Oral mucosal immunity and HIV infection: current status

Salivary biochemical parameters in people living with HIV on ART and dental caries: a cross-sectional study in Monastir, Tunisia

BACKGROUND

Studies regarding salivary biochemical parameters and dental caries in adult people living with HIV/AIDS (PLWHA) are scanty.

AIM

To investigate salivary biochemical parameters and dental caries in adult PLWHA who are on antiretroviral therapy (ART) and compare the findings with people negative for HIV infection.

METHODS

The study included 50 HIV positive individuals as a test group (TG) and 50 HIV negative individuals as a control group (CG). Dental examination was performed according to WHO guidelines to assess DMFT. Digital panoramic radiographs were taken to detect additional infectious foci. Non-stimulated saliva was collected between 9 and 12 a. m for 5 min to evaluate 18 biochemical parameters and salivary flow rate (SFR). Parametric and non parametric tests were used according to data distribution. The level of significance was set at p < 0.05%.

RESULTS

Patients' mean ages and M/F sex ratios for TG and CG were 38.80 ± 9.69 y/o. vs. 37.98 ± 13.47 y/o. and 3.54 vs. 2.33, respectively. Higher means of decayed teeth were recorded in TG, 4.47 ± 3.00 vs. 3.88 ± 2.81 in CG with no significant difference (p = 0.41). Means of filled teeth were significantly lower in TG 2.38 ± 2.16 vs. 4.16 ± 3.35 in CG (p = 0.01), respectively. No statistical significant difference was noted in DMFT indices between the 2 groups (8.04 ± 6.90 vs. 8.52 ± 6.24, p = 0.71). The following salivary parameters were significantly lower in TG compared to CG, respectively: mean SFR 0.44 ± 0.18 ml/min vs. 0.61 ± 0.26 ml/min; median levels of sodium and chlorides, 4 mmol/L and 13.5 mmol/L vs. 9 mmol/L and 19 mmol/L (p < 0.001) and uric acid, 103.50 mmol/L vs. 163 (p = 0.009). However, higher median levels were recorded with calcium, 1.09 mmol/L vs. 0.54 (p < 0.001) and sIgA 23 mg/dl vs. 5 mg/dl (p < 0.001). In TG, a positive correlation was found between DC, potassium, urea, and chlorides (p < 0.05). Salivary renal and hepatic biomarkers were comparable between the two groups.

CONCLUSIONS

PLWHA have shown an alteration in some salivary parameters, more decayed teeth and less filled teeth. Preventive measures should be implemented to lower dental caries and enhance accessibility to oral care services. In addition, saliva can be utilized to monitor oral and general health status among PLWHA on ART.

Molecular Pathogenesis of Human Immunodeficiency Virus-Associated Disease of Oropharyngeal Mucosal Epithelium

The oropharyngeal mucosal epithelia have a polarized organization, which is critical for maintaining a highly efficient barrier as well as innate immune functions. In human immunodeficiency virus (HIV)/acquired immune deficiency syndrome (AIDS) disease, the barrier and innate immune functions of the oral mucosa are impaired via a number of mechanisms. The goal of this review was to discuss the molecular mechanisms of HIV/AIDS-associated changes in the oropharyngeal mucosa and their role in promoting HIV transmission and disease pathogenesis, notably the development of opportunistic infections, including human cytomegalovirus, herpes simplex virus, and Epstein-Barr virus. In addition, the significance of adult and newborn/infant oral mucosa in HIV resistance and transmission was analyzed. HIV/AIDS-associated changes in the oropharyngeal mucosal epithelium and their role in promoting human papillomavirus-positive and negative neoplastic malignancy are also discussed.

The initial interplay between HIV and mucosal innate immunity

Human Immunodeficiency Virus (HIV) is still one of the major global health issues, and despite significant efforts that have been put into studying the pathogenesis of HIV infection, several aspects need to be clarified, including how innate immunity acts in different anatomical compartments. Given the nature of HIV as a sexually transmitted disease, one of the aspects that demands particular attention is the mucosal innate immune response. Given this scenario, we focused our attention on the interplay between HIV and mucosal innate response: the different mucosae act as a physical barrier, whose integrity can be compromised by the infection, and the virus-cell interaction induces the innate immune response. In addition, we explored the role of the mucosal microbiota in facilitating or preventing HIV infection and highlighted how its changes could influence the development of several opportunistic infections. Although recent progress, a proper characterization of mucosal innate immune response and microbiota is still missing, and further studies are needed to understand how they can be helpful for the formulation of an effective vaccine.

Functional Perturbation of Mucosal Group 3 Innate Lymphoid and Natural Killer Cells in Simian-Human Immunodeficiency Virus/Simian Immunodeficiency Virus-Infected Infant Rhesus Macaques

