JR14a: A novel antagonist of C3aR attenuates neuroinflammation in cerebral ischemia-reperfusion injury.

Cerebral ischemia-reperfusion injury (CIRI), a prevalent stroke-related complication, can lead to severe brain damage. Inflammation is a crucial factor in CIRI pathogenesis, and the complement component 3a receptor (C3aR) could be a key mediator in the post-CIRI inflammatory cascade. In this study, the role of C3aR in CIRI was investigated utilizing a middle cerebral artery occlusion (MCAO) model in C3aR knockout (KO) mice. Magnetic resonance imaging (MRI) and neurofunctional assessments revealed that C3aR KO mice exhibited significantly diminished cerebral infarction and improved neurological impairments. Consequently, the focus shifted to searching for a small molecule antagonist of C3aR. JR14a, a new potent thiophene antagonist of C3aR, was injected intraperitoneally into mice 1-h post-MCAO model implementation. The mass spectrometry (MS) results indicated the ability of JR14a to penetrate the blood-brain barrier. Subsequent TTC staining and neurofunctional assessments revealed the efficacy of JR14a in reducing cerebral infarct volume and neurological impairment following MCAO. In addition, immunofluorescence (IF) and immunohistochemistry (IHC) demonstrated attenuated microglial activation, neutrophil infiltration, and blood-brain barrier disruption by JR14a in the MCAO model. Furthermore, enzyme-linked immunosorbent assay (ELISA) and Western blotting supported the role of JR14a in downregulating the expression levels of C3aR, tumor necrosis factor-alpha (TNF-α), and interleukin-6 (IL-6), as well as the phosphorylation of p65. In conclusion, the findings suggested that C3aR could be a potential therapeutic target for CIRI, and JR14a emerged as a promising treatment candidate.

The Complement C3a-C3a Receptor Axis Regulates Epithelial-to-Mesenchymal Transition by Activating the ERK Pathway in Pancreatic Ductal Adenocarcinoma.

BACKGROUND: We aimed to clarify the role of complement C3a and its receptor C3aR in progression of pancreatic ductal adenocarcinoma (PDAC). MATERIALS AND METHODS: We evaluated the serum levels of C3 and C3a in patients with PDAC. C3aR expression in tissue was assessed using a tissue microarray. To confirm the protumoral effects of C3a in PDAC, we conducted in vitro experiments using PDAC cell lines (Panc-1 and MiaPaca-2) that exhibit high C3aR expression. RESULTS: Serum levels of both C3 and C3a were higher in 26 patients with PDAC than in 28 nontumor-bearing controls. In the tissue microarray, we observed increased expression of C3aR in PDAC cells, especially in cases with metastatic lesions. In vitro experiments showed that C3a facilitated tumor cell proliferation, migration and invasion by activating the extracellular-regulated kinase signaling pathway and inducing epithelial-to-mesenchymal transition. Inhibition of the C3a-C3aR axis by pharmacological blockade and short-hairpin RNA-mediated knockdown of C3aR alleviated its protumoral effect. CONCLUSION: These findings provide a new approach for the development of treatments targeting the C3a-C3aR axis.

Complement C3a and C5a receptor blockade modulates regulatory T cell conversion in head and neck cancer.

BACKGROUND: Resistance to therapy is a major problem in treating head and neck squamous cell carcinomas (HNSCC). Complement system inhibition has been shown to reduce tumor growth, metastasis, and therapeutic resistance in other tumor models, but has yet to be explored in the context of HNSCC. Here, we tested the effects of complement inhibition and its therapeutic potential in HNSCC. METHODS: We conducted our studies using two Human Papilloma Virus (HPV)-negative HNSCC orthotopic mouse models. Complement C3aR and C5aR1 receptor antagonists were paired with radiation therapy (RT). Tumor growth was measured and immune populations from tumor, lymph node, and peripheral blood were compared among various treatment groups. Genetically engineered mouse models DEREG and C3-/- were used in addition to standard wild type models. Flow cytometry, clinical gene sets, and in vitro assays were used to evaluate the role complement receptor blockade has on the immunological makeup of the tumor microenvironment. RESULTS: In contrast to established literature, inhibition of complement C3a and C5a signaling using receptor antagonists accelerated tumor growth in multiple HNSCC cell lines and corresponded with increased frequency of regulatory T cell (Treg) populations. Local C3a and C5a signaling has importance for CD4 T cell homeostasis and eventual development into effector phenotypes. Interruption of this signaling axis drives a phenotypic conversion of CD4+ T cells into Tregs, characterized by enhanced expression of Foxp3. Depletion of Tregs reversed tumor growth, and combination of Treg depletion and C3a and C5a receptor inhibition decreased tumor growth below that of the control groups. Complete knockout of C3 does not harbor the expected effect on tumor growth, indicating a still undetermined compensatory mechanism. Dexamethasone is frequently prescribed to patients undergoing RT and inhibits complement activation. We report no deleterious effects associated with dexamethasone due to complement inhibition. CONCLUSIONS: Our data establish Tregs as a pro-tumorigenic driver during complement inhibition and provide evidence that targeted C3a and C5a receptor inhibition may add therapeutic advantage when coupled with anti-Treg therapy.

