Cell-bound complement activation products in antiphospholipid antibody-positive patients without other systemic autoimmune rheumatic diseases.

The objective of this study was to analyze complement activation in antiphospholipid antibody (aPL)-positive patients without other systemic autoimmune rheumatic diseases, using C3/C4 and cell-bound complement activation products (CB-CAPs) (B-lymphocytes [BC4d], erythrocytes [EC4d], and platelets [PC4d]). Persistently aPL-positive patients with or without aPL-related clinical manifestations (thrombotic APS [TAPS], microvascular APS [MAPS], obstetric APS, thrombocytopenia [TP], and/or hemolytic anemia [HA]) were enrolled in a single center study. Blood and clinical data were collected at baseline; a subgroup of patients completed 6- or 12-month follow-up. At baseline, 4/31 (13%) patients had decreased C3/C4, while 7/29 (24%) had elevated BC4d, 11/33 (33%) EC4d, and 12/32 (38%) PC4d. Based on different aPL profiles, all patients with decreased C3/C4 or elevated BC4d, EC4d, and PC4d had triple aPL or isolated lupus anticoagulant positivity. Based on different aPL clinical phenotypes, the number of patients with strongly positive EC4d and PC4d were proportionally higher in those with MAPS/TP/HA, compared to TAPS or no APS. Compared to baseline, the frequencies of BC4d, EC4d, and PC4d positivity were not significantly different in the subgroup of patients during their 6- or 12-month follow-up. There was a weak correlation between C3/C4 and CB-CAPs, especially for PC4d. In summary, complement activation in aPL-positive patients varies based on aPL profiles and clinical phenotypes. Given the higher percentage of aPL-positive patients with abnormal CB-CAPs, compared to C3/C4, and the poor inverse correlation between CB-CAPs and C3/C4, our study generates the hypothesis that CB-CAPs have a role in assessing disease activity and thrombosis risk in aPL-positive patients.

Transplacental SARS-CoV-2 protein ORF8 binds to complement C1q to trigger fetal inflammation.

Prenatal SARS-CoV-2 infection is associated with higher rates of pregnancy and birth complications, despite that vertical transmission rates are thought to be low. Here, multi-omics analyses of human placental tissues, cord tissues/plasma, and amniotic fluid from 23 COVID-19 mother-infant pairs revealed robust inflammatory responses in both maternal and fetal compartments. Pronounced expression of complement proteins (C1q, C3, C3b, C4, C5) and inflammatory cytokines (TNF, IL-1α, and IL-17A/E) was detected in the fetal compartment of COVID-19-affected pregnancies. While ~26% of fetal tissues were positive for SARS-CoV-2 RNA, more than 60% of fetal tissues contained SARS-CoV-2 ORF8 proteins, suggesting transplacental transfer of this viral accessory protein. ORF8-positive fetal compartments exhibited increased inflammation and complement activation compared to ORF8-negative COVID-19 pregnancies. In human placental trophoblasts in vitro, exogenous ORF8 exposure resulted in complement activation and inflammatory responses. Co-immunoprecipitation analysis demonstrated that ORF8 binds to C1q specifically by interacting with a 15-peptide region on ORF8 (C37-A51) and the globular domain of C1q subunit A. In conclusion, an ORF8-C1q-dependent complement activation pathway was identified in COVID-19-affected pregnancies, likely contributing to fetal inflammation independently of fetal virus exposure.

TMT-proteomics reveals the therapeutic effects of Lianling decoction against atopic dermatitis through Staphylococcus aureus infection.