Mother-to-child transmission of human immunodeficiency virus type 1 (HIV-1) via breastfeeding is responsible for nearly half of new infections of children with HIV. Although innate lymphoid cells (ILC) and natural killer (NK) cells are found throughout the oral mucosae, the effects of HIV/simian-human immunodeficiency virus (SHIV) in these tissues are largely unknown. To better understand the mechanics of postnatal transmission, we performed a comprehensive study of simian immunodeficiency virus (SIV)/SHIV-infected infant rhesus macaques (RM) and tracked changes in frequency, trafficking, and function of group 3 ILC (ILC3) and NK cells using polychromatic flow cytometry and cell stimulation assays in colon, tonsil, and oral lymph node samples. Infection led to a 3-fold depletion of ILC3 in the colon and an increase in the levels of NK cells in tonsils and oral lymph nodes. ILC3 and NK cells exhibited alterations in their trafficking repertoires as a result of infection, with increased expression of CD103 in colon NK cells and curtailment of CXCR3, and a significant decrease in α4β7 expression in colon ILC3. SPICE analyses revealed that ILC3 and NK cells displayed distinct functional profiles by tissue in naive samples. Infection perturbed these profiles, with a nearly total loss of interleukin-22 (IL-22) production in the tonsil and colon; an increase in the levels of CD107a, gamma interferon (IFN-γ), and tumor necrosis factor alpha (TNF-α) from ILC3; and an increase in the levels of CD107a, macrophage inflammatory protein 1 beta (MIP-1β), and TNF-α from NK cells. Collectively, these data reveal that lentivirus infection alters the frequencies, receptor repertoires, and functions of innate cells in the oral and gut mucosa of infants. Further study will be required to delineate the full extent of the effect that these changes have on oral and gut homeostasis, SHIV/SIV pathogenesis, and oral opportunistic disease.IMPORTANCE Vertical transmission of HIV from mother to child accounts for many of the new cases seen worldwide. There is currently no vaccine to mitigate this transmission, and there has been limited research on the effects that lentiviral infection has on the innate immune system in oral tissues of infected children. To fill this knowledge gap, our laboratory studied infant rhesus macaques to evaluate how acute SIV/SHIV infections impacted ILC3 and NK cells, which are immune cells critical for mucosal homeostasis and antimicrobial defense. Our data revealed that SIV/SHIV infection led to a depletion of ILC3 and an increase of NK cells and to a functional shift from a homeostatic to a multifunctional proinflammatory state. Taking the results together, we describe how lentiviral infection perturbs the oral and gastrointestinal mucosae of infant macaques through alterations of resident innate immune cells giving rise to chronic inflammation and potentially exacerbating morbidity and mortality in children living with HIV.

Correlation of High Interleukin 17A and Interleukin 6 Levels with High Virus Load Among Subtype C HIV-infected, Antiretroviral Therapy-naive Zimbabwean Patients: A Cross-sectional Study

Introduction:

In response to the human immunodeficiency virus (HIV) infection, activated immune cells produce several cytokines that alter the immune response and HIV disease progression. We quantified Th1/Th2/Th17 cytokines in an antiretroviral therapy naïve (ART) cohort to investigate their correlation with traditional markers of HIV disease progression; CD4+ T-lymphocytes and virus load (VL).

Methods:

We enrolled 247 HIV-infected ART-naïve participants into the study. CD4+ T- and CD8+ T-lymphocytes were enumerated using flow cytometry. VL was quantified using the Cavidi ExaVirTM Load assay. IL-2, IL-4, IL-6, IL-10, IL-17A, TNF-α, and IFN-γ levels were quantified using the BD Cytometric Bead Array Human Th1/Th2/Th17 cytokine assay. The Kendall’s rank correlation coefficient was used to determine the correlation between log10 transformed data for cytokine levels and CD4+ T- and CD8+ T-lymphocytes, CD4/CD8 ratio, and VL.

Results:

The median CD4+ T- and CD8+ T-lymphocyte counts were 458 cells/µL (IQR:405-556) and 776 cells/µL (IQR:581-1064), respectively. The median CD4/CD8 ratio was 0.6 (IQR: 0.45-0.86). The median VL was log103.3.copies/mL (IQR:2.74-3.93). Low CD4+ T-lymphocyte counts (p=0.010) and CD4/CD8 ratio (p=0.044) were significantly correlated with high VL. There was no significant correlation of cytokine levels with CD4+ T-, CD8+ T-lymphocyte counts and CD4/CD8 ratio. However, high levels of IL-17A (p=0.012) and IL-6 (p=0.034) were significantly correlated with high VL.

Conclusion:

Our study contributes to the little knowledge available on the role of cytokine profiles in the immune response to subtype C HIV infection.

The Effects of HIV Infection on Oral Mucosal Immunity

Oral mucosal infections, especially candidiasis, are a feature of HIV disease, suggesting that compromised mucosal immunity within the oral cavity is a consequence of the viral infection. However, how this mucosal immunity is compromised and at what stage of HIV infection this occurs are unclear. Better understanding of the protection of the oral cavity against infection has allowed us to gain some insight into the local consequences of HIV infection. From a humoral perpective, IgA2 subclasses are reduced in HIV infection in saliva, and total secretory IgA levels are reduced in later disease. Similarly, mucosal antibody responses appear near normal in early HIV infection but reduced in AIDS. There is now convincing evidence that salivary IgA can be neutralizing to HIV 1 and HIV 2, as well as block epithelial transmigration. Oral cellular immunity is also affected by HIV infection. Transmission of HIV from one oral cell type to another appears to be confirmed by work showing that HIV can bind to or infect epithelial cells, Langerhans cells, and other mucosal cells. CXCR4 tropic ( via GalCer and CXCR4) and dual tropic HIV strains have been shown to be able to infect normal human oral keratinocytes (NHOKs), and infectious HIV virions can also be conveyed from NHOKs to activated peripheral blood lymphocytes, suggesting a potential role of oral epithelial cells in the transmission of HIV infection. There is evidence of up-regulation of various receptors, including HIV receptors, on the surface of oral epithelium, and the epithelium may become more permeable. HIV may exploit this antigen uptake mechanism to cross epithelial barriers during co-infection with damage-inducing pathogens such as Candida. Immune responsiveness to many of the co-pathogens associated with HIV has been demonstrated to depend on a family of innate recognition molecules, known as Toll-like receptors (TLR), and recognition of a single pathogen can involve activation of multiple TLRs. Consequently, TLR-pathogen interactions could play an indirect but major role in regulating HIV-associated disease in the oral cavity. Thus, HIV infection appears to have both direct and indirect effects on oral mucosal immunity, affecting both cellular and humoral immunity as well as both specific and innate immunity.

