C5a Receptor Expression Research Articles

Complement C3a/C3aR inhibition alleviates the formation of aortic aneurysm in Marfan syndrome mice

Mutations in fibrillin 1 (FBN1) is the main cause of Marfan syndrome (MFS) with thoracic aortic aneurysm (TAA) as the main complication. Activation of the complement system plays a key role in the formation of thoracic and abdominal aortic aneurysms. However, the role of the complement system in MFS-associated aortic aneurysms remains unclear. In this study, we observed increased levels of complement C3a and C5a in the plasma of MFS patients and mouse, and the increased deposition of the activated complement system product C3b/iC3b was also observed in the elastic fiber rupture zone of 3-month-old MFS mice. The expression of C3a receptor (C3aR) was increased in MFS aortas, and recombinant C3a promoted the expression of cytokines in macrophages. The administration of a C3aR antagonist (C3aRA) attenuated the development of thoracic aortic aneurysms in MFS mice. The increased inflammation response and matrix metalloproteinases activities were also attenuated by C3aRA treatment in MFS mice. Therefore, these findings indicate that the complement C3a/C3aR inhibition alleviates the formation of aortic aneurysm in Marfan syndrome mice.

C5a-C5aR1 axis controls mitochondrial fission to promote podocyte injury in lupus nephritis

Podocytes are essential to maintaining the integrity of the glomerular filtration barrier, yet they are frequently affected in lupus nephritis (LN). Here, we show that the significant upregulation of Drp1S616 phosphorylation in podocytes promotes mitochondrial fission, leading to mitochondrial dysfunction and podocyte injury in LN. Inhibition or knockdown of Drp1 promotes mitochondrial fusion and protects podocytes from injury induced by LN serum. In vivo, pharmacological inhibition of Drp1 reduces the phosphorylation of Drp1S616 in podocytes in lupus-prone mice. Podocyte injury is reversed when Drp1 is inhibited, resulting in the alleviation of proteinuria. Mechanistically, complement component C5a (C5a) upregulates the phosphorylation of Drp1S616 and promotes mitochondrial fission in podocytes. Moreover, the expression of C5a receptor 1 (C5aR1) is notably upregulated in podocytes in LN. C5a-C5aR1 axis-controlled phosphorylation of Drp1S616 and mitochondrial fission are substantially suppressed when C5aR1 is knocked down by siRNA. Moreover, lupus-prone mice treated with C5aR inhibitor show reduced phosphorylation of Drp1S616 in podocytes, resulting in significantly less podocyte damage. Together, this study uncovers a novel mechanism by which the C5a-C5aR1 axis promotes podocyte injury by enhancing Drp1-mediated mitochondrial fission, which could have significant implications for the treatment of LN.

Abstract WP294: Endothelial Deletion of Complement C3a Receptor is Neuroprotective in Murine Stroke

Background: Stroke is among the leading causes of death and disability worldwide. We and others have shown that endothelial C3a receptor (C3aR) expression is enhanced in murine stroke models as well as in OGD induced brain endothelial cells. Therefore, it is critical to investigate the role of endothelial C3aR in post-stroke neurovascular dysfunction. Hypothesis: Genetic ablation of endothelial C3aR will afford neuroprotection in stroke. Methods: We used a loxP-cre approach (C3aR Flox/Flox x Cdh5 Cre ) to generate conditional C3aR endothelial deficient or sufficient mice (C3aR Endo+/+ or C3aR Endo-/- ) of both sexes (3-4 months old) which were subjected to photothrombotic stroke. WT littermates were used as controls. We assessed cerebral blood flow (CBF), Infarct volume, BBB integrity, and myeloid cell infiltration. Neurobehavioral functions were tested at 3 and 21 days. P<0.05 was considered statistically significant. Results: Photothrombotic (PT) stroke resulted in decreased CBF in C3aR Endo +/+ mice compared with sham animals. However, infarct volume and CBF were improved after 72 h post PT in C3aR Endo-/- vs C3aR Endo +/+ . C3aR Endo-/- mice showed improved motor and cognitive function when compared with C3aR Endo+/+ . Furthermore, reduced myeloid cell/neutrophil infiltration and improved BBB integrity in C3aR Endo -/- vs C3aR Endo+/+ were observed. Conclusion: Genetic deletion of C3aR expression from endothelial cells is neuroprotective in a PT murine stroke model through suppression of inflammation. Further work is warranted to explore underlying mechanisms of C3aR mediated brain injury in stroke.

