Cancer Associated Fibroblasts Derived from Pancreatic Adenocarcinoma and Their Role in Cell Migration.

BACKGROUND/AIM: Pancreatic ductal adenocarcinoma (PDAC) shows poor survival and early systemic dissemination. Cancer associated fibroblasts (CAFs) enhance migration and invasion of cancer cells. We aimed to investigate the role of CAFs in cell migration and their underlying paracrine effects. MATERIALS AND METHODS: Using Transwell® migration assays, PDAC cells (PANC-1) and three distinct types of fibroblasts were analyzed: CAFs, genetically transformed human foreskin-fibroblasts (BJeLR), and non-transformed human foreskin-fibroblasts (VH7). IL6 in the culture supernatant was measured to investigate paracrine communication in monocultures and direct/indirect cocultures. RESULTS: CAFs showed a significantly higher capacity to migrate in vitro when compared to benign fibroblasts (p=0.009). They also facilitated the migration of PDAC cells in coculture (p=0.001). Neither BJeLR, nor VH7 displayed such features. This was accompanied by a significant increase in IL-6 when CAFs were cocultured with PANC-1 (p=0.009). CONCLUSION: CAFs are a key element of intra-tumoral migration and should be further investigated as a potential therapeutic target.

Celastrol Alleviates Gamma Irradiation-Induced Damage by Modulating Diverse Inflammatory Mediators.

The present study aimed to explore the possible radioprotective effects of celastrol and relevant molecular mechanisms in an in vitro cell and in vivo mouse models exposed to gamma radiation. Human keratinocytes (HaCaT) and foreskin fibroblast (BJ) cells were exposed to gamma radiation of 20Gy, followed by treatment with celastrol for 24 h. Cell viability, reactive oxygen species (ROS), nitric oxide (NO) and glutathione (GSH) production, lipid peroxidation, DNA damage, inflammatory cytokine levels, and NF-κB pathway activation were examined. The survival rate, levels of interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α) in blood, and p65 and phospho-p65 expression were also evaluated in mice after exposure to gamma radiation and celastrol treatment. The gamma irradiation of HaCaT cells induced decreased cell viability, but treatment with celastrol significantly blocked this cytotoxicity. Gamma irradiation also increased free radical production (e.g., ROS and NO), decreased the level of GSH, and enhanced oxidative DNA damage and lipid peroxidation in cells, which were effectively reversed by celastrol treatment. Moreover, inflammatory responses induced by gamma irradiation, as demonstrated by increased levels of IL-6, TNF-α, and IL-1ß, were also blocked by celastrol. The increased activity of NF-κB DNA binding following gamma radiation was significantly attenuated after celastrol treatment. In the irradiated mice, treatment with celastrol significantly improved overall survival rate, reduced the excessive inflammatory responses, and decreased NF-κB activity. As a NF-κB pathway blocker and antioxidant, celastrol may represent a promising pharmacological agent with protective effects against gamma irradiation-induced injury.

Identification and Evaluation of New Immunoregulatory Genes in Mesenchymal Stromal Cells of Different Origins: Comparison of Normal and Inflammatory Conditions.

BACKGROUND Mesenchymal stromal cells (MSCs) possess potent immunomodulatory properties that increase their value as a cell-based therapeutic tool for managing various immune-based disorders. Over the past years, accumulated results from trials using MSCs-based therapy have shown substantial contradictions. Although the reasons underlying these discrepancies are still not completely understood, it is well known that the immunomodulatory activities mediated by distinct MSCs differ in a manner dependent on their tissue origin and adequate response to inflammation priming. Thus, characterization of new molecular pathway(s) through which distinct MSC populations can exert their immunomodulatory effects, particularly during inflammation, will undoubtedly enhance their therapeutic potential. MATERIAL AND METHODS After confirming their compliance with ISCT criteria, quantitative real time-PCR (qRT-PCR) was used to screen new immunoregulatory genes in MSCs, derived from adipose tissue, foreskin, Wharton's jelly or the bone-marrow, after being cultivated under normal and inflammatory conditions. RESULTS FGL2, GAL, SEMA4D, SEMA7A, and IDO1 genes appeared to be differentially transcribed in the different MSC populations. Moreover, these genes were not similarly modulated following MSCs-exposure to inflammatory signals. CONCLUSIONS Our observations suggest that these identified immunoregulatory genes may be considered as potential candidates to be targeted in order to enhance the immunomodulatory properties of MSCs towards more efficient clinical use.

