Cannabis Use and Biomarkers of Inflammation, Immune Activation, and Microbial Translocation in Persons with HIV

Background: The relationship between cannabis and inflammation among persons with HIV (PWH) remains unclear. We examined whether the cannabis metabolite 11-nor-9-carboxy THC (THC-COOH) is associated with lower levels of plasma biomarkers of inflammation, immune activation, and microbial translocation in PWH. We hypothesized that cannabis use would be associated with lower levels of plasma inflammatory biomarkers than noncannabis use. Methods: We quantified THC-COOH in plasma, with THC-COOH levels between 5.1-69.9 μg/L and ≥70 μg/L being classified as moderate and heavy cannabis use, respectively, with noncannabis use defined as undetected THC-COOH. We measured a panel of plasma biomarkers of inflammation (interleukin [IL]-1-β, tumor necrosis factor-alpha, IL-18, IL-6, and C-reactive protein), immune activation (CD14 and CD163), and microbial translocation (iFABP2 and lipopolysaccharide binding protein [LBP]), with all biomarkers collected on the same day. We used a cross-sectional design and linear regression models to test whether cannabis use is associated with lower biomarker levels. Results: Participants were (N=107) sexual minority men with HIV (median age=32 years, IQR=28, 38), of whom 65% were virally suppressed; 36%, 44%, and 20% were classified as nonuse, moderate, and heavy cannabis, respectively. In linear regression models adjusted for viral suppression, stimulant use, and CD4 counts, heavy cannabis use was significantly associated with lower levels of log10 LBP (β=-0.14, 95% confidence interval: -0.24 to -0.04; false discovery rate=0.0029; partial eta squared=0.07) than noncannabis users. No precise associations were observed for other biomarkers (all p>0.05). Conclusions: Our findings suggest that cannabis use may be associated with lower plasma LBP. Further work is needed to clarify the relationship between cannabis use and biomarkers of microbial translocation in PWH.

1931. Antibodies to SARS-CoV-2 in a Medical School Department of Pediatrics

Background

Healthcare workers are at high risk of Covid-19 (C19) infection and received priority for C19 vaccinations. Therefore, we conducted a serosurvey to determine anti-C19 antibodies and evidence of C19 infection in health care employees who did or did not have direct contact with patients.

Methods

49 participants provided finger stick blood samples collected onto filter papers and tested for antibodies to C19 using Bio-Plex Pro Human SARS-CoV-2 IgG reagents. Antibodies to C19 nucleocapsid (N), receptor-binding domain (RBD), spike 1 (S1), and spike 2 (S2) were measured. Samples were collected 8 to 11 months after C19 vaccines were made available.

Results

All participants received two doses of Pfizer BioNTech or Moderna RNA-based C19 vaccines, and all showed serological evidence of antibodies to C19 RBD, S1, and S2. Antibodies to N, considered a marker of C19 infection, were detected in 16 individuals, of whom 10 reported having a PCR documented C19 infections. 6 individuals had evidence of C19 infection of which they were not aware. Antibody levels were notably higher following infection and for not infected participants following Pfizer-BioNTech vaccination. There was a 20% higher infection rate in participants with direct patient contact.

Conclusion

This vaccinated population had significant rates of strong antibody responses to C19 infection and a notable rate of C19 infections, most notable in those providing direct patient care.

Disclosures

All Authors: No reported disclosures.

Evaluation of Six Weekly Oral Fecal Microbiota Transplants in People with HIV

Background

Reduced microbiota diversity (dysbiosis) in people with HIV (PWH) likely contributes to inflammation, a driver of morbidity and mortality. We aimed to evaluate the safety and tolerability of 6 weekly oral fecal microbiota transplants (FMT) administered to reverse this dysbiosis.

Methods

Six PWH on suppressive antiretroviral therapy (ART) received 6 weekly doses of lyophilized fecal microbiota product from healthy donors. Shotgun sequencing on stool before, after last FMT, and 20 weeks thereafter was performed. Inflammation and gut permeability biomarkers were measured.

Results

Median age at week 0 was 39 years, CD4⁺ T cell count 496 cells/mm³, HIV RNA levels <20 copies/mL. FMT was safe and well-tolerated. α diversity increased in 4 participants from weeks 0 to 6, including the 3 with the lowest α diversity at week 0. At week 26, α diversity more closely resembled week 0 than week 6 in these 4 participants. Metagenomic analysis showed no consistent changes across all participants. One participant had high gut permeability and inflammation biomarker levels and low α diversity that improved between weeks 0 and 6 with a shift in distribution.

Conclusions

Weekly FMT was safe and well-tolerated. α diversity increased in participants with the lowest baseline α diversity during the treatment period. Future randomized, controlled trials of FMT should consider evaluating PWH with greater inflammation, gut damage, or dysbiosis as this population may be most likely to show a significant response.ClinicalTrials.gov Identifier: NCT03329560.