Background: Lianling Tang (LLT), a traditional Chinese herbal decoction, is utilized for managing inflammatory skin conditions in China. This study explores the therapeutic effects and molecular mechanisms of LLT on atopic dermatitis (AD) in a mouse model, employing proteomics techniques. Methods: We evaluated the therapeutic efficacy of LLT on AD in mice by assessing skin inflammation scores, conducting histopathological examinations, and measuring serum levels of IgE, IL-4, and IL-6. Using Tandem Mass Tag (TMT) technology, we performed proteomics analysis of skin samples from Control, Model, LLT-treated, and positive control drug-treated mice, and identified differentially expressed proteins (DEPs). These proteins were then analyzed via GO and KEGG pathways to elucidate LLT's mechanisms in treating AD. Results: LLT markedly reduced skin inflammation scores, epidermal thickening, and mast cell infiltration, and decreased serum IgE, IL-4, and IL-6 levels in AD model mice, highlighting its therapeutic potential. Proteomics analysis identified Staphylococcus aureus infection as a pivotal AD pathogenesis mechanism and revealed critical proteins such as C1QA, C4B, C5, and FCGR3. LLT's mechanisms, such as modulating the complement activation, and influencing phagocytosis, effectively reduce inflammation and alleviate symptoms caused by Staphylococcus aureus in AD. Conclusion: LLT shows potential in AD treatment by modulating pathways associated with Staphylococcus aureus infection, effectively alleviating symptoms.

SARS-CoV-2 hijacks host CD55, CD59 and factor H to impair antibody-dependent complement-mediated lysis.

The complement system is a vital anti-microbial defence mechanism against circulating pathogens. Excessive complement activation can have deleterious outcomes for the host and is consequently tightly modulated by a set of membrane-associated and fluid-phase regulators of complement activation (RCAs). Here, we demonstrate that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) hijacks host cellular RCA members CD55 and CD59 and serum-derived Factor H (FH) to resist antibody-dependent complement-mediated lysis triggered by immunized human sera. Blockage of the biological functions of virion-associated CD55 and CD59 and competition of FH recruitment with functionally inactive recombinant FH-derived short consensus repeats SCR18-20 restore SARS-CoV-2 complement sensitivity in a synergistic manner. Moreover, complement-mediated virolysis is dependent on classical pathway activation and does not occur in the absence of virus-specific antibodies. Altogether, our findings present an intriguing immune escape mechanism that provides novel insights into the immunopathology observed in severe coronavirus disease 2019 (COVID-19).

Complement activation targeted inhibitor C2-FH ameliorates acetaminophen-induced liver injury in mice.

BACKGROUND: Complement activation is recognized as an important factor in the progression of liver damage caused by acetaminophen (APAP). However, the role of the complement inhibitor C2-FH in APAP-induced liver injury remains unclear. AIM: To explore C2-FH in protecting against APAP-induced liver injury by inhibiting complement activation. METHODS: A model of APAP-induced liver injury was used to study the protective effect of C2-FH on liver injury. C2-FH was administered through intraperitoneal injection 30 minutes after APAP treatment. We detected the effects of C2-FH on liver function, inflammatory response and complement activation. Additionally, RNA-sequencing (RNA-Seq) analysis was conducted to understand the mechanism through which C2-FH provides protection against APAP-induced liver injury. RESULTS: C2-FH inhibited the increase in serum alanine aminotransferase activity, aspartate aminotransferase activity and lactate dehydrogenase, and reduced liver tissue necrosis caused by APAP. Moreover, it attenuated the inflammatory response and inhibited complement activation in APAP-induced liver injury. RNA-Seq analysis provided additional explanations for the protective role of C2-FH against APAP-induced liver injury. CONCLUSION: C2-FH attenuates APAP-induced liver injury by inhibiting complement activation.

Targeted management of coexistent severe thrombophilias-A case report of a successful pregnancy despite paroxysmal nocturnal hemoglobinuria and hereditary protein C deficiency.