Emerging role of C5aR2: novel insights into the regulation of uterine immune cells during pregnancy.

Pregnancy is a fascinating immunological phenomenon because it allows allogeneic fetal and placental tissues to survive inside the mother. As a component of innate immunity with high inflammatory potential, the complement system must be tightly regulated during pregnancy. Dysregulation of the complement system plays a role in pregnancy complications including pre-eclampsia and intrauterine growth restriction. Complement components are also used as biomarkers for pregnancy complications. However, the mechanisms of detrimental role of complement in pregnancy is poorly understood. C5a is the most potent anaphylatoxin and generates multiple immune reactions via two transmembrane receptors, C5aR1 and C5aR2. C5aR1 is pro-inflammatory, but the role of C5aR2 remains largely elusive. Interestingly, murine NK cells have been shown to express C5aR2 without the usual co-expression of C5aR1. Furthermore, C5aR2 appears to regulate IFN-γ production by NK cells in vitro. As IFN-γ produced by uterine NK cells is one of the major factors for the successful development of a vital pregnancy, we investigated the role anaphylatoxin C5a and its receptors in the establishment of pregnancy and the regulation of uterine NK cells by examinations of murine C5ar2-/- pregnancies and human placental samples. C5ar2-/- mice have significantly reduced numbers of implantation sites and a maternal C5aR2 deficiency results in increased IL-12, IL-18 and IFN-γ mRNA expression as well as reduced uNK cell infiltration at the maternal-fetal interface. Human decidual leukocytes have similar C5a receptor expression patterns showing clinical relevance. In conclusion, this study identifies C5aR2 as a key contributor to dNK infiltration and pregnancy success.

Pro-inflammatory regulatory mechanism of C5a/C5aR pathway in GCRV-infected grass carp (Ctenopharyngodon idella)

Death of grass carp (Ctenopharyngodon idella) caused by grass carp reovirus (GCRV) infection severely restricts the development of the grass carp industry. The interaction of C5a and C5a receptor (C5aR) in the complement system promotes inflammation and aggravates bleeding in grass carps. To reveal the regulatory mechanism of the C5a/C5aR pro-inflammatory response after GCRV infection, the expression of C5 in the liver and muscle tissues of grass carp after GCRV infection was analyzed using immunofluorescence. The effects of over expression of C5a and the C5aR antagonist PMX205 in grass carp kidney cell line (CIK) on the phosphorylation of p38 and ERK and the gene and protein expression of IL-6 and TNF-α were also analyzed using RT-qPCR and western blot. The results showed that the expression of the C5a protein in the liver and muscle of grass carp infected with GCRV first increased and then decreased, and the C5a protein level peaked on the 5th day after infection. In CIK cells, over expression of C5a significantly increased C5aR expression, phosphorylation of p38 and ERK, and overexpression of IL-6 and TNF-α. Treatment of CIK cells with PMX205 significantly decreased the expression of C5a and C5aR, phosphorylation of p38 and ERK proteins, and expression of IL-6 and TNF-α after GCRV infection. These results implied that the interaction of C5a and C5aR in grass carp resulted in the phosphorylation of p38 and ERK proteins, a significant increase in the expression of IL-6 and TNF-α, and ultimately induction of an inflammatory response of grass carp infected with GCRV. These results provide a theoretical basis for relieving grass carp hemorrhagic diseases by regulating the interaction of C5a and C5aR.

