Modulation Of Complement Activation Research Articles

DNA Nanostructure-Templated Antibody Complexes Provide Insights into the Geometric Requirements of Human Complement Cascade Activation.

The classical complement pathway is activated by antigen-bound IgG antibodies. Monomeric IgG must oligomerize to activate complement via the hexameric C1q complex, and hexamerizing mutants of IgG appear as promising therapeutic candidates. However, structural data have shown that it is not necessary to bind all six C1q arms to initiate complement, revealing a symmetry mismatch between C1 and the hexameric IgG complex that has not been adequately explained. Here, we use DNA nanotechnology to produce specific nanostructures to template antigens and thereby spatially control IgG valency. These DNA-nanotemplated IgG complexes can activate complement on cell-mimetic lipid membranes, which enabled us to determine the effect of IgG valency on complement activation without the requirement to mutate antibodies. We investigated this using biophysical assays together with 3D cryo-electron tomography. Our data revealed the importance of interantigen distance on antibody-mediated complement activation, and that the cleavage of complement component C4 by the C1 complex is proportional to the number of ideally spaced antigens. Increased IgG valency also translated to better terminal pathway activation and membrane attack complex formation. Together, these data provide insights into how nanopatterning antigen-antibody complexes influence the activation of the C1 complex and suggest routes to modulate complement activation by antibody engineering. Furthermore, to our knowledge, this is the first time DNA nanotechnology has been used to study the activation of the complement system.

Advancements in the treatment of geographic atrophy: focus on pegcetacoplan in age-related macular degeneration

Geographic atrophy (GA) is a progressive form of age-related macular degeneration characterized by the degeneration of retinal pigment epithelial cells and photoreceptor death. The dysregulation of the complement cascade has been implicated in GA progression. This review provides a comprehensive overview of the pathophysiology of age-related macular degeneration and GA, discusses current therapeutic options, and focuses on the recent breakthrough drug, pegcetacoplan (SYFOVRE). Pegcetacoplan is a complement inhibitor that selectively targets the C3 complement protein, effectively modulating complement activation. Clinical trials, including the OAKS and DERBY studies, have demonstrated the efficacy of SYFOVRE in reducing the growth of GA lesions compared to placebo. The FDA approval of SYFOVRE as the first and only definitive therapy for GA marks a significant milestone in the management of this debilitating condition. The review also explores potential future treatment strategies, including immune-modulating agents and ocular gene therapy. While SYFOVRE offers new hope for GA patients, further research is needed to evaluate its long-term benefits, safety profile, and optimal treatment regimens.

MAP-2:CD55 chimeric construct effectively modulates complement activation.

The complement system is a complex, tightly regulated protein cascade involved in pathogen defense and the pathogenesis of several diseases. Thus, the development of complement modulators has risen as a potential treatment for complement-driven inflammatory pathologies. The enzymatically inactive MAP-2 has been reported to inhibit the lectin pathway by competing with its homologous serine protease MASP-2. The membrane-bound complement inhibitor CD55 acts on the C3/C5 convertase level. Here, we fused MAP-2 to the four N-terminal domains of CD55 generating a targeted chimeric inhibitor to modulate complement activation at two different levels of the complement cascade. Its biological properties were compared in vitro with the parent molecules. While MAP-2 and CD55 alone showed a minor inhibition of the three complement pathways when co-incubated with serum (IC50MAP-2+CD55 1-4 = 60.98, 36.10, and 97.01 nM on the classical, lectin, and alternative pathways, respectively), MAP-2:CD551-4 demonstrated a potent inhibitory activity (IC50MAP-2:CD55 1-4 = 2.94, 1.76, and 12.86 nM, respectively). This inhibitory activity was substantially enhanced when pre-complexes were formed with the lectin pathway recognition molecule mannose-binding lectin (IC50MAP-2:CD55 1-4 = 0.14 nM). MAP-2:CD551-4 was also effective at protecting sensitized sheep erythrocytes in a classical hemolytic assay (CH50 = 13.35 nM). Finally, the chimeric inhibitor reduced neutrophil activation in full blood after stimulation with Aspergillus fumigatus conidia, as well as phagocytosis of conidia by isolated activated neutrophils. Our results demonstrate that MAP-2:CD551-4 is a potent complement inhibitor reinforcing the idea that engineered fusion proteins are a promising design strategy for identifying and developing drug candidates to treat complement-mediated diseases.