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare hematological disorder characterized by the absence of complement regulatory proteins on the surface of erythrocytes, leading to intravascular hemolysis and thrombosis. Managing PNH during pregnancy poses significant challenges due to increased risks of morbidity and mortality. This case report describes the detailed obstetric course of a 44-year-old woman with PNH and additional hereditary protein C deficiency who had previously experienced multiple thrombotic events and adverse pregnancy outcomes (two early miscarriages and one stillbirth at 25 weeks gestation [WG]), treated with eculizumab (terminal C5 inhibitor) and optimal anticoagulation management. Close monitoring of hemolysis and hemostasis parameters was conducted throughout the gestation period together with increased obstetrical surveillance. The pregnancy progressed without thrombotic complications or breakthrough hemolysis, and the patient delivered a healthy newborn at 36 WG after induction of labor due to restricted fetal growth. To the best of our knowledge, this is the first reported case of a positive pregnancy outcome despite PNH in conjunction with hereditary thrombophilia. This case report highlights the importance of a multidisciplinary approach involving hematologists and obstetricians in the management of pregnant women with PNH. Tailored therapy, close monitoring, and comprehensive care are crucial to minimize risks and optimize outcomes.

Complement as a major mediator of ANCA vasculitis and a target for precision therapy.

INTRODUCTION: Complement was long thought not to be involved in ANCA vasculitis pathogenesis until studies in murine models demonstrated its central role. The current theory is ANCA-activated neutrophils degranulate and release factors that activate complement, which, in turn, recruits more neutrophils and causes an inflammatory amplification loop that results in the vascular inflammation characteristic of disease. Targeting this amplification loop through complement inhibition has proven to be effective in ANCA vasculitis treatment. AREAS COVERED: A PubMed search was conducted using key terms 'ANCA vasculitis' AND 'complement system.' We review findings from experimental mouse models, in vitro studies, and human ANCA vasculitis that support a role for complement activation in disease pathogenesis. We also summarize results from pivotal clinical studies demonstrating the safety and efficacy of complement inhibition in ANCA vasculitis treatment. EXPERT OPINION: While complement activation is undoubtedly involved in ANCA vasculitis pathogenesis, less clear is whether measuring complement activation markers can reliably assess disease activity, predict those who will benefit from complement-targeting therapy, or identify patients in stable remission and able to stop therapy. Better understanding the clinical implications of complement activation will shed more light on the utility of complement inhibition and facilitate precision medicine in ANCA vasculitis.

IgG4 glycosylation contributes to the pathogenesis of IgG4 Hashimoto's thyroiditis via the complement pathway.

Background: To explore whether IgG4 is involved in the pathogenesis of IgG4 HT. Methods: Serum TgAb IgG4 and TPOAb IgG4 were measured in IgG4 HT and non-IgG4 HT. C1q, mannose-binding lectin (MBL), Bb, C3d, C4d, and membrane attack complex (MAC) in thyroid tissues from IgG4 HT, non-IgG4 HT, and controls were examined by immunohistochemistry. We assessed IgG4 and MAC deposition in mouse thyroid by immunohistochemistry after injecting purified IgG4 into mice. The glycosylation patterns of TgAb IgG4 from IgG4 HT were identified by MALDI-TOF-MS. The ability of IgG4 to bind to MBL before and after deglycosylation was assessed by ELISA. MBL and MAC fluorescence were detected in thyrocytes after the addition of IgG4 or deglycosylated IgG4. Results: Serum TgAb IgG4 and TPOAb IgG4 levels were significantly higher in the IgG4 HT group. MBL, Bb, C3d, C4d, and MAC levels were significantly higher in the thyroid tissues of IgG4 HT than in non-IgG4 HT (all P < 0.001). IgG4 colocalized with MBL by immunofluorescence. In mice, follicular cell structure disruption was observed after the injection of IgG4 from IgG4 HT, as well as the colocalization of IgG4 with MAC. High levels of TgAb IgG4 glycosylation patterns, including monogalactose glycan (G1F), galactose-deficient glycan (G0F), and high-mannose glycan (M5), were detected in IgG4 HT. After deglycosylation, IgG4 reduced its ability to bind to MBL, and there was low MBL and MAC activation in thyrocytes. Conclusion: High levels of IgG4 glycosylation patterns, including G1F, G0F, and M5, may activate the complement lectin pathway, thereby participating in the pathogenesis of IgG4 HT.