Reducing complement activation during sleep deprivation yields cognitive improvement by dexmedetomidine

BackgroundSleep loss and its associated conditions (e.g. cognitive deficits) represent a large societal burden, but the underlying mechanisms of these cognitive deficits remain unknown. This study assessed the effect of dexmedetomidine (DEX) on cognitive decline induced by sleep loss. MethodsC57BL/6 mice were subjected to chronic sleep restriction (CSR) for 20 h (5 pm–1 pm the next day) daily for 7 days, and cognitive tests were subsequently carried out. The neuromolecular and cellular changes that occurred in the presence and absence of DEX (100 μg kg−1, i.v., at 1 pm and 3 pm every day) were also investigated. ResultsCSR mice displayed a decline in learning and memory by 12% (P<0.05) in the Y-maze and by 18% (P<0.01) in the novel object recognition test; these changes were associated with increases in microglial activation, CD68+ microglial phagosome counts, astrocyte-derived complement C3 secretion, and microglial C3a receptor expression (all P<0.05). Synapse elimination, as indicated by a 66% decrease in synaptophysin expression (P=0.0004) and a 45% decrease in postsynaptic density protein-95 expression (P=0.0003), was associated with the occurrence of cognitive deficits. DEX activated astrocytic α2A adrenoceptors and inhibited astrocytic complement C3 release to attenuate synapse elimination through microglial phagocytosis. DEX restored synaptic connections and reversed cognitive deficits induced by CSR. ConclusionsThe results demonstrate that complement pathway activation associated with synapse elimination contributes to sleep loss-related cognitive deficits and that dexmedetomidine protects against sleep deprivation-induced complement activation. Dexmedetomidine holds potential for preventing cognitive deficits associated with sleep loss, which warrants further study.

Determination of the optimal concentration and duration of C5aR antagonist application in an inflammatory model of human dental pulp cells.

Deep tooth decay approaching the pulp may develop into pulpitis; to prevent this, pulp cells need to balance the rapid immune response to avoid rapid swelling of the pulp. Current treatment of deep decay that approaches the pulp involves the application of drugs that induce low-level inflammation in the dental pulp to promote its repair, but this treatment is sometimes insufficient. However, the unsuccessful treatment often resulted in pulpitis. The C5a-C5aR is the initial stage of the immune cascade response. Blocking the binding of C5a-C5aR can slow the immune response in the narrow pulp cavity, so that dental pulp cells have enough time to proliferate, migrate, and differentiate. In this study, we compared lipoteichoic acid (LTA) and lipopolysaccharides (LPS) at different concentrations and time points and used the C5aR antagonist W54011 to block the C5a-C5aR axis. The blocking effect was detected by analyzing the expression of C5a, C5aR, interleukin (IL)-6, and Toll-like receptors 2 and 4 (TLR-2, 4). Next, we determined the optimal concentration and duration of LTA and LPS treatment in combination with W54011. Based on our results, we selected 1.0 μg·mL-1 LPS treatment for 48 h to generate an inflammatory model of human dental pulp cells. We then regrouped the cells and conducted expression analyses to monitor the expression of C5a, C5aR, IL-6, and TLR-4 at the protein and mRNA levels. LPS stimulation for 48 h and treatment with W54011 for 48 h effectively inhibited inflammation and did not affect C5a expression. This study provides a basis for follow-up studies of W54011 in dental pulp cells.

Complement Is Required for Microbe-Driven Induction of Th17 and Periodontitis.