Timing of Antiretroviral Therapy Initiation Determines Rectal Natural Killer Cell Populations

Despite antiretroviral therapy (ART), innate and adaptive immunologic damage persists in the periphery and gut. T memory stem cells (Tscm) and natural killer (NK) cells are pivotal for host defense. Tscm are memory cells capable of antigen response and self-renewal, and circulating and gut NK cell populations may facilitate HIV control. The impact of early ART on circulating and gut Tscm and NK cells is unknown. We enrolled participants who initiated ART during acute versus chronic HIV-1 infection versus no ART in chronic infection. We performed flow cytometry to identify NK and Tscm cells in the blood and rectum and polymerase chain reaction to quantify the HIV-1 reservoir in both sites. We used the Mann-Whitney U-test and Spearman correlation coefficients for analysis. Participants who started ART in acute infection had lower rectal CD56^brightCD16^dim cell frequencies than participants who started ART in chronic HIV-1 infection and lower CD56^bright and CD56^brightCD16^- cell frequencies than participants with chronic infection without ART. Higher circulating NK cell, CD56^-CD16^bright, CD56^dim, and CD56^dimCD16^bright frequencies correlated with higher HIV-1 DNA levels in rectal CD4⁺ T cells, whereas higher circulating CD4⁺ T cell counts correlated with higher rectal NK, CD56^brightCD16^dim, and CD56^dimCD16^bright frequencies. Peripheral CD56^brightCD16^- cells were inversely associated with rectal CD56^-CD16^bright cells. Rectal CD8⁺ Tscm frequencies were higher in participants without ART than participants with chronic infection on ART. Timing of ART initiation determines rectal NK cell populations, and ART may influence rectal Tscm populations. Whether the gut reservoir contributes to NK cell activation requires further study.

Stunting Is Preceded by Intestinal Mucosal Damage and Microbiome Changes and Is Associated with Systemic Inflammation in a Cohort of Peruvian Infants

Stunting, defined as height-for-age Z score equal to or lower than -2, is associated with increased childhood mortality, cognitive impairment, and chronic diseases. The aim of the study was to investigate the relationship between linear growth, intestinal damage, and systemic inflammation in infants at risk of stunting. We followed up 78 infants aged 5-12 months living in rural areas of Peru for 6 months. Blood samples for biomarkers of intestinal damage (intestinal fatty-acid-binding protein [I-FABP] and zonulin) and systemic inflammation (interleukin-1β, interleukin-6, tumor necrosis factor α [TNF-α], soluble CD14, and lipopolysaccharide-binding protein [LBP]) and fecal samples for microbiome analysis were collected at baseline and closure of the study. The children's growth and health status were monitored through biweekly home visits by trained staff. Twenty-one percent of the children became stunted: compared with non-stunted children, they had worse nutritional parameters and higher levels of serum I-FABP at baseline. The likelihood of becoming stunted was strongly associated with an increase in sCD14 over time; LBP and TNF-α showed a trend toward increase in stunted children but not in controls. The fecal microbiota composition of stunted children had an increased beta diversity compared with that of healthy controls throughout the study. The relative abundance of Ruminococcus 1 and 2, Clostridium sensu stricto, and Collinsella increased in children becoming stunted but not in controls, whereas Providencia abundance decreased. In conclusion, stunting in our population was preceded by an increase in markers of enterocyte turnover and differences in the fecal microbiota and was associated with increasing levels of systemic inflammation markers.

376. Effect of Parasitic Infections on Gut Epithelial Barrier and Immune Activation among Foreign-Born HIV-infected Patients

Background

Strongyloides stercoralis often causes an asymptomatic infection despite continuous autoinfection for the lifetime of the host. Both HIV and recurrent enteric parasitic infections cause gut damage and increased microbial translocation, but little is known about the effects of co-infection. We aimed to evaluate changes in immune activation, mucosal damage, and microbial translocation in people with HIV-1 (PWH) and parasite co-infection.

Methods

In this pilot prospective cohort study, we enrolled foreign-born PWH on suppressive antiretroviral therapy (ART) in an ambulatory clinic in Houston, Texas. We evaluated serum Strongyloides IgG using ELISA with an S. stercoralis-specific recombinant protein. Intestinal fatty acid-binding protein (I-FABP), soluble CD14 (sCD14), sCD163, IL-6, and sTNFRII were analyzed as markers of enterocyte turnover, inflammation, and immune activation. Non-parametric tests were used for analysis.

Results

52 participants born in 14 countries were enrolled February–March 2019. Median CD4 count was 464/uL [95% CI 315–598]. Fourteen (27%) were positive for Strongyloides IgG. Strongyloides IgG levels correlated positively with sCD14 levels [r=0.36; P = 0.008]. Strongyloides+ participants had significantly higher sCD14 levels compared with Strongyloides− participants [1.67 vs. 1.48 μg/mL, P = 0.031]. Among the Strongyloides+ participants, Strongyloides IgG levels correlated with sCD163 levels [r=0.65, P = 0.026]. There were no difference in the other biomarkers. Logistical regression analysis showed that predictors of Strongyloides+ include absolute eosinophil count (AEC) (OR 1.45 for every 100 increase of AEC [95% CI: 1.02, 2.15; P = 0.047]). CD4 count, number of years living in the United States, country of origin, and years from HIV diagnosis were not associated with test positivity.

Conclusion

Strongyloides co-infection is common among foreign-born PWH and may contribute to chronic monocyte/macrophage activation, a predictor of morbidity and mortality in PWH. Future directions include stool PCR confirmation of these infections, continued enrollment, and follow-up assays 6 months after treatment of Strongyloides to determine the impact on inflammation and risk of co-morbidities.

Disclosures

All authors: No reported disclosures.

2517. Oral Fecal Microbiota Transplantation Increases Gut Microbiome Diversity and Alters the Microbiome Distribution in People with HIV

Background

Reduced microbiota diversity (dysbiosis) in people with HIV (PWH) can damage the intestinal barrier and increase microbial translocation, resulting in inflammation, a driver of morbidity and mortality. We hypothesized that fecal microbiota transplants (FMT) would reverse dysbiosis in PWH.

Methods

We administered 6 weekly oral doses of a novel lyophilized fecal microbiota product from 2 healthy donors to 6 men who have sex with men with HIV on suppressive ART. Shotgun sequencing on stool before, after 6 weekly FMT, and 20 weeks after the last FMT (Weeks 0, 6 and 26), and from donors, was performed to determine bacterial community profiles. Biomarkers were measured by Luminex assays and ELISAs. All comparisons used Wilcoxon matched-pairs signed rank test.

