J Med Primatol doi:10.1111/j.1600-0684.2010.00429.x
ORIGINAL ARTICLE
Microbial translocation in simian immunodeficiency virus (SIV)-infected rhesus monkeys (Macaca mulatta) C. Leinert1, C. Stahl-Hennig4, A. Ecker1, T. Schneider2, D. Fuchs3, U. Sauermann4 & S. Sopper1,5 1 German Primate Center, Infection Biology Unit, Kellnerweg, Go¨ttingen, Germany 2 Department of Gastroenterology, Infectious Diseases and Rheumatology, Medical Clinic I, Campus Benjamin Franklin, Charite´-University Medicine Berlin, Hindenburgdamm, Berlin, Germany 3 Division of Biological Chemistry, Biocentre, Innsbruck Medical University, Innsbruck, Austria 4 German Primate Center, Infection Models Unit, Kellnerweg, Go¨ttingen, Germany 5 Hematology and Oncology, Innsbruck Medical University, Innsbruck, Austria
Keywords disease progression – HIV – immune activation – lipopolysaccharide Correspondence Sieghart Sopper, Innsbruck Medical University, Hematology and Oncology, Anichstr. 25, 6020 Innsbruck, Austria. Tel.: +43 512 504 26332; fax.: +43 512 504 25615; e-mail:
[email protected] Accepted May 19, 2010.
Abstract Background Chronic immune activation is a hallmark of HIV infection and has been postulated as major factor in the pathogenesis of AIDS. Recent evidence suggests that activation of immune cells is triggered by microbial translocation through the impaired gastrointestinal barrier. Methods To determine the association between microbial translocation and disease progression, we have retrospectively analyzed microbial products, viral load and markers of immune activation in a cohort of 37 simian immunodeficiency virus-infected rhesus monkeys, divided in two groups with distinct disease courses. Results As seen in HIV-infected patients, we found elevated levels of lipopolysaccharide (LPS) in infected animals. However, LPS levels or LPS control mechanisms like endotoxin core antibodies or LPS-binding protein did not differ between groups with different disease progression. In contrast, neopterin, a metabolic product of activated macrophages, was higher in fast progressors than in slow progressors. Conclusion Our data indicate that translocation of microbial products is not the major driving force of immune activation in HIV infection.
Introduction Pathogenesis of AIDS and the mechanisms leading to CD4 loss in HIV infection are not completely understood. Several lines of evidence point to chronic immune activation as the major driving force to HIV immunopathogenesis [1]. Immune activation is a common finding in HIV-infected patients and correlates well with disease progression, in some studies even better than viral load [2, 3]. Similarly, little evidence for immune activation has been found in apathogenic simian immunodeficiency virus (SIV)/monkey models despite comparable viral replication [4]. As immune activation is not necessarily correlated with viral replication, additional mechanisms have been postulated to explain the activated state of the immune system in J Med Primatol 39 (2010) 243–251 ª 2010 John Wiley & Sons A/S
HIV-infected patients. Under normal circumstances, immune activation occurs upon contact with pathogens or their metabolic products. The major site where the immune system is constantly confronted with foreign microorganisms is the gastrointestinal tract consequently harboring the majority of activated T cells. Because these activated CD4+ T cells are the optimal targets for HIV infection, this is also the place where the massive viral replication and a dramatic loss of T-helper cells take place during primary viremia [5]. With the resulting changes in the microenvironment, gut functions are compromised ultimately leading to the enteropathy commonly fond in HIV patients [6]. Increased permeability of the mucosal barrier is well documented in all stages of HIV infection [7, 8] and may facilitate translocation of microbes or microbial 243
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products into the circulation. This may then lead to chronic immune stimulation comparable to that seen in chronic inflammatory bowel diseases [9]. Initially developed more than a decade ago [10], this concept has recently gained more and more attention. Over the past years, several studies have demonstrated increased levels of the endotoxin lipopolysaccharide (LPS) in plasma in HIV-infected humans and SIV-infected macaques [11–15]. In addition, presence of microbes in the circulation has been demonstrated using quantitative PCR specific for bacterial DNA [11, 16]. Furthermore, butyrate, a metabolic products of bacteria, has been found at elevated concentrations in the urine of HIV patients [10]. As demonstrated by these different approaches, it is now clear that microbial translocation is a regular finding of HIV infection. Its association with immune activation and more important with disease progression, however, is less substantiated. The group of Brenchley [13, 16] has found a correlation between LPS levels and bacterial DNA with parameters of activation of both the innate and the adaptive immune response. This is corroborated by reports that show an