The anti-HIV-1 activity associated with saliva

Biogeographical Impacts of Dental, Oral, and Craniofacial Microbial Reservoirs

The human mouth, or oral cavity, is at the crossroads of our external and internal environments, and it is increasingly evident that local colonization of dental, oral, and craniofacial (DOC) tissues and cells by bacteria and viruses may also have systemic effects across myriad diseases and disorders. Better understanding of this phenomenon will require a holistic understanding of host-microbial interactions in both spatiotemporal and biogeographical contexts while also considering person-, organ-, tissue-, cell-, and molecular-level variation. After the acute phase interaction with microbes, the establishment of site-specific reservoirs constitutes an important relationship to understand within the human body; however, despite a preliminary understanding of how viral reservoirs originate and persist across the human body, the landscape of single-cell and spatial multiomic tools has challenged our current understanding of what cells and niches can support microbial reservoirs. The lack of complete understanding impacts research into these relevant topics and implementing precision care for microbial-induced or microbial-influenced diseases. Here, via the lens of acute and chronic microbial infections of the DOC tissues, the goal of this review is to highlight and link the emerging spatiotemporal biogeography of host-viral interactomics at 3 levels: (1) DOC cell types in distinct tissues, (2) DOC-associated microbes, and (3) niche-specific DOC pathologies. Further, we will focus on the impact of postacute infectious syndromes such as long COVID, neurodegenerative disorders, and other underappreciated postviral conditions. We will provide hypotheses about how DOC tissues may play roles systemically in these conditions. Throughout, we will underscore how COVID-19 has catalyzed a new understanding of these biological questions, discuss future directions to study these phenomena, and highlight the utility of noninvasive oral biofluids in screening, monitoring, and intervening to prevent and/or ameliorate human infectious diseases.

Gingival tissue as a reservoir for human immunodeficiency virus type-1: Preliminary results of a cross-sectional observational study

BACKGROUND

Despite combined antiretroviral therapy (cART), total cure of immunodeficiency virus type 1 (HIV-1) infection remains elusive. Chronic periodontitis (CP) is strongly associated with HIV-1 infection. This condition is characterized by an intense inflammatory infiltrate mainly constituted of immune cells which in turn may be a valuable source of HIV-1 reactivation. This study aimed to determine if gingival tissue could act as a reservoir for HIV-1.

METHODS

Twelve HIV-1-infected patients with CP and 12 controls (no HIV-1-infection and no CP) were evaluated in a cross-sectional study. RNA viral load and interleukin (IL) levels were determined in blood plasma and saliva. Histological sections of gingival tissue were stained with fluorescent antibodies against p24 antigen and different cellular biomarkers.

RESULTS

In 6 of the 12 patients, HIV RNA load was detected, despite cART; in three of them, expression of viral RNA was also detected in saliva. The levels of IL-2, IL-6 and IL-12 were higher in blood and saliva of HIV-infected patients with CP than controls. HIV-1 p24 antigen was detected by Immunostaining in gingival biopsies of 10 of the 12 patients but in no control. Immune markers for T cells and antigen-presenting cells were also identified in most patients and some controls.

CONCLUSION

These preliminary data showing the detection of HIV-1 p24 antigen in the gingival biopsies of a significant part of HIV-1 infected patients with CP under cART together with the presence of immune cells, plead for the existence of a HIV-1 reservoir in the gingival tissue of this population. This article is protected by copyright. All rights reserved.

Expert consensus statement on the science of HIV in the context of criminal law

INTRODUCTION

Globally, prosecutions for non-disclosure, exposure or transmission of HIV frequently relate to sexual activity, biting, or spitting. This includes instances in which no harm was intended, HIV transmission did not occur, and HIV transmission was extremely unlikely or not possible. This suggests prosecutions are not always guided by the best available scientific and medical evidence.

DISCUSSION

Twenty scientists from regions across the world developed this Expert Consensus Statement to address the use of HIV science by the criminal justice system. A detailed analysis of the best available scientific and medical research data on HIV transmission, treatment effectiveness and forensic phylogenetic evidence was performed and described so it may be better understood in criminal law contexts. Description of the possibility of HIV transmission was limited to acts most often at issue in criminal cases. The possibility of HIV transmission during a single, specific act was positioned along a continuum of risk, noting that the possibility of HIV transmission varies according to a range of intersecting factors including viral load, condom use, and other risk reduction practices. Current evidence suggests the possibility of HIV transmission during a single episode of sex, biting or spitting ranges from no possibility to low possibility. Further research considered the positive health impact of modern antiretroviral therapies that have improved the life expectancy of most people living with HIV to a point similar to their HIV-negative counterparts, transforming HIV infection into a chronic, manageable health condition. Lastly, consideration of the use of scientific evidence in court found that phylogenetic analysis alone cannot prove beyond reasonable doubt that one person infected another although it can be used to exonerate a defendant.

CONCLUSIONS

The application of up-to-date scientific evidence in criminal cases has the potential to limit unjust prosecutions and convictions. The authors recommend that caution be exercised when considering prosecution, and encourage governments and those working in legal and judicial systems to pay close attention to the significant advances in HIV science that have occurred over the last three decades to ensure current scientific knowledge informs application of the law in cases related to HIV.