P-505 Role of intramuscular immunoglobulin in improving the live birth rate in ANA positive women with recurrent pregnancy loss

Abstract Study question In ANA positive women with Recurrent Pregnancy Loss, could addition of intramuscular Immunoglobulin along with appropriate adjuvant therapy improve the live birth rate ? Summary answer In ANA positive RPL patients, addition of Intramuscular immunoglobulin along with glucocorticoids and low dose aspirin improves the live birth rate What is known already RPL is a frustrating condition which affects 1-3% of women trying to conceive. Presence of ANA is associated with autoimmunity, which affects trophoblast development and vascular remodeling process thereby resulting in pregnancy loss. Latest ESHRE guidelines also suggest ANA testing for explanatory purpose. Aspirin has anti-platelet and anti-inflammatory effects, and glucocorticoids exhibit a beneficial effect in autoimmune diseases. Therefore, they are considered conventional adjuvant therapies in ANA-positive women with RPL. Addition of Immunoglobulin for RPL patients benefits by the down-regulation of primary antibody production, the modulation of complement activation and Suppresses Nk cell cytotoxicity Study design, size, duration 72 ANA positive patients with Unexplained RPL were enrolled in the study. Anatomical, metabolic ,genetic and other immunological causes for RPL were excluded. Out of 72 patients 36 patients were allotted to the treatment group, who received intramuscular immunoglobulins along with Low dose aspirin and glucocorticoids, remaining 36 patients were allotted to the control group, who received only Aspirin and glucocorticoids. Duration of study extended from jan2021 till Dec 2022 Participants/materials, setting, methods 72 patients with unexplained RPL underwent ANA screening using Indirect Immunofluorescence technique in the pre conception period. Patients with a titre ≥1:80 were considered to be significant and enrolled in the study. Patients were allotted to the Treatment and Control group based on personal choice of the patient after informed consent. Live birth rate was the primary outcome analyzed. Main results and the role of chance There were no significant differences in socio-demographic characteristics between group. Patient characteristics – Age, BMI, Ovarian reserve, sperm factor and number of previous Pregnancy losses were matched.Treatment group who received Intramuscular immunoglobulin once in 3 weeks right from the time of positive pregnancy test till 28 weeks along with low dose aspirin and glucocorticoids had a live birth rate of (23/36 ) 63.8 % whereas Control group who received only Low dose Aspirin (75 mg) and Glucocorticoids had a live birth rate of 41.6 % (15/36). Other obstetric outcomes which were analysed were Pre Eclampsia and GDM which were comparable between both the groups.Preterm labour was marginally higher in the control group. Limitations, reasons for caution Because of limited sample size results need to be interpreted with caution. Screening for ANA antibodies in patients were done only preconceptionally, and we were not aware about their ANA titres in pregnancy. This study involves only patients who conceived with IVF treatment and doesn't include spontaneous natural conception Wider implications of the findings ANA screening in RPL cases is suggested to prognosticate the outcome. Addition of Immunoglobulins significantly increases the live birth rate in these cases. Role of Immunoglobulin in patients with altered cellular immunity has to be further studied which is likely to benefit other cases of unexplained RPL. Trial registration number not applicable

A Review of the Effect of Estrogen on Immune Efficacy in Zebrafish (Danio rerio) with Comparisons to Human and Murine Homologs

A review was conducted on current research surrounding the effect of estrogen, and the estrogen receptor, on immune development. Estrogen can regulate many processes and genes throughout immune development, from modulating complement activation and regulating genes crucial for hematopoiesis, to elevating toll-like receptor gene expression. Estrogen has also been shown to have a pronounced effect on regulating certain cancers through inducing macrophage infiltration. It has also been demonstrated to play an important role in the regulation of microRNAs that are important for proper immune development. A greater understanding of this hormone’s effect gained through the zebrafish model can lead to the development of better practices to improve both human and ecological health. Contemporary reviews typically examine the effect of estrogen-like compounds (oftentimes referred to as estrogenic endocrine disrupting compounds) on a sequestered part of immune system development. A distinct lack of cohesion exists in combining contemporary and past reports of the effects of estrogen on various aspects of immune system development in zebrafish. This review serves to fill that gap in knowledge, and to provide a gateway for other researchers interested in this topic. KEYWORDS: Zebrafish; Immune development; Zebrafish immunology; Estrogen; Estrogen receptor; Autoimmunity; Altered signaling; Hematopoiesis