Unraveling the CDK9/PP2A/ERK Network in Transcriptional Pause Release and Complement Activation in KRAS-mutant Cancers.

Selective inhibition of the transcription elongation factor (P-TEFb) complex represents a promising approach in cancer therapy, yet CDK9 inhibitors (CDK9i) are currently limited primarily to certain hematological malignancies. Herein, while initial responses to CDK9-targeted therapies are observed in vitro across various KRAS-mutant cancer types, their efficacy is far from satisfactory in nude mouse xenograft models. Mechanistically, CDK9 inhibition leads to compensatory activation of ERK-MYC signaling, accompanied by the recovery of proto-oncogenes, upregulation of immediate early genes (IEGs), stimulation of the complement C1r-C3-C3a cascade, and induction of tumor immunosuppression. The "paradoxical" regulation of PP2Ac activity involving the CDK9/Src interplay contributes to ERK phosphorylation and pause-release of RNA polymerase II (Pol II). Co-targeting of CDK9 and KRAS/MAPK signaling pathways eliminates ERK-MYC activation and prevents feedback activation mediated by receptor tyrosine kinases, leading to more effective control of KRAS-mutant cancers and overcoming KRASi resistance. Moreover, modulating the tumor microenvironment (TME) by complement system intervention enhances the response to CDK9i and potently suppresses tumor growth. Overall, the preclinical investigations establish a robust framework for conducting clinical trials employing KRASi/SOS1i/MEKi or immunomodifiers in combination with CDK9i to simultaneously target cancer cells and their crosstalk with the TME, thereby yielding improved responses in KRAS-mutant patients.

DNA/RNA heteroduplex technology with cationic oligopeptide reduces class-related adverse effects of nucleic acid drugs.

Antisense oligonucleotides (ASOs) are a therapeutic modality for incurable diseases. However, systemic injection of gapmer-type ASOs causes class-related toxicities, including prolongation of activated partial thromboplastin time (aPTT) and thrombocytopenia. We previously reported that cholesterol-conjugated DNA/RNA heteroduplex oligonucleotides (Chol-HDOs) exhibit significantly enhanced gene-silencing effects compared to ASOs, even in the central nervous system, by crossing the blood-brain barrier. In the present study, we initially evaluated the effect of the HDO structure on class-related toxicities. The HDO structure ameliorated the class-related toxicities associated with ASOs, but they remained to some extent. As a further antidote, we have developed artificial cationic oligopeptides, L-2,4-diaminobutanoic acid oligomers (DabOs), which bind to the phosphates in the major groove of the A-type double-helical structure of HDOs. The DabO/Chol-HDO complex showed significantly improved aPTT prolongation and thrombocytopenia in mice while maintaining gene-silencing efficacy. Moreover, the conjugation with DabOs effectively prevented cerebral infarction, a condition frequently observed in mice intravenously injected with high-dose Chol-HDO. These approaches, combining HDO technology with DabOs, offer distinct advantages over conventional strategies in reducing toxicities. Consequently, the DabO/HDO complex represents a promising platform for overcoming the class-related toxicities associated with therapeutic ASOs.

Complement system activation: bridging physiology, pathophysiology, and therapy.

