 and BRCA1), efficient DNA repair and phospho-p53 was found to be translocated to the nucleus of A549 cells exposed to fractionated irradiation. MCF-7 cells responded differently in fractionated regimen. Silencing of the Rad52 gene in fractionated group of A549 cells made the cells radiosensitive. The above result indicated increased radioresistance in A549 cells due to the activation of Rad52 gene.

DNA damage response signaling in lung adenocarcinoma A549 cells following gamma and carbon beam irradiation.

Carbon beams (5.16MeV/u, LET=290keV/µm) are high linear energy transfer (LET) radiation characterized by higher relative biological effectiveness than low LET radiation. The aim of the current study was to determine the signaling differences between γ-rays and carbon ion-irradiation. A549 cells were irradiated with 1Gy carbon or γ-rays. Carbon beam was found to be three times more cytotoxic than γ-rays despite the fact that the numbers of γ-H2AX foci were same. Percentage of cells showing ATM/ATR foci were more with γ-rays however number of foci per cell were more in case of carbon irradiation. Large BRCA1 foci were found in all carbon irradiated cells unlike γ-rays irradiated cells and prosurvival ERK pathway was activated after γ-rays irradiation but not carbon. The noteworthy finding of this study is the early phase apoptosis induction by carbon ions. In the present study in A549 lung adenocarcinoma, authors conclude that despite activation of same repair molecules such as ATM and BRCA1, differences in low and high LET damage responses might be due to their distinct macromolecular complexes rather than their individual activation and the activation of cytoplasmic pathways such as ERK, whether it applies to all the cell lines need to be further explored.

Activation of DNA damage response signaling in lung adenocarcinoma A549 cells following oxygen beam irradiation.

Oxygen beams are high linear energy transfer (LET) radiation characterized by higher relative biological effectiveness than low LET radiation. The aim of the current study was to determine the signaling differences between γ- and oxygen ion-irradiation. Activation of various signaling molecules was looked in A549 lung adenocarcinoma cells irradiated with 2Gy oxygen, 2Gy or 6Gy γ-radiation. Oxygen beam was found to be three times more cytotoxic than γ-radiation. By 4h there was efficient repair of DNA in A549 cells exposed to 2Gy or 6Gy gamma radiation but not in cells exposed to 2Gy oxygen beam as determined by γ-H2AX counting. Number of ATM foci was found to be significantly higher in cells exposed to 2Gy oxygen beam. Percentage of cells showing ATR foci were more with gamma however number of foci per cell were more in case of oxygen beam. Oxygen beam irradiated cells showed phosphorylation of Chk1, Chk2 and p53. Many apoptotic nuclei were seen by DAPI staining in cells exposed to oxygen beam. The noteworthy finding of this study is the activation of the sensor proteins, ATM and ATR by oxygen irradiation and the significant activation of Chk1, Chk2 and p53 only in the oxygen beam irradiated cells.

Low energy proton beam induces efficient cell killing in A549 lung adenocarcinoma cells.

The aim of the current study was to determine the signaling differences between gamma- and proton beam-irradiations. A549 lung adenocarcinoma cells were irradiated with 2 Gy proton beam or gamma-radiation. Proton beam was found to be more cytotoxic than gamma-radiation. Proton beam-irradiated cells showed phosphorylation of H2AX, ATM, Chk2, and p53. The mechanism of excessive cell killing in proton beam-irradiated cells was found to be upregulation of Bax and downregulation of Bcl-2. The noteworthy finding of this study is the biphasic activation of the sensor proteins, ATM, and DNA-PK and no activation of ATR by proton irradiation.

Curcumin mediates time and concentration dependent regulation of redox homeostasis leading to cytotoxicity in macrophage cells.

The present study was designed to test a hypothesis that curcumin may be modulating oxidative stress parameters including reactive oxygen species, non-protein thiols and expression of antioxidant genes in a concentration and time dependent manner in exhibiting cytotoxic effects in macrophage cell line RAW 264.7. The results have shown that curcumin elevated the reactive oxygen species levels accompanied by a decrease in levels of intracellular non-protein thiols at 2 h after its addition to cells. However, the levels of reactive oxygen species decreased and non-protein thiols content increased at 18 h after its addition. Whereas the expression of glutathione peroxidase (GPx), catalase, Cu,Zn-superoxide dismutase (Cu,Zn-SOD) and heme oxygenase-1 (HO-1) increased with curcumin concentration and also with increase in time of incubation, the expression of Mn- superoxide dismutase (Mn-SOD) showed concentration dependant repression upon treatment with curcumin. The cell viability was significantly reduced at high concentration (25 microM) of curcumin treatment but not at low concentration (5 microM). Curcumin at 5 microM scavenged gamma-radiation induced reactive oxygen species and inhibited cell death. On the contrary, at 25 microM, curcumin increased radiation induced reactive oxygen species production and augmented cell death. Interestingly pretreatment with reducing agents glutathione (GSH) or N-acetyl-cysteine (NAC), modified the curcumin mediated redox changes and cell death differentially, due to the inhibition of cellular uptake of curcumin by GSH but not by NAC. The important finding of the study is that the concentration and time dependent dual effect of curcumin may be attributed to changes in oxidative stress and antioxidant gene expression levels leading to inhibition or promotion of cell death.