A basic investigation on evolution of CL-L1 in vertebrates and its bioactivities in black rockfish (Sebastes schlegelii)

Collectins, which belong to C-type lectins, are pattern recognition molecules of the innate immune system exhibiting binding ability to carbohydrate structures on microorganisms. CL-L1, a member of the collectin family, participates in host defense via recognizing pathogen structures and modulating complement activation, and also plays roles in developmental processes. Although research progress obtained in mammals, comparative studies of CL-L1s outside mammals are still very limited so far. In this research, CL-L1s from a range of vertebrates were analyzed in gene synteny, phylogenetic relationship and protein features. It's revealed that CL-L1 is widely distributed and generally conserved in vertebrates. The gene locus of CL-L1 exists stably and protein modules, i.e. the N-terminal region, collagen-like region, neck region and CRD, are conserved in a series of vertebrates. But it's worth noting that some characteristic motifs, i.e. EPN and WND, which are important in binding carbohydrates, are partly or completely lost in the CRDs of CL-L1s in teleost species. The CL-L1 in a marine teleost, the black rockfish, designated as SsCL-L1, is analyzed next. SsCL-L1 has incomplete motifs in its CRD, but shows different binding affinities to a series of monosaccharide. SsCL-L1 can bind different bacteria with different intensities, and agglutinate bacteria in the presence of Ca2+. Sugar binding mechanism of SsCL-L1 needs further studies and results in this work will promote the understanding of CL-L1 evolution in vertebrates and facilitate knowledge of immunological roles of fish collectins.

Factor H related proteins modulate complement activation on kidney cells

Complement activation at a particular location is determined by the balance of activating and inhibitory proteins. Factor H is a key regulator of the alternative pathway of complement, and genetic or acquired impairments in Factor H are associated with glomerular injury. The human Factor H-related proteins (FHRs) comprise a family of five proteins that are structurally related to Factor H. Variations in the genes or expression levels of the FHRs are also associated with glomerular disease, although the mechanisms of glomerular protection/injury are incompletely understood. To explore the role of the FHRs on complement regulation/dysregulation in the kidney, we expressed and purified recombinant murine FHRs (FHRs A, B, C and E). These four distinct FHRs contain binding regions with high amino acid sequence homology to binding regions within Factor H, but we observed different interactions of the FHRs with Factor H binding ligands, including heparin and C3d. There was differential binding of the FHRs to the resident kidney cell types (mesangial, glomerular endothelial, podocytes, and tubular epithelial). All four FHRs caused complement dysregulation on kidney cell surfaces invitro, although the magnitude of the effect differed among the FHRs and also varied among the different kidney cells. However, only FHR E caused glomerular complement dysregulation when injected invivo but did not exacerbate injury when injected into mice with ischemic acute kidney injury, an alternative pathway-mediated model. Thus, our experiments demonstrate that the FHRs have unique, and likely context-dependent, effects on the different cell types within the kidney.

Development and Optimization of Bifunctional Fusion Proteins to Locally Modulate Complement Activation in Diseased Tissue