The complement system is a set of over 50 proteins that constitutes an essential part of the innate immune system. Complement system activation involves an organized proteolytic cascade. Overactivation of complement system activation is the main pathogenic mechanism of several diseases and contributes to the manifestations of many other conditions. This review describes the normal complement system and the role for complement dysregulation in critical illnesses, notably sepsis and acute respiratory distress syndrome. Complement activation is involved in the immune system response to pathogens but, when excessive, can contribute to tissue damage, runaway inflammation, and capillary leakage syndrome. Complement overactivation may play a key role in severe forms of coronavirus disease 2019 (COVID-19). Two diseases whose manifestations are mainly caused by complement overactivation, namely, atypical hemolytic and uremic syndrome (aHUS) and myasthenia gravis, are discussed. A diagnostic algorithm for aHUS is provided. Early complement-inhibiting therapy has been proven effective. When renal transplantation is required, complement-inhibiting drugs can be used prophylactically to prevent aHUS recurrence. Similarly, acetylcholine-receptor autoantibody-positive generalized myasthenia gravis involves complement system overactivation and responds to complement inhibition. The two main complement inhibitors used in to date routine are eculizumab and ravulizumab. The main adverse event is Neisseria infection, which is rare and preventable, but can be fatal. The complement system is crucial to health but, when overactivated, can cause or contribute to disease. Effective complement inhibitors are now available, although additional data are required to determine optimal regimens. Further research is also needed to better understand the complement system, develop advanced diagnostic tools, and identify markers that allow the personalization of treatment strategies.

The Role of Ficolins in Lung Injury.

BACKGROUND: Respiratory diseases seriously threaten human health worldwide, and lung injury is an important component of respiratory disease. Complement activation is an important function of the innate immune system. Complement activation helps the body defend against invasion by external microorganisms, whereas excessive complement activation can exacerbate tissue damage or lead to unwanted side effects. Ficolins are a class of immune-related proteins in the lectin pathway that play important roles in the body's immune defense. Although individual ficolins are not well understood, current information suggests that ficolins may play an important regulatory role in lung injury. SUMMARY: Several studies have shown that ficolins are involved in the immune response in the lung, particularly in the response to infectious and inflammatory processes. KEY MESSAGES: This review summarizes the role of ficolins in lung injury. Ficolins may influence the development and repair of lung injury by recognizing and binding pathogenic microorganisms, modulating the inflammatory response, and promoting the clearance of immune cells. In addition, ficolins are associated with the development and progression of lung diseases (such as pneumonia and ARDS) and may have an important impact on the pathophysiological processes of inflammatory diseases.

Apical tubular complement activation and the loss of kidney function in proteinuric kidney diseases.

Many kidney diseases are associated with proteinuria. Since proteinuria is independently associated with kidney function loss, anti-proteinuric medication, often in combination with dietary salt restriction, comprises a major cornerstone in the prevention of progressive kidney failure. Nevertheless, complete remission of proteinuria is very difficult to achieve, and most patients with persistent proteinuria slowly progress toward kidney failure. It is well-recognized that proteinuria leads to kidney inflammation and fibrosis via various mechanisms. Among others, complement activation at the apical side of the proximal tubular epithelial cells is suggested to play a crucial role as a cause of progressive loss of kidney function. However, hitherto limited attention is given to the pathophysiological role of tubular complement activation relative to glomerular complement activation. This review aims to summarize the evidence for tubular epithelial complement activation in proteinuric kidney diseases in relation to loss of kidney function.

Proteomic analysis of laser captured tubular tissues reveals complement activation and mitochondrial dysfunction in autoimmune related kidney diseases.

Autoimmune related kidney diseases (ARKDs), including minimal change nephropathy (MCN), membranous nephropathy (MN), IgA nephropathy (IgAN), and lupus nephritis (LN), significantly affect renal function. These diseases are characterized by the formation of local immune complexes and the subsequent activation of the complement system, leading to kidney damage and proteinuria. Despite the known patterns of glomerular injury, the specific molecular mechanisms that contribute to renal tubular damage across ARKDs remain underexplored. Laser capture microdissection and liquid chromatography-tandem mass spectrometry (LC-MS/MS) were used to conduct a comparative proteomic analysis of renal tubular tissues from formalin-fixed paraffin-embedded samples. The cohort comprised of 10 normal controls (NC), 5 MCN, 4 MN, 17 IgAN, and 21 LN patients. Clinical parameters and histopathological assessments were integrated with proteomic findings to comprehensively investigate underlying pathogenic processes. Clinical evaluation indicated significant glomerular damage, as reflected by elevated urinary protein levels and reduced plasma albumin levels in patients with ARKD. Histological analyses confirmed varying degrees of tubular damage and deposition of immune complexes. Proteomic analyses identified significant changes in protein expression, particularly in complement components (C3, C4A, C4B, C8G, CFB, and SERPINA1) and mitochondrial proteins (ATP5F1E and ATP5PD), highlighting the common alterations in the complement system and mitochondrial proteins across ARKDs. These alterations suggest a novel complement-mitochondrial-epithelial-mesenchymal transition (EMT) pathway axis that contributes to tubular damage in ARKDs. Notably, significant alterations in CFB in tubular ARKD patients were revealed, implicating it as a therapeutic target. This study underscores the importance of complement activation and mitochondrial dysfunction in the pathogenesis of ARKDs, and proposes CFB as a potential therapeutic target to inhibit complement activation and mitigate tubular damage. Future research should validate the complement-mitochondrial-EMT pathway axis and explore the effects and mechanisms of CFB inhibitors in alleviating ARKD progression.