association between LPS concentrations in plasma and markers of monocyte activation [12] or the proliferation rate of T cells [11]. In contrast, other studies failed to find a correlation between LPS levels and the expression of activation markers on NK cells [14] or T cells [15]. Similarly, conflicting results have been reported on the association between viral load and LPS levels [12, 15, 16]. Data regarding the impact of microbial translocation on disease progression are sparse. In the single longitudinal study, no differences in LPS levels were found between groups with different disease courses [17]. Therefore, we set out to investigate the relation between microbial translocation, immune activation and disease course SIV-infected macaques. In a retrospective cross-sectional study, we compared viral load, mucosal function, LPS levels and several immunologic parameters in two groups of monkeys stratified according to their survival times. Similar to previous reports, we found that three to four months after infection the ability of the mucosa to absorb ß-carotene was reduced in all animals and that translocation of microbial products, as evidenced by increased levels of LPS in plasma, had occurred. In parallel, LPS-binding protein (LBP) was increased compared to preinfection values. However, no difference in any of these parameters between fast and slow progressing animals was evident. In contrast, the two progression groups differed significantly in their viral load as well as in the various parameters of immune activation. These results indicate that microbial translocation 244
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albeit frequently found in pathogenic immunodeficiency virus infection does not contribute substantially to the chronic immune activation and the progression to AIDS. Methods Experimental animals, viruses and study design Juvenile rhesus monkeys (Macaca mulatta) of Indian origin were housed individually in indoor facilities on a 12:12 light:dark schedule at the German Primate Center (Go¨ttingen, Germany). Dry food supplemented with fresh fruits (bananas and apples) was provided twice a day, and water was available ad libidum. Prior to inoculation, animals were demonstrated to be seronegative for STLV-1, SRV-1 (type D retrovirus), herpes B virus and SIV. Nineteen monkeys were atraumatically infected under ketamine anesthesia (10 mg/kg) by touching the tonsils with a cotton-wool swab soaked with culture medium containing approximately 6000 median TCID50 of the cell-free viral clone SIVmac239 [18] propagated on monkey PBMC [19]. Eighteen animals were intravenously inoculated with 100 MID50 (50% monkey infective dose) of SIVmac251MPBMC [20]. Animals were monitored clinically, and physical examinations were performed at regular intervals under ketamine anesthesia from experienced veterinarians in the German primate Center Go¨ttingen. Blood was collected multiple times before and after infection by venipuncture. Samples were stored at )80C. Monkeys were euthanized when they presented with signs of AIDS between 14 and 155 wpi. In addition, some monkeys were killed in late chronic stage of infection at pre-determined time points without sign of simian AIDS. Animal experiments were approved by and performed according to the guidelines of the ethics committee for animal experimentation of the Bezirksregierung Braunschweig (604.42502/08-02.95) and the revised Directive 86/609/EEC ‘on the protection of animals used for experimental and other scientific purposes’. RNA extraction and Real-time PCR Viral RNA was isolated from frozen plasma samples following the MagAttract Virus Mini M48 protocol (Qiagen, Hilden, Germany). Purified SIV-RNA was quantified using TaqMan-based real-time PCR on an ABI-Prism 7500 sequence detection system (Applied Biosystems, Darmstadt, Germany) as described (s.u.). Primers and standards used for the PCR have been J Med Primatol 39 (2010) 243–251 ª 2010 John Wiley & Sons A/S
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described elsewhere [21]. Amplified viral RNA was expressed as SIV-RNA copies per ml plasma. Total serum carotene Total serum carotene concentrations were determined as described previously [22]. Briefly, serum was deproteinized by ethanol and extracted into petroleum ether. By photometrically measuring at 456-nm wavelength, mainly ß-carotene is determined. Concentrations were calculated in reference to a ß-carotene standard curve.
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matic flow cytometry as described previously [24]. Briefly, Ficoll density gradient–isolated PBMC were incubated for 30 min at 4C in the dark with a mixture of pre-titrated antibodies. Among others, antibodies against the following antigens were used: CD3 (SP342, Alexa700), CD4 (SK3, Alexa405), CD8 (RPA-T8, AmCyan) and HLA-DR (L243, APC-Cy7), all from Biosciences, Heidelberg, Germany. After washing and fixation with 3% formaldehyde, samples were measured on an LSRII flow cytometer (Biosciences, Heidelberg, Germany. Data were analyzed using FlowJo v8 software (Tree Star, Ashland, OR, USA).