Repurposed Drugs That Block the Gonococcus-Complement Receptor 3 Interaction Can Prevent and Cure Gonococcal Infection of Primary Human Cervical Epithelial Cells.

In the absence of a vaccine, multidrug-resistant Neisseria gonorrhoeae has emerged as a major human health threat, and new approaches to treat gonorrhea are urgently needed. N. gonorrhoeae pili are posttranslationally modified by a glycan that terminates in a galactose. The terminal galactose is critical for initial contact with the human cervical mucosa via an interaction with the I-domain of complement receptor 3 (CR3). We have now identified the I-domain galactose-binding epitope and characterized its galactose-specific lectin activity. Using surface plasmon resonance and cellular infection assays, we found that a peptide mimic of this galactose-binding region competitively inhibited the N. gonorrhoeae-CR3 interaction. A compound library was screened for potential drugs that could similarly prohibit the N. gonorrhoeae-CR3 interaction and be repurposed as novel host-targeted therapeutics for multidrug-resistant gonococcal infections in women. Two drugs, methyldopa and carbamazepine, prevented and cured cervical cell infection by multidrug-resistant gonococci by blocking the gonococcal-CR3 I-domain interaction.IMPORTANCE Novel therapies that avert the problem of Neisseria gonorrhoeae with acquired antibiotic resistance are urgently needed. Gonococcal infection of the human cervix is initiated by an interaction between a galactose modification made to its surface appendages, pili, and the I-domain region of (host) complement receptor 3 (CR3). By targeting this crucial gonococcal-I-domain interaction, it may be possible to prevent cervical infection in females. To this end, we identified the I-domain galactose-binding epitope of CR3 and characterized its galactose lectin activity. Moreover, we identified two drugs, carbamazepine and methyldopa, as effective host-targeted therapies for gonorrhea treatment. At doses below those currently used for their respective existing indications, both carbamazepine and methyldopa were more effective than ceftriaxone in curing cervical infection ex vivo This host-targeted approach would not be subject to N. gonorrhoeae drug resistance mechanisms. Thus, our data suggest a long-term solution to the growing problem of multidrug-resistant N. gonorrhoeae infections.

C3a receptor blockade protects podocytes from injury in diabetic nephropathy.

Renal activation of the complement system has been described in patients with diabetic nephropathy (DN), although its pathological relevance is still ill-defined. Here, we studied whether glomerular C3a, generated by uncontrolled complement activation, promotes podocyte damage, leading to proteinuria and renal injury in mice with type 2 diabetes. BTBR ob/ob mice exhibited podocyte loss, albuminuria, and glomerular injury accompanied by C3 deposits and increased C3a and C3a receptor (C3aR) levels. Decreased glomerular nephrin and α-actinin4 expression, coupled with integrin-linked kinase induction, were also observed. Treatment of DN mice with a C3aR antagonist enhanced podocyte density and preserved their phenotype, limiting proteinuria and glomerular injury. Mechanistically, ultrastructural and functional mitochondrial alterations, accompanied by downregulation of antioxidant superoxide dismutase 2 (SOD2) and increased protein oxidation, occurred in podocytes and were normalized by C3aR blockade. In cultured podocytes, C3a induced cAMP-dependent mitochondrial fragmentation. Alterations of mitochondrial membrane potential, SOD2 expression, and energetic metabolism were also found in response to C3a. Notably, C3a-induced podocyte motility was inhibited by SS-31, a peptide with mitochondrial protective effects. These data indicate that C3a blockade represents a potentially novel therapeutic strategy in DN for preserving podocyte integrity through the maintenance of mitochondrial functions.