In both mice and humans, complement and Th17 cells have been implicated in periodontitis, an oral microbiota-driven inflammatory disease associated with systemic disorders. A recent clinical trial showed that a complement C3 inhibitor (AMY-101) causes sustainable resolution of periodontal inflammation, the main effector of tissue destruction in this oral disease. Although both complement and Th17 are required for periodontitis, it is uncertain how these immune components cooperate in disease development. In this study, we dissected the complement-Th17 relationship in the setting of ligature-induced periodontitis (LIP), a model that previously established that microbial dysbiosis drives Th17 cell expansion and periodontal bone loss. Complement was readily activated in the periodontal tissue of LIP-subjected mice but not when the mice were placed on broad-spectrum antibiotics. Microbiota-induced complement activation generated critical cytokines, IL-6 and IL-23, which are required for Th17 cell expansion. These cytokines as well as Th17 accumulation and IL-17 expression were significantly suppressed in LIP-subjected C3-deficient mice relative to wild-type controls. As IL-23 has been extensively studied in periodontitis, we focused on IL-6 and showed that LIP-induced IL-17 and bone loss required intact IL-6 receptor signaling in the periodontium. LIP-induced IL-6 was predominantly produced by gingival epithelial cells that upregulated C3a receptor upon LIP challenge. Experiments in human gingival epithelial cells showed that C3a upregulated IL-6 production in cooperation with microbial stimuli that upregulated C3a receptor expression in ERK1/2- and JNK-dependent manner. In conclusion, complement links the periodontal microbiota challenge to Th17 cell accumulation and thus integrates complement- and Th17-driven immunopathology in periodontitis.

Complement C3a and C3a Receptor Activation Mediates Podocyte Injuries in the Mechanism of Primary Membranous Nephropathy.

The complement system is highly activated in primary membranous nephropathy (MN). Identifying the complement components that damage podocytes has important therapeutic implications. This study investigated the role of C3a and the C3a receptor (C3aR) in the pathogenesis of MN. C3aR expression in kidneys and circulating levels of C3a of MN patients were examined. Human podocyte damage was assessed after exposure to MN plasma +/- C3aR blockade (SB290157, JR14a). C3aR antagonists were administered to rats with Heymann nephritis on day 0 or after proteinuria. Clinical and pathologic parameters, specific IgG and complement activation, and podocyte injuries were then assessed. In the glomeruli, C3aR staining merged well with podocin. Overexpression of C3aR correlated positively with proteinuria, serum creatinine, and no response to treatments. Human podocytes exposed to MN plasma showed increased expression of PLA2R, C3aR, and Wnt3/β-catenin, reduced expression of synaptopodin and migration function, downregulated Bcl-2, and decreased cell viability. C3aR antagonists could block these effects. In Heymann nephritis rats, C3aR blockade attenuated proteinuria, electron-dense deposition, foot process width, and glomerular basement membrane thickening in glomeruli. The increased plasma C3a levels and overexpression of C3aR were also alleviated. Specific, but not total, IgG levels decreased, with less deposition of rat IgG in glomeruli and subsequent reduction of C1q, factor B, and C5b-9. C3a anaphylatoxin is a crucial effector of complement-mediated podocyte damage in MN. The C3aR antagonist may be a potentially viable treatment for this disease.

MERS-CoV infection causes brain damage in human DPP4-transgenic mice through complement-mediated inflammation.

The highly pathogenic Middle East Respiratory Syndrome Coronavirus (MERS-CoV) is a severe respiratory virus. Recent reports indicate additional central nervous system (CNS) involvement. In this study, human DPP4 transgenic mice were infected with MERS-CoV, and viral antigens were first detected in the midbrain-hindbrain 4 days post-infection, suggesting the virus may enter the brainstem via peripheral nerves. Neurons and astrocytes throughout the brain were infected, followed by damage of the blood brain barrier (BBB), as well as microglial activation and inflammatory cell infiltration, which may be caused by complement activation based on the observation of deposition of complement activation product C3 and high expression of C3a receptor (C3aR) and C5a receptor (C5aR1) in neurons and glial cells. It may be concluded that these effects were mediated by complement activation in the brain, because of their reduction resulted from the treatment with mouse C5aR1-specific mAb. Such mAb significantly reduced nucleoprotein expression, suppressed microglial activation and decreased activation of caspase-3 in neurons and p38 phosphorylation in the brain. Collectively, these results suggest that MERS-CoV infection of CNS triggers complement activation, leading to inflammation-mediated damage of brain tissue, and regulating of complement activation could be a promising intervention and adjunctive treatment for CNS injury by MERS-CoV and other coronaviruses.