In men at risk of HIV infection, IgM, IgG1, IgG3, and IgA reach the human foreskin epidermis.

We profiled the humoral response in the penis, an area that has been minimally explored but may be relevant for protecting insertive men against HIV and other sexually acquired infections. Comparing paired tissue samples from 20 men at risk of HIV infection, foreskin contains less immunoglobulin A (IgA) and more IgG2 than colon. Using foreskin dermal and epidermal explants and paired plasma from 17 men, we examined Ig accumulation by normalizing Ig to human serum albumin (HSA) transudation. Dermal IgM, IgG2, IgA, and IgE ratios were greater than that in plasma, suggesting there is local antibody secretion at the dermis. Local Ig transcription was concentrated at the inner rather than the outer foreskin, and inner foreskin Ig ratios did not correlate with blood, indicating that localized production can contribute to the foreskin response. IgM, IgG1, IgG3, and IgA have preferential access to the foreskin epidermis, whereas IgG2, IgG4, and IgE are restricted to the dermis. Lastly, Ad5-specific IgA was selectively present in the colon, whereas foreskin Ad5 IgG was mainly derived from blood, and reached the inner epidermis at higher ratios than the outer (P<0.002). In summary, the foreskin antibody response combines local and systemic sources, and there is selective isotype accumulation in the epidermis.

Visualization of HIV-1 interactions with penile and foreskin epithelia: clues for female-to-male HIV transmission.

To gain insight into female-to-male HIV sexual transmission and how male circumcision protects against this mode of transmission, we visualized HIV-1 interactions with foreskin and penile tissues in ex vivo tissue culture and in vivo rhesus macaque models utilizing epifluorescent microscopy. 12 foreskin and 14 cadaveric penile specimens were cultured with R5-tropic photoactivatable (PA)-GFP HIV-1 for 4 or 24 hours. Tissue cryosections were immunofluorescently imaged for epithelial and immune cell markers. Images were analyzed for total virions, proportion of penetrators, depth of virion penetration, as well as immune cell counts and depths in the tissue. We visualized individual PA virions breaching penile epithelial surfaces in the explant and macaque model. Using kernel density estimated probabilities of localizing a virion or immune cell at certain tissue depths revealed that interactions between virions and cells were more likely to occur in the inner foreskin or glans penis (from local or cadaveric donors, respectively). Using statistical models to account for repeated measures and zero-inflated datasets, we found no difference in total virions visualized at 4 hours between inner and outer foreskins from local donors. At 24 hours, there were more virions in inner as compared to outer foreskin (0.0495 +/- 0.0154 and 0.0171 +/- 0.0038 virions/image, p = 0.001). In the cadaveric specimens, we observed more virions in inner foreskin (0.0507 +/- 0.0079 virions/image) than glans tissue (0.0167 +/- 0.0033 virions/image, p<0.001), but a greater proportion was seen penetrating uncircumcised glans tissue (0.0458 +/- 0.0188 vs. 0.0151 +/- 0.0100 virions/image, p = 0.099) and to significantly greater mean depths (29.162 +/- 3.908 vs. 12.466 +/- 2.985 µm). Our in vivo macaque model confirmed that virions can breach penile squamous epithelia in a living model. In summary, these results suggest that the inner foreskin and glans epithelia may be important sites for HIV transmission in uncircumcised men.

The brighter (and evolutionarily older) face of the metabolic syndrome: evidence from Trypanosoma cruzi infection in CD-1 mice.

