A radio pulsar phase from SGR J1935+2154 provides clues to the magnetar FRB mechanism.

The megajansky radio burst, FRB 20200428, and other bright radio bursts detected from the Galactic source SGR J1935+2154 suggest that magnetars can make fast radio bursts (FRBs), but the emission site and mechanism of FRB-like bursts are still unidentified. Here, we report the emergence of a radio pulsar phase of the magnetar 5 months after FRB 20200428. Pulses were detected in 16.5 hours over 13 days using the Five-hundred-meter Aperture Spherical radio Telescope, with luminosities of about eight decades fainter than FRB 20200428. The pulses were emitted in a narrow phase window anti-aligned with the x-ray pulsation profile observed using the x-ray telescopes. The bursts, conversely, appear in random phases. This dichotomy suggests that radio pulses originate from a fixed region within the magnetosphere, but bursts occur in random locations and are possibly associated with explosive events in a dynamically evolving magnetosphere. This picture reconciles the lack of periodicity in cosmological repeating FRBs within the magnetar engine model.

The pharmacological mechanism of ß-elemene in the treatment of esophageal cancer revealed by network pharmacology and experimental verification.

The study aimed to investigate the mechanism of action of ß-elemene (ELE) in the treatment of esophageal cancer (EC). In this study, public databases were used to predict related targets in ELE and EC. The network analysis was performed to identify key targets of ELE in EC treatment. Further, bioinformatics and DAVID databases were used for GO and KEGG enrichment analysis, respectively. Ultimately, molecular docking and in vitro cell experiments were conducted to validate the results of network pharmacology enrichment. As a result, 34 candidate targets for ELE in the treatment of EC were obtained, and five key targets (STAT3, EGFR, CTNNB1, BCL2L1 and CASP9) were identified. GO functional annotation yielded 2200 GO entries (p < 0.05). KEGG signaling pathway enrichment analysis screened 100 pathways (p < 0.05). Molecular docking results showed that ELE had similar affinity with five key targets. In vitro experiments showed that the expressions of STAT3, EGFR and BCL2L1 were significantly decreased, and the expression of CASP9 in the ELE intervention group was significantly increased compared with that in the control group. All in all, ELE may play a key role in the treatment of EC by regulating the expression of STAT3, EGFR, BCL2L1 and CASP9.

A Prognostic Signature for Colon Adenocarcinoma Patients Based on m6A-Related lncRNAs.

N6-methyladenosine (m6A) modification is a common epigenetic modification. It is reported that lncRNA can be regulated by m6A modification. Previous studies have shown that lncRNAs associated with m6A regulation (m6A-lncRNAs) serve as ideal prognostic biomarkers. However, whether lncRNAs are involved in m6A modification in colon adenocarcinoma (COAD) needs further exploration. The objective of this study was to construct an m6A-lncRNAs-based signature for patients with COAD. We obtained the RNA sequencing data and clinical information from The Cancer Genome Atlas (TCGA). Pearson correlation analysis was employed to recognize lncRNAs associated with m6A regulation (m6A-lncRNAs). 24 prognostic m6A-lncRNAs was identified by univariate Cox regression analysis. Gene set enrichment analysis (GSAE) was used to investigate the potential cellular pathways and biological processes. We have also explored the relationship between immune infiltrate levels and m6A-lncRNAs. Then, a predictive signature based on the expression of 13 m6A-lncRNAs was constructed by the Lasso regression algorithm, including UBA6-AS1, AC139149.1, U91328.1, AC138207.5, AC025171.4, AC008760.1, ITGB1-DT, AP001619.1, AL391422.4, AC104532.2, ZEB1-AS1, AC156455.1, and AC104819.3. ROC curves and K M survival curves have shown that the risk score has a well-predictive ability. We also set up a quantitative nomogram on the basis of risk score and prognosis-related clinical characteristics. In summary, we have identified some m6A-lncRNAs that correlated with prognosis and tumor immune microenvironment in COAD. In addition, a potential alternative signature based on the expression of m6A-lncRNAs was provided for the management of COAD patients.

Frequency-dependent polarization of repeating fast radio bursts-implications for their origin.