Results

Median age at Week 0 was 41 years, CD4+ T-cell count 504 cells/mm³, VL < 20 copies/mL. Mean α diversity by observed species index increased from Week 0 to 6 (61.2 to 70.2, P = 0.29; Figure 1) and decreased by Week 26 (70.2 to 52.2, P = 0.33) to be similar to the donors’ (63.5, P = 0.86). Microbiome distribution by principal component analysis shifted toward the donors’ distribution in most participants at Week 6 but shifted away by Week 26 (Figure 2). Biomarkers did not change significantly during the study. PID3, with HIV > 35 years, had chronic constipation that resolved with FMT with a large shift in distribution but recurred at Week 26. Fusobacterium gonidiaformans, Porphyromonas somerae, and Haemophilus parainfluenzae comprised 27% of his microbiome at Week 0 but 0.73% at Week 6; untyped Bacteroides comprised 35% at Week 6. I-FABP (6,899 to 2,736 pg/mL), sCD14 (1.67 to 1.31 μg/mL), IL-6 (1.51 to 1.13 pg/mL) and sTNFRII (11,659 to 8,300 pg/mL) levels decreased in PID3; Week 0 levels in PID3 were higher than in other recipients. No related serious adverse events occurred.

Conclusion

Weekly FMT resulted in increased intestinal microbiome α diversity and a shift in microbiome distribution in most participants. These changes did not persist after stopping FMT. PWH with long-term HIV and/or greater inflammation or gut damage may be most likely to benefit from FMT. The effects of recurrent FMT were transient, suggesting longer duration of treatment or intermittent FMT boosting may be required to maintain its benefits.

Disclosures

All authors: No reported disclosures.

Serum Bovine Immunoglobulins Improve Inflammation and Gut Barrier Function in Persons with HIV and Enteropathy on Suppressive ART

Background

Systemic inflammation persists in chronic HIV infection and is associated with increased rates of non-AIDS events such as cardiovascular and liver disease. Increased gut permeability and systemic exposure to microbial products are key drivers of this inflammation. Serum-derived bovine immunoglobulin/protein isolate (SBI) supports gut healing in other conditions such as inflammatory bowel disease.

Methods

In this randomized, double-blind study, participants receiving suppressive antiretroviral therapy (ART) with chronic diarrhea received placebo or SBI at 2.5 g BID or 5 g BID for 4 weeks, followed by a 20-week placebo-free extension phase with SBI at either 2.5 or 5 g BID. Intestinal fatty acid binding protein (I-FABP), zonulin, flagellin, lipopolysaccharide (LPS) and LPS-binding protein, and inflammatory markers were measured by ELISA or multiplex assays. Non-parametric tests were used for analysis.

Results

One hundred three participants completed the study. By week 24 SBI significantly decreased circulating levels of I-FABP (-0.35 ng/μL, P=0.002) and zonulin (-4.90 ng/μL, P=0.003), suggesting improvement in gut damage, and interleukin-6 (IL-6) (-0.40 pg/μL, P=0.002), reflecting improvement in systemic inflammation. In participants with the lowest quartile of CD4+ T-cell counts at baseline (189-418 cells/μL), CD4+ T-cell counts increased significantly (26 cells/μL; P=0.002).

Conclusions

Oral SBI may decrease inflammation and warrants further exploration as a potential strategy to improve gut integrity and decrease systemic inflammation among persons receiving prolonged suppressive ART.

Adiponectin and the steatosis marker Chi3L1 decrease following switch to raltegravir compared to continued PI/NNRTI-based antiretroviral therapy

BACKGROUND

People with HIV are at for metabolic syndrome (MetS) and fatty liver disease, but the role of Antiretroviral therapy (ART) is poorly understood. MetS and fatty liver disease been associated with changes in adiponectin, soluble ST2 (sST2), chitinase 3-like 1 (Chi3L1), hyaluronic acid (HA), tissue inhibitor of metalloproteinase-1 (TIMP-1), lysyl oxidase-like-2 (LOXL2) and transforming growth factor β (TGF-β) concentrations in HIV-uninfected populations. Protease (PI) and non-nucleoside reverse transcriptase inhibitors (NNRTI) may contribute to these comorbidities, but the effects of switching from PI- or NNRTI to raltegravir (RAL) on these biomarkers is unknown.

METHODS

Cryopreserved plasma was obtained from a completed, prospective trial of HIV-infected women with central adiposity on NNRTI- or PI-based ART during which they were randomized to remain on their current ART or switch to a RAL based regimen. Biomarker concentrations were quantified using ELISA and Multiplex assays at baseline and 24 weeks after randomization. Wilcoxon-signed rank test evaluated within-group changes, Spearman and linear regression models evaluated correlations between biomarkers and clinical covariates.

RESULTS

Participants had a median age of 43 years, CD4+ T lymphocyte count 558 cells/mm3 and BMI 32 kg/m2; 35% met criteria for MetS. At baseline, higher adiponectin levels correlated with higher Chi3L1 levels (r = 0.42, p = 0.02), as did declines after 24 weeks (r = 0.40, p = 0.03). Changes in sST2 correlated with changes in Chi3L1 (r = 0.43, p = 0.02) and adiponectin (r = 0.40, p = 0.03). Adiponectin and Chi3L1 levels decreased significantly in women switched to RAL vs continue PI/NNRTI.

CONCLUSION

In women with HIV and central obesity, the hepatic steatosis/fibrosis marker Chi3L1 and adiponectin decrease in conjunction with sST2 decreases following switch to RAL. Whether switching from NNRTI/PI-based regimens to RAL can improve hepatic steatosis and dysmetabolism requires further study.