BACKGROUND: Infection with Trypanosoma cruzi, the protozoan parasite that causes Chagas disease, results in chronic infection that leads to cardiomyopathy with increased mortality and morbidity in endemic regions. In a companion study, our group found that a high-fat diet (HFD) protected mice from T. cruzi-induced myocardial damage and significantly reduced post-infection mortality during acute T. cruzi infection. METHODS: In the present study metabolic syndrome was induced prior to T. cruzi infection by feeding a high fat diet. Also, mice were treated with anti-diabetic drug metformin. RESULTS: In the present study, the lethality of T. cruzi (Brazil strain) infection in CD-1 mice was reduced from 55% to 20% by an 8-week pre-feeding of an HFD to induce obesity and metabolic syndrome. The addition of metformin reduced mortality to 3%. CONCLUSIONS: It is an interesting observation that both the high fat diet and the metformin, which are known to differentially attenuate host metabolism, effectively modified mortality in T. cruzi-infected mice. In humans, the metabolic syndrome, as presently construed, produces immune activation and metabolic alterations that promote complications of obesity and diseases of later life, such as myocardial infarction, stroke, diabetes, Alzheimer's disease and cancer. Using an evolutionary approach, we hypothesized that for millions of years, the channeling of host resources into immune defences starting early in life ameliorated the effects of infectious diseases, especially chronic infections, such as tuberculosis and Chagas disease. In economically developed countries in recent times, with control of the common devastating infections, epidemic obesity and lengthening of lifespan, the dwindling benefits of the immune activation in the first half of life have been overshadowed by the explosion of the syndrome's negative effects in later life.

Chemical allergens stimulate human epidermal keratinocytes to produce lymphangiogenic vascular endothelial growth factor.

Allergic contact dermatitis (ACD) is a cell-mediated immune response that involves skin sensitization in response to contact with various allergens. Angiogenesis and lymphangiogenesis both play roles in the allergic sensitization process. Epidermal keratinocytes can produce vascular endothelial growth factor (VEGF) in response to UV irradiation and during wound healing. However, the effect of haptenic chemical allergens on the VEGF production of human keratinocytes, which is the primary contact site of toxic allergens, has not been thoroughly researched. We systematically investigated whether immune-regulatory cytokines and chemical allergens would lead to the production of VEGF in normal human keratinocytes (NHKs) in culture. VEGF production significantly increased when NHKs were treated with IFNγ, IL-1α, IL-4, IL-6, IL-17A, IL-22 or TNFα. Among the human sensitizers listed in the OECD Test Guideline (TG) 429, we found that CMI/MI, DNCB, 4-phenylenediamine, cobalt chloride, 2-mercaptobenzothiazole, citral, HCA, cinnamic alcohol, imidazolidinyl urea and nickel chloride all significantly upregulated VEGF production in NHKs. In addition, common human haptenic allergens such as avobenzone, formaldehyde and urushiol, also induced the keratinocyte-derived VEGF production. VEGF upregulation by pro-inflammatory stimuli, IFNγ, DNCB or formaldehyde is preceded by the production of IL-8, an acute inflammatory phase cytokine. Lymphangiogenic VEGF-C gene transcription was significantly increased when NHKs were treated with formaldehyde, DNCB or urushiol, while transcription of VEGF-A and VEGF-B did not change. Therefore, the chemical allergen-induced VEGF upregulation is mainly due to the increase in lymphangiogenic VEGF-C transcription in NHKs. These results suggest that keratinocyte-derived VEGF may regulate the lymphangiogenic process during the skin sensitization process of ACD.

The mucosal expression pattern of interferon-ε in rhesus macaques.