The polarization of fast radio bursts (FRBs), which are bright astronomical transient phenomena, contains information about their environments. Using wide-band observations with two telescopes, we report polarization measurements of five repeating FRBs and find a trend of lower polarization at lower frequencies. This behavior is modeled as multipath scattering, characterized by a single parameter, σRM, the rotation measure (RM) scatter. Sources with higher σRM have higher RM magnitude and scattering time scales. The two sources with the highest σRM, FRB 20121102A and FRB 20190520B, are associated with compact persistent radio sources. These properties indicate a complex environment near the repeating FRBs, such as a supernova remnant or a pulsar wind nebula, consistent with their having arisen from young stellar populations.

Value of Liver Regeneration in Predicting Short-Term Prognosis for Patients with Hepatitis B-Related Acute-on-Chronic Liver Failure.

BACKGROUND AND AIMS: The value of hepatocyte regeneration in predicting the outcomes of hepatitis B-related acute-on-chronic liver failure (HBV-ACLF) is not fully assessed. The present study was aimed at establishing a novel scoring system to predict patients' outcomes within 3 months by applying serological indicators of hepatic regeneration and liver injury. METHODS: Patients with chronic hepatitis B who had a rapid deterioration were investigated. Patients were observed for 90 days, and the endpoint of follow-up was death or liver transplantation. Serum parameters were estimated on the diagnosis of acute-on-chronic liver failure (ACLF). Cox proportional hazard regression was used to identify independent prognostic factors and create a novel prognostic scoring system, and a receiver operating characteristic (ROC) curve was used to analyze the performance of the model. RESULTS: A total of 308 patients with HBV-ACLF were incorporated and divided into the training cohort (n = 206) and testing cohort (n = 102) randomly. Creatine (Cre), age, total bilirubin (TBil), alpha-fetoprotein (AFP), and international normalized ratio (INR) were found to be independent prognostic factors. According to the results of Cox regression analysis, a new prognostic model (we named it the TACIA score) was calculated. The areas under ROC (AUROC) for the new model were 0.861 and 0.763 in the training and testing cohorts, respectively, and patients with lower TACIA scores (<4.34) would survive longer (P < 0.001). CONCLUSIONS: A pertinent prognostic scoring system for patients with HBV-ACLF was established in our study, and the novel model could predict patients' short-term survival effectively.

Epigenetic knockdown of Notch1 inhibits hepatitis B virus X protein­induced hepatocarcinogenesis of L02/HBx cells.

The present study aimed to investigate the effects of Notch1 on the development of hepatitis B virus X protein (HBx)­induced hepatocarcinogenesis. The L02/HBx cells were transfected with a short hairpin RNA (shRNA) specially targeting Notch1 (Notch1­shRNA). The mRNA and protein expression levels of Notch1 signaling pathway­related molecules (Notch1, Hes1 and NICD) were detected after knockdown of Notch1. The effects of Notch1 knockdown on the proliferation was analyzed by Cell Counting Kit­8 assay, and cell cycle and apoptosis of L02/HBx cells in vitro were investigated by flow cytometry. The in vivo tumor xenograft model was established by subcutaneously injection of mice with Notch1­shRNA or sh­NC transfected cells. The effects of Notch1 knockdown on tumor progression in vivo were then explored by H&E staining and immunohistochemistry. The results showed that knockdown of Notch1 inhibited the activation of the Notch1 signaling pathway. In addition, decreased viability and colony formation ability of L02/HBx cells were detected along with downregulated protein expression levels of Ki­67 and PCNA (proliferating cell nuclear antigen). In addition, knockdown of Notch1 led to L02/HBx cell cycle arrest at G0/G1 phase by decreasing the expression of cyclin D1, CDK4, E2F1 and increasing the expression of p21 and retinoblastoma gene (Rb). Moreover, knockdown of Notch1 promoted the apoptosis of L02/HBx cells by activation of caspase­3 and caspase­9. In vivo experiments demonstrated that knockdown of Notch1 inhibited the tumorigenicity of L02/HBx cells. Our findings revealed that inhibition of the Notch1 signaling pathway may inhibit the development of HBx­induced hepatocellular carcinoma. Notch1 may serve as a promising therapeutic target for HCC.

Transplantation of human matrix metalloproteinase-1 gene-modified bone marrow-derived mesenchymal stem cell attenuates CCL4-induced liver fibrosis in rats.