TRIAL REGISTRATION

Clinicaltrials.gov NCT00656175.

Long-term Use of Proton Pump Inhibitors Is Associated With Increased Microbial Product Translocation, Innate Immune Activation, and Reduced Immunologic Recovery in Patients With Chronic Human Immunodeficiency Virus-1 Infection

BACKGROUND

Translocation of microbial products from the damaged gut causes increased immune activation in human immunodeficiency virus (HIV). Proton pump inhibitors (PPIs) predispose to bacterial overgrowth in the gut. We hypothesized that long-term use of PPIs is associated with greater microbial translocation and immune activation in HIV.

METHODS

HIV-infected persons on suppressive antiretroviral therapy (ART), including those receiving long-term PPIs (PPI+ group) or not (PPI- group), were enrolled. We determined CD38+HLA-DR+CD8+ (activated) T-cell frequency, and plasma levels of lipopolysaccharide (LPS), LPS binding protein (LBP), soluble CD14 (sCD14), and intestinal fatty acid binding protein (I-FABP).

RESULTS

We recruited 77 HIV-infected participants (37 PPI+ and 40 PPI-) and 20 HIV-uninfected volunteers. PPI+ subjects were older and more likely to have hypertension and receive statins than PPI-. Nadir and enrollment CD4 counts, activated T-cells, and time on ART were similar in both groups. PPI+ group had higher sCD14 (2.15 vs. 1.50 mcg/mL, P < .01), and LBP (21.78 vs. 18.28 mcg/mL, P = .02) but lower I-FABP levels (608.5 vs. 2281.7 pg/mL, P = .05) than PPI-. In multivariate analysis, sCD14 levels remained associated with PPIs. In the year prior to enrollment, PPI+ group lost more CD4 cells than PPI- (-18 vs. 54 cells/mm3, P = .03). HIV-infected subjects had higher immune activation and microbial translocation biomarkers than uninfected volunteers.

CONCLUSION

In HIV, long-term use of PPIs was associated with increased microbial translocation, innate immune activation, and reduced immune reconstitution. Further studies are needed to evaluate the clinical implications of our findings. In the meantime, cautious use of PPIs is advised.

Circulating LOXL2 Levels Reflect Severity of Intestinal Fibrosis and GALT CD4+ T Lymphocyte Depletion in Treated HIV Infection

BACKGROUND

Incomplete immune reconstitution may occur despite successful antiretroviral therapy (ART). Gut-associated lymphoid tissue (GALT) fibrosis may contribute via local CD4+ T lymphocyte depletion, intestinal barrier disruption, microbial translocation, and immune activation.

METHODS

In a cross-sectional analysis, we measured circulating fibrosis biomarker levels on cryopreserved plasma from adult HIV-infected (HIV+) SCOPE study participants on suppressive ART who also had fibrosis quantification on recto-sigmoid biopsies. Relationships among biomarker levels, clinical and demographic variables, GALT lymphoid aggregate (LA) collagen deposition, and LA CD4+ T lymphocyte density were analyzed using simple regression. Biomarker levels were also compared to levels in HIV+ viremic SCOPE participants and a convenience sample of HIV-uninfected (HIV-) samples.

RESULTS

HIV+ aviremic participants (n = 39) were 92% male and 41% non-white, with median age 48 years, CD4+ T lymphocyte count 277 cells/mm3, and 17 years since HIV diagnosis. Most biomarkers were lower in HIV- (n = 36) vs HIV+ aviremic individuals, although CXCL4 levels were higher. HIV+ viremic individuals (N = 18) had higher median TGF-β3, CIC-C1Q, and TIMP-1 (P < 0.05) and lower LOXL2 levels (P = 0.08) than HIV+ aviremic individuals. Only higher LOXL2 levels correlated with more GALT collagen deposition (R = 0.44, P= 0.008) and lower LA CD4+ T lymphocyte density (R = -0.32, P = 0.05) among aviremic individuals.

CONCLUSIONS

Circulating LOXL2 levels may be a noninvasive measure of intestinal fibrosis and GALT CD4+ T lymphocyte depletion in treated HIV infection. LOXL2 crosslinks elastin and collagen, and elevated LOXL2 levels occur in pathologic states, making LOXL2 inhibition a potential interventional target for intestinal fibrosis and its sequelae.

Unchanged Levels of Soluble CD14 and IL-6 Over Time Predict Serious Non-AIDS Events in HIV-1-Infected People

HIV-1-infected persons have increased risk of serious non-AIDS events (SNAEs) despite suppressive antiretroviral therapy. Increased circulating levels of soluble CD14 (sCD14), soluble CD163 (sCD163), and interleukin-6 (IL-6) at a single time point have been associated with SNAEs. However, whether changes in these biomarker levels predict SNAEs in HIV-1-infected persons is unknown. We hypothesized that greater decreases in inflammatory biomarkers would be associated with fewer SNAEs. We identified 39 patients with SNAEs, including major cardiovascular events, end stage renal disease, decompensated cirrhosis, non-AIDS-defining malignancies, and death of unknown cause, and age- and sex-matched HIV-1-infected controls. sCD14, sCD163, and IL-6 were measured at study enrollment (T1) and proximal to the event (T2) or equivalent duration in matched controls. Over ∼34 months, unchanged rather than decreasing levels of sCD14 and IL-6 predicted SNAEs. Older age and current illicit substance abuse, but not HCV coinfection, were associated with SNAEs. In a multivariate analysis, older age, illicit substance use, and unchanged IL-6 levels remained significantly associated with SNAEs. Thus, the trajectories of sCD14 and IL-6 levels predict SNAEs. Interventions to decrease illicit substance use may decrease the risk of SNAEs in HIV-1-infected persons.