Soluble CD93 in allergic asthma.

CD93 has been shown critical roles in inflammatory and immune diseases. However, in allergic asthma, the potential roles of soluble CD93 (sCD93) have not been well studied. We conducted house dust mite (HDM) stimulation with Der p 1 in BEAS-2B and U937 cells, followed by treatment with dexamethasone or small interfering RNA against CD93. A HDM-induced murine allergic asthma model was also established. We estimated the power of sCD93 to predict allergic asthma in a retrospective post-hoc analysis containing 96 human samples. HDM-stimulated BEAS-2B cells showed increased mRNA expression levels of IL-6, IL-8, IL-33, TSLP, and CD93. The CD93 level in culture supernatants steadily increased for 24 h after allergen stimulation, which was significantly suppressed by both dexamethasone and CD93 silencing. CD93 silencing increased IL-6 and TSLP, but not IL-33 levels in culture supernatants. HDM-induced asthma mice showed significant airway hyperresponsiveness and inflammation with Th2 cytokine activation, along with decreased CD93 expression in bronchial epithelial cells and lung homogenates but increased serum CD93 levels. The sCD93 level in asthma patients was significantly higher than that in healthy controls and could predict asthma diagnosis with moderate sensitivity (71.4%) and specificity (82.4%) (AUC = 0.787, P < 0.001). The level of sCD93 which has potential role to predict asthma significantly increased after HDM stimulation via IL-6 and TSLP in vitro and in vivo.

Potent Thiophene Antagonists of Human Complement C3a Receptor with Anti-Inflammatory Activity.

Structure-activity relationships for a series of small-molecule thiophenes resulted in potent and selective antagonism of human Complement C3a receptor. The compounds are about 100-fold more potent than the most reported antagonist SB290157. A new compound JR14a was among the most potent of the new antagonists in vitro, assessed by (a) inhibition of intracellular calcium release (IC50 10 nM) induced in human monocyte-derived macrophages by 100 nM C3a, (b) inhibition of ß-hexosaminidase secretion (IC50 8 nM) from human LAD2 mast cells degranulated by 100 nM C3a, and (c) selectivity for human C3aR over C5aR. JR14a was metabolically stable in rat plasma and in rat liver microsomes and efficacious in rats when given orally to suppress rat paw inflammation, macrophage and mast cell activation, and histopathology induced by intraplantar paw administration of a C3aR agonist. Potent C3aR antagonists are now available for interrogating C3a receptor activation and suppressing C3aR-mediated inflammation in mammalian physiology and disease.

Intracortical Administration of the Complement C3 Receptor Antagonist Trifluoroacetate Modulates Microglia Reaction after Brain Injury.

Worldwide, millions of individuals suffer an ischemic stroke each year, causing major disability, especially in the elderly, where stroke is the number one cause of disability. However, to date, no effective therapy exists that targets the functional recovery after stroke. After necrosis, neuroinflammation is a common feature of the acute stroke and a major obstacle to tissue restoration. In the lesioned area, the dying neurons release chemotactic signals, such as fractalkine/CX3CL1, which evoke "eat-me" signals that are recognized by microglia expressing complement C3a receptor (C3aR), resulting in phagocytosis of the dying but still viable neurons, known as secondary phagocytosis. Using a mouse model of stroke and two-photon microscopy, we aimed to attenuate poststroke phagocytosis of the dying but still viable neurons by using SB 290157, an antagonist of C3aR. We found that intracortical administration of SB 290157 reduced the number of inflammatory microglial cells expressing ED1 and Iba1 antigens at the lesion site. We could show, in vivo, that two days after a needle-induced cortical lesion there were less microglial cells present around the injury site, displaying less high-order branches and an increase in the lower order ones, suggesting an attenuated phagocytic phenotype in treated animals as compared with controls. We conclude that the C3aR antagonist, SB 290157, may be used in the future to limit the neuronal death by limiting secondary phagocytosis after stroke.

The new complement inhibitor CRIg/FH ameliorates lupus nephritis in lupus-prone MRL/lpr mice.