It has been reported that bone marrow-derived mesenchymal stem cells (BMSCs) alleviated liver fibrosis. We investigated whether BMSCs transfected with human matrix metalloproteinase 1 (BMSCs/MMP1) would improve their therapeutic effect in liver fibrosis induced by carbon tetrachloride (CCl4) in rats. BMSCs were transfected with an adenovirus carrying enhanced green fluorescence protein (GFP) and human MMP1 gene. BMSCs or BMSCs/MMP1 were directly injected into fibrotic rats via the tail vein. GFP-labeled cells appeared in the fibrotic liver after BMSC transplantation. The expression of BMSCs/MMP1 elevated levels of MMP1 in vitro. Although BMSC administration reduced liver fibrosis, transplantation of BMSCs/MMP1 enhanced the reduction of liver fibrosis to a higher level. Treatment with BMSCs/MMP1 not only decreased collagen content but also suppressed activation of hepatic stellate cells (HSCs) in fibrotic liver, which led to subsequent improvement of both liver injury and fibrosis. Treatment with BMSCs/MMP1 resulted in an improved therapeutic effect compared with BMSCs alone, which is probably because of the sustainably expressed MMP1 level in the liver. BMSCs/MMP1 transplantation not only improved biochemical parameters but also attenuated progression of liver fibrosis, suggesting that BMSCs may be a potential cell source in preventing liver fibrosis and MMP1 gene may enhance the anti-fibrotic effect of BMSCs.

Pancreatic T/histiocyte-rich large B-cell lymphoma: A case report and review of literature.

Primary pancreatic lymphoma (PPL) is an extremely rare form of extranodal malignant lymphoma. The most common histological subtype of PPL is diffuse large B cell lymphoma (DLBCL). In rare cases, PPL can also present as follicular lymphoma, small lymphocytic lymphoma, and T cell lymphoma either of non-Hodgkin's lymphoma or of Hodgkin's lymphoma. T-cell/histiocyte-rich large B-cell lymphoma (T/HRBCL) is an uncommon morphologic variant of DLBCL with aggressive clinical course, it is predominantly a nodal disease, but extranodal sites such as bone marrow, liver, and spleen can be involved. Pancreatic involvement of T/HRBCL was not presented before. Herein, we report a 48-year-old male who was hospitalized with complaints of jaundice, dark brown urine, pale stools, and nausea. The radiological evaluation revealed a pancreatic head mass and, following operative biopsy, the tumor was diagnosed as T/HRBCL. The patient achieved remission after six cycles of CHOP chemotherapy. Therefore, T/HRBCL can be treated similarly to the stage-matched DLBCL and both of them get equivalent outcomes after chemotherapy.

Hepatoprotective effect of juglone on dimethylnitrosamine-induced liver fibrosis and its effect on hepatic antioxidant defence and the expression levels of α-SMA and collagen III.

The present study aimed to investigate the antifibrotic effects of juglone on dimethylnitrosamine (DMN)­induced fibrosis in rats. Juglone, which is a quinone, significantly decreased DMN­induced rat hepatic fibrosis, which was associated with increased superoxide dismutase (SOD) activity, decreased oxidative stress and reduced levels of α­smooth muscle actin (α­SMA) and collagen (Col) III in the liver. Serum levels of alanine aminotransferase, aspartate aminotransferase, hyaluronic acid, laminin, type III precollagen and type IV collagen were significantly reduced by treatment with juglone. Liver fibrosis was induced in male Sprague­Dawley rats by subcutaneous injections of DMN solution and hepatic fibrosis was assessed using Massons trichome staining. The expression levels of α­SMA and Col III were determined using immunohistochemical techniques. The activities of SOD and malondialdehyde in liver homogenates were also determined. The results suggested that juglone augmented the antioxidative capability of the liver, possibly by stimulating the activity of SOD, which promoted the inactivation of hepatic stellate cells (HSCs) and decreased the accumulation of extracellular matrix collagen in the liver, thereby alleviating hepatic fibrosis. Silymarin was used as a positive control for liver fibrosis protection. It was hypothesized that juglone alleviates or mitigates oxidative stress­mediated hepatic fibrosis by upregulating the expression of peroxisome proliferator­activated receptor γ and inhibiting the activation of HSC.

Quantification of serum hepatitis B surface antigen in predicting the response of pegylated interferon alfa-2a in HBeAg-positive chronic hepatitis B with prior lamivudine exposure.