Lipopolysaccharides (LPS) Lipopolysaccharides were determined in heat-inactivated plasma using a commercially available limulus amebocyte lysate (LAL) test (LONZA, Basel, Switzerland) according to the manufacturer’s instructions. Briefly, samples were diluted tenfold with endotoxinfree water and heated at 70C for 10 min to inactivate interfering plasma components. After incubation with the LAL reagent and the chromogen, samples were measured in duplicates at 405 nm in a photometric plate reader. LBP, EndoCAb and sCD14 Lipopolysaccharide-binding protein, endotoxin core antibodies (EndoCAb) and sCD14 were determined by ELISA. The LBP ELISA (Hbt, Uden, the Netherlands) had been developed for a wide variety of species including macaques. The other ELISAs were first tested for suitability to measure macaque antigens. Of the different ELISAs for the various EndoCAb classes (Hbt, Uden), only the one for IgM showed sufficient cross reactivity with monkey antibodies. sCD14 ELISA (R&D Systems, Minneapolis, MN, USA) showed comparable performance for both human and macaque samples. All kits were used according to the manufacturer’s instructions, and samples were measured in duplicate. Urinary neopterin Neopterin concentrations in urine were measured using HPLC as previously described [23]. Data are expressed in relation to the creatinine concentrations measured in parallel. Flow cytometry In a subset of 17 animals, expression of HLA-DR on T-cells subsets in blood was determined by polychroJ Med Primatol 39 (2010) 243–251 ª 2010 John Wiley & Sons A/S
Statistics All statistical analyses were performed using Prism 5.0 software (GraphPad, La Jolla, CA, USA). Infection-induced changes in the different parameters were compared with individual pre-infection values using Wilcoxon matched pairs test for non-Gaussian distributions. Mann–Whitney U-test was applied to compare data from the different progression groups. All tests were performed two-sided with a confidence interval of 95%. Values in the figures are depicted as medians with the interquartile and interdecile ranges. Numbers in the text show mean ± SE. Results For this retrospective study, a total of 37 rhesus monkeys were selected from eight different historical experiments. These animals had served as controls in vaccination experiments or had been used in pathogenesis studies and were thus neither immunized nor received any disease modulating treatment. Approximately half of the animals had been inoculated with the lymphotropic viral clone SIVmac239 (19 animals), the other half had been challenged with the pleiotropic swarm virus stock SIVmac251MPBMC. Thirty monkeys were observed until the development of AIDS-defining symptoms like Pneumocystic jirovecii pneumonia or untreatable diarrhea. As published previously [25], the disease course varied widely between animals. Time to sacrifice due to AIDS ranged from 14 to 155 wpi. The remaining seven animals had been killed in the late chronic phase, after more than 1 year after infection, according to the experimental schedule without any signs of AIDS. The respective Kaplan– Meyer curve is shown in Fig. 1A. The viral strain used for infection had no effect on the survival times. By about 40 wpi, roughly 50% of the animals had succumbed to the infection. Based on the survival times, the animals of this study were divided in two roughly 245
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Fig. 1 Disease progression and viral load in simian immunodeficiency virus (SIV)-infected macaques. Thirty-seven SIV-infected rhesus monkeys were observed for at least one year or until they developed signs of AIDS. In panel A, a Kaplan–Meyer curve for 19 animals infected with SIVmac239 (black line) and 18 monkeys inoculated with SIVmac251 (gray line) is shown. In panel B, set point plasma viral load (average of measurements between 12 and 16 wpi) is shown for 18 monkeys (FP), which developed signs of AIDS before 40 wpi, and 19 monkeys (SP), which survived beyond that time point. Data are shown as median with 25 and 75 percentiles (box) and 10 and 90 percentiles (whiskers).
equal groups. Group one, the so-called fast progressors (FP), comprised 18 monkeys had that had to be euthanized before 40 wpi because of severe AIDS-related symptoms. The remaining animals, surviving beyond 37 wpi, were summarized as slow progressors in a second group. Of these, twelve monkeys developed signs of AIDS and were necropsied between 44 and 155 wpi. Another seven monkeys remained free of AIDS symptoms for up to more than 3 years. Monkeys from all historical experiments were equally represented in both groups. We have then determined plasma viral RNA loads. To reflect set point viremia and to minimize the influence of day-to-day fluctuations, we have combined the data for 12 and 16 wpi. For the two animals, which were killed before 16 wpi, the values at necropsy (14, 15 wpi) were used as second time point. This procedure was applied to all the parameters investigated. As
expected from previous studies [25–27], the different disease progression is also reflected by differences in the viral load (Fig. 1B). Fast progressors had about 100 times higher RNA copy numbers in plasma than slow progressors. As parameter for mucosal functions [22], we have determined ß-carotene in plasma in a subgroup of eight animals. When compared to individual pre-infection levels, ß-carotene was decreased in seven out of the eight monkeys (Fig. 2A). This reduction was significant when taking all animals together (445 ± 89 lg/ ml vs. 283 ± 36 lg/ml; P < 0.05) but did not reach significance when the two progression groups were analyzed separately, because of the low number of animals. The extent of reduction in ß-carotene levels was similar for both groups, and the groups did differ in their plasma ß-carotene concentrations neither before nor after infection.