Sustained complement activation is an underlying pathologic driver in many inflammatory and autoimmune diseases. Currently approved anti-complement therapies are directed at the systemic blockade of complement. Consequently, these therapies provide widespread inhibition of complement pathway activity, beyond the site of ongoing activation and the intended pharmacodynamic (PD) effects. Given the essential role for complement in both innate and adaptive immunity, there is a need for therapies that inhibit complement in diseased tissue while limiting systemic blockade. One potential approach focuses on the development of novel fusion proteins that enable tissue-targeted delivery of complement negative regulatory proteins. These therapies are expected to provide increased potency and prolonged tissue PD, decreased dosing frequency, and the potential for improved safety profiles. We created a library of bifunctional fusion proteins that direct a fragment of the complement negative regulator, complement receptor type 1 (CR1) to sites of tissue injury. Tissue targeting is accomplished through the binding of the fusion protein to complement C3 fragments that contain a surface-exposed C3d domain and which are covalently deposited on tissues where complement is being activated. To that end, we generated a fusion protein that contains an anti-C3d monoclonal antibody recombinantly linked to the first 10 consensus repeats of CR1 (CR11-10) with the intention of delivering high local concentrations of this complement negative regulatory domain to tissue-bound complement C3 fragments iC3b, C3dg and C3d. Biochemical and in vitro characterization identified several fusion proteins that inhibit complement while maintaining the C3d domain binding properties of the parent monoclonal antibody. Preclinical in vivo studies further demonstrate that anti-C3d fusion proteins effectively distribute to injured tissue and reduce C3 fragment deposition for periods beyond 14 days. The in vitro and in vivo profiles support the further evaluation of C3d mAb-CR11-10 as a novel approach to restore proper complement activation in diseased tissue in the absence of continuous systemic complement blockade.

997. RLS-0071 Improves Survival in a Rat Model of Intestinal Necrosis

BackgroundIntestinal necrosis and perforation are potentially life-threatening medical conditions that can lead to bacterial sepsis and systemic inflammatory response syndrome. Various etiologies can compromise the intestinal wall causing leakage of luminal contents including enteric bacteria and precipitate aggressive immunological responses including the complement system and neutrophils. RLS-0071 is a peptide inhibitor of the classical and lectin pathways and known modulator of various neutrophil mediated effectors including myeloperoxidase activity and NETosis.MethodsIn this study we evaluated the extent to which immunomodulation via inhibition of the complement system and neutrophil effectors would alter survival in the setting of intestinal necrosis. Adolescent male Long-Evans rats were subject to cecal ligation and puncture (CLP) with one cohort receiving 40 mg/kg of RLS-0071 thirty minutes after surgery while the control group received no treatment. Survival of the rats was then assessed up to 5 days after surgery. ResultsAnimals treated with RLS-0071 demonstrated nearly 1.5-fold increase in survival compared to the untreated group. In order to further elucidate the increase in survival we explored inflammatory responses as assessed by markers of NETosis i.e., free DNA in plasma, and the pro-inflammatory cytokine, IL-6. A reduction in blood levels of free DNA and the inflammatory cytokine IL-6 were observed for animals treated with RLS-0071.RLS-0071 increases survival of rats after cecal ligation Kaplan-Meier survival curve assessment. The red line indicates the outcome after 75% CLP in animals not receiving treatment (n=13), whereas red curves represent the outcome after animals received a single dose of 40 mg/kg RLS-0071 (n=11).RLS-0071 reduces free DNA levels in the blood Plasma was isolated before surgery (pre-bleed) (n=7) and from animals subject to CLP with (n=4) and without (n=3) RLS-0071 administration 24 hours post-surgery. Plasma samples were incubated with PicoGreen. Fluorescence was read at an excitation wavelength of 485 nm and an emission wavelength of 520nm in a microplate reader. Data are means and standard error of the meansRLS-0071 reduces IL-6 levels in the blood Plasma was isolated before surgery (pre-bleed) (n=8) and from animals subject to CLP with (n=3) and without (n=5) RLS-0071 administration 24 hours post-surgery. Plasma samples were analyzed in an IL-6 ELISA according to the manufacturer’s instructions. Data are means and standard error of the means.ConclusionThe results of these experiments demonstrate that RLS-0071 can increase survival after intestinal perforation by multi-pronged modulation of complement activation, neutrophil immune mechanisms and cytokine mediated inflammatory responses.Disclosures Kenji Cunnion, MD, MPH, ReAlta Life Sciences Inc (Board Member, Employee, Shareholder) Parvathi Kumar, MBBS, ReAlta Life Sciences Inc (Employee) Brittany Lassiter, BS, ReAlta Life Sciences Inc (Employee) Katherine LaValle, DVM, ReAlta Life Sciences Inc (Employee) Neel Krishna, PhD, ReAlta Life Sciences Inc (Employee, Shareholder)

Predicting the In Vivo Performance of Cardiovascular Biomaterials: Current Approaches In Vitro Evaluation of Blood-Biomaterial Interactions.