Structural characterization and immunomodulating assessment of ultra-purified water extracted fucoidans from Saccharina latissima, Alaria esculenta and Laminaria hyperborea.

Fucoidans, a group of high molecular weight polysaccharides derived mainly from brown algae, are characterized by their high fucose content, degree of sulfation (DS), and intra- and interspecific structural variation. Fucoidans are increasingly recognized due to various reported bioactivities, potentially beneficial for human health. To unlock their potential use within biomedical applications, a better understanding of their structure-functional relationship is needed. To achieve this, systematic bioactivity studies based on well-defined, pure fucoidans, and the establishment of standardized, satisfactory purification protocols are required. We performed a comprehensive compositional and structural characterization of crude and ultra-purified fucoidans from three kelps: Saccharina latissima (SL), Alaria esculenta (AE) and Laminaria hyperborea (LH). Further, the complement-inhibiting activity of the purified fucoidans was assessed in a human whole blood model. The purification process led to fucoidans with higher DS and fucose and lower concentrations of other monosaccharides. Fucoidans from SL and LH resembles homofucans, while AE is a heterofucan rich in galactose with comparably lower DS. Fucoidans from SL and LH showed complement-inhibiting activity in blood and blood plasma, while no inhibition was observed for AE under the same conditions. The results emphasize the importance of high DS and possibly fucose content for fucoidans' bioactive properties.

Liposomes with Low Levels of Grafted Poly(ethylene glycol) Remain Susceptible to Destabilization by Anti-Poly(ethylene glycol) Antibodies.

Binding of anti-PEG antibodies to poly(ethylene glycol) (PEG) on the surface of PEGylated liposomal doxorubicin (PLD) in vitro and in rats can activate complement and cause the rapid release of doxorubicin from the liposome interior. Here, we find that irinotecan liposomes (IL) and L-PLD, which have 16-fold lower levels of 1,2-distearoyl-sn-glycero-3-phosphoethanolamine (DSPE)-PEG2000 in their liposome membrane as compared to PLD, generate less complement activation but remain sensitive to destabilization and drug release by anti-PEG antibodies. Complement activation and liposome destabilization correlated with the theoretically estimated number of antibody molecules bound per liposome. Drug release from liposomes proceeded through the alternative complement pathway but was accelerated by the classical complement pathway. In contrast to PLD destabilization by anti-PEG immunoglobulin G (IgG), which proceeded by the insertion of membrane attack complexes in the lipid bilayer of otherwise intact PLD, anti-PEG IgG promoted the fusion of L-PLD, and IL to form unilamellar and oligo-vesicular liposomes. Anti-PEG immunoglobulin M (IgM) induced drug release from all liposomes (PLD, L-PLD, and IL) via the formation of unilamellar and oligo-vesicular liposomes. Anti-PEG IgG destabilized both PLD and L-PLD in rats, indicating that the reduction of PEG levels on liposomes is not an effective approach to prevent liposome destabilization by anti-PEG antibodies.