Improving vascular maturation using noncoding RNAs increases antitumor effect of chemotherapy

Current antiangiogenesis therapy relies on inhibiting newly developed immature tumor blood vessels and starving tumor cells. This strategy has shown transient and modest efficacy. Here, we report a better approach to target cancer-associated endothelial cells (ECs), reverse permeability and leakiness of tumor blood vessels, and improve delivery of chemotherapeutic agents to the tumor. First, we identified deregulated microRNAs (miRs) from patient-derived cancer-associated ECs. Silencing these miRs led to decreased vascular permeability and increased maturation of blood vessels. Next, we screened a thioaptamer (TA) library to identify TAs selective for tumor-associated ECs. An annexin A2-targeted TA was identified and used for delivery of miR106b-5p and miR30c-5p inhibitors, resulting in vascular maturation and antitumor effects without inducing hypoxia. These findings could have implications for improving vascular-targeted therapy.

Pharmacokinetics, Safety, and CCR2/CCR5 Antagonist Activity of Cenicriviroc in Participants With Mild or Moderate Hepatic Impairment

Cenicriviroc, a dual CCR2/CCR5 antagonist, is being evaluated for treatment of nonalcoholic steatohepatitis and liver fibrosis (CENTAUR; NCT02217475). As it is metabolized by the liver, cenicriviroc was investigated in hepatic-impaired participants for pharmacokinetic changes. Participants with mild-to-moderate hepatic impairment (HI) (Child-Pugh class A (N  =  7) or B (N = 8)) and matched controls (N = 15) received cenicriviroc 150 mg once daily for 14 days. Serial blood samples were obtained on Days 1 and 14. Safety, tolerability, and effects on CCR2/CCR5 ligands, cytokines, and bacterial translocation biomarkers were evaluated. Cenicriviroc exposures were increased by moderate HI (AUC0-τ  55%, Cmax 29% higher) but were not with mild HI (AUC0-τ 38%, Cmax 40% lower). Cenicriviroc was well tolerated. Rapid and potent CCR2/CCR5 blockade was observed, not associated with increases in hepatic inflammation or bacterial translocation biomarkers. Study findings suggest that cenicriviroc 150 mg can be used in patients with mild-to-moderate HI.

MRSA Infections in HIV-Infected People Are Associated with Decreased MRSA-Specific Th1 Immunity

People with HIV infection are at increased risk for community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) skin and soft tissue infections (SSTIs). Lower CD4 T-cell counts, higher peak HIV RNA levels and epidemiological factors may be associated with increased risk but no specific immune defect has been identified. We aimed to determine the immunologic perturbations that predispose HIV-infected people to MRSA SSTIs. Participants with or without HIV infection and with MRSA SSTI, MRSA colonization or negative for MRSA were enrolled. Peripheral blood and skin biopsies from study participants were collected. Flow cytometry, flow cytometry with microscopy, multiplex assays of cell culture supernatants and immunohistochemistry were used to evaluate the nature of the immune defect predisposing HIV-infected people to MRSA infections. We found deficient MRSA-specific IFNγ+ CD4 T-cell responses in HIV-infected people with MRSA SSTIs compared to MRSA-colonized participants and HIV-uninfected participants with MRSA SSTIs. These IFNγ+ CD4 T cells were less polyfunctional in HIV-infected participants with SSTIs compared to those without SSTIs. However, IFNγ responses to cytomegalovirus and Mycobacterium avium antigens and MRSA-specific IL-17 responses by CD4 T cells were intact. Upon stimulation with MRSA, peripheral blood mononuclear cells from HIV-infected participants produced less IL-12 and IL-15, key drivers of IFNγ production. There were no defects in CD8 T-cell responses, monocyte responses, opsonization, or phagocytosis of Staphylococcus aureus. Accumulation of CD3 T cells, CD4 T cells, IL-17+ cells, myeloperoxidase+ neutrophils and macrophage/myeloid cells to the skin lesions were similar between HIV-infected and HIV-uninfected participants based on immunohistochemistry. Together, these results indicate that MRSA-specific IFNγ+ CD4 T-cell responses are essential for the control of initial and recurrent MRSA infections in HIV-infected people.

Elite Control, Gut CD4 T Cell Sparing, and Enhanced Mucosal T Cell Responses in Macaca nemestrina Infected by a Simian Immunodeficiency Virus Lacking a gp41 Trafficking Motif

Deletion of Gly-720 and Tyr-721 from a highly conserved GYxxØ trafficking signal in the SIVmac239 envelope glycoprotein cytoplasmic domain, producing a virus termed ΔGY, leads to a striking perturbation in pathogenesis in rhesus macaques (Macaca mulatta). Infected macaques develop immune activation and progress to AIDS, but with only limited and transient infection of intestinal CD4(+) T cells and an absence of microbial translocation. Here we evaluated ΔGY in pig-tailed macaques (Macaca nemestrina), a species in which SIVmac239 infection typically leads to increased immune activation and more rapid progression to AIDS than in rhesus macaques. In pig-tailed macaques, ΔGY also replicated acutely to high peak plasma RNA levels identical to those for SIVmac239 and caused only transient infection of CD4(+) T cells in the gut lamina propria and no microbial translocation. However, in marked contrast to rhesus macaques, 19 of 21 pig-tailed macaques controlled ΔGY replication with plasma viral loads of <15 to 50 RNA copies/ml. CD4(+) T cells were preserved in blood and gut for up to 100 weeks with no immune activation or disease progression. Robust antiviral CD4(+) T cell responses were seen, particularly in the gut. Anti-CD8 antibody depletion demonstrated CD8(+) cellular control of viral replication. Two pig-tailed macaques progressed to disease with persisting viremia and possible compensatory mutations in the cytoplasmic tail. These studies demonstrate a marked perturbation in pathogenesis caused by ΔGY's ablation of the GYxxØ trafficking motif and reveal, paradoxically, that viral control is enhanced in a macaque species typically predisposed to more pathogenic manifestations of simian immunodeficiency virus (SIV) infection.