Type I IFNs play an important role in innate and adaptive immunity against viral infections. A novel type I IFN, namely IFN-ε, which can protect against vaginal transmission of HSV2 and Chlamydia muridarum bacterial infection, has been described in mice and humans. Nevertheless, the principle cell type and the expression pattern of IFN-ε in tissues remain uncertain. In addition, the expression of IFN-ε in Indian rhesus macaques (Macaca mulatta) has not been reported. Here, we analyzed IFN-ε expression in multiple mucosal sites of uninfected or SIV-infected Indian rhesus macaques using IHCS. We report for the first time the detection of IFN-ε expression in situ in the lung, foreskin, vaginal, cervical, and small and large intestinal mucosae of rhesus macaques. We found that the expression of IFN-ε was exclusive to the epithelial cells in all of the aforementioned mucosal tissues. Furthermore, the macaque IFN-ε sequence in this study revealed that macaque IFN-ε is highly conserved among human and other nonhuman primates. Lastly, SIV rectal infection did not significantly alter the expression of IFN-ε in rectal mucosae. Together, these findings indicate that IFN-ε may function as the first line of defense against the invasion of mucosal pathogens. Further studies should be conducted to examine IFN-ε protection against gastrointestinal as well as respiratory infections.

Adenovirus serotype 26 and 35 vectors induce simian immunodeficiency virus-specific T lymphocyte responses in foreskin in rhesus monkeys.

UNLABELLED: Foreskin is the principal site of heterosexual HIV-1 infection in men. However, little is known about HIV-1-specific immune responses or inflammation in foreskin. To the best of our knowledge, no previous studies have assessed immune responses to candidate HIV-1 vaccines in foreskin. Using the rhesus monkey model, we show that intramuscular immunization with adenovirus serotype 26 and 35 vectors expressing SIV antigens elicited durable SIV Gag-specific CD4(+) and CD8(+) T cell responses in foreskin that were detectable for more than 1 year following vaccination. Gag-specific CD4(+) and CD8(+) T cells were also detectable in foreskin of SIV- and SHIV-infected animals and were at least comparable in magnitude to those in peripheral blood. However, unlike peripheral blood T cells, the majority of foreskin T cells exhibited transitional memory or effector memory phenotype and expressed higher levels of the activation markers CD69, HLA-DR, and CCR5, although vaccination did not further enhance foreskin CD4(+) T cell activation. These findings suggest that systemic vaccination strategies can elicit potentially important SIV-specific cellular immunity in foreskin. Further characterization of vaccine-elicited immune responses and inflammation in foreskin is warranted. IMPORTANCE: We demonstrate here the induction of SIV-specific cellular immune responses in foreskin by adenovirus serotype 26 and 35 vaccine vectors. Foreskin T cells were more activated than peripheral blood T cells, but foreskin T cells were not further activated by vaccination. These findings suggest that alternative serotype adenovirus vectors induce potentially important immune responses in foreskin.

Immune correlates of HIV exposure without infection in foreskins of men from Rakai, Uganda.

Human immunodeficiency virus (HIV) susceptibility is heterogenous, with some HIV-exposed but seronegative (HESN) individuals remaining uninfected despite repeated exposure. Previous studies in the cervix have shown that reduced HIV susceptibility may be mediated by immune alterations in the genital mucosa. However, immune correlates of HIV exposure without infection have not been investigated in the foreskin. We collected sub-preputial swabs and foreskin tissue from HESN (n=20) and unexposed control (n=57) men undergoing elective circumcision. Blinded investigators assayed swabs for HIV-neutralizing IgA, innate antimicrobial peptides, and cytokine levels. Functional T-cell subsets from foreskin tissue were assessed by flow cytometry. HESN foreskins had elevated α-defensins (3,027 vs. 1,795 pg ml(-1), P=0.011) and HIV-neutralizing IgA (50.0 vs. 13.5% of men, P=0.019). Foreskin tissue from HESN men contained a higher density of CD3 T cells (151.9 vs. 69.9 cells mm(-2), P=0.018), but a lower proportion of these was Th17 cells (6.12 vs. 8.04% of CD4 T cells, P=0.007), and fewer produced tumor necrosis factor α (TNFα) (34.3 vs. 41.8% of CD4 T cells, P=0.037; 36.9 vs. 45.7% of CD8 T cells, P=0.004). A decrease in the relative abundance of susceptible CD4 T cells and local TNFα production, in combination with HIV-neutralizing IgA and α-defensins, may represent a protective immune milieu at a site of HIV exposure.