Factors contributing to salivary human immunodeficiency virus type-1 levels measured by a Poisson distribution-based PCR method

Objective To elucidate the mechanism underlying secretion of human immunodeficiency virus type 1 (HIV-1) into the oral cavity, by examining the relationships between various oral and systemic factors and the viral load in saliva. Methods Plasma and saliva samples from HIV-1 infected patients were assayed using the COBAS® AmpliPrep/COBAS® TaqMan® HIV-1 Test, version 1.0 and a Poisson distribution-based polymerase chain reaction (PCR) method for quantifying HIV-1 RNA and DNA. Results Forty-four pairs of samples were obtained from 18 patients. Salivary viral load was approximately 10% of the plasma viral load, but higher than the plasma load in two patients. The salivary viral DNA load was < 1% of the total HIV-1 nucleic acid load except in one patient who had more viral DNA than RNA. Multiple regression analysis showed that salivary viral load was significantly correlated with plasma viral load (partial correlation coefficient, 0.90) and the community periodontal index (-0.63). Conclusions The present results suggest that excretion through salivary glands, but not occult bleeding, may be a major pathway of HIV-1 into the oral cavity.

Mucus and Mucins: do they have a role in the inhibition of the human immunodeficiency virus?

BACKGROUND

Mucins are large O-linked glycosylated proteins which give mucus their gel-forming properties. There are indications that mucus and mucins in saliva, breast milk and in the cervical plug inhibit the human immunodeficiency virus (HIV-1) in an in vitro assay. Crude mucus gels form continuous layers on the epithelial surfaces of the major internal tracts of the body and protect these epithelial surfaces against aggressive luminal factors such as hydrochloric acid and pepsin proteolysis in the stomach lumen, the movement of hard faecal pellets in the colon at high pressure, the effects of shear against the vaginal epithelium during intercourse and the presence of foreign substances in the respiratory airways. Tumour-associated epitopes on mucins make them suitable as immune-targets on malignant epithelial cells, rendering mucins important as diagnostic and prognostic markers for various diseases, even influencing the design of mucin-based vaccines. Sub-Saharan Africa has the highest prevalence of HIV-AIDS in the world. The main points of viral transmission are via the vaginal epithelium during sexual intercourse and mother-to-child transmission during breast-feeding. There have been many studies showing that several body fluids have components that prevent the transmission of HIV-1 from infected to non-infected persons through various forms of contact. Crude saliva and its purified mucins, MUC5B and MUC7, and the purified mucins from breast milk, MUC1 and MUC4 and pregnancy plug cervical mucus (MUC2, MUC5AC, MUC5B and MUC6), inhibit HIV-1 in an in vitro assay. There are conflicting reports of whether crude breast-milk inhibits HIV-1 in an in vitro assay. However studies with a humanised BLT mouse show that breast-milk does inhibit HIV and that breast-feeding is still advisable even amongst HIV-positive women in under-resourced areas, preferably in conjunction with anti-retroviral treatment.

CONCLUSION

These findings raise questions of how such a naturally occurring biological substance such as mucus, with remarkable protective properties of epithelial surfaces against aggressive luminal factors in delicate locations, could be used as a tool in the fight against HIV-AIDS, which has reached epidemic proportions in sub-Saharan Africa.

HIV Infection and Compromised Mucosal Immunity: Oral Manifestations and Systemic Inflammation

Mucosal surfaces account for the vast majority of HIV transmission. In adults, HIV transmission occurs mainly by vaginal and rectal routes but rarely via oral route. By contrast, pediatric HIV infections could be as the result of oral route by breastfeeding. As such mucosal surfaces play a crucial role in HIV acquisition, and spread of the virus depends on its ability to cross a mucosal barrier. HIV selectively infects, depletes, and/or dysregulates multiple arms of the human immune system particularly at the mucosal sites and causes substantial irreversible damage to the mucosal barriers. This leads to microbial products translocation and subsequently hyper-immune activation. Although introduction of antiretroviral therapy (ART) has led to significant reduction in morbidity and mortality of HIV-infected patients, viral replication persists. As a result, antigen presence and immune activation are linked to “inflammaging” that attributes to a pro-inflammatory environment and the accelerated aging process in HIV patients. HIV infection is also associated with the prevalence of oral mucosal infections and dysregulation of oral microbiota, both of which may compromise the oral mucosal immunity of HIV-infected individuals. In addition, impaired oral immunity in HIV infection may predispose the patients to periodontal diseases that are associated with systemic inflammation and increased risk of cardiovascular diseases. The purpose of this review is to examine existing evidence regarding the role of innate and cellular components of the oral cavity in HIV infection and how HIV infection may drive systemic hyper-immune activation in these patients. We will also discuss current knowledge on HIV oral transmission, HIV immunosenescence in relation to the oral mucosal alterations during the course of HIV infection and periodontal disease. Finally, we discuss oral manifestations associated with HIV infection and how HIV infection and ART influence the oral microbiome. Therefore, unraveling how HIV compromises the integrity of the oral mucosal tissues and innate immune components of the oral cavity and its association with induction of chronic inflammation are critical for the development of effective preventive interventions and therapeutic strategies.

