HIV infects over 33 million people worldwide with a new infection occurring every 9 seconds. Sex is the primary mode of transmission and the majority of new infections occur during unprotected sexual contact between an HIV-infected individual and an uninfected sexual partner(s) since HIV infected individuals tend to shed virus in their genital secretions. The infectiousness of an individual is closely tied to the amount of virus in blood, which is closely associated with HIV levels shed in semen or vaginal fluid or rectal secretions. Although, Highly Active Antiretroviral Therapy (HAART) is associated with complete suppression of HIV RNA in blood to undetectable levels, the impact of HAART on semen HIV RNA levels is less clear. I evaluated the correlation between systemic and mucosal HIV-specific CD8+ T cell immune responses and HIV RNA levels in blood and semen. Overall, there was a strong positive correlation between HIV RNA levels in blood and semen. Neither systemic nor mucosal (in semen) HIV-specific CD8+ responses were associated with HIV RNA levels in blood or semen, in fact CD8+ T cell immune responses in semen correlated with increased HIV RNA levels in semen. Furthermore, inflammatory cytokines (IL-6, and IL-8) CMV levels in semen were associated with increased semen HIV RNA shedding. HAART initiation was associated with complete suppression of HIV viremia, but a significant proportion of individuals on suppressive HAART continue to shed HIV RNA in semen even after 6 months, and this isolated virus was infectious and often present at high levels (> 5000 copies/mL). Nevertheless, long-term HAART was associated with complete immune reconstitution of CD4+ T cells in the sigmoid colon of HIV-infected individuals on long-term therapy. These findings demonstrate that neither systemic nor mucosal HIV-specific CD8+ responses, when assayed with IFN- production as an endpoint, were associated with reduced HIV RNA levels in blood or semen. Semen HIV RNA levels did correlate with local inflammatory cytokines and CMV reactivation. Furthermore, despite effective HAART a significant proportion of HIV-infected men continued to shed HIV RNA in semen. However, long-term completely suppressive HAART was associated with complete immune reconstitution of the sigmoid colon.

HIV infects over 33 million people worldwide with a new infection occurring every 9 seconds. Sex is the primary mode of transmission and the majority of new infections occur during unprotected sexual contact between an HIV-infected individual and an uninfected sexual partner(s) since HIV infected individuals tend to shed virus in their genital secretions. The infectiousness of an individual is closely tied to the amount of virus in blood, which is closely associated with HIV levels shed in semen or vaginal fluid or rectal secretions. Although, Highly Active Antiretroviral Therapy (HAART) is associated with complete suppression of HIV RNA in blood to undetectable levels, the impact of HAART on semen HIV RNA levels is less clear. I evaluated the correlation between systemic and mucosal HIV-specific CD8+ T cell immune responses and HIV RNA levels in blood and semen. Overall, there was a strong positive correlation between HIV RNA levels in blood and semen. Neither systemic nor mucosal (in semen) HIV-specific CD8+ responses were associated with HIV RNA levels in blood or semen, in fact CD8+ T cell immune responses in semen correlated with increased HIV RNA levels in semen. Furthermore, inflammatory cytokines (IL-6, and IL-8) CMV levels in semen were associated with increased semen HIV RNA shedding. HAART initiation was associated with complete suppression of HIV viremia, but a significant proportion of individuals on suppressive HAART continue to shed HIV RNA in semen even after 6 months, and this isolated virus was infectious and often present at high levels (> 5000 copies/mL). Nevertheless, long-term HAART was associated with complete immune reconstitution of CD4+ T cells in the sigmoid colon of HIV-infected individuals on long-term therapy. These findings demonstrate that neither systemic nor mucosal HIV-specific CD8+ responses, when assayed with IFN- production as an endpoint, were associated with reduced HIV RNA levels in blood or semen. Semen HIV RNA levels did correlate with local inflammatory cytokines and CMV reactivation. Furthermore, despite effective HAART a significant proportion of HIV-infected men continued to shed HIV RNA in semen. However, long-term completely suppressive HAART was associated with complete immune reconstitution of the sigmoid colon.