Fig. 2 Mucosal function and microbial translocation. Panel A shows plasma ß-carotene levels in macaques before and 12 weeks after infection. Panel B depicts lipopolysaccharide (LPS) levels in plasma of animals before and after infection (average of measurements between 12 and 16 wpi). Values of infected animals are differentiated in fast progressors (FP) and slow progressors (SP). Data are shown as median with 25 and 75 percentiles (box) and 10 and 90 percentiles (whiskers).
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Lipopolysaccharide is an integral part of gram-negative bacteria and has been used to determine endotoxemia in sepsis [28] and as marker for microbial translocation in several settings such as inflammatory bowel disease [9]. Recently, increased levels of LPS have been described in HIV-infected patients and SIVinfected rhesus monkeys [13]. For this study, we have used limulus assay to quantify LPS. Similar to the previous reports, we found significantly increased LPS concentrations in the chronic phase 12–16 weeks after SIV infection (115 ± 23 pg/ml) in comparison with the individual pre-infection values (54 ± 7 pg/ml). Although the increase seemed to be slightly more pronounced for the slow progressors, both groups did not differ in their plasma LPS concentrations (Fig. 2B). Presence of bacterial products in the body leads to activation of the innate immune system and the upregulation of counteractive scavenging mechanisms [29]. One of these is the LPS-binding protein (LBP) which is produced in the liver. Using a multispecies LBP ELISA, we found that LPB levels were strongly increased in infected animals (529 ± 74 ng/ml) compared to the values before infection (123 ± 28 ng/ml). This rise remained significant when analyzed for both groups separately (Fig. 3A). There was, however, no difference in the LBP titers between fast progressors and slow progressors. Another part of the specific defense mechanism against systemic LPS exposure is antibodies directed against the endotoxin core (EndoCAb) [30]. In contrast to LBP, EndoCAb titers were not altered 3– 4 months after infection with SIV (9.2 ± 1.2 MMU/
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ml) compared to pre-infection levels (8.7 ± 0.7 MMU/ ml). Also, there were no differences in plasma EndoCAb concentrations between the two progression groups (Fig. 2B). A similar picture was seen with sCD14 concentrations. sCD14 is shed from the surface of macrophages upon activation [31] and facilitates the interaction of LPS with LPS-sensing receptors on cells of the innate immune system [32]. SCD14 concentrations remained unchanged after SIV infection (7.1 ± 0.4 ng/ml) compared to baseline (6.3 ± 0.4 ng/ ml). Both progression groups showed comparable levels of sCD14. Immune activation is a common finding in immunodeficiency virus infections. Recently, it had been hypothesized that microbial products seeping through a compromised gut lining may be responsible for the chronic immune activation seen in HIV patients. Therefore, we have measured commonly used markers of activation of both the innate and the adaptive immune system. Neopterin is produced by activated myeloid cells and has been used as an unspecific but sensitive marker for viral infections [33]. In addition, several studies showed a good correlation between neopterin levels and disease progression in HIVinfected patients [34]. Neopterin rose almost fivefold from 94 ± 6 before infection to 441 ± 127 during set point viremia. Consistent with its prognostic value in HIV infection, neopterin levels were much higher in animals with fast disease progression than in those which survived longer (Fig. 4A). Regarding activation of the adaptive immunity, we determined the expression of MHC II on T cells in
Fig. 3 Endotoxin defense mechanisms. LBP levels (panel A), EndoCAb titers (panel B) and sCD14 concentrations in plasma of animals before and after infection (average of measurements between 12 and 16 wpi) are shown. Values of infected animals are differentiated in fast progressors (FP) and slow progressors (SP). Data are shown as median with 25 and 75 percentiles (box) and 10 and 90 percentiles (whiskers). J Med Primatol 39 (2010) 243–251 ª 2010 John Wiley & Sons A/S
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Fig. 4 Immune activation. Panel A displays urinary neopterin levels. Panel B and C depict the proportion of HLA-DR-positive cells among CD4+ (panel B) and CD8+ (panel C) T cells, respectively, before and after infection (average of measurements between 12 and 16 wpi). Values of infected animals are differentiated in fast progressors (FP) and slow progressors (SP). Data are shown as median with 25 and 75 percentiles (box) and 10 and 90 percentiles (whiskers).