IMPORTANCE

The pathogenesis of human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) reflects a balance between viral replication, host innate and adaptive antiviral immune responses, and sustained immune activation that in humans and Asian macaques is associated with persistent viremia, immune escape, and AIDS. Among nonhuman primates, pig-tailed macaques following SIV infection are predisposed to more rapid disease progression than are rhesus macaques. Here, we show that disruption of a conserved tyrosine-based cellular trafficking motif in the viral transmembrane envelope glycoprotein cytoplasmic tail leads in pig-tailed macaques to a unique phenotype in which high levels of acute viral replication are followed by elite control, robust cellular responses in mucosal tissues, and no disease. Paradoxically, control of this virus in rhesus macaques is only partial, and progression to AIDS occurs. This novel model should provide a powerful tool to help identify host-specific determinants for viral control with potential relevance for vaccine development.

The dual role of tetraspanin CD63 in HIV-1 replication

Background

Previously, we showed that the tetraspanin membrane protein CD63 mediates both early and post-integration stages of the HIV-1 replication cycle. The temporal roles of CD63 were discerned using monoclonal antibodies and small interfering RNAs (siRNAs) to block CD63 function, and determining which of the sequential steps in HIV-1 replication were disrupted. Inhibition was shown to occur during early infection, suggestive of involvement in virus entry or reverse transcription. In addition, we have shown that treatment with CD63 siRNA post-infection, significantly inhibited virus production in supernatant, suggesting an important role for CD63 in macrophages during HIV-1 replication events occurring after proviral integration, and possibly during egress.

Results

In this study we used CD63 siRNA to investigate the infectivity of pseudotyped viruses (carrying an NL4-3 Env-negative luciferase backbone) in primary human macrophages. We demonstrated that lab adapted R5- and R5X4-tropic HIV-1 strains are significantly inhibited by CD63 silencing. However, the infectivity of MLV or VSV-pseudotyped strains, which enter though receptor-mediated endocytosis, is unaffected by silencing CD63. These results indicate that CD63 may support Env-mediated entry or fusion events facilitated though CD4 and CCR5. Also, antibody and siRNA-based CD63 inhibition studies indicate a potential role for CD63 following proviral integration. Further, we show that CD63 expression is key for efficient replication in primary CD4⁺ T cells, complementing our prior studies with primary human macrophages and immortalized cell lines.

Conclusions

Collectively, these findings indicate that CD63 may support Env-mediated fusion as well as a late (post-integration) step in the HIV-1 replication cycle.

X-aptamers: a bead-based selection method for random incorporation of druglike moieties onto next-generation aptamers for enhanced binding

By combining pseudorandom bead-based aptamer libraries with conjugation chemistry, we have created next-generation aptamers, X-aptamers (XAs). Several X-ligands can be added in a directed or random fashion to the aptamers to further enhance their binding affinities for the target proteins. Here we describe the addition of a drug (N-acetyl-2,3-dehydro-2-deoxyneuraminic acid), demonstrated to bind to CD44-HABD, to a complete monothioate backbone-substituted aptamer to increase its binding affinity for the target protein by up to 23-fold, while increasing the drug's level of binding 1-million fold.

Thioaptamer conjugated liposomes for tumor vasculature targeting

Recent developments in multi-functional nanoparticles offer a great potential for targeted delivery of therapeutic compounds and imaging contrast agents to specific cell types, in turn, enhancing therapeutic effect and minimizing side effects. Despite the promise, site specific delivery carriers have not been translated into clinical reality. In this study, we have developed long circulating liposomes with the outer surface decorated with thioated oligonucleotide aptamer (thioaptamer) against E-selectin (ESTA) and evaluated the targeting efficacy and PK parameters. In vitro targeting studies using Human Umbilical Cord Vein Endothelial Cell (HUVEC) demonstrated efficient and rapid uptake of the ESTA conjugated liposomes (ESTA-lip). In vivo, the intravenous administration of ESTA-lip resulted in their accumulation at the tumor vasculature of breast tumor xenografts without shortening the circulation half-life. The study presented here represents an exemplary use of thioaptamer for targeting and opens the door to testing various combinations of thioaptamer and nanocarriers that can be constructed to target multiple cancer types and tumor components for delivery of both therapeutics and imaging agents.

Combinatorial selection of DNA thioaptamers targeted to the HA binding domain of human CD44

CD44, the primary receptor for hyaluronic acid, plays an important role in tumor growth and metastasis. CD44-hyaluronic acid interactions can be exploited for targeted delivery of anticancer agents specifically to cancer cells. Although various splicing variants of CD44 are expressed on the plasma membrane of cancer cells, the hyaluronic acid binding domain (HABD) is highly conserved among the CD44 splicing variants. Using a novel two-step process, we have identified monothiophosphate-modified aptamers (thioaptamers) that specifically bind to the CD44's HABD with high affinities. Binding affinities of the selected thioaptamers for the HABD were in the range of 180-295 nM, an affinity significantly higher than that of hyaluronic acid (K(d) above the micromolar range). The selected thioaptamers bound to CD44 positive human ovarian cancer cell lines (SKOV3, IGROV, and A2780) but failed to bind the CD44 negative NIH3T3 cell line. Our results indicated that thio substitution at specific positions of the DNA phosphate backbone results in specific and high-affinity binding of thioaptamers to CD44. The selected thioaptamers will be of great interest for further development as a targeting or imaging agent for the delivery of therapeutic payloads for cancer tissues.