BACKGROUNDS: The aberrant activation of complement system is critically involved in lupus nephropathy. Recent study showed complement C3 inhibitor was effective in the treatment of lupus nephropathy. In this study, we investigate the effect of a novel complement C3 inhibitor, CRIg/FH, in the treatment of lupus nephropathy in MRL/lpr lupus mice. METHODS: We treated MRL/lpr female mice with a dose escalation of CRIg/FH (10, 5 and 2 mg/kg) by intraperitoneal injection twice weekly since 12 weeks age. In addition, MRL/lpr mice treated with intraperitoneal injection of normal saline or oral prednisone, along with C57BL/6 J healthy mice were maintained to serve as controls. We started 8-h urine collection weekly to screen proteinuria by measuring the levels of urine urea/creatinine. Serum samples was collected at week 16 and 20 to measure levels of urea nitrogen, creatinine, and immunological markers (C3, C4, A-ds-DNA) before the mice were sacrificed at 20 weeks age to collect kidneys for histopathological examinations. RESULTS: Overt skin lesions were observed in MRL/lpr mice treated with normal saline, while skin lesion was not observed in CRIg/FH treated MRL/lpr mice. There was no overt proteinuria observed in MRL/lpr mice treated with CRIg/FH. Serum creatinine and BUN levels in MRL/lpr mice was maintained in highest CRIg/FH dose (10 mg/kg twice a week) to be significantly lower than that in prednisone treated MRL/lpr mice at 20 weeks age. In addition, CRIg/FH treatment in MRL/lpr mice results in a significantly elevated serum C3 and C4 levels when compared to prednisone treatment at both 16 and 20 weeks. Furthermore, our study identified that serum level of A-ds-DNA was also significantly lower in CRIg/FH treatment than that in predisone treated MRL/lpr mice. Renal pathology confirmed that kidneys from CRIg/FH treated MRL/lpr mice suffered less from nephritis and complement disposition. CONCLUSION: Our results showed that the complement inhibitor CRIg/FH can protect MRL/lpr mice from lupus nephropathy by preserving renal function and glomerulus complement activation. Our findings support the positive effect of complement inhibitors in the treatment of lupus nephropathy.

The Role of Complement C3a Receptor in Stroke.

The complement system is a key regulator of the innate immune response against diseased tissue that functions across multiple organ systems. Dysregulation of complement contributes to the pathogenesis of a number of neurological diseases including stroke. The C3a anaphylatoxin, via its cognate C3a receptor (C3aR), mediates inflammation by promoting breakdown of the blood-brain barrier and the massive infiltration of leukocytes into ischemic brain in experimental stroke models. Studies utilizing complement deficient mice as well as pharmacologic C3aR antagonists have shown a reduction in tissue injury and mortality in murine stroke models. The development of tissue-specific C3aR knockout mice and more specific C3aR antagonists is warranted to facilitate our understanding of the role of the C3aR in brain ischemia with the ultimate goal of clinical translation of therapies targeting C3aR in stroke patients.

Acute physiological changes caused by complement activators and amphotericin B-containing liposomes in mice.

PURPOSE: Undesirable complement (C) activation by nanomedicines can entail an adverse immune reaction known as C activation-related pseudoallergy (CARPA) in sensitive patients. The syndrome includes cardiopulmonary, hemodynamic, and a variety of other physiological changes that have been well described in man, pigs, dogs, and rats. However, the information on CARPA is scarce and ambiguous in mice, a species widely used in preclinical studies. The present study aimed to fill this gap by exploring signs of CARPA in mice following i.v. administration of AmBisome and Abelcet, which are nano-formulations of Amphotericin B with high risk to cause CARPA. MATERIALS AND METHODS: Anesthetized NMRI mice were intravenously injected with liposomal amphotericin B (Abelcet and AmBisome; 30-300 mg phospholipid/kg), drug-free high cholesterol multilamellar vesicles (HC-MLV), and positive controls, cobra venom factor (CVF) and zymosan, followed by the measurement of blood pressure (BP), heart rate, white blood cell, and platelet counts and plasma thromboxane B2 (TXB2) levels. C activation was assessed by C3a ELISA, a C3 consumption assay (PAN-C3) and a modified sheep red blood cell hemolytic assay. RESULTS: All test agents, except HC-MLV, caused transient hypertension, thrombocytopenia, and elevation of plasma TXB2, which were paralleled by significant rises of plasma C3a in CVF and zymosan-treated animals, wherein the initial hypertension turned into hypotension and shock. Abelcet and AmBisome caused minor, delayed rise of C3a that was not associated with hypertension. The C3a receptor inhibitor SB-290157 attenuated the hypertension caused by Abelcet and decreased the BP thereafter. CONCLUSION: The parallelism between C3a anaphylatoxin production and severity of physiological changes caused by the different agents is consistent with CARPA underlying these changes. Although the reactive dose of liposomal phospholipids was substantially higher than that in other species (pigs, dogs), the mouse seems suitable for studying the mechanism of hypersensitivity reactions to liposomal formulations of amphotericin B, a frequent side effect of these drugs.

