Expression Of Complement Components Research Articles

Complement system molecules: Expression and regulation at the maternal-conceptus interface during pregnancy in pigs

The complement system, composed of complement components and complement control proteins, plays an essential role in innate immunity. Complement system molecules are expressed at the maternal-conceptus interface, and inappropriate activation of the complement system is associated with various adverse pregnancy outcomes in humans and rodents. However, the expression, regulation, and function of the complement system at the maternal-conceptus interface in pigs have not been studied. In this study, we investigated the expression, localization, and regulation of complement system molecules at the maternal-conceptus interface in pigs. Complement components and complement control proteins were expressed in the endometrium, early-stage conceptus, and chorioallantoic tissues during pregnancy. The expression of complement components acting on the early stage of complement activation increased in the endometrium on Day 15 of pregnancy, with greater levels on that day compared with the estrous cycle. Localization of several complement components and complement control proteins was cell-type specific in the endometrium. The expression of C1QC, C2, C3, C4A, CFI, ITGB2, MASP1, and SERPING1 was increased by IFNG in endometrial explant tissues. Furthermore, cleaved C3 fragments were detected in endometrial tissues and uterine flushings on Day 15 of the estrous cycle and Day 15 of pregnancy, with greater levels on Day 15 of pregnancy. These results suggest that complement system molecules in pigs expressed at the maternal-conceptus interface play important roles in the establishment and maintenance of pregnancy by regulating innate immunity and modulating the maternal immune environment during pregnancy.

Pleural Mesothelial Cells-Induced Monocytes to the Pleural Cavity through the Effect of C3 Lytic Products in Tuberculous Pleural Effusion

Background. The activation of complement is involved in monocyte recruitment in tuberculous pleural effusion (TPE), while the role of the cleavage product of complement C3 in this process needs further research. Methods. The expression of complement components in pleural biopsy specimens of TPE patients was measured. The concentration of cleavage products of complement was tested in TPE by ELISA. Moreover, the colocalizations of C3b and CR1, C3d and CR3, and CXCL12 and CXCR4 in monocytes and pleural mesothelial cells (PMCs) isolated from TPE were determined by an immunofluorescent assay. Monocyte chemotaxis assay was analyzed via transwell chambers. Results. Three pathways of the complement system were activated in tuberculous pleurisy. In patients with TPE, C3 lysis was more active than peripheral blood in pleural cavity. Tuberculous protein Mpt64 and anaphylatoxin C3a could significantly promote CXCL12 production in human PMCs isolated from TPE. C3b-CR1, C3d-CR3, and CXCL12-CXCR4 were colocalized in PMCs and monocytes from TPE. The recruitment of monocytes into TPE mediated by PMCs could be inhibited by anti-CR1, anti-CR3, and anti-CXCL12 monoclonal antibodies (mAbs). Conclusions. Complement activates strongly in TPE, and PMCs induced monocytes to the pleural cavity through C3a, C3b, and C3d.

The activated complement pathway in the fibrous process of benign prostatic hyperplasia.

To elucidate the changes in activated complement pathway in the fibrous process of benign prostatic hyperplasia (BPH), we analyzed the correlation between complement component expression and histological types of fibrosis using human BPH tissue. Fifty-six histological BPH patients who underwent prostate needle biopsy at our institution (mean age 68.6 ± 6.5 years), divided into two histological groups, fibromuscular and fibrous, were compared. Inflammatory cell infiltration in BPH tissue was evaluated by immunohistochemical staining using CD45, with complement expression analysis performed using C3, factor B, and C5b-9 antibody, and the occupancy ratio of the stained region was calculated. Further, correlation between the histological types of fibrous components in BPH tissue and lower urinary tract symptoms questionnaires was analyzed. Twenty-seven (48.2%) and 29 (51.8%) cases were classified in the fibromuscular and fibrous groups, respectively. The proportion of CD45-positive cells in BPH tissue was significantly higher in the fibromuscular group. In complement component analysis, factor B did not significantly differ between groups, while C3 (fibromuscular group; 10.7 ± 8.2%, fibrous group; 16.4 ± 12.7%) and C5b-9 (fibromuscular group; 15.9 ± 6.2%, fibrous group; 17.6 ± 9.2%) were significantly higher in the fibrous group (p = 0.04, p = 0.04, respectively). International Prostate Symptom Score Q5 subscore, indicating slow stream, was significantly higher in the fibrous group (p = 0.04). In fibrous BPH with abundant fibrosis, the late complement pathway in addition to alternative pathway was activated compared to fibromuscular BPH. These results suggested that the alternative and late complement pathways were involved in the histological fibrous process of BPH.