AIMS: Majority of previous studies of pegylated interferon α-2a (PegIFNα-2a) forced on naïve chronic hepatitis B (CHB) patients, and the data of PegIFNα-2a in therapy of patients with prior exposure to nucleos(t)ide analogues is rare. This study aimed to investigate the predictive role of serum quantitative hepatitis B surface antigen (HBsAg) in predicting sustained response of PegIFNα-2a in HBeAg-positive CHB patients with prior lamivudine exposure. METHODS: Forty-six patients with prior lamivudine exposure received PegIFNα-2a for 12 months and followed-up for 6 months. The clinical features of responders and non-responders were compared, and the predictive role of quantitative HBsAg in predicting responders at the end of follow-up was evaluated. Responders were defined as an ALT normalization, HBeAg seroconversion and sustained virological response at the end of follow-up. RESULTS: In this cohort, only 26.1% (12/46) patients were responders. The baseline characteristics of the responders and non-responders were similar; however, the rates of ALT normalization, HBV DNA undetectability and HBeAg seroconversion were all significantly higher in responders than that in non-responders. During the treatment and follow-up, the HBsAg levels were all significantly lower in responders than that in non-responders. In predicting reponders, the serum HBsAg cutoff of 6000 IU/mL at months 6 had a positive predictive value of 73.3 and a negative predictive value of 96.8%, and with an area under the receiver operating characteristic curve of 0.869. CONCLUSION: The responders toward PegIFNα-2a in CHB patients with prior lamivudine exposure is not high, and serum HBsAg <6000 IU/Ml at months 6 of on-treatment had a high value to predict long-term outcomes of treatment.

Production of interferon α by human immunodeficiency virus type 1 in human plasmacytoid dendritic cells is dependent on induction of autophagy.

BACKGROUND: The mechanisms responsible for interferon α (IFN-α) production by plasmacytoid dendritic cells (pDCs) during human immunodeficiency virus type 1 (HIV-1) infection are unknown. This research examined the roles of Toll-like receptor 7 (TLR7) and autophagy in IFN-α production by pDCs during HIV-1 infection. METHODS: pDCs from human peripheral blood mononuclear cells were incubated with infectious or aldrithiol 2 (AT-2)-inactivated HIV-1 or with uridine-rich single-stranded RNA40 (ssRNA40) from the HIV-1 long terminal repeat. IFN-α was quantified by enzyme-linked immunosorbant assay. Autophagic proteins were detected by Western blot, and autophagosomes were identified using immunofluorescent and confocal microscopy. To inhibit autophagy, pDCs were treated with the phosphoinositide-3 kinase inhibitor 3-methyladenine (3-MA) or were transfected with autophagy-related protein 7 or TLR7 small interfering RNA (siRNA). RESULTS: Increased levels of IFN-α were present in culture supernatants following 16-hour incubation of pDCs with infectious or AT-2-inactivated HIV-1. Treatment of pDCs with ssRNA40 but not ssRNA41 resulted in high levels of IFN-α. pDCs exposed to HIV-1 gp120, rapamycin, or 3-MA alone failed to induce IFN-α. Pretreatment of pDCs with 3-MA significantly reduced the induction of IFN-α by ssRNA40. Similarly, knock down of autophagy-related protein 7 and TLR7 by use of siRNA significantly reduced the induction of IFN-α by ssRNA40 or HIV-1. CONCLUSIONS: These findings demonstrate that IFN-α production by pDCs exposed to infectious or noninfectious HIV-1 and ssRNA40 occurs through induction of autophagy following TLR7 signaling.

Autophagy is increased in postmortem brains of persons with HIV-1-associated encephalitis.

BACKGROUND: Autophagy is critical to maintaining cell homeostasis and is implicated in neurodegenerative diseases. This research examined the role of autophagy in human immunodeficiency virus type 1 (HIV-1)-associated encephalitis, the pathologic hallmark of neuroAIDS. METHODS: The frontal cortex from 32 HIV-infected persons (12 without evidence HIV-1 encephalitis or clinical signs of central nervous system impairment and 20 with histopathological findings of HIV-1 encephalitis) and 8 persons without HIV infection and any neuropathology were examined postmortem. Green fluorescent protein-labeled (GFP) light chain 3 (LC3)-expressing neuroblastoma SK-N-SH cells treated with gp120 from CXCR4 and CCR5 viruses were also examined. Autophagic markers were assessed by means of Western blot analysis, transmission electron microscopy (TEM), and confocal microscopy. RESULTS: Autophagic proteins Beclin 1, Autophagy-related gene (Atg)-5, Atg-7, and LC3-II were significantly increased in brains with HIV-1 encephalitis (P < .05). These findings were confirmed by TEM and immunostaining of brain tissue. Additionally, levels of autophagic proteins and autophagosomes were increased in neuronal cells treated with both CXCR4- or CCR5-tropic HIV-1 gp120. No increase in the level of autophagy was observed in the brains of HIV-infected persons without HIV-1 encephalitis compared with the level in brains of HIV-uninfected persons. CONCLUSIONS: Postmortem brains with HIV-1 encephalitis exhibit increased markers of autophagy compared with brains from HIV-infected persons without HIV-1 encephalitis or HIV-uninfected control brains, which suggests that dysregulation of autophagy may be important in the pathogenesis of neuroAIDS.

