Antagonist G-targeted liposomes for improved delivery of anticancer drugs in small cell lung carcinoma.

Ligand-mediated targeted liposomes have the potential to increase therapeutic efficacy of anticancer drugs. This work aimed to evaluate the ability of antagonist G, a peptide targeting agent capable of blocking the action of multiple neuropeptides, to selectivity improve targeting and internalization of liposomal formulations (long circulating liposomes, LCL, and stabilized antisense lipid particles containing ionizable amino lipid, SALP) to H69 and H82 small cell lung carcinoma (SCLC) cell lines. Antagonist G-targeted LCL and SALP were prepared by two different methods (either by direct covalent linkage at activated PEG grafted onto the liposomal surface or by post-insertion of DSPE-PEG-antagonist-G-conjugates into pre-formed liposomes). Association of the liposomal formulations with target SCLC cells was studied by fluorescence microscopy using fluorescence-labelled liposomes and confirmed quantitatively with [3H]-CHE-labelled liposomes. An antisense oligodeoxynucleotide against the overexpressed oncogene c-myc(as(c-myc)) was efficiently loaded into SALP formulations, the encapsulation efficiency decreased due to the inclusion of the targeting ligand. Also, liposome size was affected by as(c-myc) physical chemical properties. The amount of antagonist G linked to the surface of the liposomal formulations was dependent on the coupling method and lipid composition used. Covalent attachment of antagonist G increased liposomes cellular association and internalization via receptor-mediated and clathrin-dependent endocytosis, as assessed in SCLC cell lines. Biodistribution studies in healthy mice revealed a preferential lung accumulation of antagonist G-targeted SALP as compared to the non-targeted counterpart. Lung levels of the former were up to 3-fold higher 24 h after administration, highlighting their potential to be used as delivery vectors for SCLC treatment.

Dipeptidyl Peptidase-4 Is a Pro-Recovery Mediator During Acute Hepatotoxic Damage and Mirrors Severe Shifts in Kupffer Cells.

Dipeptidyl peptidase-4 (DPP-4 or clusters of differentiation [CD]26) is a multifunctional molecule with established roles in metabolism. Pharmacologic inhibition of DPP-4 is widely used to improve glycemic control through regulation of the incretin effect. Colaterally, CD26/DPP-4 inhibition appears to be beneficial in many inflammatory conditions, namely in delaying progression of liver pathology. Nevertheless, the exact implications of CD26/DPP-4 enzymatic activity in liver dysfunction remain unclear. In this work, we investigated the involvement of CD26/DPP-4 in experimental mouse models of induced hepatocyte damage that severely impact Kupffer cell (KC) populations. Liver dysfunction was evaluated in CD26 knockout (KO) and B6 wild-type mice during acute liver damage induced by acetaminophen, chronic liver damage induced by carbon tetrachloride, and KC-depleting treatment with clodronate-loaded liposomes. We found that necrosis resolution after hepatotoxic injury was delayed in CD26KO mice and in B6 mice treated with the CD26/DPP-4 inhibitor sitagliptin, suggesting that DPP-4 enzymatic activity plays a role in recovering from acute liver damage. Interestingly, the severe KC population reduction in acute and chronic liver injury was concomitant with increased CD26/DPP-4 serum levels. Remarkably, both chronic liver damage and noninflammatory depletion of KCs by clodronate liposomes were marked by oscillation in CD26/DPP-4 serum activity that mirrored the kinetics of liver KC depletion/recovery. Conclusion:CD26/DPP-4 enzymatic activity contributes to necrosis resolution during recovery from acute liver injury. Serum CD26/DPP-4 is elevated when severe perturbations are imposed on KC populations, regardless of patent liver damage. We propose that serum CD26/DPP-4 is a potential systemic surrogate marker of severe impairments in the KC population imposed by clinical and subclinical liver conditions.