HIV Infection in Uncircumcised Men Is Associated With Altered CD8 T-cell Function But Normal CD4 T-cell Numbers in the Foreskin.

BACKGROUND: Human immunodeficiency virus (HIV)-infected (HIV+) men are more susceptible to sexually transmitted infections, and may be superinfected by HIV. We hypothesized that HIV induces immune alterations in the foreskin that may impact the subsequent acquisition/clearance of genital coinfections. METHODS: Foreskin tissue and blood were obtained from 70 HIV-uninfected and 20 HIV+ men undergoing circumcision. T cells were characterized by flow cytometry, immunohistochemistry, and polymerase chain reaction. RESULTS: There was substantial influx of CD8 T-cells into the foreskins of HIV+ men (108.8 vs 23.1 cells/mm(2); P < .001); but foreskin CD4 T-cell density was unchanged (43.0 vs 33.7/mm(2); P = .67), despite substantial blood depletion (409.0 vs 877.8 cells/µL; P < .001). While frequencies of foreskin C-C chemokine receptor type 5(+) (CCR5(+)) T cells, T regulatory cells, and T-helper 17 cells were unaltered in HIV+ men, CD8 T-cell production of tumor necrosis factor α (TNFα) was decreased. HIV-specific CD8 T cells were present in the foreskins of HIV+ men, although their frequency and function was reduced compared to the blood. CONCLUSIONS: Foreskin CD4 T-cell density and CCR5 expression were not reduced during HIV infection, perhaps explaining susceptibility to HIV superinfection. Foreskin CD8 T-cell density was increased, but decreased production of TNFα may enhance susceptibility to genital coinfections in HIV+ men.

Human dendritic cells transfected with a human papilloma virus-18 construct display decreased mobility and upregulated cytokine production.

The marked depletion of dendritic cells (DCs) in skin cancers, as well as preneoplastic and neoplastic cervical epithelium, suggests a central role for DCs in productive human papillomavirus (HPV) infection and cancer promotion. It has been suggested that HPV may facilitate tumor development by reducing DC density, contributing to a decrease in local immune surveillance. In this study, we have examined the response of human DCs transfected with a construct containing the HPV18 genome and their subsequent expression of papilloma virus proteins. Transfected cells expressed the L1 major capsid protein and upregulated E6 and E7 oncoprotein transcripts as detected by RT-PCR. Transfection of DCs also resulted in a significant increase in cytokine production. Finally, we observed that HPV18 transfection decreased the migratory activity of DCs. Our data indicate that HPV transfection of DCs leads to changes in migratory activity and cytokine production, which potentially can suppress or delay immune responses to viral antigens. Additionally, changes in cytokine production by HPV-transformed human fibroblasts and human cervical epithelial cells revealed that the migratory and antigen-presenting functions of DCs may be impaired by the suppressive effects of cytokines produced by HPV-infected epithelial and stromal cells.

Human papillomavirus clearance among males is associated with HIV acquisition and increased dendritic cell density in the foreskin.