Autophagy: an overlooked mechanism of HIV-1 pathogenesis and neuroAIDS?

Human immunodeficiency virus type 1 (HIV-1) establishes a persistent infection characterized by progressive depletion of CD4(+) lymphocytes and immunosuppression. Although extensive research has examined the importance of apoptosis as a cause of cell death associated with HIV-1 infection, the role of autophagy has been largely ignored. Our laboratory has examined the autophagic process in HIV-1-infected cells. Following infection of human peripheral blood CD4(+) T-cells or U937 cells with HIV-1 for 48 hours, the autophagy proteins Beclin 1 and LC3-II were found to be markedly decreased. Beclin 1 mRNA expression and autophagosomes were also reduced in HIV-1 infected cells. Thus, our data indicate that HIV-1 infection inhibits autophagy in infected cells in contrast to the previously described induction of autophagy by gp120 in uninfected bystander cells. It is likely that HIV-1 has evolved this mechanism as part of an elaborate attempt to evade the immune system while promoting its own replication. We believe that autophagy is an overlooked mechanism in HIV-1 pathogenesis and plays a particularly important role in the early cognitive impairment and dementia often associated with advanced AIDS. A model is presented that describes the potential role of autophagy in NeuroAIDS.

Human immunodeficiency virus type-1 infection inhibits autophagy.

OBJECTIVES: Human immunodeficiency virus type-1 (HIV-1) induces a series of alterations in the host cell that modify the intracellular environment in favor of viral replication, survival and spread. This research examined the impact of HIV-1 infection on autophagy in HIV-1 infected cells. METHODS: Protein extracts of HIV-1 infected and control CD4+ T-lymphocytes and U937 cells were semi-quantified by western blot. The autophagy-related protein Beclin 1, a Bcl-2 associated protein, and the 16 kD microtubule-associated protein (MAP) light chain three (LC3) which is essential for autophagy were quantified and validated using the intracellular protein GAPDH as an internal standard. Beclin 1 mRNA was quantified by real-time reverse transcriptase-polymerase chain reaction. Autophagosomes were assessed by visualization under confocal microscopy following intracellular staining of the LC3 protein. RESULTS: Following infection of human peripheral blood CD4+ T-cells or U937 cells with HIV-1 for 48 h, the autophagy protein Beclin 1 and LC3 II, which is essential for autophagy, were found to be markedly decreased. Beclin 1 mRNA expression was also reduced. Autophagosomes were reduced in HIV-1-infected cells. The reduction of autophagic protein expression and autophagosomes in HIV-1-infected cells could be overcome by amino acid starvation or rapamycin. CONCLUSIONS: These data demonstrate that HIV-1 infection can down-regulate autophagy in infected cells during acute infection, and provide new insights into HIV-1-induced cell death and disease-related pathogenesis.

Gamma/Delta T-cell functional responses differ after pathogenic human immunodeficiency virus and nonpathogenic simian immunodeficiency virus infections.

