Nano-carrier Macrophage Interaction: Role of Secondary Toxicity

  • Author / Creator
    Sarfraz, Muhammad K
  • Macrophages are the primary cells of innate immunity that provide the first line of defence against any external stimuli. Their phagocytic properties enable them to engulf invading microbes or foreign particles. The phagocytic capability of macrophages plays a major role in interfering with drug targeting strategies, but can be used as a treatment advantage if the macrophage is itself the target cell. Although nano-drug delivery systems might deliver a drug contained in polymeric micelles or nanoparticles into a targeted area, the rapid accumulation of these vesicles/particles in macrophages reduces the efficiency of the targeted drug delivery. Additionally, biodegradation of polymeric nanoparticles in macrophages causes secondary toxicity, characterized by the release of different cytokines and chemokines (e.g., TNF-α, IFN-γ, IL-1β, IL-10) by macrophages. In tuberculosis, the mycobacterium tubercle can only cause infection after invading and growing inside alveolar macrophages; where as, in cancer, macrophages are the only infiltrating immune cells into tumours and can represent up to half of its mass. They play a major role in tumour angiogenesis. Using murine alveolar macrophages (MH-S), the first study investigated secondary toxicity produced when macrophages were a target with nanocarriers and assessed the implication for disease conditions like TB. In a second study, a co-culture model for alveolar macrophages and lung cancer cells was investigated for assessing secondary toxicity effects on the viability of the cancer cells. In the first study, two different nanocarriers—HA-TS polymeric micelles and gelatin and polyisobutyl cyanoacrylate (PIBCA) nanoparticles—were used, and their induction of secondary toxicity was evaluated. HA-TS micelles were synthesized by chemical conjugation of hydrophobic α-tocopherol succinate (TS) to hydrophilic hyaluronic acid (HA) and characterized by Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (NMR). The results confirmed the structural changes incorporated during micelle synthesis. The rifampicin (RIF) entrapment efficiency of micelles, studied by HPLC, showed a drug loading of 70.7–79.1% (w/w). In vitro release curves revealed a sustained release of RIF from RIF-loaded HA-TS (RIF-HA-TS) micelles. Cellular uptake of RIF-HA-TS by murine alveolar macrophages (MH-S) showed that both phagocytosis (endocytosis) and active transport were responsible for cellular uptake. Cytokine profiling revealed that both E. coli lipopolysaccharide (LPS) and RIF-HA-TS micelles induced secondary toxicity. Similarly, gelatin and polyisobutyl cyanoacrylate (PIBCA) nanoparticles were evaluated for secondary toxicity using murine alveolar macrophages (MH-S). The antituberculosis drugs moxifloxacin and rifampicin were loaded into gelatin and polyisobutyl-cyanoacrylate nanoparticles synthesized by a two-step desolvation and anionic emulsion polymerization technique. IC50 values of polyisobutyl-cyanoacrylate nanoparticles were lower than the IC50 values of gelatin nanoparticles. Cytokine ELISA analysis revealed that both types of nanoparticle induced a higher release of Th1 type cytokines. The use of nanoparticles produced significantly more secondary toxicity than the use of micelles. In the second study, secondary toxicity was further evaluated with a lung cancer model. Doxorubicin loaded nanoparticles were synthesized with the method used for gelatin and polyisobutyl-cyanoacrylate nanoparticles. The lung cancer model consists of confluent alveolar macrophage MH-S and A-549 lung cancer cells separated by a 0.4 µm porous membrane. Macrophages were treated with nanoparticles and secondary toxicity was assessed by measuring A-549 lung cancer cell viability. These effects were also investigated using anti-inflammatory dugs. The result showed that nanoparticle treatment of macrophages produced a secondary cytotoxic effect that decreased the A-549 cell viability 40–62%. However, this effect was significantly reduced to 10–48% if the macrophages were exposed to anti-inflammatory drugs. The data suggest that anti-inflammatory treatments can decrease nanoparticle-induced macrophage cytotoxicity and thus decrease its anti-tumor effectiveness. Macrophages exposed to nanocarriers showed secondary toxicity in murine alveolar macrophages (MH-S). This pro-inflammatory effect might strengthen the macrophage immune response to control diseases like TB. In cancer, the pro-inflammatory effect caused a significant reduction in cancer cell viability. This effect was significantly reduced with the concomitant use of anti-inflammatory drugs. The insight gained in these studies can be utilized for new treatments approaches toward macrophage oriented diseases or utilization of macrophages for other diseases like arthritis and osteoporosis as demonstrated for cancer.

  • Subjects / Keywords
  • Graduation date
    Fall 2016
  • Type of Item
  • Degree
    Doctor of Philosophy
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.