blood by flow cytometry, HLA-DR expression on T cells [35]. In average, 3.7 ± 0.3% of CD4+ T cells and 9.7 ± 1% of CD8+ T cells in blood of uninfected macaques expressed HLA-DR. After infection, the proportion of cells positive for HLA-DR (3.5 ± 0.6%) among T-helper cells remained essentially unchanged when all animals were analyzed. However, a dichotomous picture with regard to the disease progression was seen (Fig. 4B). Whereas the proportion of activated, HLA-DR-expressing cells among CD4+ T cells decreased significantly in fast progressors, it was slightly albeit not significantly increased in slow progressors. As for CD8+ T cells, the proportion of cells staining positive for HLA-DR increased substantially to 15 ± 2% after infection. Again, slow progressors displayed a strong increase. In contrast, the proportion of activated CD8+ T cells was slightly reduced in fast progressors. In summary, whereas higher levels of neopterin, reflecting an activation of the innate immune response, were associated with poor prognosis and higher viral load, activation of the T-cell compartment, as measured by expression of HLA-DR, was related to prolonged survival and restricted viral replication. Discussion Human immunodeficiency virus infection is characterized by chronic immune activation. Initial massive viral replication and loss of CD4+ T cells in the gastrointestinal tract are followed by early changes in the local microenvironment leading to abnormal mucosal func248
tions and ultimately to enteropathy in many HIV patients and in the SIV/macaque model for AIDS [6, 22, 36, 37]. Based on recent findings of increased levels of microbial products in the circulation, it has been hypothesized that persistent microbial translocation across the mucosal barrier constantly stimulates the immune system and thus contributes to the pathogenesis of AIDS [10, 13]. However, studies aimed at determining the impact of microbial translocation on the disease course are rare. In a single longitudinal study, no correlation between microbial translocation and the progression rate to AIDS has been found [17]. In this report, we wanted to elucidate the role of microbial translocation for disease progression in the SIV/macaque model for AIDS. To this end, we have investigated a total of 37 SIV-infected monkeys with different disease course in a retrospective cross-sectional study. By stratifying the animals according to the time until development of AIDS, we were able to determine the relative influence of the different parameters for disease progression. As expected, plasma RNA copies differed between the two progression groups in the early chronic phase (12–16 wpi) by several decades, underlining the utility of viral load as marker for disease progression in both HIV-infected patients and SIV-infected macaques [26, 27]. Concurrently, we found increased levels of LPS in plasma 3–4 months after SIV inoculation. This corroborates a previous report using a limited number of SIV-infected macaques [13] and is in line with the findings in HIV-infected patients [11–15]. Together with reports using other methods to determine microbial J Med Primatol 39 (2010) 243–251 ª 2010 John Wiley & Sons A/S
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products in the circulation [10, 16], these results indicate that there is indeed microbial translocation across the gut barrier in the chronic phase of immunodeficiency virus infection. Using ß-carotene levels in serum as marker for absorptive capacity of the mucosa, we could show that mucosal functions are disturbed in the same time frame, which corroborates previous findings in both HIV-infected humans and SIV-infected macaques [7, 37]. There was, however, no difference in the extent of malabsorption between animals with different disease courses. Similarly, we could also not detect differences in the plasma LPS concentrations between fast and slow progressing animals. LPS is quickly removed from the circulation in healthy individuals by several scavenging mechanisms [29]. Of the three proteins with known LPS-binding capacities, which we investigated in this work, only LBP was altered in infected animals. Compared to the pre-infection levels, LBP concentrations in plasma were increased about fivefold. However, no difference between the two progression groups was evident. In line with our results, elevated levels of LBP in HIV-infected patients have been demonstrated by several groups [12, 13, 17]. Naturally occurring endotoxin antibodies (EndoCAb IgM) and sCD14 were not altered in our cohort of infected monkeys. Although similarly unchanged levels have been reported in a study