The objective of this study was to functionally assess gamma/delta (gammadelta) T cells following pathogenic human immunodeficiency virus (HIV) infection of humans and nonpathogenic simian immunodeficiency virus (SIV) infection of sooty mangabeys. gammadelta T cells were obtained from peripheral blood samples from patients and sooty mangabeys that exhibited either a CD4-healthy (>200 CD4(+) T cells/mul blood) or CD4-low (<200 CD4 cells/mul blood) phenotype. Cytokine flow cytometry was utilized to assess production of Th1 cytokines tumor necrosis factor alpha and gamma interferon following ex vivo stimulation with either phorbol myristate acetate/ionomycin or the Vdelta2 gammadelta T-cell receptor agonist isopentenyl pyrophosphate. Sooty mangabeys were observed to have higher percentages of gammadelta T cells in their peripheral blood than humans did. Following stimulation, gammadelta T cells from SIV-positive (SIV(+)) mangabeys maintained or increased their ability to express the Th1 cytokines regardless of CD4(+) T-cell levels. In contrast, HIV-positive (HIV(+)) patients exhibited a decreased percentage of gammadelta T cells expressing Th1 cytokines following stimulation. This dysfunction is primarily within the Vdelta2(+) gammadelta T-cell subset which incurred both a decreased overall level in the blood and a reduced Th1 cytokine production. Patients treated with highly active antiretroviral therapy exhibited a partial restoration in their gammadelta T-cell Th1 cytokine response that was intermediate between the responses of the uninfected and HIV(+) patients. The SIV(+) sooty mangabey natural hosts, which do not proceed to clinical AIDS, provide evidence that gammadelta T-cell dysfunction occurs in HIV(+) patients and may contribute to HIV disease progression.

Virally induced CD4+ T cell depletion is not sufficient to induce AIDS in a natural host.

Peripheral blood CD4+ T cell counts are a key measure for assessing disease progression and need for antiretroviral therapy in HIV-infected patients. More recently, studies have demonstrated a dramatic depletion of mucosal CD4+ T cells during acute infection that is maintained during chronic pathogenic HIV as well as SIV infection. A different clinical disease course is observed during the infection of natural hosts of SIV infection, such as sooty mangabeys (Cercocebus atys), which typically do not progress to AIDS. Previous studies have determined that SIV+ mangabeys generally maintain healthy levels of CD4+ T cells despite having viral replication comparable to HIV-infected patients. In this study, we identify the emergence of a multitropic (R5/X4/R8-using) SIV infection after 43 or 71 wk postinfection in two mangabeys that is associated with an extreme, persistent (>5.5 years), and generalized loss of CD4+ T cells (5-80 cells/microl of blood) in the absence of clinical signs of AIDS. This study demonstrates that generalized CD4+ T cell depletion from the blood and mucosal tissues is not sufficient to induce AIDS in this natural host species. Rather, AIDS pathogenesis appears to be the cumulative result of multiple aberrant immunologic parameters that include CD4+ T cell depletion, generalized immune activation, and depletion/dysfunction of non-CD4+ T cells. Therefore, these data provide a rationale for investigating multifaceted therapeutic strategies to prevent progression to AIDS, even following dramatic CD4 depletion, such that HIV+ humans can survive normal life spans analogous to what occurs naturally in SIV+ mangabeys.

Timely triggering of homeostatic mechanisms involved in the regulation of T-cell levels in SIVsm-infected sooty mangabeys.

Sooty mangabeys, the natural host of simian immunodeficiency virus (SIVsm), generally avoid progressive depletion of CD4+ T cells and opportunistic infections associated with infection of humans (HIV) and macaques (SIVmac). The means by which the SIVsm-infected mangabeys maintain CD4+ T-cell levels despite high rates of viral replication is unknown. One cytokine that has a key role in the regulation of T-cell levels is interleukin-7 (IL-7). Here, the longitudinal assessment of 6 SIVsm-infected mangabeys identified an early increase in plasma IL-7 levels at weeks 1 to 5 after infection. This IL-7 increase correlated with an early decline in CD4+ T-cell levels (decline of 492-1171 cells/microL) accompanying acute viremia. Elevated IL-7 levels were followed by increased T-cell proliferation (Ki67) and maintenance of lower but stable (more than 500 cells/microL) CD4+ T-cell levels in each mangabey through 37 weeks of infection. These data contrast with our earlier studies in SIVmac-infected macaques, in which the IL-7 increase was delayed until 20 to 40 weeks after infection, just before the onset of simian AIDS. Taken together, these data suggest that timely triggering of IL-7 is important for stabilizing healthy T-cell levels in mangabeys and that timely administration of exogenous IL-7 may show benefit during pathogenic SIVmac and HIV infection.

Inhibition of adaptive Vgamma2Vdelta2+ T-cell responses during active mycobacterial coinfection of simian immunodeficiency virus SIVmac-infected monkeys.

