Modulation of Nanostructure-Based Lipopolysaccharide Active Immunotherapy in Cancer: Size and Composition Determine Short- and Long-Term Tolerability.

Despite holding promise for cancer immunotherapy, the strong pro-inflammatory properties of lipopolysaccharide (LPS) also account for severe localized and systemic side effects, restricting its administrable dosage and the possibility of chronic dosing. Herein, we exploited the surface-active properties of LPS molecules to develop pathogen-mimicking LPS-decorated nanostructures with different compositions (lipid nanoemulsion vs polymeric nanospheres) and sizes (volumetric mean diameters of 100 nm vs 700 nm). The formulations were tested in cell culture for their immunostimulatory properties and in vivo against a murine subcutaneous colorectal cancer model. While all nanostructures resulted in similar levels of apoptotic cell death in tumor cells cultured with splenocytes, both the size and the composition of the nanostructures were found to govern the short- and long-term tolerability of LPS-based immunotherapy in vivo. The toxicity-related end point of the animal trials was decided upon in the case of a body condition score (BCS) of 1 and poor hair coat, or more than 15% loss of the original body weight, while in the absence of long-term intolerability, the experiments were terminated in the case of full remission or once the tumor surpassed a volume of 1000 mm3. Size was an important determinant of short-term tolerability, with larger particles being associated with higher incidence and extent of localized necrosis (3-6% necrotic surface area). Nanostructure composition, on the other hand, predominantly governed the long-term systemic tolerability. Within this context, the higher affinity of LPS molecules to the triglyceride core of the nanoemulsion compared to the polymeric matrix significantly improved the tolerability of the former over time. In fact, the mean survival estimate of the animals treated with small LPS nanoemulsion (LPS-NE (small)) was at least 42 days longer than that of the LPS and the LPS-decorated polymeric nanoparticle (LPS-NP) groups. Unlike other treatment groups, the experiments on 80% of the animals in LPS-NE (small) were terminated due to complete remission or tumor volume >1000 mm3. While a better understanding of these findings requires a larger scale, mechanistic-oriented trial on larger animal models, they indicate the role of nanostructures as beyond the carriers of the incorporated immunotherapeutic cargos. This highlights the importance of a wise selection of nanoparticle composition and a purposeful tuning of their physicochemical properties to enhance the safety profile and improve the eventual immunotherapeutic outcome.

Nanoparticle-based delivery enhances anti-inflammatory effect of low molecular weight heparin in experimental ulcerative colitis.

Epithelial administration of low molecular weight heparin (LMWH) has proven its therapeutic efficiency in ulcerative colitis (UC) but still lacks of a sufficiently selective drug delivery system. Polymeric nanoparticles were used here not only to protect LMWH from intestinal degradation but also to provide targeted delivery to inflamed tissue in experimental colitis mice. LMWH was associated with polymethacrylate nanoparticles (NP) type A (PEMT-A) or type B (PEMT-B) of a size: 150 nm resulting in a maximum drug loading: 0.1 mg/mg. In a lipopolysaccharide-stimulated macrophages both, free LMWH and LMWH-NP have significantly reduced the cytokines secretion independently from cellular uptake. The in-vivo therapeutic efficiency was dose dependent as at low doses (100 IU/kg) only minor differences between free LMWH and LMWH-NP were found and the superiority of LMWH-NP became prominent with dose increase (500 IU/kg). Administration of LMWH-NP at 500 IU/kg has markedly improved the clinical activity as compared to LMWH while similarly pathophysiological indicators revealed increased therapeutic outcome in presence of NP compared to LMWH alone: Myeloperoxidase (Colitis control: 10 480 ± 5335, LMWH-PEMT-A NP: 1507 ± 2165, LMWH-PEMT-B NP: 382 ± 143, LMWH: 8549 ± 5021 units/g) and tumor necrosis factor: (Colitis control: 1636 ± 544, LMWH-PEMT-A NP: 511 ± 506, LMWH-PEMT-B NP: 435 ± 473, LMWH: 1110 ± 309 pg/g). Associating LMWH with NP is improving the anti-inflammatory efficiency of LMWH in-vivo by its protection against degradation in luminal environment and selective drug delivery. Such a combination holds promise for a highly specific therapy by its double selectivity towards the inflamed intestinal tissue. LMWH-PEMT NP have significantly improved the clinical activity in-vivo in comparison to free LMWH.