Human-specific staphylococcal virulence factors enhance pathogenicity in a humanised zebrafish C5a receptor model

Staphylococcus aureus infects ∼30% of the human population and causes a spectrum of pathologies ranging from mild skin infections to life-threatening invasive diseases. The strict host specificity of its virulence factors has severely limited the accuracy of in vivo models for the development of vaccines and therapeutics. To resolve this, we generated a humanised zebrafish model and determined that neutrophil-specific expression of the human C5a receptor conferred susceptibility to the S. aureus toxins PVL and HlgCB, leading to reduced neutrophil numbers at the site of infection and increased infection-associated mortality. These results show that humanised zebrafish provide a valuable platform to study the contribution of human-specific S. aureus virulence factors to infection in vivo that could facilitate the development of novel therapeutic approaches and essential vaccines.

Venoarterial extracorporeal membrane oxygenation induces early immune alterations

BackgroundVenoarterial extracorporeal membrane oxygenation (VA-ECMO) provides heart mechanical support in critically ill patients with cardiogenic shock. Despite important progresses in the management of patients under VA-ECMO, acquired infections remain extremely frequent and increase mortality rate. Since immune dysfunctions have been described in both critically ill patients and after surgery with cardiopulmonary bypass, VA-ECMO initiation may be responsible for immune alterations that may expose patients to nosocomial infections (NI). Therefore, in this prospective study, we aimed to study immune alterations induced within the first days by VA-ECMO initiation.MethodsWe studied immune alterations induced by VA-ECMO initiation using cytometry analysis to characterize immune cell changes and enzyme-linked immunosorbent assay (ELISA) to explore plasma cytokine levels. To analyze specific changes induced by VA-ECMO initiation, nine patients under VA-ECMO (VA-ECMO patients) were compared to nine patients with cardiogenic shock (control patients).ResultsBaseline immune parameters were similar between the two groups. VA-ECMO was associated with a significant increase in circulating immature neutrophils with a significant decrease in C5a receptor expression. Furthermore, we found that VA-ECMO initiation was followed by lymphocyte dysfunction along with myeloid-derived suppressor cells (MDSC) expansion. ELISA analysis revealed that VA-ECMO initiation was followed by an increase in pro-inflammatory cytokines such as IL-6, IL-8 and TNF-α along with IL-10, a highly immunosuppressive cytokine.ConclusionVA-ECMO is associated with early immune changes that may be responsible for innate and adaptive immune alterations that could confer an increased risk of infection.

Complement 5a regulates the function of dendritic cells to induce pathogenic polarization of regulatory T cell/helper T cell 17 in sepsis