Differential activation of mitogen-activated protein kinases following high and low LET radiation in murine macrophage cell line.

Mitogen-activated protein kinases have been shown to respond to various stimuli including cytokines, mitogens and gamma irradiation, leading to cell proliferation, differentiation, or death. The duration of their activation determines the specificity of response to each stimulus in various cells. In this study, the crucial intracellular kinases, ERK, JNK, and p38 kinase involved in cell survival, death, or damage and repair were examined for their activity in RAW 264.7 cells at various time points after irradiation with 2 Gy doses of proton ions or X-rays. This is the first report that shows that the MAPK signaling induced after heavy ion or X-ray exposure is not the same. Unlike gamma irradiation, there was prolonged but marginal activation of prosurvival ERK pathway and significant activation of proapoptotic p38 pathway in response to high LET radiation.

Role of iNOS in bystander signaling between macrophages and lymphoma cells.

PURPOSE: The present report describes the bystander effects of radiation between similar and dissimilar cells and the role of iNOS in such communication. MATERIALS AND METHODS: EL-4 and RAW 264.7 cells were exposed to 5 Gy gamma-irradiation. The medium from irradiated cells was transferred to unirradiated cells. RESULTS: Irradiated EL-4 cells as well as those cultured in the presence of medium from gamma-irradiated EL-4 cells showed an upregulation of NF-kappaB, iNOS, p53, and p21/waf1 genes. The directly irradiated and the bystander EL-4 cells showed an increase in DNA damage, apoptosis, and NO production. Bystander signaling was also found to exist between RAW 264.7 (macrophage) and EL-4 (lymphoma) cells. Unstimulated or irradiated RAW 264.7 cells did not induce bystander effect in unirradiated EL-4 cells, but LPS stimulated and irradiated RAW 264.7 cells induced an upregulation of NF-kappaB and iNOS genes and increased the DNA damage in bystander EL-4 cells. Treatment of EL-4 or RAW 264.7 cells with L-NAME significantly reduced the induction of gene expression and DNA damage in the bystander EL-4 cells, whereas treatment with cPTIO only partially reduced the induction of gene expression and DNA damage in the bystander EL-4 cells. CONCLUSIONS: It was concluded that active iNOS in the irradiated cells was essential for bystander response.

Effect of nitric oxide donor and gamma irradiation on MAPK signaling in murine peritoneal macrophages.

Irradiation (IR) of cells is known to activate enzymes of mitogen activated protein kinase (MAPK) family. These are known to be involved in cellular response to stress and are determinants of cell death or survival. When radiotherapy is delivered to malignant cells, macrophages, being radioresistant, survive, get activated, and produce large amounts of nitric oxide. As a result of activation they recognize and phagocytose tumor and normal cell apoptotic bodies leading to tumor regression. In this study, the MAPK signaling in peritoneal macrophages was investigated which plays an important role in its various functions, in an environment which is predominantly nitric oxide, as is after IR. The behavior of macrophages in such an environment was also looked at. The three MAPK (ERK1/2, p38, and JNK) respond differently to Sodium nitroprusside (SNP) alone or IR alone. All the three were activated following IR but only JNK was activated following SNP treatment. Surprisingly, when both the stresses were given simultaneously or one after the other, this differential response was lost and there was a complete inhibition of phosphorylation of all the three MAPKs, irrespective of the order of the two insults (IR and SNP). The noteworthy observation was that despite the complete inhibition of MAPK signaling there was no effect on either the viability or the phagocytic efficiency of peritoneal macrophages.

Fractionated and acute irradiation induced signaling in a murine tumor.

The effect of fractionated doses of Co(60) gamma-irradiation (2 Gy per fraction over 5 days), as is delivered in cancer radiotherapy, was compared with acute doses of 10 and 2 Gy, in a serially transplanted mouse fibrosarcoma grown in Swiss mice. The aspects that were studied included the three major mitogen-activated protein (MAP) kinases, namely p44 MAP kinase, p38 MAP kinase, and stress-activated protein (SAP) kinase, which are known to be involved in determining the cell fate following exposure to ionizing radiation. The response of dual specificity phosphatase PAC1 which is involved in the dephosphorylation of MAP kinases was also looked at. There were significant differences in the response to different dose regimens for all the factors studied. Fractionated irradiation elicited an adaptive response with a sustained activation over 7 days of prosurvival p44 MAP kinase which was balanced by the increased activation of proapoptotic p54 SAP kinase up to 1 day post-irradiation, whereas, phosphorylated p38 MAP kinase showed a decrease at most time points. PAC1 was induced following fractionated irradiation and may be acting as a feed back regulator of p44 MAP kinase. The activation of SAP kinase after fractionated irradiation may be a stress response, whereas, constitutively activated p44 MAP kinase may play an important role in the induction of radioresistance during fractionated radiotherapy of cancer and may serve as a promising target for specific inhibitors to enhance the efficacy of radiotherapy.