Objective: The rectal mucosa is highly susceptible to HIV infection. Mucosal fluid contains soluble immune proteins that influence HIV infection, and previous studies have shown unique mucosal protein expression in HIV-exposed seronegative (HESN) populations, which may contribute to reduced HIV susceptibility. However, the key correlates of susceptibility at the rectal mucosa have not been well defined, which is a critical knowledge gap for our understanding of HIV pathogenesis. Methods: Rectal lavage from low risk men was screened for HIV-neutralizing activity in a TZM-bl reporter cell line against an R5-tropic HIV virus. Label-free tandem mass spectrometry was used to characterize soluble proteins within rectal lavage samples from a low-risk cohort of men (n=15), and HESN men who have sex with men (MSM; n=25). Protein expression between populations was compared using adjusted t tests (p<0.05), and was interpreted using hierarchical clustering and DAVID biofunctional analysis. Protein expression was further analyzed using survey data on sexual behaviours. Proteins associated with the HESN population were screened for antiviral activity in TZM-bl and PBMC culture against an R5- and X4-tropic virus. Major Results: Rectal mucosal fluid was able to inhibit HIV infection in vitro by 40% (p<0.05). Mass spectrometry identified 30/341 (9%) proteins deferentially expressed (DE) in HESN MSM. DE proteins held functions in immunity (p=6.68x10-6, p=0.001) and epithelial barrier development (p=1.81x10-4; p=0.01); notably, specific antiproteases were elevated in HESN secretions, two of which were screened for antiviral activity. Serpin B4 (+2.52 L2FD; p=1.09x10-5), showed significant inhibition of HIV in TZM-bl (45% BaL, 34% IIIB; p<0.05) and PBMC culture (37% BaL, 49% IIIB; p<0.05); cystatin A (+1.52 L2FD; p=1.40x10-3) showed no inhibitory effects. Serpin B4 expression was not associated with frequency of oral intercourse (p=0.32), partner viral load (r=0.16; p=0.29) or presence of HIV neutralizing IgA in secretions (p=0.52). Conclusions: This thesis reports the use of proteomics to understand HIV-susceptibility at the rectal mucosa, and identified serpin B4 as a novel antiviral immune correlate in a population of HESN MSM. These results may help guide future studies of prevention technologies, such as microbicides or vaccines, which would ultimately help limit the spread of HIV. / February 2016

The distinctive feature of the Human Immunodeficiency Virus (HIV) epidemic in the 21st century is the burden it places on women. Scientists believe that the best opportunities for successful interventions to prevent sexual HIV transmission lie in the initial stages of infection at the portal of entry, the genital tract (GT), which offers the greatest host advantages and viral vulnerabilities. However, understanding of the correlates of protection/vulnerability and innate immunity at the portal of entry is poor. First and foremost, there is no agreement about which GT sub-compartment is the primary site of HIV/SIV infection. Second, the epithelium, previously studied solely for its function as a barrier, has hardly been investigated for its role in innate immunity in the context of SIV/HIV infection. MIP-3&alpha;, a chemokine secreted by epithelial cells, was previously proposed to have a role in amplifying the early Simian Immunodeficiency Virus (SIV) infection events in the GT of female macaques. Specifically, MIP-3&alpha; was shown to be secreted by epithelial cells of the endocervix, accumulating subepithelially within the first 24 hours post exposure, following deposition of an intravaginal inoculum of SIV. Similar studies in humans have not been reported. We hence undertook to study MIP-3&alpha; for its role in early HIV infection events in the endocervix of humans. In order to achieve this, we first characterised MIP-3&alpha; constitutive secretion patterns in different sub-compartments of the GT before proceeding to determine its induced secretion patterns, stimulating with HIV-1 and various Toll-like receptor ligands. For completeness we determined constitutive and induced secretion patterns of multiple soluble proteins (SPs) and antimicrobial peptides (AMPs) in the endocervices of humans and macaques. The GT being an immunohormonal system, we further studied the influence of endogenous hormonal changes on the stability of MIP-3&alpha; and that of other innate immune markers. We quantified MIP-3&alpha; with a sandwich Elisa, and SPs and AMPs with the Luminex multiplex bead assay. Our results showed that the GT is a rich source of MIP-3&alpha; with its levels being among those of the highest SPs in the GT. Constitutive levels were highest in the endocervical sub-compartment of all the sub-compartments studied. Further, the GT is an inflammatory environment, which would explain the high levels of MIP-3&alpha;. The primary driver of MIP-3&alpha; levels appears to be inflammation rather than hormonal levels. MIP-3&alpha; levels are significantly higher in the GT of humans than in macaques. There was no evidence that MIP-3&alpha; levels are elevated on exposure to HIV and SIV in humans and macaques, respectively. We therefore concluded that since the endocervix is unlikely to respond to HIV/SIV by secreting MIP-3&alpha; in vivo, contrary to the previous reports, MIP-3&alpha; is hence not a key player in amplifying early events in infection. And as such, it should not be a prime target for preventive therapy. Further, the human GT having a pre-existing inflammatory profile may explain the high rates of HIV sexual transmission. Lastly, we concluded that the infection mechanisms described in the macaque model (i.e. the 'outside-in' signaling) are likely not required for human infection.