The therapeutic efficacy of a cardiovascular device after implantation is highly dependent on the host-initiated complement and coagulation cascade. Both can eventually trigger thrombosis and inflammation. Therefore, understanding these initial responses of the body is of great importance for newly developed biomaterials. Subtle modulation of the associated biological processes could optimize clinical outcomes. However, our failure to produce truly blood compatible materials may reflect our inability to properly understand the mechanisms of thrombosis and inflammation associated with biomaterials. In vitro models mimicking these processes provide valuable insights into the mechanisms of biomaterial-induced complement activation and coagulation. Here, we review (i) the influence of biomaterials on complement and coagulation cascades, (ii) the significance of complement-coagulation interactions for the clinical success of cardiovascular implants, (iii) the modulation of complement activation by surface modifications, and (iv) in vitro testing strategies.

Adeno-Associated Virus Vector Gene Delivery Elevates Factor I Levels and Downregulates the Complement Alternative Pathway In Vivo.

The complement system is a key component of innate immunity, but impaired regulation influences disease susceptibility, including age-related macular degeneration and some kidney diseases. While complete complement inhibition has been used successfully to treat acute kidney disease, key unresolved challenges include strategies to modulate rather than completely inhibit the system and to deliver therapy potentially over decades. Elevating concentrations of complement factor I (CFI) restricts complement activation in vitro and this approach was extended in the current study to modulate complement activation in vivo. Sustained increases in CFI levels were achieved using an adeno-associated virus (AAV) vector to target the liver, inducing a 4- to 5-fold increase in circulating CFI levels. This led to decreased activity of the alternative pathway as demonstrated by a reduction in the rate of inactive C3b (iC3b) deposition and more rapid formation of C3 degradation products. In addition, vector application in a mouse model of systemic lupus erythematosus (NZBWF1), where tissue injury is, in part, complement dependent, resulted in reduced complement C3 and IgG renal deposition. Collectively, these data demonstrate that sustained elevation of CFI reduces complement activation in vivo providing proof-of-principle support for the therapeutic application of AAV gene delivery to modulate complement activation.

Complement Decay-Accelerating Factor is a modulator of influenza A virus lung immunopathology.

Clearance of viral infections, such as SARS-CoV-2 and influenza A virus (IAV), must be fine-tuned to eliminate the pathogen without causing immunopathology. As such, an aggressive initial innate immune response favors the host in contrast to a detrimental prolonged inflammation. The complement pathway bridges innate and adaptive immune system and contributes to the response by directly clearing pathogens or infected cells, as well as recruiting proinflammatory immune cells and regulating inflammation. However, the impact of modulating complement activation in viral infections is still unclear. In this work, we targeted the complement decay-accelerating factor (DAF/CD55), a surface protein that protects cells from non-specific complement attack, and analyzed its role in IAV infections. We found that DAF modulates IAV infection in vivo, via an interplay with the antigenic viral proteins hemagglutinin (HA) and neuraminidase (NA), in a strain specific manner. Our results reveal that, contrary to what could be expected, DAF potentiates complement activation, increasing the recruitment of neutrophils, monocytes and T cells. We also show that viral NA acts on the heavily sialylated DAF and propose that the NA-dependent DAF removal of sialic acids exacerbates complement activation, leading to lung immunopathology. Remarkably, this mechanism has no impact on viral loads, but rather on the host resilience to infection, and may have direct implications in zoonotic influenza transmissions.

How Does Complement Affect Hematological Malignancies: From Basic Mechanisms to Clinical Application.

Complement, as a central immune surveillance system, can be activated within seconds upon stimulation, thereby displaying multiple immune effector functions. However, in pathologic scenarios (like in tumor progression), activated complement can both display protective effects to control tumor development and passively promotes the tumor growth. Clinical investigations show that patients with several hematological malignancies often display abnormal level of specific complement components, which in turn modulates complement activation or deregulated cascade. In the past decades, complement-dependent cytotoxicity and complement-dependent cell-mediated phagocytosis were fully approved to display vital roles in monoclonal antibody-based immunotherapies, especially in therapies against hematological malignancies. However, tumor-mediated complement evasion presents a big challenge for such a therapy. This review aims to provide an integrative overview on the roles of the complement in tumor promotion, highlights complement mediated effects on antibody-based immunotherapy against distinct hematological tumors, hopefully provides a theoretical basis for the development of complement-based cancer targeted therapies.