Expression of oral cytokines in HIV-infected subjects with long-term use of antiretroviral therapy

OBJECTIVES

The objectives of this study were to determine (i) the expression of oral pro-inflammatory cytokines in HIV-infected subjects compared with non-HIV individuals, (ii) the cytokine expression in the subjects with antiretroviral therapy (ART) compared with those without ART, and (iii) factors associated with the expression of the cytokines.

MATERIALS AND METHODS

Oral examination was performed and saliva samples were collected and analyzed for the expression of pro-inflammatory cytokines using ELISA. Logistic regression analysis was performed to determine the association between HIV/ART status and the cytokine expression.

RESULTS

One hundred and fifty-seven HIV-infected subjects with and without ART, and 50 non-HIV individuals were enrolled. TNF-α and IL-6 in saliva were significantly decreased, while IL-8 was significantly increased in HIV infection (P < 0.05). Changes in the expression of IL-8 were also observed between HIV-infected subjects who were and were not on ART (P < 0.05). Duration of HIV infection and smoking was significantly associated with the expression of pro-inflammatory cytokines in saliva (P < 0.05).

CONCLUSION

Oral innate immunity is affected by HIV infection and use of ART. IL-8 may be the useful biomarker to identify subjects at risk of infection and malignant transformation due to HIV infection and long-term use of ART.

A systems biology examination of the human female genital tract shows compartmentalization of immune factor expression

Many mucosal factors in the female genital tract (FGT) have been associated with HIV susceptibility, but little is known about their anatomical distribution in the FGT compartments. This study comprehensively characterized global immune factor expression in different tissue sites of the lower and upper FGT by using a systems biology approach. Tissue sections from the ectocervix, endocervix, and endometrium from seven women who underwent hysterectomy were analyzed by a combination of quantitative mass spectrometry and immunohistochemical staining. Of the >1,000 proteins identified, 281 were found to be differentially abundant in different tissue sites. Hierarchical clustering identified four major functional pathways distinguishing compartments, including innate immune pathways (acute-phase response, LXR/RXR) and development (RhoA signaling, gluconeogenesis), which were enriched in the ectocervix/endocervix and endometrium, respectively. Immune factors important for HIV susceptibility, including antiproteases, immunoglobulins, complement components, and antimicrobial factors, were most abundant in the ectocervix/endocervix, while the endometrium had a greater abundance of certain factors that promote HIV replication. Immune factor abundance is heterogeneous throughout the FGT and shows unique immune microenvironments for HIV based on the exposure site. This may have important implications for early events in HIV transmission and site-specific susceptibility to HIV in the FGT.

Sampling human indigenous saliva peptidome using a lollipop-like ultrafiltration probe: simplify and enhance peptide detection for clinical mass spectrometry

Although human saliva proteome and peptidome have been revealed they were majorly identified from tryptic digests of saliva proteins. Identification of indigenous peptidome of human saliva without prior digestion with exogenous enzymes becomes imperative, since native peptides in human saliva provide potential values for diagnosing disease, predicting disease progression, and monitoring therapeutic efficacy. Appropriate sampling is a critical step for enhancement of identification of human indigenous saliva peptidome. Traditional methods of sampling human saliva involving centrifugation to remove debris may be too time-consuming to be applicable for clinical use. Furthermore, debris removal by centrifugation may be unable to clean most of the infected pathogens and remove the high abundance proteins that often hinder the identification of low abundance peptidome. Conventional proteomic approaches that primarily utilize two-dimensional gel electrophoresis (2-DE) gels in conjugation with in-gel digestion are capable of identifying many saliva proteins. However, this approach is generally not sufficiently sensitive to detect low abundance peptides/proteins. Liquid chromatography-Mass spectrometry (LC-MS) based proteomics is an alternative that can identify proteins without prior 2-DE separation. Although this approach provides higher sensitivity, it generally needs prior sample pre-fractionation and pre-digestion with trypsin, which makes it difficult for clinical use. To circumvent the hindrance in mass spectrometry due to sample preparation, we have developed a technique called capillary ultrafiltration (CUF) probes. Data from our laboratory demonstrated that the CUF probes are capable of capturing proteins in vivo from various microenvironments in animals in a dynamic and minimally invasive manner. No centrifugation is needed since a negative pressure is created by simply syringe withdrawing during sample collection. The CUF probes combined with LC-MS have successfully identified tryptic-digested proteins. In this study, we upgraded the ultrafiltration sampling technique by creating a lollipop-like ultrafiltration (LLUF) probe that can easily fit in the human oral cavity. The direct analysis by LC-MS without trypsin digestion showed that human saliva indigenously contains many peptide fragments derived from various proteins. Sampling saliva with LLUF probes avoided centrifugation but effectively removed many larger and high abundance proteins. Our mass spectrometric results illustrated that many low abundance peptides became detectable after filtering out larger proteins with LLUF probes. Detection of low abundance saliva peptides was independent of multiple-step sample separation with chromatography. For clinical application, the LLUF probes incorporated with LC-MS could potentially be used in the future to monitor disease progression from saliva.

Changes in oral cytokeratin expression in HIV-infected subjects with long-term use of HAART

OBJECTIVES

The objectives of this study were to determine (i) the expression of oral cytokeratins (CKs) among human immunodeficiency virus (HIV)-infected subjects compared with non-HIV controls, (ii) the oral CK expression in the subjects with highly active antiretroviral therapy (HAART) compared with those without HAART, and (iii) factors associated with the expression of oral CKs.