Complement C3a receptor antagonist attenuates tau hyperphosphorylation via glycogen synthase kinase 3ß signaling pathways.

Neurofibrillary tangles aggregated from hyperphosphorylated tau protein are the main pathological feature of Alzheimer's disease (AD). Complement C3 (or C3a) is the core component of the complement system and is associated with AD pathological processes. However, it remains unclear whether C3a or the C3a receptor has any effect on tau phosphorylation. In this study, we found that exposure of SH-SY5Y cells to okadaic acid (OA) decreased cell viabilities and induced tau hyperphosphorylation. These effects were alleviated by C3a receptor antagonist SB290157 and were further validated by C3a receptor siRNA in OA-treated SH-SY5Y cells. In addition, our results demonstrated that SB290157 markedly inhibited the activities of glycogen synthase kinase 3ß (GSK3ß), but had no effect on protein phosphatase 2A C subunit (PP2Ac) and cyclin-dependent kinases 5 (CDK5). Our findings here indicate the unique role of the C3a receptor in regulating tau phosphorylation via GSK3ß signaling pathways and suggest that the C3a receptor may be a viable target for treating AD.

Effect of Timing and Complement Receptor Antagonism on Intragraft Recruitment and Protolerogenic Effects of Mesenchymal Stromal Cells in Murine Kidney Transplantation.

BACKGROUND: Mesenchymal stromal cells (MSCs) have protolerogenic effects in renal transplantation, but they induce long-term regulatory T cells (Treg)-dependent graft acceptance only when infused before transplantation. When given posttransplant, MSCs home to the graft where they promote engraftment syndrome and do not induce Treg. Unfortunately, pretransplant MSC administration is unfeasible in deceased-donor kidney transplantation. METHODS: To make MSCs a therapeutic option also for deceased organ recipients, we tested whether MSC infusion at the time of transplant (day 0) or posttransplant (day 2) together with inhibition of complement receptors prevents engraftment syndrome and allows their homing to secondary lymphoid organs for promoting tolerance. We analyzed intragraft and splenic MSC localization, graft survival, and alloimmune response in mice recipients of kidney allografts and syngeneic MSCs given on day 0 or on posttransplant day 2. C3a receptor (C3aR) or C5a receptor (C5aR) antagonists were administered to mice in combination with the cells or were used together to treat MSCs before infusion. RESULTS: Syngeneic MSCs given at day 0 homed to the spleen increased Treg numbers and induced long-term graft acceptance. Posttransplant MSC infusion, combined with a short course of C3aR or C5aR antagonist or administration of MSCs pretreated with C3aR and C5aR antagonists, prevented intragraft recruitment of MSCs and graft inflammation, inhibited antidonor T-cell reactivity, but failed to induce Treg, resulting in mild prolongation of graft survival. CONCLUSIONS: These data support testing the safety/efficacy profile of administering MSCs on the day of transplant in deceased-donor transplant recipients and indicate that complement is crucial for MSC recruitment into the kidney allograft.

C3a receptor antagonism as a novel therapeutic target for chronic rhinosinusitis.