HIV Infection and Compromised Mucosal Immunity: Oral Manifestations and Systemic Inflammation

Mucosal surfaces account for the vast majority of HIV transmission. In adults, HIV transmission occurs mainly by vaginal and rectal routes but rarely via oral route. By contrast, pediatric HIV infections could be as the result of oral route by breastfeeding. As such mucosal surfaces play a crucial role in HIV acquisition, and spread of the virus depends on its ability to cross a mucosal barrier. HIV selectively infects, depletes, and/or dysregulates multiple arms of the human immune system particularly at the mucosal sites and causes substantial irreversible damage to the mucosal barriers. This leads to microbial products translocation and subsequently hyper-immune activation. Although introduction of antiretroviral therapy (ART) has led to significant reduction in morbidity and mortality of HIV-infected patients, viral replication persists. As a result, antigen presence and immune activation are linked to "inflammaging" that attributes to a pro-inflammatory environment and the accelerated aging process in HIV patients. HIV infection is also associated with the prevalence of oral mucosal infections and dysregulation of oral microbiota, both of which may compromise the oral mucosal immunity of HIV-infected individuals. In addition, impaired oral immunity in HIV infection may predispose the patients to periodontal diseases that are associated with systemic inflammation and increased risk of cardiovascular diseases. The purpose of this review is to examine existing evidence regarding the role of innate and cellular components of the oral cavity in HIV infection and how HIV infection may drive systemic hyper-immune activation in these patients. We will also discuss current knowledge on HIV oral transmission, HIV immunosenescence in relation to the oral mucosal alterations during the course of HIV infection and periodontal disease. Finally, we discuss oral manifestations associated with HIV infection and how HIV infection and ART influence the oral microbiome. Therefore, unraveling how HIV compromises the integrity of the oral mucosal tissues and innate immune components of the oral cavity and its association with induction of chronic inflammation are critical for the development of effective preventive interventions and therapeutic strategies.

Estimation and comparison of salivary secretory leukocyte protease inhibitor in human immunodeficiency virus patients and healthy individuals

Aim:

Transmission of human immunodeficiency virus (HIV) in the oral cavity is a rare event, despite detectable virus in saliva and oropharyngeal tissues of infected persons, unlike other mucosal sites. Secretory leukocyte protease inhibitor (SLPI) has been suggested as the main soluble factor responsible for the HIV inhibitory effect of saliva. The study was designed to estimate and compare the salivary SLPI levels in HIV patients and healthy controls. Furthermore, the relationship between salivary SLPI levels and disease severity was also investigated.

Materials and Methods:

Unstimulated whole saliva specimens were collected from 60 HIV-infected and 20 healthy subjects. Disease severity was determined by CD4 count in HIV subjects, who were divided into two groups: ≥200 cells/μL (n = 30) and < 200 cells/μL n = 30. Salivary SLPI levels were determined by enzyme-linked immunosorbent assay.

Results:

Numerically higher SLPI levels were observed in HIV subjects 193.342 ng/mL vs. 190.587 ng/mL; P = 0.517. A nonsignificant negative correlation was noted between CD4 counts and SLPI levels r = −0.037, P = 0.781.

Conclusion:

The salivary anti-HIV factor, SLPI, is not only preserved in HIV infection but its concentration may even get enhanced in the infection. However, the clinical significance of SLPI levels and disease severity should be investigated further with a larger sample of patients.

Innate Immunity in Simian Immunodeficiency Virus Infection

The past decade has seen the emergence of innate immunity as a mature field. The study of innate immunity has had a significant impact on the concepts of HIV immunity, pathogenesis, and vaccines. In this chapter, basic concepts of innate immunity at the anatomical, cellular, and molecular levels will be introduced from the perspective of their interplay with HIV and simian immunodeficiency virus (SIV). An emphasis will be placed on studies using SIV/non-human primate (NHP) models that shape current models of HIV pathogenesis. Finally, studies modulating the innate system in vivo in NHPs will be discussed.

Acute phase protein and cytokine levels in serum and saliva: a comparison of detectable levels and correlations in a depressed and healthy adolescent sample

Recent research has examined associations between inflammation and mental health, and has increasingly focused on utilising younger samples to characterise the temporal relationship between inflammatory responses and the emergence of other symptoms. These studies have typically used blood to measure inflammation, although rates of detection for many inflammatory markers appear to be low. Saliva is a safe and low-cost alternative, and adult research has shown that levels of some salivary markers correlate well with those in serum. However, no research has examined this association in young people. This study examined 16 inflammatory markers in serum and saliva in 17 depressed adolescents and 18 healthy controls, aged 13-18 years. In general, detection rates were higher in saliva compared to in serum. When non-detectable levels were excluded, serum levels of C-reactive protein (CRP) correlated with salivary CRP (r=0.424, p=0.015), and this correlation appeared to only exist for those individuals with high levels of serum CRP (r=0.599, p=0.014). However, when non-detectable levels were included as zero, salivary levels of CRP, interleukin (IL)-2, IL-12p70, and interferon (IFN)-γ correlated with their serum counterparts. No significant clinical group differences in any acute phase proteins or cytokines were present. This study suggests that saliva can be used to measure inflammation in studies with adolescent participants, especially CRP, as it appears to correlate with systemic inflammation for those individuals who are expected to have high levels of inflammation. Implications for future directions in research on salivary inflammatory markers are discussed.

Comparative Evaluation of HIV-1 Neutralization in External Secretions and Sera of HIV-1-Infected Women

Objectives:

Although human immunodeficiency virus type 1 (HIV-1)-specific antibodies are detectable in external secretions by ELISA and western blot (WB), the presence of HIV-1 neutralizing antibodies is difficult to evaluate due to the low levels of immunoglobulins (Ig) and the presence of humoral factors of innate immunity. The objective of this study was to determine virus neutralization activity and the relative contribution of HIV-1-specific antibodies of various isotypes to virus neutralization in serum/plasma samples, cervicovaginal lavages (CVL), and rectal lavages (RL).

Design:

Serum/plasma, CVL, and RL samples were examined by ELISA, WB and HIV-1 neutralization assays. Selected samples were Ig depleted and analyzed for virus neutralization.