O objetivo desta pesquisa foi avaliar a influência do envelhecimento e da perda dos elementos dentais nos níveis totais de imunoglobulina secretória do tipo A (SIgA) na saliva. Foram selecionados 76 pacientes (entre 20 e 87 anos), os quais foram divididos em três grupos de acordo com sua faixa etária e condição bucal: adultos jovens com idades de 20 a 40 anos (Grupo I ou Grupo controle); idosos com idade entre 65 e 78 anos, desdentados parciais, portadores de prótese total unimaxilar (Grupo II) e idosos com idade entre 65 e 87 anos, desdentados totais, portadores de prótese total bimaxilar (Grupo III). Os níveis totais de imunoglobulina secretória do tipo A na saliva foram determinados por meio da técnica de ensaio imunoenzimático em fase sólida ( ELISA – Enzyme-linked Imunosorbent Assay). Após obtenção dos dados experimentais foi empregada a análise de variância de ANOVA com dois fatores (sexo e grupo) para verificar o efeito significante da interação destes fatores. Os níveis totais de imunoglobulina do tipo A secretória na saliva não apresentaram, em média, diferenças significantes entre os três grupos. Em relação ao fator gênero, ou sexo, em média, homens e mulheres apresentaram comportamentos de SIgA diferentes nos grupos. Para o grupo controle o nível total de SIgA dos homens foi maior que o das mulheres enquanto que para o grupo III o nível total de SIgA das mulheres foi maior que dos homens e para o grupo II não foi observada diferença significante dos níveis de SIgA entre homens e mulheres. Pela análise comparativa dos grupos I e III foi observada diferença significante no sexo feminino, o que não foi observado quando comparados os dois grupos experimentais (Grupos II e III). Os resultados desta pesquisa sugerem que não há influência direta dos fatores envelhecimento e perda dental sobre os níveis totais de imunoglobulina secretória do tipo A na saliva. Estes resultados mostraram a influência do gênero sobre os níveis de imunoglobulina secretória do tipo A. Entretanto, a influência do gênero não é bem conhecida e merece mais estudos. / The aim of this study was to evaluate the influence of senescence and teeth loss on secretory immunoglobulin A (SIgA) levels in saliva. Seventy-six patients (20 to 87 years old) were selected and classified in three groups according to their age and oral dental state: young adults were aged 20-40 years (Group I or Control group); elderly subjects were aged 65-78 years and wore maxillary or mandibular denture (Group II); and edentulous old subjects were aged 65-87 years and wore maxillary and mandibular denture (Group III). The secretory immunoglobulin A levels were determined by the Enzyme-linked imunosorbent assay (ELISA method). All results were correlated using ANOVA statistical analysis with two factors (sex and group) to verify the significant effect of these factors. The secretory immunoglobulin A levels were not significant differences among the average values of the three groups. In gender relation , men and women showed the mean rate of SIgA levels different in the groups. The men SIgA levels of control group showed greater when compared to women levels. In Group III the women levels were greater when compared to men levels. And to Group II statistical analysis demonstrated no significant difference between the SIgA levels of men and women. The analysis showed significant differences in the women levels when compared to Groups I and III. No differences of levels were demonstrated when compared to Groups II and III. These results suggests that the senescence and teeth loss do not have a direct relationship to the secretory immunoglobulin A levels in whole saliva. The se results showed that there is influence of gender in the secretory immunoglobulin levels. However, the influence of gender is not well known and further studies are still necessary.

The last half-century has seen a dramatic and alarming rise in the incidence of autoimmune disease in industrialized nations too rapid to be accounted for by genetics alone. Among those, Inflammatory Bowel Disease (IBD) has risen from a western disease affecting industrialized populations to an emerging global threat affecting diverse populations around the world. IBD is a complex disease that combines genetic susceptibility and environmental exposure, but one aspect appears to be clear: the involvement of the gut microbiome. Current thought holds that IBD is an autoimmune attack on commensal microbiota, causing extensive collateral damage to the host intestinal tissues in the process. However, it has remained unclear in the field whether the changes observed in the IBD microbiome are causative in nature or whether the microbiome is responding to already-underway inflammatory processes within the host. This dissertation investigates one host factor in particular with regard to the microbiome and the development of inflammation: sodium-hydrogen exchange at the brush border, mediated by sodium hydrogen exchanger 3 (NHE3). NHE3 is inhibited during active IBD, but its loss in knockout animals is also enough to promote spontaneous colitis in a microbiome-dependent fashion. This dissertation investigates the specific contribution of the microbiome in NHE3 knockout animals to determine whether loss of NHE3 may be mediating the onset of colitis through pro-inflammatory changes in the microbiome. Our results suggest that the microbiome fostered in an NHE3-deficient environment may accelerate the onset and severity of experimental colitis, though likely in concert with additional host factors.