on African HIV patients [17], these findings are in contrast to results from U.S. studies, which showed lower EndoCAb levels and increased sCD14 concentrations [12, 13]. In summary, with increased LPS and LBP levels, we have found evidence for microbial translocation in SIV-infected macaques. However, we were unable to detect differences in microbial translocation in animals with different progression rates. Similarly, previous studies have also not found an association of LPS levels with disease progression or viral load. Brenchley et al. [13] failed to detect significant differences when comparing controllers with undetectable viral load and progressors. In a longitudinal study involving three different progression groups, rapid progressors, standard progressors and long-term non-progressors (LTNP), indistinguishable LPS kinetics throughout the infection were documented [17]. LBP concentrations were reported to be increased solely in progressors but not in LTNP with low to undetectable viral load [13, 17, 38]. Such an association remained undetected in our study probably because we have not differentiated a group of LTNP in our cohort. Of the parameters investigated, only viral load and the level of immune activation differed between the progression groups. HLA-DR expression was higher on both CD4+ and CD8+ T cells of slow progresJ Med Primatol 39 (2010) 243–251 ª 2010 John Wiley & Sons A/S
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sors. High expression of other activation markers such as CD38 on T cells is usually a marker of poor prognosis in HIV infection [39]. However, in line with our observations, development of HLA-DR-positive cells during seroconversion was associated with a more favorable outcome [35]. On the other hand, neopterin, a marker for activation of myeloid cells, was significantly higher in fast progressors. As documented by numerous studies, neopterin has a good predictive value for disease progression in HIV-infected patients [34, 40]. We can now extend this observation to the SIV/macaque animal model. Taken together, whereas the parameters for microbial translocation measured in our study did not differentiate the two disease progression groups, the level of immune activation was clearly distinct between fast and slow progressors. These results indicate that microbial translocation does not contribute substantially to the chronic immune activation and the progression to AIDS. However, as the present cross-sectional study presents only a snapshot of the early chronic phase in the series of events leading to AIDS, future longitudinal studies concentrating on acute and post-acute infection will be needed to finally assess the role of microbial translocation in the pathogenesis of AIDS. Acknowledgment This work was funded in part by the Europrise network of excellence, EU grant LSHP-CT-2006-037611. References 1 Douek DC, Roederer M, Koup RA: Emerging concepts in the immunopathogenesis of AIDS. Annu Rev Med 2009; 60:471–84. 2 Fahey JL, Taylor JM, Manna B, Nishanian P, Aziz N, Giorgi JV, Detels R: Prognostic significance of plasma markers of immune activation, HIV viral load and CD4 T-cell measurements. AIDS 1998; 12:1581–90. 3 Giorgi JV, Hultin LE, McKeating JA, Johnson TD, Owens B, Jacobson LP, Shih R, Lewis J, Wiley DJ, Phair JP, Wolinsky SM, Detels R: Shorter survival in advanced human immunodeficiency virus type 1 infection is more closely associated with T lymphocyte activation than with plasma virus burden or virus chemokine coreceptor usage. J Infect Dis 1999; 179: 859–70. 4 Paiardini M, Pandrea I, Apetrei C, Silvestri G: Lessons learned from the natural hosts of HIV-related viruses. Annu Rev Med 2009; 60:485–95. 5 Mattapallil JJ, Douek DC, Hill B, Nishimura Y, Martin M, Roederer M: Massive infection and loss of memory
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6
7
8
9
10
11
12
13
14
15
16
CD4+ T cells in multiple tissues during acute SIV infection. Nature 2005; 434:1093–7. Kotler DP, Gaetz HP, Lange M, Klein EB, Holt PR: Enteropathy associated with the acquired immunodeficiency syndrome. Ann Intern Med 1984; 101:421–8. Keating J, Bjarnason I, Somasundaram S, Macpherson A, Francis N, Price AB, Sharpstone D, Smithson J, Menzies IS, Gazzard BG: Intestinal absorptive capacity, intestinal permeability and jejunal histology in HIV and their relation to diarrhoea. Gut 1995; 37:623–9. Epple HJ, Schneider T, Troeger H, Kunkel D, Allers K, Moos V, Amasheh M, Loddenkemper C, Fromm M, Zeitz M, Schulzke JD: Impairment of the intestinal barrier is evident in untreated but absent in suppressively treated HIV-infected patients. Gut 2009; 58:220–7. Gardiner