Results:

IgG specific for three HIV-1 ENV antigens was detected in all serum/plasma samples, while IgA to at least one ENV glycoprotein was found at the low levels in 95% samples. Serum/plasma samples had the ability to neutralize at least one of three clade B and two clade C viruses. The neutralizing titers were reduced significantly or became undetectable after IgG removal. In corresponding CVL and RL, HIV-1 ENV-specific IgG antibodies were readily detected compared to IgA. Furthermore, IgG in CVL had greater ability than IgA to reduce virus infectivity. The difference in HIV-1 neutralization before and after Ig depletion was not observed in RL, implying that innate humoral factors were involved in anti-HIV-1 activity.

Conclusions:

Results demonstrate that HIV-1-specific neutralizing antibodies are almost exclusively of the IgG isotype in serum/plasma and CVL samples. HIV-1-specific binding antibodies detected in RL are not responsible for neutralization activity, suggesting that the antibody-mediated virus neutralization in external secretions should be verified by means of a selective depletion of Ig.

Inhibition of SLPI ameliorates disease activity in experimental autoimmune encephalomyelitis

Background

The secretory leukocyte protease inhibitor (SLPI) exerts wide ranging effects on inflammatory pathways and is upregulated in EAE but the biological role of SLPI in EAE, an animal model of multiple sclerosis is unknown

Methods

To investigate the pathophysiological effects of SLPI within EAE, we induced SLPI-neutralizing antibodies in mice and rats to determine the clinical severity of the disease. In addition we studied the effects of SLPI on the anti-inflammatory cytokine TGF-β.

Results

The induction of SLPI neutralizing antibodies resulted in a milder disease course in mouse and rat EAE. SLPI neutralization was associated with increased serum levels of TGF-β and increased numbers of FoxP3+ CD4+ T cells in lymph nodes. In vitro, the addition of SLPI significantly decreased the number of functional FoxP3+ CD25^hi CD4+ regulatory T cells in cultures of naive human CD4+ T cells. Adding recombinant TGF-β to SLPI-treated human T cell cultures neutralized SLPI's inhibitory effect on regulatory T cell differentiation.

Conclusion

In EAE, SLPI exerts potent pro-inflammatory actions by modulation of T-cell activity and its neutralization may be beneficial for the disease.

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.

Expression and characterization of recombinant human secretory leukocyte protease inhibitor (SLPI) protein from Pichia pastoris

The human secretory leukocyte protease inhibitor (SLPI) has been shown to possess anti-protease, anti-inflammatory and antimicrobial properties. Its presence in saliva is believed to be a major deterrent to oral transmission of human immunodeficiency virus-1. The 11.7kDa peptide is a secreted, nonglycosylated protein rich in disulfide bonds. Currently, recombinant SLPI is only available as an expensive bacterial expression product. We have investigated the utility of the methylotrophic yeast Pichia pastoris to produce and secrete SLPI with C-terminal c-myc and polyhistidine tags. The post-transformational vector amplification protocol was used to isolate strains with increased copy number, and culturing parameters were varied to optimize SLPI expression. Modification of the purification procedure allowed the secreted, recombinant protein to be isolated from the cell-free fermentation medium with cobalt affinity chromatography. This yeast-derived SLPI was shown to have an anti-protease activity comparable to the commercially available bacterial product. Thus, P. pastoris provides an efficient, cost-effective system for producing SLPI for structure function analysis studies as well as a wide array of potential therapeutic applications.

Characterization of secretory leukocyte protease inhibitor as an inhibitor of implantation serine proteinases

We have recently identified and characterized two implantation serine proteinase genes, ISP1 and ISP2, which give rise to a dimeric proteinase, ISP that facilitates embryo invasion during peri-implantation period. As many proteinases have cognate serpins that regulate their proteolytic activity, we have been investigating anti-tryptases, expressed during this window of implantation. Here, we report the differential expression of secretory leukocyte protease inhibitor (SLPI) in uterine endometrium around the implantation period. The co-localization of SLPI and ISP suggests the possibility that SLPI is an ISP serpin and that expression of SLPI may lead to a reduction in ISP activity. The expression of SLPI is down regulated during the window of embryo-uterine receptivity. Our results are consistent with a model suggesting that the drop in SLPI expression may help to refine the opening of the window of implantation, by allowing the proteolytic activity of embryo invasive serine proteinases such as the ISPs.

Novel role for SLPI in MOG-induced EAE revealed by spinal cord expression analysis

Background

Experimental autoimmune encephalomyelitis (EAE) induced by myelin oligodendrocyte protein (MOG) in female Dark Agouti (DA) rats is a chronic demyelinating animal model of multiple sclerosis (MS). To identify new candidate molecules involved in the evolution or repair of EAE-lesions we used Affymetrix oligonucleotide microarrays to compare the spinal cord transcriptome at the peak of EAE, during remission and at the first relapse with healthy DA rats.

Methods

Untreated DA rats and DA rats immunised with MOG protein were sacrificed at defined time points. Total RNA was isolated from spinal cord tissue and used for hybridization of Affymetrix rat genome arrays RG U34 A-C. Selected expression values were confirmed by RealTime PCR.

Adult neural stem cells were incubated with recombinant secretory leukocyte protease inhibitor (SLPI). Proliferation was assessed by BrdU incorporation, cyclin D1 and HES1 expression by RealTime PCR, cell differentiation by immunofluorescence analysis and IkappaBalpha degradation by Western blot.