MATERIALS AND METHODS

Oral tissues from buccal mucosa were obtained by punched biopsy in HIV-infected subjects with and without HAART, and non-HIV individuals. The samples were processed for immunohistochemical studies of CK1, CK13, CK14, CK16, and involucrin. The staining intensity was scored and recorded. Logistic regression analysis and multi-way ANOVA test were performed.

RESULTS

The expression of CK13, CK14, and CK16 was found to be significantly different between HIV-infected subjects and non-HIV individuals (P < 0.05). The expression of those CKs was also significantly different between those who were and were not on HAART (P < 0.05). No significant difference between the groups was observed regarding CK1 and involucrin.

CONCLUSIONS

 Oral epithelial cell differentiation as marked by the CK expression is affected by HIV infection and use of HAART. CKs may be the useful biomarkers to identify HIV-infected subjects who are at risk of malignant transformation of the oral mucosa because of HIV infection and HAART.

Oral human β-defensin 2 in HIV-infected subjects with long-term use of antiretroviral therapy

BACKGROUND

The objectives of this study were to determine (i) oral hBD2 expression in HIV-infected subjects compared with non-HIV controls, (ii) the expression of oral hBD2 in HIV-infected subjects with antiretroviral therapy (ART) compared with those without ART, and (iii) factors associated with the expression of oral hBD2.

METHODS

Oral examination and punched biopsy on buccal mucosa were performed in HIV-infected subjects with and without ART, and non-HIV individuals. The expression of hBD2 mRNA was determined by quantitative real-time PCR. Saliva samples of both un-stimulated and stimulated saliva were collected and analyzed for hBD2 levels using ELISA. Student's t-test and nonparametric multi-way ANOVA test were used for comparison of measurements between or among groups.

RESULTS

One hundred and fifty-seven HIV-infected subjects were enrolled: 99 on ART (age range, 23-57 years; mean 39 years), 58 not on ART (age range, 20-59 years; mean 34 years), and 50 non-HIV controls (age range, 19-59 years; mean 36 years). The most common ART regimen was two nucleoside reverse transcriptase inhibitors + one non-nucleoside reverse transcriptase inhibitor. Salivary levels of hBD2 were significantly increased in HIV infection (P < 0.001). The levels of hBD2 in stimulated saliva were also found to be significantly different between HIV-infected subjects who were and were not on ART (P < 0.001). No significant difference was observed with the expression of hBD2 mRNA.

CONCLUSION

Oral innate immunity is affected by HIV infection and use of ART. Salivary hBD2 levels may be the useful biomarkers to monitor those on long-term ART who are at risk of developing oral infections and malignant transformation.

Comprehensive proteomic study identifies serpin and cystatin antiproteases as novel correlates of HIV-1 resistance in the cervicovaginal mucosa of female sex workers

Not all individuals exposed to HIV-1 become infected, and evidence from HIV-1 highly exposed seronegative women (HIV-1-resistant) suggests that mucosal factors in the female genital tract, the first site of contact for the virus, are playing a role. To better understand factors mediating protection from HIV-1, we performed a large clinical study using the tools of systems biology to fully characterize the cervicovaginal mucosa proteome in HIV-1-resistant women. Cervicovaginal lavage fluid was collected from 293 HIV-1-resistant, uninfected, and infected sex workers and analyzed by 2D-LC LTQ-FT-MS. Of the more than 360 unique proteins identified, 41 were differentially abundant (>3-fold cutoff) in HIV-1-resistant women. The majority of over-abundant proteins were antiproteases (>40%), some with described anti-inflammatory and anti-HIV-1 activity. Quantification of specific anti-HIV-1 antiproteases Serpin A1, Serpin A3, and Cystatin B and an epithelial antiprotease A2ML1 found them to be significantly over-abundant in HIV-1-resistant women (p = 0.004; p = 0.046; p = 0.0003; and p = 0.04, respectively). Expression levels were not correlated to sexual practices or other epidemiological factors. Mucosal antiprotease levels correlated with pro-inflammatory cytokine concentration (p = <0.0001), but independently of pro-inflammatory cytokine levels in HIV-1-resistant women including TNF-alpha, IL-1 alpha, IL-1 beta, IL-6, and IL-8. This comprehensive systems biology approach identifies mucosal serpins and cystatins as novel correlates of HIV-1-resistance. This represents the first study characterizing these factors in the female genital tract.

Premasticating food for weaning African infants: a possible vehicle for transmission of HIV

BACKGROUND

Although premastication of food for weaning infants might have nutritional benefit, it is also associated with transmission of pathogens. We investigated premastication practices in Cape Town, South Africa, in lower socioeconomic status caregivers of infants below 2 years of age.

METHODS

A previously reported questionnaire was adapted for South African conditions. A convenience sample of infant caregivers was captured at public maternal/pediatric and HIV outpatient clinics and home visits.

RESULTS

We interviewed 154 caregivers, 92% of whom were the biological mothers (median age: 29). Of these, 70% were black, and 29% were colored. There were 106 (69%) caregivers who practiced premastication. The median age of infants who received premasticated food was 6 (interquartile range: 4-6) months. Forty-six (43%) infants were teething, and 44 (42%) had oral mucosal lesions while receiving premasticated food. Fifty-five (52%) caregivers reported an oral condition, mostly bleeding gums, mouth sores, and thrush, and 41 (39%) caregivers reported blood in the food. Premasticating caregivers had a significantly lower educational level than those caregivers who did not engage in this practice. Premastication practices were cultural (40%), habit (20%), and on mother's advice (75%). Reasons for premastication were to pretaste (68%), encourage eating (61%), estimate food temperature (85%), and homogenize food (60%).