Reciprocal Interaction with Neutrophils Facilitates Cutaneous Accumulation of Liposomes.

Liposomes are versatile drug delivery systems in clinical use for cancer and many other diseases. Unfortunately, PEGylated liposomal doxorubicin (sLip/DOX) exhibits serious dose-limiting cutaneous toxicities, which are closely related to the extravascular accumulation of sLip/DOX in the dermis. No clinical interventions have been proposed for cutaneous toxicities due to the elusive transport pathways. Herein, we showed that the reciprocal interaction between liposomes and neutrophils played pivotal roles in liposome extravasation into the dermis. Neutrophils captured liposomes via the complement receptor 3 (CD11b/CD18) recognizing the fragment of complement component C3 (iC3b) deposited on the liposomal surface. Uptake of liposomes also activated neutrophils to induce CD11b upregulation and enhanced the ability of neutrophils to migrate outside the capillaries. Furthermore, inhibition of complement activation either by CRIg-L-FH (a C3b/iC3b targeted complement inhibitor) or blocking the phosphate negative charge in mPEG-DSPE could significantly reduce liposome uptake by neutrophils and alleviate the cutaneous accumulation of liposomes. These results validated the liposome extravasation pathway mediated by neutrophils and provided potential solutions to the devastating cutaneous toxicities occurring during sLip/DOX treatment.

Long circulating liposomal platform utilizing hydrophilic polymer-based surface modification: preparation, characterisation, and biological evaluation.

Liposomes are one of the most important drug delivery vectors, nowadays used in clinics. In general, polyethylene glycol (PEG) is used to ensure the stealth properties of the liposomes. Here, we have employed hydrophilic, biocompatible and highly non-fouling N-(2-hydroxypropyl) methacrylamide (HPMA)-based copolymers containing hydrophobic cholesterol anchors for the surface modification of liposomes, which were prepared by the method of lipid film hydration and extrusion through 100 nm polycarbonate filters. Efficient surface modification of liposomes was confirmed by transmission electron microscopy, atomic force microscopy, and gradient ultracentrifugation. The ability of long-term circulation in the vascular bed was demonstrated in rabbits after i.v. application of fluorescently labelled liposomes. Compared to PEGylated liposomes, HPMA-based copolymer-modified liposomes did not induce specific antibody formation and did not activate murine and human complement. Compared with PEGylated liposomes, HPMA-based copolymer-modified liposomes showed a better long-circulating effect after repeated administration. HPMA-based copolymer-modified liposomes thus represent suitable new candidates for a generation of safer and improved liposomal drug delivery platforms.

Sulfoxide-containing polymers conjugated prodrug micelles with enhanced anticancer activity and reduced intestinal toxicity.

Poly(ethylene glycol) (PEG) is widely utilized as a hydrophilic coating to extend the circulation time and improve the tumor accumulation of polymeric micelles. Nonetheless, PEGylated micelles often activate complement proteins, leading to accelerated blood clearance and negatively impacting drug efficacy and safety. Here, we have crafted amphiphilic block copolymers that merge hydrophilic sulfoxide-containing polymers (psulfoxides) with the hydrophobic drug 7-ethyl-10-hydroxylcamptothecin (SN38) into drug-conjugate micelles. Our findings show that the specific variant, PMSEA-PSN38 micelles, remarkably reduce protein fouling, prolong blood circulation, and improve intratumoral accumulation, culminating in significantly increased anti-cancer efficacy compared with PEG-PSN38 counterpart. Additionally, PMSEA-PSN38 micelles effectively inhibit complement activation, mitigate leukocyte uptake, and attenuate hyperactivation of inflammatory cells, diminishing their ability to stimulate tumor metastasis and cause inflammation. As a result, PMSEA-PSN38 micelles show exceptional promise in the realm of anti-metastasis and significantly abate SN38-induced intestinal toxicity. This study underscores the promising role of psulfoxides as viable PEG substitutes in the design of polymeric micelles for efficacious anti-cancer drug delivery.