Results

Among approximately 26,000 transcripts studied more than 1,100 were differentially regulated. Focussing on functional themes, we noticed a sustained downregulation of most of the transcripts of the cholesterol biosynthesis pathway. Furthermore, we found new candidate genes possibly contributing to regenerative processes in the spinal cord. Twelve transcripts were solely upregulated in the recovery phase, including genes not previously associated with repair processes. Expression of SLPI was upregulated more than hundredfold during EAE attack. Using immunohistochemistry, SLPI was identified in macrophages, activated microglia, neuronal cells and astrocytes. Incubation of adult neural stem cells (NSC) with recombinant SLPI resulted in an increase of cell proliferation and of differentiation towards oligodendrocytes. These processes were paralleled by an upregulation of the cell-cycle promotor cyclin D1 and a suppression of the cell differentiation regulator HES1. Finally, SLPI prevented the degradation of IkappaBalpha, which may explain the suppression of the cell differentiation inhibitor HES1 suggesting a possible mechanism of oligodendroglial differentiation.

Conclusion

We identified novel features of gene expression in the CNS during EAE, in particular the suppression of genes of cholesterol biosynthesis and a strong upregulation of SLPI, a gene which is for the first time associated with autoimmune inflammation. The capacity of SLPI to increase proliferation of adult NSC and of oligodendroglial differentiation suggests a novel role for SLPI in the promotion of tissue repair, beyond its known functions in the prevention of tissue damages by protease inhibition damage and modulation of inflammatory reactions.

Comparison of human immunodeficiency virus type 1-specific inhibitory activities in saliva and other human mucosal fluids

Several human mucosal fluids are known to possess an innate ability to inhibit human immunodeficiency virus type 1 (HIV-1) infection and replication in vitro. This study compared the HIV-1 inhibitory activities of several mucosal fluids, whole, submandibular/sublingual (sm/sl), and parotid saliva, breast milk, colostrum, seminal plasma, and cervicovaginal secretions, from HIV-1-seronegative donors by using a 3-day microtiter infection assay. A wide range of HIV-1 inhibitory activity was exhibited in all mucosal fluids tested, with some donors exhibiting high levels of activity while others showed significantly lower levels. Colostrum, whole milk, and whole saliva possessed the highest levels of anti-HIV-1 activity, seminal fluid, cervicovaginal secretions, and sm/sl exhibited moderate levels, and parotid saliva consistently demonstrated the lowest levels of HIV-1 inhibition. Fast protein liquid chromatography gel filtration studies revealed the presence of at least three distinct peaks of inhibitory activity against HIV-1 in saliva and breast milk. Incubation of unfractionated and fractionated whole saliva with antibodies raised against human lactoferrin (hLf), secretory leukocyte protease inhibitor (SLPI), and, to a lesser extent, MG2 (high-molecular-weight mucinous glycoprotein) reduced the HIV-1 inhibitory activity significantly. The results suggest that hLf and SLPI are two key components responsible for HIV-1 inhibitory activity in different mucosal secretions. The variation in HIV inhibitory activity between the fluids and between individuals suggests that there may be major differences in susceptibility to HIV infection depending both on the individual and on the mucosal fluid involved.

Molecular interactions of human immunodeficiency virus type 1 with primary human oral keratinocytes

Infection of the oral mucosa of human immunodeficiency virus type 1 (HIV-1)-infected individuals remains an under-evaluated and somewhat enigmatic process. Nonetheless, it is of profound importance in the ongoing AIDS pandemic, based on its potential as a site of person-to-person transmission of the virus as well as a location of HIV-1 pathogenesis and potential reservoir of disease in the setting of virally suppressive highly active antiretroviral therapy. We utilized molecular and virological techniques to analyze HIV-1 infection of primary human mucosal cells and also evaluated the proapoptotic potential of selected HIV-1 proteins in primary isolated human oral keratinocytes. Primary isolated human oral keratinocytes were plated on 0.4 microM polyethylenetetraphthalate cell culture inserts to form an in vitro oral mucosal layer. The strength of this layer in forming a barrier was determined by measuring trans-epithelial electrical current passage across the monolayer. The oral keratinocyte monolayers had trans-epithelial electrical resistance of approximately 176 to 208 omega. For viral infectivity assays, the macrophage-tropic (R5) HIV-1 strains, YU-2 and ADA, and T-cell-line-tropic (X4), NL4-3 virions, incubated with or without deoxynucleoside triphosphates (dNTPs) and/or the polyamines spermine and spermidine, were used to infect oral keratinocytes. Of importance, polyamines and dNTPs have been shown to enhance natural endogenous reverse transcription (NERT), a step essential for early lentiviral infection, and are abundantly present in human semen. The infectivities of HIV-1 strains YU-2, ADA, and NL4-3 for these primary keratinocytes were dramatically increased by the addition of physiological concentrations of dNTPs, spermine, and spermidine. Binding and viral internalization assay studies showed no differences in these oral mucosal cells, with or without NERT-altering agents. It was also observed that the recombinant, cell-free HIV-1 proteins Nef, Tat, and gp120 (R5) induced apoptosis in primary oral keratinocytes compared with the results seen with nontreated cells or cells treated with glutathione S-transferase protein as a control under similar conditions. Microarray analyses suggested that HIV-1 gp120 and Tat induce apoptosis in primary human oral keratinocytes via the Fas/FasL apoptotic pathway, whereas induction of apoptosis by Nef occurs through both Fas/FasL and mitochondrial apoptotic pathways. Thus, these findings suggest molecular mechanisms by which semen in particular, as well as other bodily fluids such as cervicovaginal secretions, could increase oral transmission of HIV-1 via increasing infectivity in confluent and low-replicating oral keratinocytes. As well, the induction of apoptosis in human oral keratinocytes with relevant HIV-1-specific proteins suggests another potential complementary mechanism by which the oral mucosa barrier may be disrupted during HIV-1 infection in vivo.