CONCLUSIONS

Counselors and caregivers should be aware of the adverse effects of premastication. Education should include advice to avoid premastication and to seek health advice for oral conditions in the caregiver and child. More studies are needed to better define the extent and risks of premastication, including its possible role in increasing HIV-1 transmission.

Mucosal HIV transmission and vaccination strategies through oral compared with vaginal and rectal routes

IMPORTANCE OF THE FIELD

There are currently over thirty million people infected with HIV and there are no vaccines available to prevent HIV infections or disease. The genitourinary, rectal and oral mucosa are the mucosal HIV transmission routes. An effective vaccine that can induce both systemic and local mucosal immunity is generally accepted as a major means of protection against mucosal HIV transmission and AIDS.

WHAT THE READER WILL GAIN

Structure and cells that comprise the oral, vaginal and rectal mucosa pertaining to HIV transmission and vaccination strategies through each mucosal route to prevent mucosal and systemic infection will be discussed.

AREAS COVERED IN THIS REVIEW

Covering publications from 1980s through 2010, mucosal transmission of HIV and current and previous approaches to vaccinations are discussed.

TAKE HOME MESSAGE

Although oral transmission of HIV is far less common than vaginal and rectal transmissions, infections through this route do occur through oral sex as well as vertically from mother to child. Mucosal vaccination strategies against oral and other mucosal HIV transmissions are under intensive research but the lack of consensus on immune correlates of protection and lack of safe and effective mucosal adjuvants and delivery systems hamper progress towards a licensed vaccine.

Characterization of SIV in the oral cavity and in vitro inhibition of SIV by rhesus macaque saliva

Human immunodeficiency virus (HIV) infections are rarely acquired via an oral route in adults. Previous studies have shown that human whole saliva inhibits HIV infection in vitro, and multiple factors present in human saliva have been shown to contribute to this antiviral activity. Despite the widespread use of simian immunodeficiency virus (SIV)-infected rhesus macaques as models for HIV pathogenesis and transmission, few studies have monitored SIV in the oral cavity of infected rhesus macaques and evaluated the viral inhibitory capacity of macaque saliva. Utilizing a cohort of rhesus macaques infected with SIV(Mac251), we monitored virus levels and genotypic diversity in the saliva throughout the course of the disease; findings were similar to previous observations in HIV-infected humans. An in vitro infectivity assay was utilized to measure inhibition of HIV/SIV infection by normal human and rhesus macaque whole saliva. Both human and macaque saliva were capable of inhibiting HIV and SIV infection. The inhibitory capacity of saliva samples collected from a cohort of animals postinfection with SIV increased over the course of disease, coincident with the development of SIV-specific antibodies in the saliva. These findings suggest that both innate and adaptive factors contribute to inhibition of SIV by whole macaque saliva. This work also demonstrates that SIV-infected rhesus macaques provide a relevant model to examine the innate and adaptive immune responses that inhibit HIV/SIV in the oral cavity.

Loss of growth factor receptor signaling in the oral mucosa during primary SIV infection may enhance apoptosis and promote pathogenesis

BACKGROUND

The development of susceptibility to secondary pathogenic infections in the oral cavity during HIV infection is likely to result from or coincide with deterioration of the local mucosal immune system.

METHODS

We have utilized the SIV model to investigate the kinetics and magnitude of oral pathogenesis during systemic dissemination of intravenously inoculated SIVmac251.

RESULTS

Viral replication was detected in oropharyngeal lymph nodes at 6 weeks post-infection and shown to be coincident with a broad scale loss of growth factor receptor transcription in the oral mucosa, providing multiple avenues for blocking the normal activity of apoptosis inhibitors that function through Bcl2- and p53-dependent pathways.

CONCLUSIONS

Our findings suggest that the normal balance between cell death and regeneration may be rapidly disrupted in the oral mucosa during the early stages of immunodeficiency virus infection, setting the stage for continuing deterioration of immune function and the development of susceptibility to secondary infections.

Prevalence of oral disease among adults with primary HIV infection

OBJECTIVE

To explore the type and prevalence of oral mucosal lesions among adults with primary HIV infection (PHI) compared with HIV-negative adults at high risk for HIV disease, and in relation to HIV viral load.

METHODS

We conducted standardized oral examinations to identify specific oral mucosal lesions among adults with PHI, both pre-seroconversion and post- seroconversion-recently infected, compared with HIV-negative adults. We compared the group with oral lesions to those without oral lesions with respect to HIV-RNA load and CD4 + T-cell count.

RESULTS

Among 115 adults (predominantly men), pseudomembranous candidiasis was the most common oral lesion among those with PHI, and was found in 4% of the 23 participants in pre-seroconversion and in 9% of 69 participants with post-seroconversion recent infection, compared with none found among 23 HIV negatives. Among those with PHI, the median viral load was higher and the median CD4 + T-cell count lower among the 15 participants with an oral lesion of any type than among the 77 participants without oral lesions (P = 0.02 and 0.04, respectively).

CONCLUSION

This finding suggests that individuals with PHI who have oral lesions may be more likely to transmit HIV because of their higher viral load.

Heightened cytotoxic responses and impaired biogenesis contribute to early pathogenesis in the oral mucosa of simian immunodeficiency virus-infected rhesus macaques

Simian immunodeficiency virus (SIV) infection disseminated into the oropharyngeal tissues of rhesus macaques 6 weeks following intravenous inoculation. Severe local CD4(+) T-cell depletion coincided with increases in NK cell and proinflammatory biomarkers and the disruption of growth-associated gene transcription, demonstrating the rapid establishment of pathogenesis in the oral mucosa.