NMOSD IgG Impact Retinal Cells in Murine Retinal Explants.

Neuromyelitis optica spectrum disorders (NMOSD) are chronic inflammatory diseases of the central nervous system, characterized by autoantibodies against aquaporin-4. The symptoms primarily involve severe optic neuritis and longitudinally extensive transverse myelitis. Although the disease progression is typically relapse-dependent, recent studies revealed retinal neuroaxonal degeneration unrelated to relapse activity, potentially due to anti-aquaporin-4-positive antibodies interacting with retinal glial cells such as Müller cells. In this exploratory study, we analysed the response of mouse retinal explants to NMOSD immunoglobulins (IgG). Mouse retinal explants were treated with purified IgG from patient or control sera for one and three days. We characterized tissue response patterns through morphological changes, chemokine secretion, and complement expression. Mouse retinal explants exhibited a basic proinflammatory response ex vivo, modified by IgG addition. NMOSD IgG, unlike control IgG, increased gliosis and decreased chemokine release (CCL2, CCL3, CCL4, and CXCL-10). Complement component expression by retinal cells remained unaltered by either IgG fraction. We conclude that human NMOSD IgG can possibly bind in the mouse retina, altering the local cellular environment. This intraretinal stress may contribute to retinal degeneration independent of relapse activity in NMOSD, suggesting a primary retinopathy.

Methylmercury induces ectopic expression of complement components and apoptotic cell death in the retina of the zebrafish embryo

Methylmercury (MeHg) is a well-known neurotoxin of humans and wildlife. Visual impairments, including blindness, are frequently present in human patients with MeHg poisoning and in affected animals. It is widely assumed that MeHg-induced damage to the visual cortex is the sole or primary cause of vision loss. MeHg has been shown to accumulate in the outer segments of photoreceptor cells, and to alter the thickness of the inner nuclear layer of the fish retina. However, it is unclear whether the bioaccumulated MeHg has direct deleterious effects on the retina. Herein we report that the genes encoding complement components 5 (c5), c7a, c7b, and c9 were ectopically expressed in the inner nuclear layer of the retinas of zebrafish embryos exposed to MeHg (6–50 μg/L). The numbers of apoptotic cell deaths scored in the retinas of MeHg-treated embryos significantly increased in a concentration-dependent manner. In comparison with cadmium and arsenic, ectopic expression of c5, c7a, c7b, and c9, and the observed apoptotic cell death in the retina were specific to MeHg exposure. Our data provide evidence supporting the hypothesis that MeHg has deleterious impacts on the retinal cells, especially the inner nuclear layer. We propose that MeHg-induced retinal cell death may trigger the activation of the complement system.

An in vitro study on the stimulatory effects of extracellular glutamate on astrocytes.

In our previous research, it was found that the cerebrospinal fluid had higher levels of glutamate, astrocytes were stimulated and released pro-inflammatory factors in a subarachnoid hemorrhage model. Glutamate is a neurotransmitter produced in abundance by excitatory neurons in the central nervous system, residual glutamate can cause neurotoxicity. Recent studies indicate that most glutamate is absorbed by astrocytes, to optimize neurological functions and prevent excitotoxicity. However, it is still unclear if astrocytes could be stimulated by glutamate, and the concentration range of glutamate transportable by astrocytes. Thus, further research is necessary. This study aimed to clarify these scientific questions by stimulating primary astrocytes at different glutamate concentrations (0, 25, 50, and 100 µM) for 24h. The results showed that glutamate induced an increased response in astrocytes, the protein levels of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) were upregulated in treatment groups with 50 and 100 µM. Additionally, the protein expression of complement component 3 (C3) significantly increased following glutamate stimulation (50 and 100 µM) for 24h. Furthermore, the supernatant of the 100 µM treatment group significantly decreased the viability of HT-22 (an immortalized mouse hippocampal neuronal cell line). In summary, our results indicate that increased extracellular glutamate levels can activate astrocytes and promote pro-inflammatory factor production. Moreover, the concentration range of glutamate transported by astrocytes is approximately less than 50-100 µM. Therefore, our study suggests that experimental antagonization of glutamate excitotoxicity is feasible.