To explore the mechanism of complement 5a (C5a) in the pathogenesis of sepsis. SPF male C57BL/6J mice were selected and divided into sham operation group (Sham group), cecal ligation and puncture (CLP) group and CLP+anti-C5A monoclonal antibody intervention group (CLP+anti-C5a group) according to random number table with 20 mice in each group. A CLP model was reproduced to induce sepsis, and those in the Sham group only underwent laparotomy without ligation and perforation. In the CLP+anti-C5a group, 0.15 mg of anti-C5a monoclonal antibody was injected intraperitoneally immediately after CLP, and in the Sham group and CLP group were given equal amount of normal saline. The cumulative survival rate was analyzed by Kaplan-Meier method. Serum levels of tumor necrosis factor-α (TNF-α), interleukins (IL-12, IL-4), and interferon-γ (IFN-γ) were measured 24, 48 and 72 hours after operation by enzyme linked immunosorbent assay (ELISA). Immunohistochemical staining was used to observe the expression of C5a receptor (C5aR) in lung and kidney tissues 48 hours after operation. The proportions of dendritic cell (DC), regulatory T cell (Treg) and helper T cell 17 (Th17) in splenic mononuclear cells 48 hours after operation were analyzed by flow cytometry. The 7-day cumulative survival rate of mice in the CLP group was significantly lower than that in the Sham group (30.00% vs. 100.00%; Log-Rank test: χ2 = 47.470, P < 0.001), and the peripheral blood inflammatory mediators TNF-α, IL-12 and IL-4 were increased 24 hours after operation, followed by a significant decreasing at 48 hours, and then gradually increased at 72 hours. IFN-γ gradually increased 24 hours after operation and lasted for 72 hours. Immunohistochemistry showed that a large number of C5aR was expressed in pulmonary and renal endothelial cells 48 hours after operation in the CLP group. Compared with the Sham group, the proportion of DC [(1.80±0.30)% vs. (6.90±1.20)%, P < 0.05] and Treg [(0.38±0.02)% vs. (4.00±0.50)%, P < 0.05] in splenic mononuclear cells was down-regulated in the CLP group, the proportion of Th17 was up-regulated [(0.83±0.08)% vs. (0.32±0.03)%, P < 0.05], and disorder of immune function was found. After anti-C5A monoclonal antibody intervention, the 7-day cumulative survival rate increased significantly compared with the CLP group (54.54% vs. 30.00%; Log-Rank test: χ2 = 28.090, P < 0.001); TNF-α, IL-12 and IFN-γ were further increased, while IL-4 was significantly decreased; the expression of C5aR in lung and kidney tissues were significantly decreased, and the expression of mature DC cells [(5.10±1.20)% vs. (1.80±0.30)%, P < 0.05] and Treg [(2.58±0.05)% vs. (0.38±0.02)%, P < 0.05] in spleen were significantly increased compared with the CLP group, and Th17 was significantly decreased [(0.54±0.05)% vs. (0.83±0.08)%, P < 0.05]. It is preliminarily concluded that anti-C5A monoclonal antibody may improve the prognosis of sepsis by improving the polarization of mature DC and T cells in the spleen, and C5a plays an important role in the immune regulation of sepsis cells.

Prostate cancer C5a receptor expression and augmentation of cancer cell proliferation, invasion, and PD-L1 expression by C5a.

The treatment of castration-resistant prostate cancer (CRPC) is a urological issue. Recent studies have revealed cancer promotion via the C5a-C5a receptor (C5aR) system. To establish a new therapeutic target for CRPC, we investigated an association of the system with CRPC progression and evasion from the antitumor immune responses. C5aR and PD-L1 were immunostained in the prostate cancer (PC) tissues. The relationship of PC C5aR expression to clinicopathological parameters was analyzed. CRPC cell lines were examined for C5aR expression by real-time reverse transcription polymerase chain reaction, immunoblotting, and flow cytometry. C5a effects were examined on CRPC cell glutamine consumption, proliferation, invasion, and PD-L1 expression. PC cells expressed C5aR in 83 of the 161 patients (52%) and in three of the six CRPC patients. Basal cells, but not luminal cells, of noncancerous prostate glands expressed C5aR. Three CRPC cell lines expressed C5aR. C5a increased CRPC cell glutamine consumption 2.1-fold, proliferation 1.3-1.6-fold, and invasion 2-3-fold in a C5a-concentration and a C5aR-dependent manner. High expression of C5aR did not relate to the PC patients' clinical parameters but the PD-L1-positive rate was higher in the C5aR high-expression patients (37.5%) compared to low- or no expression patients (17.8%), and double-positive PC cells were present. C5a increased CRPC cell PD-L1 production 1.4-fold and cell-surface expression 2.6-fold. C5aR expression of PC cells in patients' tissues and C5a augmentation of C5aR-dependent CRPC proliferation, invasion, and PD-L1 expression suggestedparticipation of the C5a-C5aR system in CRPC promotion and evasion from antitumor immune responses. Targeting this signaling pathway may provide a useful therapeutic option for CRPC.

Glia-Selective Deletion of Complement C1q Prevents Radiation-Induced Cognitive Deficits and Neuroinflammation.