Abstract 5712: Identification and characterization of high affinity thioaptamer ligands against E-selectin

E-selectin (CD62E, ELAM-1 or LECAM-2) is a calcium dependent cell surface glycoprotein that mediates an adhesion of leukocytes on inflamed endothelium through recognition of specific carbohydrate ligands, sialyl Lewis X (sLeX) and sialyl Lewis A (sLeA). E-selectin expression is transcriptionally induced by NF-κB and AP-1 in response to inflammatory cytokines such as IL-1 and TNF-alpha. Accordingly, elevated E-selectin expression was reported in many types of acute and chronic inflammatory diseases including cancer. Aberrant homing of leukocytes to tumor results in tumor progression and local invasion. In addition, E-selectin and its counter ligands have also been reported to trigger the initial adhesive step of circulating cancer cells to endothelial cells. Therefore, blockade of E-selectin is a promising therapeutic strategy to control pathological infiltration of leukocytes and/or metastatic cancer cells. Thioaptamers (TA) are single stranded DNA molecules with thio substitution in the phosphate backbone, which provide stability against nucleases. Thioaptamer can fold into tertiary structures and bind with high affinity and specificity to a target molecule, and thus suitable for in vivo applications. In this study, we aimed to identify thioaptamer ligands that bind to E-selectin with high affinity and specificity. To achieve this goal, we used two-step selection strategies, recombinant protein based thioaptamer selection from a combinatorial thioaptamer library that contains 10E14 random sequences, followed by a cell based binding to tetracycline inducible E-selectin endothelial cells.

We selected 14 different groups of thioaptamer candidates following 10 iterative cycles of binding to recombinant E-selectin protein. Using Tet-on inducible E-selectin endothelial cells, we identified the lead three TA candidates that bind to E-selectin on the surface of endothelial cells at high affinity (nM range) and specificity. In addition, the TA bound to tumor associated vasculature that express E-selectin. Moreover, the TA selected demonstrated significant inhibition of leukocyte adhesion to E-selectin positive endothelial cells at low nanomolar concentrations. In summary, we identified antagonistic TA against E-selectin that binds to endothelial cells and interferes with leukocyte bindings at nM range. Potential applications of this TA could be for 1) inflamed tumor vasculature selective targeted delivery of therapeutic molecules or drug delivery carriers 2) the prevention of pathological diapedesis of leukocytes and/or metastatic cancer cells. We are currently investigating potential clinical applications of the TA.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5712.

Base-pairing properties of the oxidized cytosine derivative, 5-hydroxy uracil

The most abundant base-substitution mutation resulting from oxidative damage to DNA is the GC to AT transition mutation. 5-hydroxyuracil (5-OHU), produced by the oxidative deamination of cystosine, has been established as the major chemical precursor for this most abundant transition mutation. Results from NMR spectroscopy and UV melting experiments show that 5-OHU would form the most stable pair with G, and the least stable pair with C. The hydroxyl group in the 5th position of the 5-OHU residue may play a role in increasing the stability of the 5-OHU:G pair over the normal Watson-Crick pair, the 5-OHU:A. The 5-OHU:C base pair would be least stable, and would destabilize the base-stacking in the duplex. Our results explain why certain DNA polymerases preferentially incorporate G opposite to 5-OHU over A and why C does not get incorporated against 5-OHU during DNA replication in vivo.

Ab initio base-pairing energies of an oxidized thymine product, 5-formyluracil, with standard DNA bases at the BSSE-free DFT and MP2 theory levels

Oxidation of the thymine methyl group produces two stable products, non-mutagenic 5-hydroxymethyluracil and highly mutagenic 5-formyluracil. We have calculated the interaction energy of base-pair formation involving 5-formyluracil bound to the natural DNA bases adenine (A), cytosine (C), guanine (G), and thymine (T), and discuss the effects of the 5-formyl group with respect to similar base-pairs containing uracil, 5-hydroxyuracil, thymine (5-methyluracil), and 5-hydroxycytosine. The interaction geometries and energies were calculated four ways: (a) using density functional theory (DFT) without basis set super-position error (BSSE) corrections, (b) using DFT with BSSE correction of geometries and energies, (c) using Møller-Plesset second order perturbation theory (MP2) without BSSE correction, and (d) using MP2 with BSSE geometry and energy correction. All calculations used the 6-311G(d,p) basis set. Notably, we find that the A:5-formyluracil base-pair is more stable than the precursor A:T base-pair. The relative order of base-pair stabilities is A:5-Fo-U > G:5-Fo-U > C:5-Fo-U > T:5-Fo-U.

Delivery of double-stranded DNA thioaptamers into HIV-1 infected cells for antiviral activity

Oligonucleotide agents (ODN) are emerging as attractive alternatives to chemical drugs. However, the clinical use of ODNs as therapeutics has been hindered by their susceptibility to degradation by cellular enzymes and their limited ability to penetrate intact cells. We have used various liposome-mediated transfection agents, for the in vitro delivery of DNA thioaptamers into U373-MAGI-CCR5 cells. Our lead thioaptamer, R12-2, targets the RNase H domain of the HIV-1 reverse transcriptase (RT) and inhibits viral infection in U373-MAGI-CCR5 cells. R12-2, a 62-base-pair, double-stranded DNA molecule with a monothio-phosphate modified backbone, was selected through a novel combinatorial selection method. We studied the use of oligofectamine (OF), TFX-20, Transmessenger (TM), and Gene Jammer (GJ) for transfection of the thio-modified DNA aptamers. OF-transfected U373-MAGI-CCR5 cells resulted in 68% inhibition of HIV infection in the treated cells compared to the untreated control. Inhibition was observed in a dose-dependent manner with maximal inhibition of 83%. In this report, we demonstrate that monothioate-modified DNA duplex oligonucleotides can be efficiently delivered into cells by liposome-based transfection agents to inhibit HIV replication.