Adaptive immune responses of gammadelta T cells during active mycobacterial coinfection of human immunodeficiency virus-infected humans have not been studied. Macaques infected with the simian immunodeficiency virus (SIV) SIVmac were employed to determine the extent to which a coincident AIDS virus infection might compromise immune responses of mycobacterium-specific Vgamma2Vdelta2(+) T cells during active mycobacterial infection. Control SIVmac-negative macaques developed primary and recall expansions of phosphoantigen-specific Vgamma2Vdelta2(+) T cells after Mycobacterium bovis BCG infection and BCG reinfection, respectively. In contrast, SIVmac-infected macaques did not exhibit sound primary and recall expansions of Vgamma2Vdelta2(+) T cells in the blood and pulmonary alveoli following BCG infection and reinfection. The absence of adaptive Vgamma2Vdelta2(+) T-cell responses was associated with profound CD4(+) T-cell deficiency and subsequent development of SIVmac-related tuberculosis-like disease in the coinfected monkeys. Consistently, Vgamma2Vdelta2(+) T cells from coinfected monkeys displayed a reduced capacity to expand in vitro following stimulation with phosphoantigen. The reduced ability of Vgamma2Vdelta2(+) peripheral blood lymphocytes (PBL) to expand could be restored to some extent by coculture of these cells with CD4(+) T cells purified from PBL of SIV-negative monkeys. Furthermore, naïve monkeys inoculated simultaneously with SIVmac and BCG were unable to sustain expansion of Vgamma2Vdelta2(+) T cells at the time that the coinfected monkeys developed lymphoid depletion and a fatal tuberculosis-like disease. Nevertheless, no deletion in Vdelta2 T-cell receptor repertoire was identified in SIVmac-BCG-coinfected macaques, implicating an SIVmac-induced down-regulation rather than a clonal exhaustion of these cells. Thus, an SIVmac-induced compromise of the adaptive Vgamma2Vdelta2(+) T-cell responses may contribute to the immunopathogenesis of the SIV-related tuberculosis-like disease in macaques.

Adaptive immune response of Vgamma2Vdelta2+ T cells during mycobacterial infections.

To examine the role of T cell receptor (TCR) in gammadelta T cells in adaptive immunity, a macaque model was used to follow Vgamma2Vdelta2+ T cell responses to mycobacterial infections. These phosphoantigen-specific gammadelta T cells displayed major expansion during Mycobacterium bovis Bacille Calmette-Guérin (BCG) infection and a clear memory-type response after BCG reinfection. Primary and recall expansions of Vgamma2Vdelta2+ T cells were also seen during Mycobacterium tuberculosis infection of naive and BCG-vaccinated macaques, respectively. This capacity to rapidly expand coincided with a clearance of BCG bacteremia and immunity to fatal tuberculosis in BCG-vaccinated macaques. Thus, Vgamma2Vdelta2+ T cells may contribute to adaptive immunity to mycobacterial infections.

Induction of an AIDS virus-related tuberculosis-like disease in macaques: a model of simian immunodeficiency virus- mycobacterium coinfection.

The mechanism by which human immunodeficiency virus (HIV)-Mycobacterium tuberculosis coinfection facilitates development of HIV-related tuberculosis is poorly characterized. Macaque models of simian immunodeficiency virus (SIV(mac))-Mycobacterium bovis BCG coinfection were employed to explore the pathogenesis of AIDS virus-related tuberculosis. Following BCG coinfection, SIV (SIV)-infected macaques with high viral loads developed an SIV-related tuberculosis-like disease. This disease was characterized clinically by a syndrome of diarrhea, anorexia, weight loss, and altered levels of consciousness and pathologically by the presence of disseminated granulomas. In contrast, SIV(mac)-infected macaques with low viral loads either showed no evidence of BCG-induced disease or developed focal granulomatous lesions. Pathogenic SIV-BCG interactions appeared to play a critical role in triggering the development of this SIV-related tuberculosis-like disease. BCG coinfection enhanced the destruction of CD4(+) T cells in SIV(mac)-infected macaques whose viral loads were high. Reciprocally, exacerbations of SIV disease led to marked suppression of BCG-specific T-cell responses, persistence of the BCG infection, and development of an SIV-related tuberculosis-like disease. Furthermore, development of this SIV-related tuberculosis-like disease was also seen in naïve macaques simultaneously inoculated with SIV(mac) and BCG. These results provide in vivo evidence that coinfection of AIDS virus-infected individuals with an avirulent mycobacterium can lead to development of a tuberculosis-like disease.