MAP kinases: differential activation following in vivo and ex vivo irradiation.

Mitogen activated protein kinases (MAPK) play a critical role in controlling cell survival and repopulation following exposure to ionising radiation. Most investigations on these pathways have been done using cultured cells or by ex vivo treatments. The present study was carried out to determine whether the response of MAPKs in mouse lymphocytes differs following in vivo and ex vivo irradiation with 60Co gamma-rays. We observed that ex vivo treatment resulted in a very significant decrease in the activated p44/42 and p38 MAPK as compared to in vivo. However, stress activated protein kinase (SAPK) response showed no significant difference between in vivo and ex vivo treatments. These observations point towards the differences in response elicited when the treatment is given in vivo as compared to in vitro. Therefore the findings reported from in vitro or ex vivo treatments should be treated with caution especially if it has to be clinically applied.

Radiation-induced bystander effect: activation of signaling molecules in K562 erythroleukemia cells.

Gap junction independent signaling mechanism was investigated using K562 human erythroleukemia cells. They were exposed to 2, 5, or 10 Gy of (60)Co gamma irradiation, the medium isolated 20 min post-irradiation and added to fresh cells. Evidence of radiation-induced bystander effect was observed wherein there was activation of p21, nuclear factor-kappaB (NF-kappaB), Bax, Bcl-2 and cleavage of poly(ADP-ribose) polymerase in bystander cells. The study implicates the involvement of signaling molecules released into the medium and factors like stable free radicals that are generated in the surrounding medium. The response elicited appears to be primarily via NF-kappaB and p21 activation.

Involvement of cytoplasmic membrane damage in the copper (II)-dependent cytotoxicity of a novel naturally occurring tripyrrole.

In the presence of a nonlethal concentration of Cu(II), washed Escherichia coli ATCC8739 cells were killed by a novel tripyrrole 1, isolated as a red pigment from the Serratia sp. Cell killing was accompanied by a depletion in the potassium pools of the cells due to the damage to the cytoplasmic membrane, without any detectable DNA damage as revealed by the transformed plasmid DNA and phage induction assay. This revealed that the bactericidal activity of compound 1 in the presence of Cu(II) results from membrane damage. Induction of endogenous catalase in the E. coli cells increased their resistance against the combination of compound 1 and Cu(II). Although compound 1 alone generated large amount of reactive oxygen species (ROS), it did not show any cell killing against E. coli in the absence of Cu(II). The Cu(II)-dependent bactericidal activity of compound 1 was suppressed by ethylenediaminetetraacetate, bathocuproine, catalase and superoxide disumutase (SOD), but not by dimethyl sulfoxide. These findings suggest that recycling redox reactions between Cu(II) and Cu(I), involving compound 1 and hydrogen peroxide on the cell surface, must be important in the mechanism of the killing. Compound 1 alone showed selective bactericidal activity against the gram positive bacterium, Bacillus cereus ATCC 6630, possibly due to its differential cellular transport.

Effect of nitric oxide donor and gamma irradiation on modifications of ERK and JNK in murine peritoneal macrophages.

Mitogen activated protein kinases (MAPKs) play an important role in activation, differentiation and proliferation of macrophages. Macrophages, upon activation, produce large amounts of nitric oxide that inhibit the growth of variety of microorganisms and tumor cells. This nitric oxide which is known to interfere with tyrosine phosphorylation may result in changes in the pattern of activation of MAPKs. In a previous study we have found that tyrosine phosphorylation of MAPKs was completely abolished in the presence of nitric oxide donor and radiation but this did not affect the function of macrophages. In this study the other post translational modifications namely nitration and ubiquitination of JNK and ERK have been looked at. Both ERK and JNK were found to be nitrated. However, there was no increase in ubiquitination of ERK and JNK, indicating that ubiquitination, in this case was not a natural consequence of nitration and may serve in signaling. Additionally, when the nitration was extensive, phosphorylation was also inhibited. The activation of substrates of ERK and JNK were looked at to determine the consequences of such modifications. Inhibition of phosphorylation and extensive nitration of JNK did not prevent activation of its substrate, c-jun. This study indicates that ERK and JNK may be under regulation by different type of modifications in macrophages.