The adverse neurocognitive sequelae following clinical radiotherapy (RT) for central nervous system (CNS) malignancies are often long-lasting without any clinical recourse. Despite recent progress, the cellular mechanisms mediating RT-induced cognitive deficits (RICD) are poorly understood. The complement system is an immediate sensor of a disturbed inflammatory environment and a potent mediator of gliosis with a range of nonimmune functions in the CNS, including synaptic pruning, which is detrimental if dysregulated. We hypothesize that complement-mediated changes in glial cell function significantly contribute to RICD. The underlying alterations in CNS complement cascade proteins (C1q, C3), TLR4, and colabeling with glia (IBA1, GFAP) were examined using gene expression, immunofluorescence, and in silico modeling approaches in the adult mouse brain following 9 Gy cranial RT. Three-dimensional volumetric quantification showed elevated molecular signatures of gliosis at short- and long-term post-RT times. We found significant elevations in complement C1q, C3, and TLR4 post-RT accompanied by increased colabeling of astrocytes and microglia. To address the mechanism of RT-induced complement cascade activation, neuroinflammation, and cognitive dysfunction, we used a genetic approach-conditional, microglia-selective C1q (Flox) knockdown mice-to determine whether a glia-specific, upstream complement cascade contributes to RICD. C1q-Flox mice exposed to cranial RT showed no cognitive deficits compared with irradiated WT mice. Further, irradiated C1q-Flox mice were protected from RT-induced microglial activation and synaptic loss, elevation of anaphylatoxin C5a receptor, astrocytic-C3, and microglial-TLR4 expression in the brain. Our findings demonstrate for the first time a microglia-specific mechanism of RICD involving an upstream complement cascade component, C1q. SIGNIFICANCE: Clinically-relevant radiotherapy induces aberrant complement activation, leading to brain injury. Microglia-selective genetic deletion of CNS complement C1q ameliorates radiation-induced cognitive impairments, synaptic loss, and neuroinflammation, highlighting the potential for C1q as a novel therapeutic target.See related commentary by Korimerla and Wahl, p. 1635.

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.

Sustained activation of C3aR in a human podocyte line impairs the morphological maturation of the cells.

The C3a receptor (C3aR) has been reported to be involved in various physiological and pathological processes, including the regulation of cellular structure development. Expression of C3aR has been reported in podocytes; however, data concerning the role of C3aR in podocyte morphology is scarce. The aim of the present study was to examine the effect of C3aR activation on the architectural development of podocytes. An immortal human podocyte line (HPC) was transfected with a C3a expression lentivirus vector or recombinant C3a. SB290157 was used to block the activation of C3aR. The expression of C3a in HPC cells was analyzed by reverse transcription-quantitative PCR (RT-qPCR) and ELISAs. Phase contrast and fluorescence microscopy were used to observe the morphology of the podocytes. The adhesive ability of HPC cells was analyzed using an attachment assay. RT-qPCR, cyto-immunofluorescence and western blotting were used to determine the expression levels of the adhesion-associated genes. The expression levels of carboxypeptidases in HPC cells was also detected by RT-qPCR. Compared with the untransfected and control virus-transfected HPC cells, the C3a-overexpressing cells (HPC-C3a) failed to expand their cell bodies and develop an arborized appearance in the process of maturation, which the control cells exhibited. In addition, HPC-C3a cells presented with decreased adhesive capacity, altered focal adhesion (FA) plaques and decreased expression of FA-associated genes. These effects were blocked by a C3aR antagonist; however, the addition of purified C3a could not completely mimic the effects of C3a overexpression. Furthermore, HPC cells expressed carboxypeptidases, which have been reported to be able to inactivate C3a. In summary, the results demonstrated that sustained C3aR activation impaired the morphological maturation of HPC cells, which may be associated with the altered expression of FA-associated genes and impaired FA. Since chronic complement activation has been reported in renal diseases, which indicate sustained C3aR activation in renal cells, including podocytes and podocyte progenitors, the possible role of C3aR in the dysregulation of podocyte architecture and podocyte regeneration requires further research.

C3a and C5a facilitates the metastasis of myeloma cells by activating Nrf2.

