Smoking increases oral mucosa susceptibility to Candida albicans infection via the Nrf2 pathway: In vitro and animal studies

Smoking and Candida albicans (C. albicans) infection are risk factors for many oral diseases. Several studies have reported a close relationship between smoking and the occurrence of C. albicans infection. However, the exact underlying mechanism of this relationship remains unclear. We established a rat infection model and a C. albicans-Leuk1 epithelial cell co-culture model with and without smoke exposure to investigate the mechanism by which smoking contributes to C. albicans infection. Oral mucosa samples from healthy individuals and patients with oral leucoplakia were also analysed according to their smoking status. Our results indicated that smoking induced oxidative stress and redox dysfunction in the oral mucosa. Smoking-induced Nrf2 negatively regulated the NLRP3 inflammasome, impaired the oral mucosal defence response and increased the oral mucosa susceptibility to C. albicans. The results suggest that the Nrf2 pathway could be involved in the pathogenesis of oral diseases by mediating an antioxidative response to cigarette smoke exposure and suppressing host immunity against C. albicans.     

Estimation of salivary nitric oxide in oral precancer patients

Abstract

The role of nitric oxide (NO) in the initiation, promotion and progression of cancer has been the subject of speculation and conflicting reports in the literature. The high incidence of oral cancer and precancer has been linked to tobacco chewing and smoking habits; NO is considered an indicator of tobacco-related diseases. We compared salivary NO levels in oral precancer and normal patients. Unstimulated whole saliva was collected from 15 patients with oral precancer (group 1) and 15 healthy age and sex matched subjects (group 2). Salivary nitrite levels were estimated using a colorimetric method and a spectrophotometer. The salivary nitrite concentration of group 2 (median = 4.21 μg/ml) was significantly less than for group 1 (median = 12.91 μg/ml). We have added evidence concerning involvement of NO in the pathogenesis of oral cancer, but whether it is a potentially carcinogenic agent at the concentration at which it is present in oral precancer patients requires further evaluation.     

Modelling the early phases of bone regeneration around an endosseous oral implant

The objective of this study was to see whether a mathematical model of fracture healing was able to mimic bone formation around an unloaded screw-shaped titanium implant as it is well-believed that both processes exhibit many biological similarities. This model describes the spatio-temporal evolution of cellular activities, ranging from mesenchymal stem cell migration, proliferation, differentiation to bone formation, which are initiated and regulated by the growth factors present at the peri-implant site. For the simulations, a finite volume code was used and adequate initial and boundary conditions were applied. Two sets of analyses have been performed, in which either initial and boundary condition or model parameter values were changed with respect to the fracture healing model parameter values. For a number of combinations, the spatio-temporal evolution of bone density was well-predicted. However reducing cell proliferation rate and increasing osteoblast differentiation and osteogenic growth factor synthesis rates, the simulation results were in agreement with the experimental data.     

A Cross-Sectional Epidemiological Study of Prevalence and Severity of Bit-Induced Oral Trauma in Polo Ponies and Race Horses

Bit and bridle accessories improperly fitted in ridden horses can cause oral trauma such as bone spurs, commissure ulceration, and tongue lacerations. This study was used to identify, grade, and compare the types of oral traumas commonly found within polo ponies and race horses. Injuries were assessed visually and by palpation on the tongue, lips’ commissures, and interdental space. A total of 50 polo ponies and 50 race horses were sampled in the South of England. A Poisson model was successfully fitted to the data (p < .001), and the variables of discipline (p < .001), injury type (p < .001), and age (p < .001) were significant. Race horses with snaffle bits were predisposed to significantly higher severities and prevalence of oral trauma than were polo ponies in gag bits. Only polo ponies were observed with tongue trauma. Race horses had higher severities of injuries in the commissures and bone spurs. Positive correlations were found between age and/or time in sport and induced biting injuries. Polo ponies had been playing longer before the occurrence of injuries.     