Identification of differentially expressed proteins in the cervical mucosa of HIV-1-resistant sex workers

Novel tools are necessary to understand mechanisms of altered susceptibility to HIV-1 infection in women of the Pumwani Sex Worker cohort, Kenya. In this cohort, more than 140 of the 2000 participants have been characterized to be relatively resistant to HIV-1 infection. Given that sexual transmission of HIV-1 occurs through mucosal surfaces such as that in the cervicovaginal environment, our hypothesis is that innate immune factors in the genital tract may play a role in HIV-1 infection resistance. Understanding this mechanism may help develop microbicides and/or vaccines against HIV-1. A quantitative proteomics technique (2D-DIGE: two-dimensional difference in-gel electrophoresis) was used to examine cervical mucosa of HIV-1 resistant women ( n = 10) for biomarkers of HIV-1 resistance. Over 15 proteins were found to be differentially expressed between HIV-1-resistant women and control groups ( n = 29), some which show a greater than 8-fold change. HIV-1-resistant women overexpressed several antiproteases, including those from the serpin B family, and also cystatin A, a known anti-HIV-1 factor. Immunoblotting for a selection of the identified proteins confirmed the DIGE volume differences. Validation of these results on a larger sample of individuals will provide further evidence these biomarkers are associated with HIV-1 resistance and could help aid in the development of effective microbicides against HIV-1.

Differential regulation of the transcriptional repressor NRG1 accounts for altered host-cell interactions in Candida albicans and Candida dubliniensis

Candida dubliniensis is genetically closely related to Candida albicans, but causes fewer infections in humans and exhibits reduced virulence and filamentation in animal models of infection. We investigated the role of the C. dubliniensis transcriptional repressor-encoding gene CdNRG1 in regulating this phenotype. Deletion of both copies of CdNRG1 increased the formation of true hyphae by C. dubliniensis in response to serum, exogenous cAMP and CO2. In addition, deletion of CdNRG1 greatly enhanced filamentation and survival of C. dubliniensis in co-culture with murine macrophages. In the reconstituted human oral epithelium infection model, the nrg1Delta mutant caused increased tissue damage relative to the wild-type strain. However, deletion of CdNRG1 did not change the virulence of C. dubliniensis in the systemic mouse model of infection. The increased rate of hypha formation in C. albicans relative to C. dubliniensis in response to phagocytosis by macrophages and serum was associated with rapid downregulation of NRG1 expression in C. albicans. This study demonstrates that the reduced virulence and host cell damage elicited by C. dubliniensis may in part be due to the inability of this species to modulate NRG1 expression in response to the same environmental signals that promote filamentation in C. albicans.

Epstein-Barr virus (EBV)-infected monocytes facilitate dissemination of EBV within the oral mucosal epithelium

Epstein-Barr virus (EBV) causes hairy leukoplakia (HL), a benign lesion of oral epithelium that occurs primarily in the setting of human immunodeficiency virus (HIV)-associated immunodeficiency. However, the mechanisms of EBV infection of oral epithelium are poorly understood. Analysis of HL tissues shows a small number of EBV-positive intraepithelial macrophages and dendritic/Langerhans cells. To investigate a role for these cells in spreading EBV to epithelial cells, we used tongue and buccal explants infected ex vivo with EBV. We showed that EBV first infects submucosal CD14(+) monocytes, which then migrate into the epithelium and spread virus to oral epithelial cells, initiating productive viral infection within the terminally differentiated spinosum and granulosum layers. Incubation of EBV-infected monocytes and oral explants with antibodies to CCR2 receptor and monocyte chemotactic protein 1 prevented entry of monocytes into the epithelium and inhibited EBV infection of keratinocytes. B lymphocytes played little part in the spread of EBV to keratinocytes in our explant model. However, cocultivation of EBV-infected B lymphocytes with uninfected monocytes in vitro showed that EBV may spread from B lymphocytes to monocytes. Circulating EBV-positive monocytes were detected in most HIV-infected individuals, consistent with a model in which EBV may be spread from B lymphocytes to monocytes, which then enter the epithelium and initiate productive viral infection of keratinocytes.

Saliva can mediate HIV-1-specific antibody-dependent cell-mediated cytotoxicity

HIV is not usually transmitted by saliva from HIV-1-infected individuals. Antiviral substances in saliva responsible for this may include HIV-1-specific antibody-dependent cell-mediated cytotoxicity (ADCC). We evaluated saliva ADCC titers of 62 HIV-1-infected women from the Women's Interagency HIV Study (WIHS) and 55 uninfected individuals. HIV-1-infected women were less likely to have ADCC activity in saliva than in serum or cervical lavage fluid (CVL). 24% of HIV-1-positive women and a similar percentage of uninfected women had HIV-1-specific saliva ADCC activity. A significant amount of saliva ADCC activity in infected women was HIV-gp120-specific. These studies demonstrate that HIV-specific ADCC activity can be present in saliva. This activity may contribute to host defence against initial infection with HIV.

Oral transmission of HIV, reality or fiction? An update

Human immunodeficiency virus (HIV) and many other viruses can be isolated in blood and body fluids, including saliva, and can be transmitted by genital-genital and especially anal-genital sexual activity. The risk of transmission of HIV via oral sexual practices is very low. Unlike other mucosal areas of the body, the oral cavity appears to be an extremely uncommon transmission route for HIV. We present a review of available evidence on the oral-genital transmission of HIV and analyse the factors that act to protect oral tissues from infection, thereby reducing the risk of HIV transmission by oral sex. Among these factors we highlight the levels of HIV RNA in saliva, presence of fewer CD4+ target cells, presence of IgA antibodies in saliva, presence of other infections in the oral cavity and the endogenous salivary antiviral factors lysozyme, defensins, thrombospondin and secretory leucocyte protease inhibitor (SLPI).