Up-Regulation of Secretory Leukocyte Protease Inhibitor (SLPI) in the Brain after Ischemic Stroke: Adenoviral Expression of SLPI Protects Brain from Ischemic Injury

Secretory leukocyte protease inhibitor (SLPI) is a 12-kDa secreted protein initially identified from epithelial cells as an inhibitor of leukocyte serine proteases. In the present study, we described the identification of SLPI expression in ischemic cortex by suppression subtractive hybridization strategy. Our full-length rat SLPI cDNA shares 81% and 63% amino acid sequence identity with its mouse and human homologs, respectively, and with several polymorphisms to previous reported rat sequences. Northern blot analysis confirmed that SLPI mRNA was significantly induced in the ischemic brain tissue at 12 h (5.1-fold increase over sham controls, n = 4, p < 0.05), peaked at 2 days (26.1-fold increase, p < 0.001), and sustained up to 5 days (5.1-fold increase, p < 0.05). SLPI was localized in neurons and astrocytes in the peri-infarct zone from 24 to 72 h after middle cerebral artery occlusion by means of immunohistochemical and confocal microscopy analysis. Administration of a recombinant adenovirus overexpressing SLPI (Adv/SLPI) into the cortical tissue resulted in up to 58.4% reduction in ischemic lesion over controls at the site of Adv/SLPI expression (p < 0.01, n = 8) and significantly improved functional outcome (p < 0.01). These data suggest that the ischemia-induced expression of SLPI might play a neuroprotective role in focal stroke, possibly because of rapid inhibition of activated proteases and its suppression in inflammatory response.

Effect of Low-Power Radiation (Helium/Neon) upon Submandibulary Glands

OBJECTIVE

The aim of this work was to study the effect of low-power laser radiation on guinea pig salivary glands.

BACKGROUND DATA

Low-power laser radiation changes some cellular functions. The effect on salivary glands has not been sufficiently studied.

MATERIALS AND METHODS

One hundred and forty-four male guinea pigs (150 +/- 30 g body weight) were used. The animals were divided into two groups: control group (fed animals and those undergoing 2, 4, 8, 10, and 12 h of fasting) and experimental group (irradiated). Both the right and left submandibular glands were later irradiated with helium-neon laser at 7-mW power, with a 0.75-mm spot, under continuous pulse for 2 min in a one-session exposure; a 11.2 J/cm(2) energy density was applied. Then, the irradiated animals were fed, or underwent 2, 4, 8, 10 and 12 h of fasting. Samples of submandibular glands were taken with a punch (5 mm diameter) and were used for optic and transmission electron microscopy studies.

RESULTS

The structural observations showed that the irradiation effect was progressive; and showed a trophic stimulant effect at 2 h following irradiation, with vasodilatation, vascular congestion, perivascular infiltrate, and a necrotic picture of glandular parenchyma at longer times. The ultrastructural observations showed alterations of rough endoplasmic reticulum.

CONCLUSION

We propose that low-power laser radiation with the doses applied in this study disturbs protein synthesis and secretion of guinea pig submandibulary glands.

Human immunodeficiency virus type 1 infection and replication in normal human oral keratinocytes

Recent epidemiologic studies show increasing human immunodeficiency virus type 1 (HIV-1) transmission through oral-genital contact. This paper examines the possibility that normal human oral keratinocytes (NHOKs) might be directly infected by HIV or might convey infectious HIV virions to adjacent leukocytes. PCR analysis of proviral DNA constructs showed that NHOKs can be infected by CXCR4-tropic (NL4-3 and ELI) and dualtropic (89.6) strains of HIV-1 to generate a weak but productive infection. CCR5-tropic strain Ba-L sustained minimal viral replication. Antibody inhibition studies showed that infection by CXCR4-tropic viral strains is mediated by the galactosylceramide receptor and the CXCR4 chemokine coreceptor. Coculture studies showed that infectious HIV-1 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.

Secretory leukocyte protease inhibitor: inhibition of human immunodeficiency virus-1 infection of monocytic THP-1 cells by a newly cloned protein

The ability of the salivary protein, secretory leukocyte protease inhibitor (SLPI), to inhibit human immunodeficiency virus-1 (HIV-1) infection in vitro has been reported previously and has led to the suggestion that SLPI may be partially responsible for the low oral transmission rate of HIV-1. However, results contradictory to these findings have also been published. These discrepancies can be attributed to a number of factors ranging from the variability of macrophage susceptibility to HIV infection to the quality of commercially available preparations of SLPI. To resolve these differences and to study further the potential anti-HIV-1 activity of SLPI, the purified and re-folded protein, expressed from a synthetic gene, was examined using human monocytic THP-1 cells. This newly cloned SLPI reduced HIV-1(Ba-L) infection in differentiated THP-1 cells, in contrast to the results observed when using commercially available preparations of SLPI. Interestingly, while the two proteins displayed different anti-HIV effects they had comparable anti-protease activity. The identification of the THP-1 cell line as a system that supports HIV replication, which can be inhibited by a preparation of SLPI now available in large quantities, sets the stage for a thorough investigation of the molecular and structural basis for the anti-HIV activity of SLPI.

Synergism between HIV and other viruses in the mouth

The HIV family replicate in and are shed from the mouth. Oral sexual practices potentially contribute to the overall extent of HIV transmission, particularly if high-risk practices are not restricted. Herpesviruses and papillomaviruses that appear in the oral cavity can determine oral HIV replication. The mechanisms probably include heterologous transactivation, enhanced expression of HIV receptors and co-receptors in target cells, release of cytokines and chemokines, and production of superantigens. Oral diseases peculiar to, or more common in, the HIV-infected patient further predispose to heightened oral HIV replication and trafficking. Defining the mechanisms by which oral viruses interact with HIV in the co-infected host should permit intervention measures against oral HIV transmission to be more precisely targeted.

