The activation of complement by nanomedicines triggers immune uptake and proinflammatory responses. Complement pathway inhibitors could offer strategies to address these challenges. Here, we assess the efficacy of inhibitors with various nanoparticles, including dextran superparamagnetic iron oxide nanoworms, polyethylene glycol (PEG) liposomal drugs, and mRNA lipid nanoparticles. In human sera, inhibitors of the alternative pathway iptacopan and danicopan exhibit variable efficacies, ranging from high nanomolar to incomplete inhibition. However, both iptacopan and danicopan display poor efficacy with PEGylated liposomal doxorubicin. Sutimlimab, an inhibitor of the classical pathway, demonstrates poor efficacy with PEGylated liposomal doxorubicin, even in sera with anti-PEG antibodies. Iptacopan displays donor-dependent inhibition of the uptake of nanoparticles in human blood. Bolus coadministration of iptacopan with nanoworms in mice, rats, and dogs inhibits C3 opsonization and uptake by granulocytes. Iptacopan also alleviates nanoparticle-induced lethargy in rats and severe hypotension in dogs. These data suggest that complement inhibitors can enhance the immunocompatibility and hemocompatibility of nanomedicines in a donor-dependent manner.

With aging, human lenses lose the ability to focus on nearby objects due to decreases in accommodative ability, a condition known as presbyopia. An increase in stiffness or decrease in lens elasticity due to protein aggregation and insolubilization are the primary reasons for presbyopia. In this study, we tested aggrelyte-1 (S,N-diacetyl glutathione diethyl ester) for its ability to promote protein solubility and decrease the stiffness of lenses through its dual property of lysine acetylation and disulfide reduction. Treatment of water-insoluble proteins from aged human lenses (58–75 years) with aggrelyte-1 significantly increased the solubility of those proteins. A control compound that did not contain the S-acetyl group (aggrelyte-1C) was substantially less efficient in solubilizing water-insoluble proteins. Aggrelyte-1-treated solubilized protein had significant amounts of acetyllysine, as measured by Western blotting and LC-MS/MS. Aggrelytes increased the protein-free thiol content in the solubilized protein. Aged mouse (7 months) and human (44–66 years) lenses treated with aggrelyte-1 showed reduced stiffness accompanied by higher free thiol and acetyllysine levels compared with those treated with aggrelyte-1C or untreated controls. Our results suggested that aggrelyte-1 reduced lens stiffness through acetylation followed by disulfide reduction. This proof-of-concept study paves the way for developing aggrelyte-1 and related compounds to reverse presbyopia.

Cysteine cathepsin proteases are found under normal conditions in the lysosomal compartments of cells, where they play pivotal roles in a variety of cellular processes such as protein and lipid metabolism, autophagy, antigen presentation, and cell growth and proliferation. As a consequence, aberrant localization and activity contribute to several pathologic conditions such as a variety of malignancies, cardiovascular diseases, osteoporosis, and other diseases. Hence, there is a resurgence of interest to expand the toolkit to monitor intracellular cathepsin activity and better ascertain their functions under these circumstances. Previous fluorescent activity-based probes (ABPs) that target cathepsins B, L, and S enabled detection of their activity in intact cells as well as non-invasive detection in animal disease models. However, their binding potency is suboptimal compared to the cathepsin inhibitor on which they were based, as the P1 positive charge was capped by a reporter tag. Here, we show the development of an improved cathepsin ABP that has a P1 positive charge by linking the tag on an additional amino acid at the end of the probe. While enhancing potency towards recombinant cathepsins, the new probe had reduced cell permeability due to additional peptide bonds. At a second phase, the probe was trimmed; the fluorophore was linked to an extended carbobenzoxy moiety, leading to enhanced cell permeability and superb detection of cathepsin activity in intact cells. In conclusion, this work introduces a prototype design for the next generation of highly sensitive ABPs that have excellent detection of cellular cathepsin activity.