Cystatin A and HIV-1 p24 antigen expression in tonsillar lymphoid follicles during HIV-1 infection and during highly active antiretroviral therapy

Cystatin A is a natural cysteine proteinase inhibitor and is found in a wide variety of normal cells. The physiologic role of Cystatin A is not fully known, however. Cystatin A is present in large amounts in follicular dendritic cells, which are important in HIV-1 pathogenesis. We analyzed Cystatin A expression in tonsillar sections from 20 patients at various stages of HIV-1 infection. There was a significant (P < 0.001) difference in Cystatin A fractions between patients and controls, with medians (ranges) of 0.61 (0.46-0.83) and 0.86 (0.78-0.90), respectively. Inverse correlations (Spearman rho) existed between Cystatin A and the rate of follicular fragmentation (rho = -0.658) and HIV-1 p24 antigen expression (rho = -0.622) in germinal centers and the amount of HIV-1 RNA in tonsillar tissue (rho = -0.765). The Cystatin A fraction declined from early chronic HIV-1 infection and was significantly lower in patients with a CD4 count below as compared with above 300 cells/muL of blood (P < 0.001), suggesting a favorable initiation of highly active antiretroviral therapy (HAART) at this level. Regeneration of Cystatin A to normal levels was shown in 11 patients 12 and 48 weeks after initiation of HAART, whereas the rate of follicular fragmentation was still elevated. Thus, we found Cystatin A to be a sensitive marker during HIV-1 infection and for regeneration of follicular lymphoid tissue during HAART.

Differential mucosal susceptibility in HIV-1 transmission and infection

HIV infection occurs primarily through mucosal surfaces, indicating that protection at mucosal sites may be crucial in prevention and treatment. The host innate and adaptive immune elements provide a level of protection, which differs between mucosal compartments, and appears to be most successful in the oral environment, where transmission is rare. In addition to the distinct oral mucosal architecture and cellular constituents, oral fluids, unlike other mucosal secretions, are rarely a vehicle for HIV infection. Multiple soluble factors may contribute to this antiviral activity, including neutralizing antibodies, secretory leukocyte protease inhibitor (SLPI), antiviral peptides such as defensins and cystatins, glycoproteins including thrombospondin and lactoferrin, and complement components. Understanding the antiviral activities of these and other potential resistance factors is becoming increasingly important in attempts to design treatments in the era of HAART resistance. In this regard, the mechanism of anti-HIV action of SLPI has recently been further elucidated by the discovery of its binding protein/receptor, which plays a key role in the infection of macrophages and may consequently be a novel therapeutic target. Continued elucidation of the unique features of mucosal HIV immunology is essential for understanding HIV pathogenesis and for developing effective vaccines and therapeutics.

A Drosophila salivary gland mucin is also expressed in immune tissues: evidence for a function in coagulation and the entrapment of bacteria

Our studies on the developmental regulation of glycosylation in Drosophila melanogaster led us to identify and characterize gp150, an ecdysone-regulated mucin that is found in hemocytes, the gut (peritrophic membrane) and in the salivary glands. We are particularly interested in mucin immune functions and found that gp150 is released from larval hemocytes, becomes part of the clot and participates in the entrapment of bacteria. By RT-PCR and RNAi experiments, we identified gp150 as the previously described I71-7, an ecdysone-induced salivary glue protein. We discuss the evolutionary and biochemical implications of the dual use of salivary proteins for immune functions in insects. Further molecular characterization of such shared proteins may enable a better understanding of the properties of proteins involved in containment and elimination of microbes, as well as hemostasis and wound repair.

Salivary IgA to cariogenic bacteria in HIV-positive children and its correlation with caries prevalence and levels of cariogenic microorganisms

The interrelationship of HIV infection, dental caries and mucosal immune responses remains controversial. In our study population of 40 HIV-infected and 40 healthy control children (ages 2-5 years) there was a significantly higher prevalence of dental caries in HIV-infected children (P<0.05). The extent of caries correlated with the severity of HIV disease. To determine whether the immunosuppression that ensues after HIV infection could contribute to the increased caries prevalence, the concentrations of total IgA and IgA specific to cariogenic bacteria (Streptococcus mutans, Streptococcus sobrinus and Lactobacillus acidophilus) were determined in whole saliva by enzyme-linked immunosorbent assay. Levels of the same bacteria were also quantified in saliva using checkerboard DNA-DNA hybridization. A significantly increased level of total salivary IgA was found in the HIV-positive population (P < 0.05), but there were comparable titers of specific IgA to cariogenic bacteria in HIV-positive and healthy controls. The microbiological assessment also demonstrated similar levels of cariogenic microorganisms in both groups. We conclude that HIV-positive children appear to maintain the capacity to mount a mucosal immune response to cariogenic microorganisms, at least until late stages of disease.

Immunopathogenesis of oropharyngeal candidiasis in human immunodeficiency virus infection

Oropharyngeal and esophageal candidiases remain significant causes of morbidity in human immunodeficiency virus (HIV)-infected patients, despite the dramatic ability of antiretroviral therapy to reconstitute immunity. Notable advances have been achieved in understanding, at the molecular level, the relationships between the progression of HIV infection, the acquisition, maintenance, and clonality of oral candidal populations, and the emergence of antifungal resistance. However, the critical immunological defects which are responsible for the onset and maintenance of mucosal candidiasis in patients with HIV infection have not been elucidated. The devastating impact of HIV infection on mucosal Langerhans' cell and CD4(+) cell populations is most probably central to the pathogenesis of mucosal candidiasis in HIV-infected patients. However, these defects may be partly compensated by preserved host defense mechanisms (calprotectin, keratinocytes, CD8(+) T cells, and phagocytes) which, individually or together, may limit Candida albicans proliferation to the superficial mucosa. The availability of CD4C/HIV transgenic mice expressing HIV-1 in immune cells has provided the opportunity to devise a novel model of mucosal candidiasis that closely mimics the clinical and pathological features of candidal infection in human HIV infection. These transgenic mice allow, for the first time, a precise cause-and-effect analysis of the immunopathogenesis of mucosal candidiasis in HIV infection under controlled conditions in a small laboratory animal.