BACKGROUND: The association between human papillomavirus (HPV) infection and the risk of human immunodeficiency virus (HIV) seroconversion is unclear, and the genital cellular immunology has not been evaluated. METHODS: A case-control analysis nested within a male circumcision trial was conducted. Cases consisted of 44 male HIV seroconverters, and controls were 787 males who were persistently negative for HIV. The Roche HPV Linear Array Genotype Test detected high-risk HPV (HR-HPV) and low-risk HPV (LR-HPV) genotypes. Generalized estimating equations logistic regression was used to estimate adjusted odds ratios (aORs) of HIV seroconversion. In addition, densities of CD1a(+) dendritic cells, CD4(+) T cells, and CD8(+) T cells were measured using immunohistochemistry analysis in foreskins of 79 males randomly selected from participants in the circumcision trial. RESULTS: HR-HPV or LR-HPV acquisition was not significantly associated with HIV seroconversion, after adjustment for sexual behaviors. However, HR-HPV and LR-HPV clearance was significantly associated with HIV seroconversion (aOR, 3.25 [95% confidence interval {CI}, 1.11-9.55] and 3.18 [95% CI, 1.14-8.90], respectively). The odds of HIV seroconversion increased with increasing number of HPV genotypes cleared (P < .001, by the test for trend). The median CD1a(+) dendritic cell density in the foreskin epidermis was significantly higher among males who cleared HPV (72.0 cells/mm(2) [interquartile range {IQR}, 29.4-138.3 cells/mm(2)]), compared with males who were persistently negative for HPV (32.1 cells/mm(2) [IQR, 3.1-96.2 cells/mm(2)]; P = .047), and increased progressively with the number of HPV genotypes cleared (P = .05). CONCLUSIONS: HPV clearance was associated with subsequent HIV seroconversion and also with increased epidermal dendritic cell density, which potentially mediates HIV seroconversion.

[Comparative characteristics of new mesenchymal stem cell lines derived from human embryonic stem cells, bone marrow and foreskin].

New nonimmortalized fibroblast-like cell lines SC5-MSC and SC3a-MSC, FetMSC, FRSN were obtained from human embryonic stem cells (ESC), bone marrow of a 5-6-days embryo and foreskin of a 3-years-old boy, respectively. All the lines are successfully used as the feeder at human ESC cultivation. It is determined that the average cell population doublings time varies from 25.5 h for ISC5-MSC to 38.8 h for SC3a-MSC. Active proliferation of all the lines is also shown by the corresponding growth curves. Numerical and structural karyotypic analysis showed that these lines had normal karyotype: 46,XX (SC5-MSC and SC3a-MSC) and 46,XY (FetMSC and FRSN). To determine the status of the lines, their cell surface markers were analyzed by flow cytometry. This analysis revealed the presence of surface antigens CD44, CD73, CD90, CD105 and HLA-ABC, characteristic of human MSC, and the absence of CD34 and HLA-DR. Different lines were found to express CD117(c-kit) to a different level. Immunofluorescence and flow cytometry analysis did not detect TRA-1-60 and Oct-4, characteristic of human embryonic stem cells, and revealed interlinear variations in the level of SSEA, which did not depend on the cell origin. It is not clear yet whether these interlinear variations affect functional MSC status. In all the lines, immunofluorescence analysis showed the presence of the markers of early differentiation in the derivates of three germ layers which may allow MSC to be useful, in corresponding microenvironments, for reparation of tissue injures. Adipogenic and osteogenic differentiatiation of all cell lines has been shown.

Foreskin T-cell subsets differ substantially from blood with respect to HIV co-receptor expression, inflammatory profile, and memory status.

The foreskin is the main site of heterosexual human immunodeficiency virus (HIV) acquisition in uncircumcised men, but functional data regarding T-cell subsets present at this site are lacking. Foreskin tissue and blood were obtained from Ugandan men undergoing elective adult circumcision. Tissue was treated by mechanical and enzymatic digestion followed by T-cell subset identification and assessment of cytokine production using flow cytometry. Foreskin CD4(+) T cells were predominantly an effector memory phenotype, and compared with blood they displayed a higher frequency of CCR5 expression (42.0% vs. 9.9%) and interleukin-17 production. There was no difference in T-regulatory cell frequency, but interferon-γ and tumor necrosis factor-α production were increased in foreskin CD8(+) T cells. These novel techniques demonstrate that the foreskin represents a proinflammatory milieu that is enriched for HIV-susceptible T-cell subsets. Further characterization of foreskin T-cell subsets may help to define the correlates of HIV susceptibility in the foreskin.

Mucosal trafficking of vector-specific CD4+ T lymphocytes following vaccination of rhesus monkeys with adenovirus serotype 5.