Modulation of complement activation by pentraxin-3 in prostate cancer

Pentraxin 3 (PTX3) is an essential component of the innate immune system and a recognized modulator of Complement cascade. The role of Complement system in the pathogenesis of prostate cancer has been largely underestimated. The aim of our study was to investigate the role of PTX3 as possible modulator of Complement activation in the development of this neoplasia. We performed a single center cohort study; from January 2017 through December 2018, serum and prostate tissue samples were obtained from 620 patients undergoing prostate biopsy. A group of patients with benign prostatic hyperplasia (BPH) underwent a second biopsy within 12–36 months demonstrating the presence of a prostate cancer (Group A, n = 40) or confirming the diagnosis of BPH (Group B, N = 40). We measured tissue PTX3 protein expression together with complement activation by confocal microscopy in the first and second biopsy in group A and B patients. We confirmed that that PTX3 tissue expression in the first biopsy was increased in group A compared to group B patients. C1q deposits were extensively present in group A patients co-localizing and significantly correlating with PTX3 deposits; on the contrary, C1q/PTX3 deposits were negative in group B. Moreover, we found a significantly increased expression of C3a and C5a receptors within resident cells in group A patient. Interestingly, C1q/PTX3 deposits were not associated with activation of the terminal Complement complex C5b-9; moreover, we found a significant increase of Complement inhibitor CD59 in cancer tissue. Our data indicate that PTX3 might play a significant pathogenic role in the development of this neoplasia through recruitment of the early components of Complement cascade with hampered activation of terminal Complement pathway associated with the upregulation of CD59. This alteration might lead to the PTX3-mediated promotion of cellular proliferation, angiogenesis and insensitivity to apoptosis possible leading to cancer cell invasion and migration.

Abstract 1666: A comprehensive DLBCL lymphoma PDX collection to evaluate the efficacy and resistant mechanism of rituximab

Abstract Rituximab has shown great efficacy in B-cell non-Hodgkin's lymphoma (NHL), by binding CD20 to induce cell destruction through activating apoptosis, complement and cell-mediated cytotoxity. However, the response rate of patients with relapsed or refractory CD20-positive NHL to standard rituximab treatment is less than 50%, and the non-responders, especially DLBCL patients, still could express high levels of CD20. Therefore, a translational in vivo platform to understand the mechanisms behind Rituximab resistance is in urgent need. We established and characterized a series of DLBCL lymphoma PDX. Eleven non-GCB DLBCL PDX models were selected for the Rituximab efficacy study, of which 3 are relapse DLBCL. IHC and RNAseq were conducted to evaluate CD20 status and expression of other genes. The anti-tumor efficacy of Rituximab in 11 PDX models revealed that 5 of them were sensitive to rituximab and 6 had a poor response. All these models are CD20 positive judged by IHC. By analyzing the correlation of tumor growth inhibition (TGI) and the genomic background of these PDX models, we identified several candidate genes such as BCL2L1, PDK1, TGF-β, Lgalsl and p56/p53Lyn that may contribute to drug resistance mediated by elevated apoptotic threshold, modulation of complement activity or diminished cellular cytotoxicity. Further validation studies are in progress. We established a series of DLBCL lymphoma PDX; with advanced genomic profiling method and validation, these models can be precisely used for subtype-specific therapy evaluation and the investigation of the mechanism of drug resistance. Citation Format: Hui Qi, Xuzhen Tang, Zhiyuan Zou, Ying Fang, Li Wang, Weili Zhao, Qingyang Gu, Qunsheng Ji. A comprehensive DLBCL lymphoma PDX collection to evaluate the efficacy and resistant mechanism of rituximab [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1666.

