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Constitutive Host Resistance
Published in Julius P. Kreier, Infection, Resistance, and Immunity, 2022
The process of preparation of a particle for ingestion by coating with serum protein is called opsonization. Opsonins are substances in the serum that coat particles and cause them to be engulfed by phagocytic cells. The most important of the opsonins in serum are antibodies, the C3b component of the complement system, and fibronectin (see chapter 4).
Engineered Nanoparticles for Drug Delivery in Cancer Therapy *
Published in Valerio Voliani, Nanomaterials and Neoplasms, 2021
Tianmeng Sun, Yu Shrike Zhang, Pang Bo, Dong Choon Hyun, Miaoxin Yang, Younan Xia
When nanoparticles enter the plasma, opsonization (i.e., the adsorption of serum proteins) will occur immediately on their surfaces [5, 160a]. Through opsonization, foreign organisms or particles will be coated with nonspecific proteins known as opsonins to generate a corona and make the particles more visible to the phagocytic cells in the MPS. Opsonins typically contain complement proteins and immunoglobins (usually IgG) along with albumins, fibronectins, fibrinogens, and apolipoproteins [194]. Studies have shown that the corona has a layered architecture. It starts with an inner layer of proteins that strongly adsorb onto the surface, with Kd 10−6 to 10−8 m, to form the hard corona, which is then surrounded by a layer of soft corona formed by weak interactions [169, 195]. The primary driving forces for opsonization are based on hydrophobic and electrostatic interactions, together with entropic and conformational changes for the adsorbed proteins [196]. Depending on the charge and hydrophobicity of the nanoparticles, opsonization can occur within minutes. Experimental results suggest that a charged surface tends to be covered by proteins more rapidly than their counterparts with a neutral surface [160a].
The immune and lymphatic systems, infection and sepsis
Published in Peate Ian, Dutton Helen, Acute Nursing Care, 2020
Michelle Treacy, Caroline Smales, Helen Dutton
Antibodies or immunoglobulins have a number of functions and effects: On activation, they bind to the pathogen, causing clumping or agglutination.Once bound, they act as opsonins, identifying or signalling that particular antigen for phagocytosis.Binding triggers the production of identical plasma cells or clones, which all produce the same antibody; this is called clonal expansion.Phagocytosis and the complement cascade system are also activated.
Transferrin decorated PLGA encumbered moxifloxacin nanoparticles and in vitro cellular studies
Published in Drug Development and Industrial Pharmacy, 2023
Gayathri Aparnasai Reddy, Mayank Handa, Debapriya Garabadu, Ravindra Kumar, Pramod Kumar Kushawaha, Rahul Shukla
Polymeric NPs like PLGA, polycaprolactone, and poly lactic acid, when administered via the intravenous (IV) route, are rapidly uptake by the mononuclear phagocytic system (MPS). Furthermore, opsonin attachment on the surface of the NPs results in recognition by phagocytosis. It results in the elimination of NPs from the body due to the reticuloendothelial system (RES) when administered IV [16,19]. Hence, to prevent the rapid uptake by RES, PEGylation helps the NPs to escape from the RES system. Masking with PEG provides hydrophobicity to polymeric NPs by its adsorption on the surface of NPs. Moreover, delivering the drugs to the targeted site is desirable rather than the nonselective delivery of these cargos [20]. However, size of NPs plays a prominent role in RES uptake and inhibition. The size below 200 nm bypasses the RES and inhibits the need of PEGylation. To impart targeting to NPs, effective coating with ligands can be done.
Environmentally weathered polystyrene particles induce phenotypical and functional maturation of human monocyte-derived dendritic cells
Published in Journal of Immunotoxicology, 2022
Annemijne E. T. van den Berg, Maud Plantinga, Dick Vethaak, Kas J. Adriaans, Marianne Bol-Schoenmakers, Juliette Legler, Joost J. Smit, Raymond H. H. Pieters
PS particles injected intravenously are rapidly covered by blood proteins and the resulting protein biofilm has been shown to play an important role in particle–cell interaction, favoring their uptake (Lesniak et al. 2010; Tenzer et al. 2013; Schöttler et al. 2016). However, the influence of the blood-derived biofilm on MNP uptake by DC is still not well-investigated. The study here showed that pre-incubating the particles in HI human plasma significantly enhanced 0.2 µm PS particle uptake by MoDC. The uptake of 1 µm PS particles was reduced, whereas the uptake of 10 µm PS particles was only observed when the particles were pre-incubated in HI plasma. Heat-labile components of human plasma such as serum complement are not likely to be involved in the uptake observed in this study, as they were inactivated by heat-inactivation of the plasma. However, blood contains dozens of other proteins that can act as opsonins, facilitating uptake by phagocytes (Walkey et al. 2012). This highlights that the protein biofilm cannot be neglected when researching the uptake of MNP.
Lung macrophages: current understanding of their roles in Ozone-induced lung diseases
Published in Critical Reviews in Toxicology, 2020
The mechanisms by which O3 compromises phagocytosis are, however, not understood. Interestingly, S. zooepidemicus was found to develop a virulence factor, antiphagocytic capsulation, within 3 h of O3 exposure at 0.4–0.8 ppm that resisted phagocytosis by AM (Gilmour et al. 1993). O3 is known to impair the structure and function of SPA, an opsonin that is important for the phagocytic ability of macrophages (Stringer and Kobzik 1996; Benne et al. 1997; Tenner 1998; Schagat et al. 2001), thus compromising opsonin-mediated phagocytosis in the alveolar spaces (Oosting et al. 1991; Su and Gordon 1996). In fact, O3-exposed SPA-deficient mice exhibit severely compromised clearance of K. pneumonia (Mikerov, Gan, et al. 2008; Mikerov, Haque, et al. 2008) suggesting that SPA acts as a critical modulator of host defense against bacterial infections. Haque and colleagues reported that SPA plays a critical role in scavenging O3-induced reactive oxidants, thus mitigating oxidative stress, a protective response that was found to be absent in SPA knockout mice (Haque, Umstead, Ahn, et al. 2009). However, the effects of O3 on other opsonins and phagocytosis-related receptors remain largely unknown.