No description available.

No description available.

Worldwide, more than half of all HIV-infected individuals are women. Since mucosal surfaces are the primary gateway for HIV entry, maintaining the integrity of the female reproductive tract (FRT) is essential for preventing infection. The FRT employs many immune mechanisms that serve as the first line of defense against HIV transmission. Among these are vaginal fluid secretions rich in antimicrobial peptides, and commensal bacteria that colonize the vagina and prevent infections. We sought to study vaginal fluid as an innate immune component of the FRT in the prevention of HIV infection. Additionally, we investigated the anti-HIV microbicide candidate RC-101 as a possible treatment against pathogenic bacteria that disrupt the healthy microbiota of the FRT and create a suboptimal immune state that increases host susceptibility to viruses, such as HIV. Here we report that vaginal fluid collected from healthy females inhibits HIV infection. Moreover, our studies reveal that vaginal fluid collected from Black and White women exhibit disparate anti-HIV activity, possibly rendering Black women more susceptible to HIV infection. In addition, we show that RC-101, which is active against HIV, can also inhibit pathogenic bacteria that compromise FRT innate immunity, providing a dual mechanism of protection against HIV acquisition. Overall, these findings show that vaginal fluid is an important part of female innate immunity that protects the host from heterosexual HIV acquisition. Furthermore, the microbicide RC-101 may prevent HIV infection by both directly preventing viral entry, and by restricting the growth of pathogenic bacteria that disrupt the protective commensal vaginal flora. Together, innate mechanisms and bolstered protection present a multifaceted approach to maintaining effective host immunity.

Human immunodeficiency virus (HIV) infects 30 million people worldwide. In sub-Saharan Africa, the region most affected by HIV, women comprise 60% of the infected population. Heterosexual transmission is a major mode of viral acquisition, mandating further research of the process and prevention of HIV acquisition via the female reproductive tract (FRT). The FRT is a dynamic environment, protected by host immune mechanisms and commensal microbes. The disruption of either of these elements can increase susceptibility to HIV. Accordingly, one common risk factor for HIV acquisition is the microbial shift condition known as bacterial vaginosis (BV), which is characterized by the displacement of healthy lactobacilli by an overgrowth of pathogenic bacteria. As the bacteria responsible for BV pathogenicity and their interactions with host immunity are not understood, we sought to evaluate the effects of BV-associated bacteria on reproductive epithelia. Here we have characterized the interaction between BV-associated bacteria and the female reproductive tract by measuring cytokine and defensin induction in FRT epithelial cells following bacterial inoculation. Four BV-associated bacteria were evaluated alongside six lactobacilli for a comparative assessment. Our model showed good agreement with clinical BV trends; we observed a distinct cytokine and human β- defensin-2 response to BV-associated bacteria, especially Atopobium vaginae, compared to most lactobacilli. One lactobacillus species, Lactobacillus vaginalis, induced an immune response similar to that elicited by BV-associated bacteria. These iii data provide an important prioritization of BV-associated bacteria and support further characterization of reproductive bacteria and their interactions with host epithelia. We next evaluated the effect of this interaction on HIV infection by investigating the soluble effectors secreted when FRT epithelial cells were cocultured with A. vaginae. We observed increased proviral activity mediated by secreted low molecular weight effectors, and determined that this activity was not likely mediated by cytokine responses. Instead, we identified a complex mixture containing several upregulated host proteins. Selected individual proteins from the mixture exhibited HIV-enhancing activity only when applied with the complex mixture of proviral factors, suggesting that HIV enhancement might be mediated by synergistic effects. In addition to characterizing the immune interactions that mediate the enhanced HIV acquisition associated with BV, we also evaluated the safety and efficacy of RC- 101, a candidate vaginal microbicide being developed for the prevention of HIV transmission. RC-101 has been effective and well tolerated in preliminary cell culture and macaque models. However, the effect of RC-101 on primary vaginal tissues and resident vaginal microflora requires further evaluation. Here, we treated primary vaginal tissues and vaginal bacteria, both pathogenic and commensal, with RC-101 to investigate compatibility of this microbicide with FRT tissue and microflora. RC-101 was well tolerated by host tissues and commensal vaginal bacteria, while BV-associated bacteria were inhibited by RC-101. By establishing vaginal microflora, the specific antibacterial activity of RC-101 may provide a dual mechanism of HIV protection.