Salivary secretory leukocyte protease inhibitor and oral candidiasis in human immunodeficiency virus type 1-infected persons

Oropharyngeal candidiasis, typically caused by Candida albicans, is the most common oral disease associated with human immunodeficiency virus type 1 (HIV-1) infection. Secretory leukocyte protease inhibitor (SLPI), a 12-kDa antiprotease, suppresses the growth of C. albicans in vitro. To determine whether the mucosal protein plays a role in protecting oral tissues against fungal infection, we conducted a cross-sectional study investigating the oral and systemic health and salivary SLPI levels in 91 dentate HIV-1-infected adults receiving medical care in the southeastern United States. Participants with a self-reported history of clinical oropharyngeal candidiasis during the previous 2 years constituted the test group (n = 52), while the comparison group (n = 39) had no oropharyngeal candidiasis during that period. Data collected from medical records, oral examination, and SLPI enzyme-linked immunosorbent assay quantitation of whole saliva were analyzed by t test, analysis of variance, linear regression, and unconditional logistic regression. The test group had a significantly higher mean salivary SLPI level than the comparison group (1.9 microg/ml versus 1.1 microg/ml, P < 0.05). Linear regression modeling identified CD4 cell count and history of oropharyngeal candidiasis as key predictors of salivary SLPI and revealed a significant interaction (P < 0.05) between immunosuppression (CD4 cell count below 200 cells/ microl) and positive history of oropharyngeal candidiasis in predicting salivary SLPI level. By logistic regression modeling, a salivary SLPI level exceeding 2.1 microg/ml, low CD4 count, antiretroviral monotherapy, and smoking were key predictors of oropharyngeal candidiasis. These data support a key role for SLPI in the oral mucosal defense against C. albicans. The antimicrobial mucosal protein may serve as an indicator of previous oropharyngeal candidiasis infection among immunosuppressed persons.

Salivary IgA in response to periodontal treatment

There is evidence that the quantity of antigen load is crucial for the activation of IgA immune responses. In order to investigate the relevance of these findings in aggressive periodontitis, salivary antibody responses were measured during non-surgical and antibiotic treatment. Twenty-one patients with generalized aggressive periodontitis were monitored for total salivary IgA and IgA reactive to Porphyromonas gingivalis in resting and stimulated whole saliva. Non-surgical treatment included full-mouth professional tooth cleaning and subgingival scaling and root planing (SRP) under local anesthesia. Patients were recalled at 3 months and 6 months following systemic antibiotic treatment. Non-parametric statistics showed significant improvements in the clinical parameters in all patients. Between baseline and 4 wk following SRP, median concentrations of total IgA decreased both in resting (-46%) and in stimulated (-33%) saliva. The P. gingivalis-specific IgA activity showed a twofold increase at 4 wk after SRP. In addition to these changes, periodontal treatment of aggressive periodontitis did not appear to affect salivary IgA, and there were no significant correlations of IgA to the clinical parameters. In conclusion, salivary IgA responses during periodontal treatment were not found to have a diagnostic or prognostic significance.

PELA microspheres loaded H. pylori lysates and their mucosal immune response

AIM: To prepare poly (D,L-lactide)-polyethylene glycol copolymer (PELA) microspheres loaded H.pylori lysates or Cystografin and observe their targeting in gastrointestinal mucous membrane or analyze the mucosal immune responses by oral administration.

METHODS: PELA microspheres loaded H.pylori lysates or Cystografin were prepared by double emulsion evaporation method. Their distribution in gastrointestinal mucous membrane was observed by CT.Balb/c mice orally immunized in mucosal immune responses, whose antibody production in salivary and gut washing and antibody secreting cells in Peyer’s patches (PP) were estimated by ELISA and ELISPOT, respectively. The microspheres’ physical properties, such as particle size, protein level and morphology were investigated.

RESULTS: All prepared microspheres were found to have a smooth surface morphology from 3.20-4.05 μm in diameter and high encapsulation efficiency from 74.9%-82.2%. No significant correlation in their physical properties was shown, depending on their molecular weight at the similar composition ratio. Immunization with all types of PELA-Hp microspheres elevated the saliva sIgA level at week 3 by approximately 3-4 times that with soluble antigen, which was greatly enhanced after boosting. At one week after last immunization with all types of PELA-Hp microspheres (week 8), the specific sIgA-ASCs, IgG-ASCs and sIgA in salivary rose obviously. In intestinal Peyer’s patches, the specific sIgA-ASCs were 5.92-6.98 × 10⁴/mL cell and IgG-ASCs were 3.47-4.02 × 10⁴/mL cell, about 5-9 times higher than those with soluble antigen (P < 0.01). ASCs in intestine were more than those in stomach and the majority of the ASCs were sIgA-ASCs. The sIgA in gut washing fluid was 1.62-1.85 OD, about 3-6 times tthat of those with soluble antigen. There were significant differences of the ASCs and sIgA in gut washing fluid as compared with those of PBS and MS-0 (P < 0.05). There appeared to be good correlation between sIgA level in gut washing fluid and sIgA-ASCs in intestinal Peyer’s patches.

CONCLUSION: PELA microspheres may be used as vehicle to delivery antigen and adjuvant in designing oral vaccination.