Ab initio base-pairing energies of uracil and 5-hydroxyuracil with standard DNA bases at the BSSE-free DFT and MP2 theory levels

Oxidized cytosine product 5-hydroxyuracil has been shown to be the major chemical precursor for the GC to AT transition, the most frequent substitution mutation observed in aerobic organisms. We have calculated the interaction energy of base-pair formation involving uracil or 5-hydroxyuracil, which is formed in cells by oxidative deamination of cytosine, bound to any of the natural DNA bases, A, C, G, and T, and discuss the effects of the hydroxyl group in this respect. The base-pair geometries and energies were calculated using the 6-311G(dp) basis set under four conditions: using density functional theory (DFT) without out basis set super-position error (BSSE) correction, using DFT with BSSE correction of geometries and energies, using Møller-Plesset second order perturbation theory (MP2) without BSSE correction, and using MP2 with BSSE geometry and energy correction. We find that the hydroxyl group of 5-HO-U (relative to U) has little effect on the base-pairs with A, C or one conformation of T, while making a substantial energy difference in base-pairs involving G or a different conformation of T. For most of the complexes studied, the BSSE-corrected energies at the DFT and MP2 levels of theory agreed to within 0.5 kcal.

Combinatorial selection, inhibition, and antiviral activity of DNA thioaptamers targeting the RNase H domain of HIV-1 reverse transcriptase

Despite the key role played by the RNase H of human immunodeficiency virus-1 reverse transcriptase (HIV-1 RT) in viral proliferation, only a few inhibitors of RNase H have been reported. Using in vitro combinatorial selection methods and the RNase H domain of the HIV RT, we have selected double-stranded DNA thioaptamers (aptamers with selected thiophosphate backbone substitutions) that inhibit RNase H activity and viral replication. The selected thioaptamer sequences had a very high proportion of G residues. The consensus sequence for the selected thioaptamers showed G clusters separated by single residues at the 5'-end of the sequence. Gel electrophoresis mobility shift assays and nuclear magnetic resonance spectroscopy showed that the selected thioaptamer binds to the isolated RNase H domain, but did not bind to a structurally similar RNase H from Escherichia coli. The lead thioaptamer, R12-2, showed specific binding to HIV-1 RT with a binding constant (K(d)) of 70 nM. The thioaptamer inhibited the RNase H activity of intact HIV-1 RT. In cell culture, transfection of thioaptamer R12-2 (0.5 microg/mL) markedly inhibited viral production and exhibited a dose response of inhibition with R12-2 concentrations ranging from 0.03 to 2.0 microg/mL (IC(50) < 100 nM). Inhibition was also seen across a wide range of virus inoculum, ranging from a multiplicity of infection (moi) of 0.0005 to 0.05, with a reduction of the level of virus production by more than 50% at high moi. Suppression of virus was comparable to that seen with AZT when moi <or= 0.005.

5-Hydroxyuracil can form stable base pairs with all four bases in a DNA duplex

NMR studies, UV-monitored melting experiments, and ab initio calculations show that 5-hydroxyuracil, produced by the oxidative de-amination of cytosines by reactive oxygen species, can form stable base-pairs with dA, dG, dC and dT residues in a DNA duplex, providing a basis for the in-vivo incorporation of 5-hydroxyuracil during DNA replication.

Solution structure of a DNA duplex containing 8-hydroxy-2'-deoxyguanosine opposite deoxyguanosine

Deoxyguanosine residues are hydroxylated by reactive oxygen species at the C-8 position to form 8-hydroxy-2'-deoxyguanosine (8-OG), one of the most important mutagenic lesions in DNA. Though the spontaneous G:C to C:G transversions are rare events, the pathways leading to this mutation are not established. An 8-OG:G mispair, if not corrected by DNA repair enzymes, could lead to G:C to C:G transversions. NMR spectroscopy and restrained molecular dynamics calculations are used to refine the solution structure of the base mismatch formed by the 8-OG:G pair on a self complementary DNA dodecamer duplex d(CGCGAATT(8-O)GGCG)(2). The results reveal that the 8-OG base is inserted into the helix and forms Hoogsteen base-pairing with the G on the opposite strand. The 8-OG:G base-pairs are seen to be stabilized by two hydrogen bonding interactions, one between the H7 of the 8-OG and the O6 of the G, and a three-center hydrogen bonding between the O8 of the 8-OG and the imino and amino protons of the G. The 8-OG:G base-pairs are very well stacked between the Watson-Crick base-paired flanking bases. Both strands of the DNA duplex adopt right-handed conformations. All of the unmodified bases, including the G at the lesion site, adopt anti glycosidic torsion angles and form Watson-Crick base-pairs. At the lesion site, the 8-OG residues adopt syn conformations. The structural studies demonstrate that 8-OG(syn):G(anti) forms a stable pair in the interior of the duplex, providing a basis for the in vivo incorporation of G opposite 8-OG. Calculated helical parameters and backbone torsional angles, and the observed 31P chemical shifts, indicate that the structure of the duplex is perturbed near lesion sites, with the local unwinding of the double helix. The melting temperature of the 8-OG:G containing duplex is only 2.6 deg. C less than the t(m) of the unmodified duplex.