KR, Halliday MI, Barclay GR, Milne L, Brown D, Stephens S, Maxwell RJ, Rowlands BJ: Significance of systemic endotoxaemia in inflammatory bowel disease. Gut 1995; 36:897–901. Stein TP, Koerner B, Schluter MD, Leskiw MJ, Gaprindachvilli T, Richards EW, Cope FO, Condolucci D: Weight loss, the gut and the inflammatory response in aids patients. Cytokine 1997; 9:143–7. Marchetti G, Bellistri GM, Borghi E, Tincati C, Ferramosca S, La Francesca M, Morace G, Gori A, Monforte AD: Microbial translocation is associated with sustained failure in CD4+ T-cell reconstitution in HIV-infected patients on long-term highly active antiretroviral therapy. AIDS 2008; 22:2035–8. Ancuta P, Kamat A, Kunstman KJ, Kim EY, Autissier P, Wurcel A, Zaman T, Stone D, Mefford M, Morgello S, Singer EJ, Wolinsky SM, Gabuzda D: Microbial translocation is associated with increased monocyte activation and dementia in AIDS patients. PLoS ONE 2008; 3:e2516. Brenchley JM, Price DA, Schacker TW, Asher TE, Silvestri G, Rao S, Kazzaz Z, Bornstein E, Lambotte O, Altmann D, Blazar BR, Rodriguez B, Teixeira-Johnson L, Landay A, Martin JH, Hecht FM, Picker LJ, Lederman MM, Deeks SG, Douek DC: Microbial translocation is a cause of systemic immune activation in chronic HIV infection. Nat Med 2006; 12:1365–71. Gregson JN, Steel A, Bower M, Gazzard BG, Gotch FM, Goodier MR: Elevated plasma lipopolysaccharide is not sufficient to drive natural killer cell activation in HIV-1-infected individuals. AIDS 2009; 23:29–34. Papasavvas E, Pistilli M, Reynolds G, Bucki R, Azzoni L, Chehimi J, Janmey PA, DiNubile MJ, Ondercin J, Kostman JR, Mounzer KC, Montaner LJ: Delayed loss of control of plasma lipopolysaccharide levels after therapy interruption in chronically HIV-1-infected patients. AIDS 2009; 23:369–75. Jiang W, Lederman MM, Hunt P, Sieg SF, Haley K, Rodriguez B, Landay A, Martin J, Sinclair E, Asher AI, Deeks SG, Douek DC, Brenchley JM: Plasma levels of
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17
18
19
20
21
22
23
24
bacterial DNA correlate with immune activation and the magnitude of immune restoration in persons with antiretroviral-treated HIV infection. J Infect Dis 2009; 199:1177–85. Redd AD, Dabitao D, Bream JH, Charvat B, Laeyendecker O, Kiwanuka N, Lutalo T, Kigozi G, Tobian AA, Gamiel J, Neal JD, Oliver AE, Margolick JB, Sewankambo N, Reynolds SJ, Wawer MJ, Serwadda D, Gray RH, Quinn TC: Microbial translocation, the innate cytokine response, and HIV-1 disease progression in Africa. Proc Natl Acad Sci USA 2009; 106:6718–23. Kestler H, Kodama T, Ringler D, Marthas M, Pedersen N, Lackner A, Regier D, Sehgal P, Daniel M, King N, Desrosiers R: Induction of AIDS in rhesus monkeys by molecularly cloned simian immunodeficiency virus. Science 1989; 248:1109–12. Kuate S, Stahl-Hennig C, Stoiber H, Nchinda G, Floto A, Franz M, Sauermann U, Bredl S, Deml L, Ignatius R, Norley S, Racz P, Tenner-Racz K, Steinman RM, Wagner R, Uberla K: Immunogenicity and efficacy of immunodeficiency virus-like particles pseudotyped with the G protein of vesicular stomatitis virus. Virology 2006; 351:133–44. Stahl-Hennig C, Voss G, Dittmer U, Coulibaly C, Petry H, Makoschey B, Cranage MP, Aubertin AM, Luke W, Hunsmann G: Protection of monkeys by a split vaccine against SIVmac depends upon biological properties of the challenge virus. AIDS 1993; 7:787–95. Negri DR, Baroncelli S, Catone S, Comini A, Michelini Z, Maggiorella MT, Sernicola L, Crostarosa F, Belli R, Mancini MG, Farcomeni S, Fagrouch Z, Ciccozzi M, Rovetto C, Liljestrom P, Norley S, Heeney J, Titti F: Protective efficacy of a multicomponent vector vaccine in cynomolgus monkeys after intrarectal simian immunodeficiency virus challenge. J Gen Virol 2004; 85:1191– 201. Kewenig S, Schneider T, Hohloch K, Lampe-Dreyer K, Ullrich R, Stolte N, Stahl-Hennig C, Kaup FJ, Stallmach A, Zeitz M: Rapid mucosal CD4(+) T-cell depletion and enteropathy in simian immunodeficiency virus-infected rhesus macaques. Gastroenterology 1999; 116:1115–23. Fendrich C, Luke W, Stahl-Hennig C, Herchenroder O, Fuchs D, Wachter H, Hunsmann G: Urinary neopterin concentrations in rhesus monkeys after infection with simian immunodeficiency virus (SIVmac 251). AIDS 1989; 3:305–7. Schulte R, Suh YS, Sauermann U, Ochieng W, Sopper S, Kim KS, Ahn SS, Park KS, Stolte-Leeb N, Hunsmann G, Sung YC, Stahl-Hennig C: Mucosal prior to systemic application of recombinant adenovirus boosting is more immunogenic than systemic application twice but confers similar protection against SIV-challenge in DNA vaccine-primed macaques. Virology 2009; 383:300–9. J Med Primatol 39 (2010) 243–251 ª 2010 John Wiley & Sons A/S
Leinert et al.
