Variability of Complement Response toward Preclinical and Clinical Nanocarriers in the General Population

Abstract

Opsonization (coating) of nanoparticles with complement C3 component is an important mechanism that triggers immune clearance and downstream anaphylactic and proinflammatory responses. The variability of complement C3 binding to nanoparticles in the general population has not been studied. We examined complement C3 binding to dextran superparamagnetic iron oxide nanoparticles (superparamagnetic iron oxide nanoworms, SPIO NWs, 58 and 110 nm) and clinically approved nanoparticles (carboxymethyl dextran iron oxide ferumoxytol (Feraheme, 28 nm), highly PEGylated liposomal doxorubicin (LipoDox, 88 nm), and minimally PEGylated liposomal irinotecan (Onivyde, 120 nm)) in sera from healthy human individuals. SPIO NWs had the highest variation in C3 binding (n = 47) between subjects, with a 15−30 fold range in levels of C3. LipoDox (n = 12) and Feraheme (n = 18) had the lowest levels of variation between subjects (an approximately 1.5-fold range), whereas Onivyde (n = 18) had intermediate between-subject variation (2-fold range). There was no statistical difference between males and females and no correlation with age. There was a significant correlation in complement response between small and large SPIO NWs, which are similar structurally and chemically, but the correlations between SPIO NWs and other types of nanoparticles, and between LipoDox and Onivyde, were not significant. The calculated average number of C3 molecules bound per nanoparticle correlated with the hydrodynamic diameter but was decreased in LipoDox, likely due to the PEG coating. The conclusions of this study are (1) all nanoparticles show variability of C3 opsonization in the general population; (2) an individual’s response toward one nanoparticle cannot be reliably predicted based on another nanoparticle; and (3) the average number of C3 molecules per nanoparticle depends on size and surface coating. These results provide new strategies to improve nanomedicine safety.

Plasma samples from mouse strains and humans demonstrate different susceptibilities to complement activation

“…We also found that AmBisome SIs do not match Doxil SIs in the plasma of the same individuals (data not shown). Collectively, this data is in line with earlier studies by Benasutti et al, demonstrating that complement opsonization rates observed with one nanomedicine do not accurately predict complement binding to other structurally similar nanoparticles 22 . Similar to our findings in mouse plasma (Figure 2), individual levels of CFH and CFI varied in plasma of human donors ( Figure 4) and per se could not explain the magnitude of the complement activation by AmBisome.…”

“…Another valuable but not broadly used model is a pig 20,21 . Discussions about the advantages and limitations of the in vivo models have also been extensively discussed 8,9,20,22 .…”

Immunogenicity of Polyethylene Glycol Based Nanomedicines: Mechanisms, Clinical Implications and Systematic Approach

“…Although, PEGylation provides an effective strategy to have stealth and safe nanomedicines, several research papers and clinical reports demonstrate a massive complement activation in patients/animals injected with PEGylated therapeutics. [ 11,39,40 ] In vitro and in vivo experiments demonstrated the complement activation. [ 41 ] In clinical studies, the activation of complement system can result in acute hypersensitivity reactions, or pseudo‐allergic reactions, associated with flushing and/or cutaneous rush, vasoconstrictions and hemodynamic disturbances.…”

Main trends of immune effects triggered by nanomedicines in preclinical studies

“…Though it has to be noted that in most cases, a strong complement activation leads to hypersensitivity reactions, interindividual variations in human complement activation responses exist. 41 Apart from the lipid-based formulations, polymeric and inorganic NPs also, such as iron oxide NPs and gadolinium conjugates, were reported to activate the complement system. 30,31,42,43 However, surface-related properties that can have an influence on the complement system activation are more relevant than the category of a nanomaterial, since they determine the PC composition and its subsequent interaction with other plasma proteins including immunoglobulins and components of the complement system 44 (Figure 4).…”