EGFR modulates complement activation in head and neck squamous cell carcinoma

BackgroundThe epidermal growth factor receptor (EGFR) is pivotal for growth of epithelial cells and is overexpressed in several epithelial cancers like head and neck squamous cell carcinoma (HNSCC). EGFR signalling is also involved in diverse innate immune functions in epithelia. We previously found a role for EGFR in modulating the complement system in skin, this prompted an investigation into EGFR role in complement modulation in HNSCC.MethodsWe used patient derived HNSCC cell lines with varying sensitivities to EGFR inhibitors, and generated EGFR inhibition resistant cell lines to study the role of EGFR in modulating complement in HNSCC.ResultsWe found that HNSCC cell lines activate the complement system when incubated with human serum. This complement activation was increased in cell lines sensitive to EGFR inhibition following the use of the tyrosine kinase inhibitor Iressa. Sensitive cell line made resistant to EGFR-inhibitors displayed complement activation and a decrease in complement regulatory proteins even in the absence of EGFR-inhibitors. Complement activation did not cause lysis of HNSCC cells, and rather led to increased extracellular signal-regulated kinase (ERK) phosphorylation in one cell line.ConclusionThese data indicate that EGFR has a complement modulatory role in HNSCC, and that a prolonged EGFR-inhibition treatment in sensitive cancer cells increases complement activation. This has implications in understanding the response to EGFR inhibitors, in which resistance and inflammatory skin lesions are two major causes for treatment cessation.

The Long Pentraxin PTX3 as a Humoral Innate Immunity Functional Player and Biomarker of Infections and Sepsis.

The first line of defense in innate immunity is provided by cellular and humoral mediators. Pentraxins are a superfamily of phylogenetically conserved humoral mediators of innate immunity. PTX3, the first long pentraxin identified, is a soluble pattern recognition molecule rapidly produced by several cell types in response to primary pro-inflammatory signals and microbial recognition. PTX3 acts as an important mediator of innate immunity against pathogens of fungal, bacterial and viral origin, and as a regulator of inflammation, by modulating complement activation and cell extravasation, and facilitating pathogen recognition by myeloid cells. In sepsis, PTX3 plasma levels are associated with severity of the condition, patient survival, and response to therapy. In combination with other established biomarkers, PTX3 could improve stratification of sepsis patients and thus, complement the system of classification and monitoring of this disease.

Diseases associated with complement system dysregulation and the prospects of their treatment

The lack of pharmaceutical agents that could modulate complement activation is one of the most serious problems in modern medical practice. Meanwhile, the complement system plays a significant role in the pathogenesis of numerous diseases such as age-related macular degeneration (degenerative eye disease, which is the main cause of blindness in the elderly), kidney diseases such as atypical hemolytic-uremic syndrome and membranoproliferative glomerulonephritis type II, paroxysmal nocturnal hemoglobinuria (Marchiafava-Micheli disease), and hereditary angioedema. The complement and its components are involved in the development and progression of autoimmune pathological processes, such as systemic lupus erythematosus, rheumatoid arthritis, and autoimmune hemolytic anemia; neurodegenerative and neoplastic diseases; and complications after heart attacks, strokes, and transplants. This review considers the involvement of complements in the pathological processes, existing methods of treatment, and the prospects for the development of drugs that can correct the work of complement - the most important component of innate immunity.

Factor H-related proteins FHR1 and FHR5 interact with extracellular matrix ligands and modulate complement activation

Factor H-related proteins FHR1 and FHR5 interact with extracellular matrix ligands and modulate complement activation

Novel potential inhibitors of complement system and their roles in complement regulation and beyond

The complement system resembles a double-edged sword since its activation can either benefit or harm the host. Thus, regulation of this system is of utmost importance and performed by several circulating and membrane-bound complement inhibitors. The pool of well-established regulators has recently been enriched with proteins that either share structural homology to known complement inhibitors such as Sushi domain-containing (SUSD) protein family and Human CUB and Sushi multiple domains (CSMD) families or extracellular matrix (ECM) macromolecules that interact with and modulate complement activity. In this review, we summarize the current knowledge about newly discovered complement inhibitors and discuss their implications in complement regulation, as well as in processes beyond complement regulation such cancer development. Understanding the behavior of these proteins will introduce new mechanisms of complement regulation and may provide new avenues in the development of novel therapies.