Candida albicans Sap6 Initiates Oral Mucosal Inflammation via the Protease Activated Receptor PAR2

Candida albicans Sap6, a secreted aspartyl protease (Sap), contributes to fungal virulence in oral candidiasis. Beside its protease activity, Sap6 contains RGD (RGDRGD) motif required for its binding to host integrins. Sap6 activates immune cells to induce proinflammatory cytokines, although its ability to interact and activate human oral epithelial cells (OECs) remain unknown. Addition of purified recombinant Sap6 (rSap6) to OECs resulted in production of IL-1β and IL-8 cytokines similar to live hyphal C. albicans. OECs exposed to rSap6 showed phosphorylation of p38 and MKP1 and expression of c-Fos not found with C. albicans Δsap6, heat-inactivated Sap6, or rSap6ΔRGD . Heat inactivated rSap6 was able to induce IL-1β but not IL-8 in OECs, while rSap6ΔRGD induced IL-8 but not IL-1β suggesting parallel signaling pathways. C. albicans hyphae increased surface expression of Protease Activated Receptors PAR1, PAR2 and PAR3, while rSap6 increased PAR2 expression exclusively. Pretreatment of OECs with a PAR2 antagonist blocked rSap6-induced p38 MAPK signaling and IL-8 release, while rSap6ΔRGD had reduced MKP1 signaling and IL-1β release independent from PAR2. OECs exposed to rSap6 exhibited loss of barrier function as measured by TEER and reduction in levels of E-cadherin and occludin junctional proteins that was prevented by pretreating OECs with a PAR2 antagonist. OECs treated with PAR2 antagonist also showed reduced rSap6-mediated invasion by C. albicans cells. Thus, Sap6 may initiate OEC responses mediated both through protease activation of PAR2 and by its RGD domain. This novel role of PAR2 suggests new drug targets to block C. albicans oral infection.

Dental caries and head and neck cancers

IMPORTANCE

Dental caries is the demineralization of tooth structures by lactic acid from fermentation of carbohydrates by commensal gram-positive bacteria. Cariogenic bacteria have been shown to elicit a potent Th1 cytokine polarization and a cell-mediated immune response.

OBJECTIVE

To test the association between dental caries and head and neck squamous cell carcinoma (HNSCC).

DESIGN, SETTING, AND PARTICIPANTS

Case-control study in a comprehensive cancer center including all patients with newly diagnosed primary HNSCC between 1999 and 2007 as cases and all patients without a cancer diagnosis as controls. Those with a history of cancer, dysplasia, or immunodeficiency or who were younger than 21 years were excluded.

EXPOSURES

Dental caries, fillings, crowns, and endodontic treatments, measured by the number of affected teeth; missing teeth. We also computed an index variable: decayed, missing, and filled teeth (DMFT).

MAIN OUTCOMES AND MEASURES

Incident HNSCC.

RESULTS

We included 620 participants (399 cases and 221 controls). Cases had a significantly lower mean (SD) number of teeth with caries (1.58 [2.52] vs 2.04 [2.15]; P = .03), crowns (1.27 [2.65] vs 2.10 [3.57]; P = .01), endodontic treatments (0.56 [1.24] vs 1.01 [2.04]; P = .01), and fillings (5.39 [4.31] vs 6.17 [4.51]; P = .04) but more missing teeth (13.71 [10.27] vs 8.50 [8.32]; P < .001) than controls. There was no significant difference in mean DMFT. After adjustment for age at diagnosis, sex, marital status, smoking status, and alcohol use, those in the upper tertiles of caries (odds ratio [OR], 0.32 [95% CI, 0.19-0.55]; P for trend = .001), crowns (OR, 0.46 [95% CI, 0.26-0.84]; P for trend = .03), and endodontic treatments (OR, 0.55 [95% CI, 0.30-1.01]; P for trend = .15) were less likely to have HNSCC than those in the lower tertiles. Missing teeth was no longer associated with HNSCC after adjustment for confounding.

CONCLUSIONS AND RELEVANCE

There is an inverse association between HNSCC and dental caries. This study provides insights for future studies to assess potential beneficial effects of lactic acid bacteria and the associated immune response on HNSCC.

Oxidative stress markers in plasma and urine of prepubertal patients with type 1 diabetes mellitus

Markers of oxidative stress were studied in plasma and urine of prepubertal patients with type 1 diabetes mellitus (DM1) with less than 5 years of disease (n = 27). The results were compared to healthy, age- and sex-matched control children (n = 27). Oxidative stress parameters evaluated included advanced oxidation protein products (AOPP), total peroxyl radical-trapping antioxidant parameter (TRAP), and F2-isoprostanes (8-epi-prostaglandin-F2: 8-isoPGF2alpha). No statistically significant differences were found for any of the oxidative stress markers assessed between patients with DM1 and controls. In addition, weight, height, and routine metabolic tests, including creatininemia and cholesterol levels, were similar between the groups. The lack of significant differences between healthy controls and patients with DM1 suggests that treatment is able to counteract the increase in free radical production.