Influence of a partner's HIV serostatus, use of highly active antiretroviral therapy, and viral load on perceptions of sexual risk behavior in a community sample of men who have sex with men

OBJECTIVE

To assess the perceptions of gay and bisexual men concerning the risk of HIV transmission through various sexual practices with a new sex partner depending on that partner's disclosed HIV status, antiretroviral treatment status, and viral load.

METHODS

Study participants read four different scenarios describing sexual situations with a new partner and rated each scenario for risk of HIV transmission. HIV status and antiretroviral treatment status disclosed by the new sex partner were varied across four scenarios: unknown HIV status; HIV-negative; HIV-positive and not taking highly active antiretroviral therapy (HAART); and HIV-positive and taking HAART with an undetectable viral load.

RESULTS

Study participants were 472 men attending a gay pride festival who reported that they were HIV-negative. Eighty-nine percent of the men were white, and the mean age of the study participants was 35.8 years. Of the four scenarios, sex with an HIV-positive partner not taking HAART was rated as posing the greatest risk. Sex with an HIV-positive partner taking HAART who had an undetectable viral load was not consistently viewed as riskier than sex with an HIV-negative partner or a man with an unknown HIV status.

CONCLUSIONS

The current study provides preliminary evidence for the effect of disclosure of HIV serostatus, use of HAART, and the presence of an undetectable viral load on the perceptions of sexual risk for HIV-negative men. The findings suggest that some gay and bisexual men judge risk based on the perceived HIV status of their sex partners and not on the general assumption that all sex partners entail equal risk, as many prevention campaigns have emphasized.

Assessing basic HIV transmission risks and the contextual factors associated with HIV risk behavior in men who have sex with men

HIV/AIDS remains a substantial health threat to men who have sex with men. Although new HIV medications have provided great benefits for many HIV-positive individuals, they have done little to protect HIV-negative men. Consequently, changing one's sexual practices remains the most effective way to reduce risk for HIV. However, to develop an effective intervention for reducing HIV risk, it is important to fully understand risk behavior. In this article, we detail the essential elements for conducting an HIV risk assessment as well as those contextual factors that may support risk behaviors. Further, we discuss the importance of procuring an HIV test and the critical issues that may arise because of testing for HIV as well as the critical issues that may result from testing HIV-positive. Finally, we illustrate how we integrate an HIV health risk assessment into a clinical interview.

Predominate HIV1-specific IgG activity in various mucosal compartments of HIV1-infected individuals

Evaluating mucosal humoral immunity is important for understanding local immunity induced by HIV infection or vaccination and designing prophylactic strategies. To characterize the mucosal humoral immunity following HIV infection, the levels of immunoglobulins (Igs), antibodies (Abs), and HIV1-specific Ab activity were evaluated in cervicovaginal secretions (CVS), saliva, breast milk, and sera of HIV-infected individuals. HIV1-specific IgG activity was significantly higher than that of IgA in CVS, saliva, and breast milk. The highest HIV1-specific IgG activity was found in breast milk. The data suggest that anti-HIV1 Abs in CVS were most likely serum derived. However, HIV1-specific Abs in saliva and breast milk were mainly locally produced. The prevalence of HIV1-specific Abs in seropositive subjects was 97% for IgG and 95% for IgA in CVS, 100% for IgG and 80% for IgA in saliva, and 59% for IgG and 94% for IgA in breast milk. These data provide evidence for both a better understanding of the nature of humoral mucosal responses after HIV1 infection and the development of strategies to induce desirable functional mucosal immunity for preventing HIV transmission.

HIV topic update: oro-genital transmission of HIV

Several viruses, including the human immunodeficiency virus (HIV), can be found in blood and many body fluids including saliva, and are transmissible sexually across genital and particularly anal mucosae. A persisting concern has been the question of transmission of HIV by oral sexual practices. This review discusses the evidence for oro-genital transmission of HIV, detailing the presence and infectivity of HIV in genital fluids and saliva, the case reports and epidemiology of oro-genital HIV transmission, and the evidence from animal studies. Oral intercourse is not risk-free. The evidence suggests that the risk of HIV transmission from oro-genital sexual practices is substantially lower than that from penile-vaginal or penile-anal intercourse, that exposure to saliva presents a considerably lower risk than exposure to semen, and that oral trauma and ulcerative conditions might increase the risk of HIV transmission.

Salivary MUC5B-mediated adherence (ex vivo) of Helicobacter pylori during acute stress

OBJECTIVE

Biochemical host defenses at mucosal sites, such as the oral cavity, play a key role in the regulation of microbial ecology and the prevention of infectious disease. These biochemical factors have distinct features, some of which benefit the host and some that benefit bacteria. We investigated the effects of acute stress on the salivary levels of the carbohydrate structure sulfo-Lewis (sulfo-Le), which is linked to the mucosal glycoprotein MUC5B. Sulfo-Le was recently identified as an adhesion molecule for Helicobacter pylori; therefore, we also measured saliva-mediated adherence (ex vivo) of H. pylori. The oral cavity is suspected to be involved in the transmission of H. pylori.

METHODS

Saliva was collected from 17 undergraduates before (baseline), during (stress), and after (recovery) exposure to a video showing surgical procedures. In addition, blood pressure, an impedance cardiogram, and an electrocardiogram were recorded.