Multiple myeloma (MM) is still an incurable hematological malignancy, with even poorer prognosis in MM patients with distant invasion. The present study was designed to explore the effects of C3a and C5a on the migration, invasion, and adhesion of MM tumor cells and to investigate the underlying mechanisms. As a result, the levels of C3a and C5a in plasma of MM patients were significantly higher than those of healthy donors. Consistently, the expression of C3a and C5a receptors on myeloma cells of MM patients was also significantly higher than that on sorted plasma cells of normal donors. C3a and C5a have been confirmed to increase the migration, invasion and adhesion of MM cell lines by activating the MEK/ERK pathway and increasing the nuclear transfer of Nrf2 in vitro. Moreover, the MM cell line U266 with Nrf2 downregulation was incubated with C3a and C5a, followed by injection into the tail vein of NOD-SCID mice. We found that Nrf2 downregulation attenuated the migration of anaphylatoxin C3a and C5a to MM tumor cells in bone marrow, liver and lung in vivo. In conclusion, our results indicate that activation of the complement cascade in MM patients may contribute to the migration, invasion and adhesion of MM cells, and this type of tumor cells dissemination in MM is, at least partially, regulated by Nrf2. Thereby, complement suppression or Nrf2 downregulation might offer a novel therapeutic opportunity for MM.

The Potential Role of Complement System in the Progression of Ovarian Clear Cell Carcinoma Inferred from the Gene Ontology-Based Immunofunctionome Analysis.

Ovarian clear cell carcinoma (OCCC) is the second most common epithelial ovarian carcinoma (EOC). It is refractory to chemotherapy with a worse prognosis after the preliminary optimal debulking operation, such that the treatment of OCCC remains a challenge. OCCC is believed to evolve from endometriosis, a chronic immune/inflammation-related disease, so that immunotherapy may be a potential alternative treatment. Here, gene set-based analysis was used to investigate the immunofunctionomes of OCCC in early and advanced stages. Quantified biological functions defined by 5917 Gene Ontology (GO) terms downloaded from the Gene Expression Omnibus (GEO) database were used. DNA microarray gene expression profiles were used to convert 85 OCCCs and 136 normal controls into to the functionome. Relevant offspring were as extracted and the immunofunctionomes were rebuilt at different stages by machine learning. Several dysregulated pathogenic functions were found to coexist in the immunopathogenesis of early and advanced OCCC, wherein the complement-activation-alternative-pathway may be the headmost dysfunctional immunological pathway in duality for carcinogenesis at all OCCC stages. Several immunological genes involved in the complement system had dual influences on patients’ survival, and immunohistochemistrical analysis implied the higher expression of C3a receptor (C3aR) and C5a receptor (C5aR) levels in OCCC than in controls.

Production of a bispecific antibody targeting TNF-α and C5a in Pichia pastoris and its therapeutic potential in rheumatoid arthritis.

To provide an alternative therapeutic modality for rheumatoid arthritis (RA), a novel bispecific antibody (BsAb) targeting human tumor necrosis factor α (TNF-α) and human complement component C5a was constructed. BsAb was expressed in Pichia pastoris and secreted into the culture medium as a functional protein. In vitro functional study demonstrated that BsAb could simultaneously bind to TNF-α and C5a and neutralize their biological actions. Furthermore, BsAb showed significant improvements in both the antigen-binding affinity and the neutralizing ability as compared to its original antibodies produced in E. coli. It was also found that TNF-α and C5a had an additive/synergistic effect on promoting the production of inflammatory cytokines and chemokines and C5a receptor (C5aR) expression in human macrophages. Compared to single inhibition of TNF-α or C5a with respective antibody, BsAb showed a superior efficacy in blocking inflammatory cytokines, chemokines, and C5aR response, as well as in lowering the C5a-mediated chemotaxis of macrophages via C5aR in vitro. With improved production processing and the ability to simultaneously block TNF-α and C5a action, BsAb has a great potential to be developed into a therapeutic agent and may offer a better therapeutic index for RA.