25 Sauermann U, Stahl-Hennig C, Stolte N, Muhl T, Krawczak M, Spring M, Fuchs D, Kaup FJ, Hunsmann G, Sopper S: Homozygosity for a conserved Mhc class II DQ-DRB haplotype is associated with rapid disease progression in simian immunodeficiency virus-infected macaques: results from a prospective study. J Infect Dis 2000; 182:716–24. 26 Mellors J, Rinaldo C, Gupta P, White R, Todd J, Kingsley L: Prognosis in HIV-1 infection predicted by the quantity of virus in plasma. Science 1996; 272:1167– 70. 27 Ten Haaft P, Verstrepen B, Uberla K, Rosenwirth B, Heeney J: A pathogenic threshold of virus load defined in simian immunodeficiency virus- or simian-human immunodeficiency virus-infected macaques. J Virol 1998; 72:10281–5. 28 Hurley JC: Endotoxemia: methods of detection and clinical correlates. Clin Microbiol Rev 1995; 8: 268–92. 29 Bosshart H, Heinzelmann M: Targeting bacterial endotoxin: two sides of a coin. Ann NY Acad Sci 2007; 1096:1–17. 30 Barclay GR: Endogenous endotoxin-core antibody (EndoCAb) as a marker of endotoxin exposure and a prognostic indicator: a review. Prog Clin Biol Res 1995; 392:263–72. 31 Bazil V, Strominger JL: Shedding as a mechanism of down-modulation of CD14 on stimulated human monocytes. J Immunol 1991; 147:1567–74. 32 Frey EA, Miller DS, Jahr TG, Sundan A, Bazil V, Espevik T, Finlay BB, Wright SD: Soluble CD14 participates in the response of cells to lipopolysaccharide. J Exp Med 1992; 176:1665–71. 33 Fuchs D, Hausen A, Reibnegger G, Werner ER, Dierich MP, Wachter H: Neopterin as a marker for activated
J Med Primatol 39 (2010) 243–251 ª 2010 John Wiley & Sons A/S
Microbial translocation in SIV-infected macaques
34
35
36
37
38
39
40
cell-mediated immunity: application in HIV infection. Immunol Today 1988; 9:150–5. Fuchs D, Spira TJ, Hausen A, Reibnegger G, Werner ER, Felmayer GW, Wachter H: Neopterin as a predictive marker for disease progression in human immunodeficiency virus type 1 infection. Clin Chem 1989; 35:1746–9. Giorgi JV, Ho HN, Hirji K, Chou CC, Hultin LE, O’Rourke S, Park L, Margolick JB, Ferbas J, Phair JP: CD8+ lymphocyte activation at human immunodeficiency virus type 1 seroconversion: development of HLA-DR+ CD38- CD8+ cells is associated with subsequent stable CD4+ cell levels. The Multicenter AIDS Cohort Study Group. J Infect Dis 1994; 170:775–81. Kotler DP, Reka S, Clayton F: Intestinal mucosal inflammation associated with human immunodeficiency virus infection. Dig Dis Sci 1993; 38:1119–27. Heise C, Miller CJ, Lackner A, Dandekar S: Primary acute simian immunodeficiency virus infection of intestinal lymphoid tissue is associated with gastrointestinal dysfunction. J Infect Dis 1994; 169:1116–20. Brack-Werner R: Astrocytes: HIV cellular reservoirs and important participants in neuropathogenesis. AIDS 1999; 13:1–22. Giorgi J, Liu Z, Hultin L, Cumberland W, Hennessey K, Detels R: Elevated levels of CD38+CD8+ T cells in HIV infection add to the prognostic value of low CD4+,T cell levels: result of 6 years of follow-up. JAIDS 1993; 6:904–12. Mildvan D, Spritzler J, Grossberg SE, Fahey JL, Johnston DM, Schock BR, Kagan J: Serum neopterin, an immune activation marker, independently predicts disease progression in advanced HIV-1 infection. Clin Infect Dis 2005; 40:853–8.
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