Chronic rhinosinusitis with nasal polyps (CRSwNP) is an inflammatory disease with an unknown etiology. Recent studies have implicated the complement system as a potential modulator of disease immunopathology. We performed proteomic pathway enrichment analysis of differentially increased proteins, and found an enrichment of complement cascade pathways in the nasal mucus of individuals with CRSwNP as compared to control subjects. Sinonasal mucus levels of complement 3 (C3) correlated with worse subjective disease severity, whereas no significant difference in systemic C3 levels could be determined in plasma samples. Given that human sinonasal epithelial cells were the predominate sinonasal source of C3 and complement anaphylatoxin 3a (C3a) staining, we focused on their role in in vitro studies. Baseline intracellular C3 levels were higher in CRSwNP cells, and following exposure to Aspergillus fumigatus (Af) extract, they released significantly more C3 and C3a. Inhibition of complement 3a receptor (C3aR) signaling led to a decrease in Af-induced C3 and C3a release, both in vitro and in vivo. Finally, we found in vivo that C3aR deficiency or inhibition significantly reduced inflammation and CRS development in a mouse model of Af-induced CRS. These findings demonstrate that local sinonasal complement activation correlates with subjective disease severity, and that local C3aR antagonism significantly ameliorates Af-induced CRS in a rodent model.

Donor pretreatment with nebulized complement C3a receptor antagonist mitigates brain-death induced immunological injury post-lung transplant.

Donor brain death (BD) is an inherent part of lung transplantation (LTx) and a key contributor to ischemia-reperfusion injury (IRI). Complement activation occurs as a consequence of BD in other solid organ Tx and exacerbates IRI, but the role of complement in LTx has not been investigated. Here, we investigate the utility of delivering nebulized C3a receptor antagonist (C3aRA) pretransplant to BD donor lungs in order to reduce post-LTx IRI. BD was induced in Balb/c donors, and lungs nebulized with C3aRA or vehicle 30 minutes prior to lung procurement. Lungs were then cold stored for 18 hours before transplantation into C57Bl/6 recipients. Donor lungs from living donors (LD) were removed and similarly stored. At 6 hours and 5 days post-LTx, recipients of BD donor lungs had exacerbated IRI and acute rejection (AR), respectively, compared to recipients receiving LD lungs, as determined by increased histopathological injury, immune cells, and cytokine levels. A single pretransplant nebulized dose of C3aRA to the donor significantly reduced IRI as compared to vehicle-treated BD donors, and returned IRI and AR grades to that seen following LD LTx. These data demonstrate a role for complement inhibition in the amelioration of IRI post-LTx in the context of donor BD.

The secreted Candida albicans protein Pra1 disrupts host defense by broadly targeting and blocking complement C3 and C3 activation fragments.

Candida albicans the most frequently isolated clinical fungal pathogen can cause local as well as systemic and life-threatening infections particularly in immune-compromised individuals. A better and more detailed understanding how C. albicans evades human immune attack is therefore needed for identifying fungal immune-evasive proteins and develop new therapies. Here, we identified Pra1, the pH-regulated C. albicans antigen as a hierarchical complement inhibitor that targets C3, the central human complement component. Pra1 cleaved C3 at a unique site and further inhibited effector function of the activation fragments. The newly formed C3a-like peptide lacked the C-terminal arginine residue needed for C3a-receptor binding and activation. Moreover, Pra1 also blocked C3a-like antifungal activity as shown in survival assays, and the C3b-like molecule formed by Pra1 was degraded by the host protease Factor I. Pra1 also bound to C3a and C3b generated by human convertases and blocked their effector functions, like C3a antifungal activity shown by fungal survival, blocked C3a binding to human C3a receptor-expressing HEK cells, activation of Fura2-AM loaded cells, intracellular Ca2+ signaling, IL-8 release, C3b deposition, as well as opsonophagocytosis and killing by human neutrophils. Thus, upon infection C. albicans uses Pra1 to destroy C3 and to disrupt host complement attack. In conclusion, candida Pra1 represents the first fungal C3-cleaving protease identified and functions as a fungal master regulator of innate immunity and as a central fungal immune-escape protein.

Exploiting a novel conformational switch to control innate immunity mediated by complement protein C3a.

Complement C3a is an important protein in innate and adaptive immunity, but its specific roles in vivo remain uncertain because C3a degrades rapidly to form the C3a-desArg protein, which does not bind to the C3a receptor and is indistinguishable from C3a using antibodies. Here we develop the most potent, stable and highly selective small molecule modulators of C3a receptor, using a heterocyclic hinge to switch between agonist and antagonist ligand conformations. This enables characterization of C3 areceptor-selective pro- vs. anti-inflammatory actions in human mast cells and macrophages, and in rats. A C3a receptor-selective agonist induces acute rat paw inflammation by first degranulating mast cells before activating macrophages and neutrophils. An orally administered C3a receptor-selective antagonist inhibits mast cell degranulation, thereby blocking recruitment and activation of macrophages and neutrophils, expression of inflammatory mediators and inflammation in a rat paw edema model. These novel tools reveal the mechanism of C3a-induced inflammation and provide new insights to complement-based medicines.Complement C3a is an important protein in innate and adaptive immunity, but its roles in vivo are unclear. Here the authors develop novel chemical agonists and antagonists for the C3a receptor, and show that they modulate mast cell degranulation and inflammation in a rat paw edema model.