RESULTS

During stressor exposure, participants reported increased state anxiety. In addition, stroke volume increased and heart rate decreased. The stressor induced a strong increase in salivary sulfo-Le concentration (U/ml), sulfo-Le output (U/min), sulfo-Le/total protein ratio (U/mg protein), and saliva-mediated adherence (ex vivo) of H. pylori. As expected, sulfo-Le concentration correlated with the adherence of H. pylori (r = 0.72, p < .05). It was demonstrated that the observed adherence was induced by MUC5B and that the carbohydrate structure sulfo-Le contributed to this process.

CONCLUSIONS

Our study demonstrated a direct link between stress-mediated biochemical changes and altered host-microbe interactions in humans. Increased bacterial adherence may be a contributing factor in the observed relationship between stress and susceptibility to infectious disease.

Secretory leukocyte protease inhibitor (SLPI): oxidation of SLPI does not explain its variable anti-HIV activity

Secretory leukocyte protease inhibitor (SLPI) has been proposed as a potential inhibitor of HIV-1 infection in human saliva. Although the ability of recombinant (r) SLPI to inhibit HIV-1 infection of macrophages and primary T-cells has been demonstrated by two independent laboratories, evidence to the contrary has also been reported. This study re-examines the anti-HIV effect of rSLPI and investigates the effects of repeated freeze-thawing and oxidation on the anti-HIV activity of rSLPI. rSLPI inhibited HIV-1BaL infection of human macrophages in a highly variable manner. HPLC and electrospray ionization mass spectrometry (ESI) analyses indicated that variability in our inhibition data could not be attributed to the degradation or oxidation of rSLPI. These results suggest that the variable anti-HIV effect of rSLPI may be due to differential expression of the cell-surface molecule(s) to which SLPI binds rather than to changes in the rSLPI molecule.

Human bites and the risk of human immunodeficiency virus transmission

The risk of human immunodeficiency virus (HIV) transmission following a bite injury is important to many groups of people. The first are those who are likely to be bitten as an occupational risk, such as police officers and institutional staff. Another group are represented by the victims and perpetrators of crimes involving biting, both in attack and defense situations. The possibility of these bites transmitting a potentially fatal disease is of interest to the physicians who treat such patients and the legal system which may have to deal with the repercussions of such a transmission. Bite injuries represent 1% of all emergency department admissions in the United States, and human bites are the third most common following those of dogs and cats. The worldwide epidemic of HIV and acquired immunodeficiency syndrome (AIDS) continues, with >5 million new cases last year and affecting 1 in 100 sexually active adults. A review of the literature concerning human bites, HIV and AIDS, HIV in saliva, and case examples was performed to examine the current opinion regarding the transmission of HIV via this route. A bite from an HIV-seropositive individual that breaks the skin or is associated with a previous injury carries a risk of infection for the bitten individual.

Endogenous salivary inhibitors of human immunodeficiency virus

The human immunodeficiency virus type 1 (HIV-1) is rarely transmitted through salivary secretions, due in part to the presence of endogenous inhibitors. Here, the protective characteristics of the intraoral environment are summarized and inhibitory factors that reduce HIV-1 infectivity in vitro described, focusing on secretory leucocyte protease inhibitor (SLPI), a 12-kDa mucosal protein that blocks HIV infection in several cell-culture systems. SLPI appears to interact with a cellular surface molecule to limit viral entry into target cells. To determine whether the inhibitor has a similar role in vivo, the contribution of salivary SLPI to anti-HIV-1 activity was assessed. Whole unstimulated filtered salivas from infected and uninfected donors contained similar concentrations of the inhibitor. Depletion from SLPI filtered saliva produced a corresponding loss of inhibitory activity. In general, filtered whole salivas obtained from 10 donors had antiviral activities that correlated positively with SLPI concentrations. However, some samples having SLPI well below the concentration required for inhibitory activity in vitro exhibited modest inhibition, suggesting the presence of other anti-HIV-1 components in oral fluids. Thus, SLPI is a major but not sole inhibitor of this virus in saliva.

Submandibular salivary proteases: lack of a role in anti-HIV activity

Whole human saliva contains a number of proteolytic enzymes, mostly derived from white blood cells and bacteria in the oral cavity. However, less information is available regarding proteases produced by salivary glands and present in salivary secretions. In the present study, we have analyzed submandibular saliva, collected without contaminating cells, and identified multiple proteolytic activities. These have been characterized in terms of their susceptibility to a series of protease inhibitors. The submandibular saliva proteases were shown to be sensitive to both serine and acidic protease inhibitors. We also used protease inhibitors to determine if salivary proteolytic activity was involved in the inhibition of HIV infectivity seen when the virus is incubated with human saliva. This anti-HIV activity has been reported to occur in whole saliva and in ductal saliva obtained from both the parotid and submandibular glands, with highest levels of activity present in the latter fluid. Protease inhibitors, at concentrations sufficient to block salivary proteolytic activity in an in vitro infectivity assay, did not block the anti-HIV effects of saliva, suggesting that the salivary proteases are not responsible for the inhibition of HIV-1 infectivity.

HIV topic update: salivary testing for antibodies

Salivary antibody testing for HIV is proving to be a sensitive and specific procedure, especially useful for epidemiological studies, and has the advantages of being simple and non-invasive. This paper reviews the field and discusses antibody testing of dental patients.

Postexposure chemoprophylaxis for occupational exposure to HIV in the dental office

Occupational exposure to HIV continues to be a concern for health care workers. Preventing exposure through the use of universal precautions is the primary means of protection. New Public Health Service interagency work group recommendations for postexposure chemoprophylaxis provide information to help manage occupational exposure to HIV.