PHOTOINACTIVATION EFFECT ON NONTUBERCULOUS MYCOBACTERIA USING ZN-PHTHALOCYANINE LOADED INTO LIPOSOMES

MARIANA MIRETTI; LETICIA JURI; ALEJANDRA PERALTA; M CRISTINA COSIANSI; TOMAS C. TEMPESTI; MARIA TERESA BAUMGARTNER

Congreso; SAIB-SAIGE 2021; 2021

Sociedad Argentina de Investigación Bioquímica y Biología Molecular Y Asociación Civil de Microbiología General

Nontuberculous mycobacteria (NTM) represent a heterogeneous group of environmental bacteria. NTM infections are difficult to diagnose and include many species that can cause severe disease as lymphadenitis, lung, skin, bone, and soft tissue infections, or disseminated disease.[1] NTM infections are multisystem and multigenic-based diseases and depend on the entry and host susceptibility factors. Disseminated NTM infections impact severely on immunocompromised patients.[2] Among the most clinically relevant species of rapid growth NTMs are Mycobacterium chelonae and Mycobacterium fortuitum.Antimicrobial photodynamic therapy (aPDT) has reemerged over the last decade as an alternative to eliminate pathogens, principally those antimicrobials resistant. aPDT involves a compound innocuous in the darkness denominated photosensitizer (PS), light, and oxygen. The excitation of PS leads to reactive species oxygen (ROS) and/or singlet oxygen (1O2). These species react with biomolecules, producing cell damage and microorganism destruction.[3] Phthalocyanines (Pcs) are considered promising second-generation PS. However, due to its lipophilic nature, Pcs tend to form aggregates in aqueous media, and consequently, the efficacy of aPDT decreases.[4] The incorporation of Pcs in delivery systems such as liposomes improve solubility and reduces aggregation.[5] Liposomes are biocompatible and biodegradable nanocarriers constituted by phospholipids bilayers that surround an aqueous compartment.[6] Several reports showed Pcs encapsulated in different liposomal formulations with high efficacy in vitro. This work evaluates the effectiveness of Zn-phthalocyanine (ZnPc) loaded into DPPC-chol liposomes (ZnPc-liposomes) to photoinactivate two NTM M.fortuitum and M.chelonae. ZnPc-liposomes are prepare by the injection method previously descript.[7] Both mycobacteria were incubated with ZnPc-liposomes for 4 h in the dark at 37 °C. The photoinactivation was determinate for different irradiation times (0, 45 and 90 min); it was evaluated based on the decrease of the viable bacterial number (log10) in the tested and control samples. Significant photokilling effect was defined as ≥ 3 log10 reductions in CFU/mL. Control liposomes and ZnPc-liposomes non showed antimicrobial action in mycobacteria. The bacterial viability was almost unaffected for in vitro experiments of ZnPc solution in dimethylsulfoxide against M. fortuitum. However, photoinactivation effects are observed both in M. fortuitum as M. chelonae after irradiation using ZnPc-liposomes. The results show 3log10 CFU/ml reduction after a higher irradiation dose. For that, a light dose-dependent cytotoxic effect of ZnPc-liposomes was observed. Finally, antimicrobial photodynamic therapy using ZnPc-liposomes could be an alternative to treat NTM as M. fortuitum and M. chelonae.