Immunological Intolerance and Tolerance by Antigenic Co-Stimulation

The plasticity and dynamism in the immune responses to both self and environmental stimulation promote the maintenance and adaptation of a system that tends to harmoniously survive and evolve. Fluctuating antigenic forces coexist within the immune system and oscillate between order and chaos to the equilibrium. Thus, when mounting a response to internal or environmental antigens, the main host responses can be divided into two immunological categories. The first, a well-adapted mechanism of complex multi-cellular organisms classically known as tolerance, promotes persistent immunological responses. In the second, opposite way, the modulation of inflammatory immune responses occurs, which we call “intolerance”. Tolerance and intolerance can be mediated by humoral molecules, such as inflammatory compounds, complement, and antibodies, and by different cell types, such as sentinel cells, antigen-presenting cells, and cells that orchestrate the immune response. Tolerogenesis is important in vertebrates because it predisposes species to adapt to self and environmental negative-selective forces. This process depends, in large part, on antigenic co-stimulation (AgCS), which operates as a multi-integrated network formed by all immune and non-immune cells of the body that establishes tolerant immunoregulatory interactions from cells to cells and from cells to the environment. Antigenic distribution, quantity, nature, route of administration, and antigenic convergence on co-stimulatory pathways, and concurrent infections, and the presence of microorganisms (commensals and pathogens) in more than one site are important factors for activating AgCS. To conclude, the AgCS route is a natural immune response generated by heterogeneous APC profile with centralized regulation that promote the counterbalance between intolerant e tolerant status, which can have several applications in the medical and biological fields.

<i>In Vitro</i>Effects of Photodynamic Therapy with Three Photosensitizers on <i>Candida</i>spp from Complicated Vulvovaginitis and Asymptomatic Women

Aim: To evaluate photodynamic therapy (PDT) in vitro to reduce the growth of Candida spp, and its synergy with the antifungals fluconazole and ketoconazole for inhibition of resistant, DDS and susceptible isolates from asymptomatic carriers and with complicated vulvovaginitis. Methods: Between 2017 and 2020, we evaluated 230 women with vulvovaginal candidiasis and 400 asymptomatic. We obtained 130 positive cultures for Candida spp from vulvovaginitis and 94 asymptomatic. Yeasts were characterized by classical and molecular tests. Sensitivity to fluconazole and ketoconazole was evaluated by E-test. We used photodynamic light through blue LED, wavelengths between 450 to 470 nm, power of 260 mW, energy fluence of 270 J/cm2, for 15 minutes over all colonies of Candida spp. Methylene blue (MB) at 450 mg/mL, 2% gentian violet (VG) and 50 μM curcumin (CR) were used in association or not with LED irradiation. Suspensions of Candida spp of 106 CFU/mL, subjected to the different assays, were introduced in 96-well microplates, incubated for 48 hours at 35˚C and the readings at 530 nm. The samples were finally cultivated in Petri plates containing Sabouraud dextrose agar to assess the growth inhibition. All procedures were in triplicate. Results: C. albicans was prevalent in vulvovaginal candidiasis, however, we also isolated non-albicans species such as C. glabrata, C. tropicalis and C. parapsilosis. There was a substantial reduction (66.6% to 83.8%) of the CFU/mL of the isolates treated with FDT. Gentian violet at 2% alone reduced the growth of CFU/ml of Candida spp from 69% to 75%. Among isolates of vaginitis and asymptomatic carriers, after using FDT, we found a reduction in resistant phenotypes and DDS for fluconazole in percentages from 20% to 100% for C. albicans, from 50% to 100% C. glabrata, 33.3% to 100% C. parapsilosis and 100% C. tropicalis. For ketoconazole in the same isolates, there was a reduction in phenotypes with MIC > 16 μg/mL of up to 50% in C. albicans, 50% to 100% C. glabrata, 50% to 100% C. tropicalis. Conclusions: PDT with MB, GV and CR revealed efficacy in vitro in reducing the growth of C. albicans and non-albicans, especially due to chronic recurrent vulvovaginitis.