TNFalpha increases in vitro migration of human HPV18-positive SW756 cervical carcinoma cells

TNFalpha has been associated with both, tumor survival and apoptosis. This cytokine is also involved in promoting cell migration during wound healing and tumorigenesis. SW756 is a HPV18-positive cervical carcinoma cell line, which has been used to study different mechanisms of cervical cancer progression. An in vitro assay of scratch wound healing onto monolayers of SW756 cells was used to assess the effect of TNFalpha on cell migration into a wound space. It was found that SW756 cells have the ability to migrate, but not proliferate in response to scratch wounding in a serum-free medium supplemented with TNFalpha. RT-PCR analysis showed that SW756 cells express TNFalpha mRNA when incubated in medium with and without serum. Wound closure and migration rate of SW756 cells were significantly increased in the presence of serum-free media supplemented with TNFalpha (10 ng/mL) as compared to serum-free media, and media supplemented with either anti-TNFalpha antibody or both TNFalpha and anti-TNFalpha antibody (p < 0.05). The results showed a stimulatory effect of TNFalpha on the migration of SW756 cervical carcinoma cells, suggesting a novel and important role for TNFalpha in cervical cancer progression.

Characterization of mast cell subpopulations in lip cancer

BACKGROUND

Lip squamous cell carcinoma (SCC) is the most common form of oral cancer. Human mast cells (MCs), which are increased in lip SCC, are classified by their protease content in tryptase-positive (MC(T)) and tryptase/chymase-positive (MC(TC)). MC proteases are associated with tumor progression and angiogenesis. The aim of this study was to quantify and characterize MC subpopulations in lip SCC.

METHODS

Serial sections from lip SCC (n = 21) and normal lip vermilion (n = 8) biopsies were stained immunohistochemically for tryptase and enzymehistochemically for chymase to determine MC subpopulation density and distribution.

RESULTS

MC(T) and MC(TC) were increased in lip SCC when compared with normal lip (P < 0.0001), where MC(T) predominated over MC(TC) (P < 0.01). In lip SCC neither subpopulation predominated. Regarding distribution, MC(T) were higher than MC(TC) at the intratumoral stroma, whereas MC(TC) were higher than MC(T) at the peritumoral stroma (P < 0.01).

CONCLUSIONS

The results suggest that MC subpopulations may contribute to lip SCC progression. While intratumoral MC(T) may stimulate angiogenesis, peritumoral MC(TC) may promote extracellular matrix degradation and tumor progression at the invasion front.

Expression of apoptotic and cell proliferation regulatory proteins in actinic cheilitis

BACKGROUND

Actinic cheilitis (AC) is a pre-malignant lesion caused by ultraviolet (UV) radiation. The apoptotic proteins p53, bax, bcl-2, and the proliferation marker Ki-67, are known to play an important role in UV-exposed skin and carcinomas, therefore, these markers were assessed in AC and compared with normal lip and oral mucosa.

METHODS

AC (n = 13), normal lip (n = 7) and oral mucosa (n = 6) biopsies were stained immunohistochemically for p53, bax, bcl-2 and Ki-67, to determine their expression and distribution.

RESULTS

p53 was over-expressed in AC as compared with normal lip and oral mucosa (P < 0.003). Although bcl-2 expression was higher in AC than in oral mucosa (P < 0.002), it was significantly reduced as compared with normal lip (P < 0.04). Bax expression remained unchanged, and Ki-67 was significantly increased in AC and normal lip as compared with oral mucosa (P < 0.05).

CONCLUSION

The results suggest that DNA-damaged cells by UV radiation in AC are eliminated by apoptosis.

Increased mast cell density and protease content in actinic cheilitis

BACKGROUND

Actinic cheilitis (AC) is a pre-malignant lesion caused by ultraviolet (UV) radiation and characterized by epithelial and connective tissue alterations. Mast cells (MCs), key contributors to solar elastosis in murine UV-irradiated skin, were characterized in order to assess their potential contribution to connective tissue degeneration in AC.

METHODS

Actinic cheilitis (n = 15) and normal lip (n = 8) biopsies were stained immunohistochemically for tryptase and enzymehistochemically for chymase to determine MC density and protease content. MC subpopulations (i.e. MC(T) containing only tryptase, and MC(TC) containing chymase and tryptase) and their distribution were also determined.

RESULTS

Mast cells and their proteases were increased in AC as compared with normal lip (P < 0.0001), and appeared degranulated especially around elastotic areas. MC(T) predominated over MC(TC) in AC and normal lip (P < 0.05). However, in AC MC(T) were increased in the epithelium/connective junction and connective area (P < 0.05), while in normal lip MC(T) predominated in connective and submucosal areas (P < 0.05).

CONCLUSION

The results suggest that increased MC density and protease content may contribute to elastosis formation in AC. In addition, changes in MC(T) distribution may favor AC malignization.

The role of protein kinase C and calcium in induction of human polymorphonuclear leukocyte IL-1 beta gene expression by GM-CSF

At infection sites, synthesis of interleukin (IL-)1beta by polymorphonuclear leukocytes (PMNs) facilitates the recruitment of inflammatory cells and enhances the inflammatory response. We investigated the role of protein kinase C (PKC) and Ca2+ in the induction of PMN IL-1beta gene expression by GM-CSF. The PKC inhibitors chelerythrine and H7 blocked induction of IL-1beta mRNA expression in human PMNs. HA1004, an H7 analogue with little activity towards PKC, had no inhibitory effect. Similarly, H7 blocked IL-1beta transcription in nuclear run-on analysis, while HA1004 had little effect. The intracellular Ca2+ chelator BAPTA/AM inhibited induction of IL1beta mRNA accumulation and transcription by GM-CSF. At concentrations similar to those used to inhibit IL-1beta gene expression, H7, chelerythrine, and BAPTA all inhibited substrate phosphorylation by PKC isolated from PMN lysates. Thus, PKC and Ca2+ are potential targets for modulating an important PMN immunoregulatory function.