Post hoc analysis of the phase 2b Step study evaluating a recombinant adenovirus serotype 5 (rAd5)-based HIV-1 vaccine candidate suggested a potential increased risk of HIV-1 acquisition in subjects who were baseline Ad5 seropositive and uncircumcised. These concerns had a profound impact on the HIV-1 vaccine development field, although the mechanism underlying this observation remains unknown. It has been hypothesized that rAd5 vaccination of baseline Ad5-seropositive individuals may have resulted in anamnestic, vector-specific CD4(+) T lymphocytes that could have trafficked to mucosal sites and served as increased targets for HIV-1 infection. Here we show that Ad5-specific CD4(+) T lymphocyte responses at mucosal sites following rAd5-Gag/Pol/Nef vaccination were comparable in rhesus monkeys with and without baseline Ad5 immunity. Moreover, the total cellular inflammatory infiltrates and the CD3(+), CD4(+), HLA-DR(+), Ki67(+), and langerin(+) cellular subpopulations in colorectal and foreskin mucosa were similar in both groups. Thus, no greater trafficking of Ad5-specific CD4(+) T lymphocytes to mucosal target sites was observed following rAd5 vaccination of rhesus monkeys with baseline Ad5 immunity. These findings from this nonhuman primate model provide evidence against the hypothesis that recruitment of vector-specific target cells to mucosal sites led to increased HIV-1 acquisition in Ad5-seropositive, uncircumcised vaccinees in the Step study.

Enhanced cellular responses and environmental sampling within inner foreskin explants: implications for the foreskin's role in HIV transmission.

The decrease in HIV acquisition after circumcision suggests a role for the foreskin in HIV transmission. However, the mechanism leading to protection remains undefined. Using tissue explant cultures we found that Langerhans cells (LCs) in foreskin alter their cellular protein expression in response to external stimuli. Furthermore, we observe that upon treatment with TNF-alpha, tissue-resident LCs became activated and that stimulatory cytokines can specifically cause an influx of CD4+ T-cells into the epithelial layer. Importantly, both of these changes are significant in the inner, but not outer, foreskin. In addition, we find that LCs in the inner foreskin have increased ability to sample environmental proteins. These results suggest differences in permeability between the inner and outer foreskin and indicate that HIV target cells in the inner foreskin have increased interaction with external factors. This increased responsiveness and sampling provides novel insights into the underlying mechanism of how circumcision can decrease HIV transmission.

NKG2D and natural cytotoxicity receptors are involved in natural killer cell interaction with self-antigen presenting cells and stromal cells.

It is thought that human natural killer (NK) lymphocytes should not damage self-tissues due to the inhibiting signal initiated by the engagement of one or another inhibitory receptor superfamily (IRS) members with self-human histocompatibility antigen (HLA)-I. During viral infection, the low expression of self-HLA-I on infected-cells leads to a reduction of the inhibiting signal and thus NK cells kill self-cells (missing self-hypothesis). Here, we have analyzed human NK cell interaction with self-cells as antigen-presenting cells (APC) or stromal cells isolated from bone marrow or skin. Despite the expression of high levels of HLA-I, APC and stromal cells are killed by interleukin (IL)-2-activated NK cells upon lymphocyte function antigen (LFA)1-(intracellular adhesion molecule) (ICAM)1 interaction. The natural cytotoxicity receptors NKp30 and NKp46 are responsible for the delivery of lethal hit to APC, whereas NKG2D-activating receptor, the ligand of the major histocompatibility complex (MHC)-related molecule MICA, and the UL16-binding protein are involved in stromal cell killing. These events are dependent on the activation of phosphoinositol 3-kinase and consequent release of perforins and granzymes. Both bone marrow stromal cells and skin fibroblasts inhibit T cell proliferation to alloantigen or triggering through CD3/T cell receptor complex. Importantly, NK cells can revert this veto effect. Altogether, these findings support the notion that NK cells can recognize self-cells possibly affecting both APC function and interaction between lymphocytes and microenvironment leading to autoreactivity.