[The effect of complement C3a receptor antagonist in the kidney immune injury in trichloroethylene-sensitized mice].

Objective: To explore the effect of complement C3 a-C3a receptor in the kidney immune inju-ry in trichloroethylene-sensitized mice by using C3a receptor specific antagonist C3aRA and discuss the patho-genesis of kidney injury in occupational dermatitis medicamentosa-like of trichloroethylene (ODMLT) . Methods: 42 female 6~8 weeks old BALB/c mice of specific pathogen free were randomly divided into blank control group (5) , solvent control group (5) , TCE treatment group (16) and TCE+C3aRA treatment group (16) . The TCE treat-ment group and TCE+C3aRA treatment group were further divided into the sensitized group and the non-sensi-tized group according to the skin sensitization test score. Renal function was detected by biochemical detection kit; expression of C3aR in kidney tissue was detected by qPCR; expression of IL-1ß and TNF-α protein were de-tected by immunohistochemical. Results: Compared with solvent control group and corresponding non-sensitized group, CRE and BUN in TCE sensitized group and TCE + C3aRA sensitized group were significantly increased (P<0.05) . Compared with TCE sensitized group, CRE and BUN in TCE+C3aRA sensitized group were signifi-cantly decreased (P<0.05) . Compared with solvent control group and TCE non-sensitized group, the expression level of C3aR gene in kidney tissue in TCE sensitized group was significantly increased (P<0.05) . There was a large number of IL-1ß and TNF-α protein expression in kidney tissue in TCE sensitized group and TCE+C3aRA sensitized group. Compared with the TCE sensitized group, the expression level of IL-1ß and TNF-α protein in kidney tissue in TCE+C3aRA sensitized group was significantly decreased (P<0.05) . Conclusion: C3a-C3aR may be involved in the kidney immune injury in TCE sensitized mice, C3aRA has a protective effect on the kid-ney immune injury in TCE sensitized mice.

Elevated expression of CD93 promotes angiogenesis and tumor growth in nasopharyngeal carcinoma.

CD93, also known as the complement component C1q receptor (C1qRp), has been reported to promote the progression of some cancer types. However, the expression and physiological significance of CD93 in nasopharyngeal carcinoma (NPC) remain largely elusive. In this study, we first examined the expression of CD93 in NPC and experimentally manipulated its expression. We observed that vascular CD93 expression is elevated in NPC and is correlated with T classification, N classification, distant metastasis, clinical stage and poor prognosis (all P < 0.05). In addition, overexpression of CD93 promoted angiogenesis in vitro. What's more, we found that CD93 was highly expressed in NPC tissues and cells, and the regulation of CD93 on cell proliferation was determined by cell counting kit (CCK)-8 assay and cell cycle analyses. Our findings provide unique insight into the pathogenesis of NPC and underscore the need to explore novel therapeutic targets such as CD93 to improve NPC treatment.

Complement Involvement in Periodontitis: Molecular Mechanisms and Rational Therapeutic Approaches.

The complement system is a network of interacting fluid-phase and cell surface-associated molecules that trigger, amplify, and regulate immune and inflammatory signaling pathways. Dysregulation of this finely balanced network can destabilize host-microbe homeostasis and cause inflammatory tissue damage. Evidence from clinical and animal model-based studies suggests that complement is implicated in the pathogenesis of periodontitis, a polymicrobial community-induced chronic inflammatory disease that destroys the tooth-supporting tissues. This review discusses molecular mechanisms of complement involvement in the dysbiotic transformation of the periodontal microbiome and the resulting destructive inflammation, culminating in loss of periodontal bone support. These mechanistic studies have additionally identified potential therapeutic targets. In this regard, interventional studies in preclinical models have provided proof-of-concept for using complement inhibitors for the treatment of human periodontitis.