Avaliação da ativação de macrófagos por alfa-quitosanas sulfatadas microestruturadas

Abstract

Several therapeutic strategies lead to unwanted side effects that increase patients’ avoidance of treatment degree. In this context, the search for substances with low or nil toxicity that are capable of stimulating the individuals’ immune system, known as Biological Response Modifiers (BRM), is very important for therapeutic success. Macrophages (Mφs) have a high phenotypical plasticity, displaying a broad spectrum of functional profiles, dependant on environmental signals from which they are localized. Located within the extreme sides of the spectrum is the Antitumor Phenotype (M1-like) and the Protumor Phenotype (M2-like). Polysaccharides, like chitosans, have been recently deliberated as potent immunostimulant substances. Moreover, chitosan also escalations drug delivery because of its beneficial properties encapsulated within biocompatibility, biodegradability and atoxicity. The objective of this study was to evaluate the immunostimulatory potential of alpha-chitosan particles on the RAW264.7 macrophages activation to a M1-like profile. The Structured Sulfate Chitosan (QSE) samples were tested regarding to its cytotoxic effect and its immunostimulatory potential on macrophages by their Nitric Oxide production and cytokines released after activation. The assays were also comparative with the Neutral Chitosan (QN), Structured Neutral Chitosan (QNE) and non-structured Sulfate Chitosan (QS) samples. None of the samples presented cytotoxicity, however, in vitro assays suggest that QS and QSE have an immunostimulating potential, inducing macrophages to produce Nitric Oxide and Tumor Necrosis Factor-alpha (TNF-α). A cell proliferation stimulated by contact with QS and QSE in up to approximately 45% has been reported. The average of the nitrite production results induced by 300 μg/mL of QS and QSE were between 11 and 14 μM of Nitrite respectively, slightly less than LPS (approximately 16 μM). The QS and QSE samples induced TNF-α production in an amount between 17 and 24 ng/mL, and the LPS in 44 ng/mL. Together, the results obtained represent the first steps to the functionalization of sulfate chitosan particles in several pharmacological applications, particularly as delivery systems and therapeutic adjuvant.