Investigation of carvedilol-evoked Ca2+ movement and death in human oral cancer cells

The effect of carvedilol on cytosolic free Ca²⁺ concentrations ([Ca²⁺]_i) in OC2 human oral cancer cells is unknown. This study examined if carvedilol altered basal [Ca²⁺]_i levels in suspended OC2 cells by using fura-2 as a Ca²⁺-sensitive fluorescent probe. Carvedilol at concentrations between 10 and 40 µM increased [Ca²⁺]_i in a concentration-dependent fashion. The Ca²⁺ signal was decreased by 50% by removing extracellular Ca²⁺. Carvedilol-induced Ca²⁺ entry was not affected by the store-operated Ca²⁺ channel blockers nifedipine, econazole, and SK&F96365, but was enhanced by activation or inhibition of protein kinase C. In Ca²⁺-free medium, incubation with the endoplasmic reticulum Ca²⁺ pump inhibitor thapsigargin did not change carvedilol-induced [Ca²⁺]_i rise; conversely, incubation with carvedilol did not reduce thapsigargin-induced Ca²⁺ release. Pretreatment with the mitochondrial uncoupler carbonylcyanide m-chlorophenylhydrazone (CCCP) inhibited carvedilol-induced [Ca²⁺]_i release. Inhibition of phospholipase C with U73122 did not alter carvedilol-induced [Ca²⁺]_i rise. Carvedilol at 5–50 µM induced cell death in a concentration-dependent manner. The death was not reversed when cytosolic Ca²⁺ was chelated with 1,2-bis(2-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid acetoxymethyl ester (BAPTA/AM). Annexin V/propidium iodide staining assay suggests that apoptosis played a role in the death. Collectively, in OC2 cells, carvedilol induced [Ca²⁺]_i rise by causing phospholipase C-independent Ca²⁺ release from mitochondria and non-endoplasmic reticulum stores, and Ca²⁺ influx via protein kinase C-regulated channels. Carvedilol (up to 50 μM) induced cell death in a Ca²⁺-independent manner that involved apoptosis.     

Feasibility of Histological Scoring and Colony Count for Evaluating Infective Severity in Mouse Vaginal Candidiasis

Qualitative measurement of the infective level is relatively difficult in experimental vaginal candidiasis. Female BALB/c mice aged 8 to 10 weeks were randomly divided into E1, E2 and E0 groups, which received subcutaneous injection of 0.05 mg, 0.1 mg of estradiol benzoate or 0.1 ml soybean oil 3 days before vaginal inoculation, respectively, and hormone treatment continued every other day thereafter. Each group was further divided into infected and noninfected subgroups. The infected mice were inoculated intravaginally with 10 µl (5 × 10⁴ conidia) of Candida albicans suspension, while the noninfected mice were inoculated with 10 µl phosphate-buffered saline. Direct microscopic examination, colony count and vaginal histopathology including infection degree and inflammation extent were performed at 3, 7 and 14 days post inoculation. Estrogen treatment increased the vaginal fungal burden and extent of infection and inflammation compared with the control group, and 0.3 mg/week estrogen generally induced more severe infection and inflammation than 0.15 mg/week estrogen did. Colony count peaked on day 3 and decreased remarkably after 7 days. Infection score increased gradually during the first 7 days and decreased on day 14, while inflammation extent exacerbated progressively over the course of 14 days. This study demonstrates that the modified histological scoring system might be more feasible than colony count for evaluation of infectivity and dynamic change in experimental vaginal candidiasis.     

Characterization of a surrogate murine antibody to model anti-human CD3 therapies

Fc-modified anti-human CD3ε monoclonal antibodies (mAbs) are in clinical development for the treatment of autoimmune diseases. These next generation mAbs have completed clinical trials in patients with type-1 diabetes and inflammatory bowel disease demonstrating a narrow therapeutic window. Lowered doses are ineffective, yet higher pharmacologically-active doses cause an undesirable level of adverse events. Thus, there is a critical need for a return to bench research to explore ways of improving clinical outcomes. Indeed, we recently reported that a short course of treatment affords synergy, providing long-term disease amelioration when combining anti-mouse CD3 and anti-mouse tumor necrosis factor mAbs in experimental arthritis. Such strategies may widen the window between risk and benefit; however, to more accurately assess experimentally the biology and pharmacology, reagents that mimic the current development candidates were required. Consequently, we engineered an Fc-modified anti-mouse CD3ε mAb, 2C11-Novi. Here, we report the functional characterization of 2C11-Novi demonstrating that it does not bind FcγR in vitro and elicits little cytokine release in vivo, while maintaining classical pharmacodynamic effects (CD3-TCR downregulation and T cell killing). Furthermore, we observed that oral administration of 2C11-Novi ameliorated progression of remitting-relapsing experimental autoimmune encephalitis in mice, significantly reducing the primary acute and subsequent relapse phase of the disease. With innovative approaches validated in two experimental models of human disease, 2C11-Novi represents a meaningful tool to conduct further mechanistic studies aiming at exploiting the immunoregulatory properties of Fc-modified anti-CD3 therapies via combination therapy using parenteral or oral routes of administration.