Hepatitis B virus suppresses complement C9 synthesis by limiting the availability of transcription factor USF-1 and inhibits formation of membrane attack complex: implications in disease pathogenesis

BackgroundThe complement system functions primarily as a first-line host defense against invading microbes, including viruses. However, the interaction of Hepatitis B virus (HBV) with the complement-components during chronic HBV infection remains largely unknown. We investigated the mechanism by which HBV inhibits the formation of cytolytic complement membrane-attack complex (MAC) and studied its impact on MAC-mediated microbicidal activity and disease pathogenesis.MethodsBlood/liver tissues were collected from chronically HBV-infected patients and controls. HepG2hNTCP cells were infected with HBV particles and Huh7 cells were transfected with full-length linear HBV-monomer or plasmids containing different HBV-ORFs and expression of complement components or other host genes were evaluated. Additionally, ELISA, Real-time PCR, Western blot, bioinformatics analysis, gene overexpression/knock-down, mutagenesis, chromatin immunoprecipitation, epigenetic studies, immunofluorescence, and quantification of serum HBV-DNA, bacterial-DNA and endotoxin were performed.ResultsAmong the MAC components (C5b-C9), significant reduction was noted in the expression of C9, the major constituent of MAC, in HBV-infected HepG2hNTCP cells and in Huh7 cells transfected with full-length HBV as well as HBX. C9 level was also marked low in sera/liver of chronic hepatitis B (CHB) and Immune-tolerant (IT) patients than inactive carriers and healthy controls. HBX strongly repressed C9-promoter activity in Huh7 cells but CpG-island was not detected in C9-promoter. We identified USF-1 as the key transcription factor that drives C9 expression and demonstrated that HBX-induced hypermethylation of USF-1-promoter is the leading cause of USF-1 downregulation that in turn diminished C9 transcription. Reduced MAC formation and impaired lysis of HBV-transfected Huh7 and bacterial cells were observed following incubation of these cells with C9-deficient CHB sera but was reversed upon C9 supplementation. Significant inverse correlation was noted between C9 concentration and HBV-DNA, bacterial-DNA and endotoxin content in HBV-infected patients. One-year Tenofovir therapy resulted in improvement in C9 level and decline in viral/bacterial/endotoxin load in CHB patients.ConclusionCollectively, HBX suppressed C9 transcription by restricting the availability of USF-1 through hypermethylation of USF-1-promoter and consequently hinder the formation and lytic functions of MAC. Early therapy is needed for both CHB and IT to normalize the aberrant complement profile and contain viral and bacterial infection and limit disease progression.

Bilirubin Induces A1-Like Reactivity of Astrocyte.

Astrocytes play an important role in the pathogenesis of bilirubin neurotoxicity, and activated astrocytes might be potential mediators of neuroinflammation processes contributing to neuronal cell death and tissue injury. Recent studies have reported that activated microglia induce two types of reactive astrocytes. A1 astrocytes could cause neuronal death and synaptic damage, as well as impaired phagocytosis. Therefore, the purpose of this study was to investigate whether unconjugated bilirubin (UCB)-induced A1-like astrocytes take on a neuroinflammation type and the underlying regulatory mechanisms. In this study, primary cortical astrocytes were treated with UCB in vitro. We detected the expression of complement component 3 (C3), S100 calcium binding protein A10 (S100A10), nuclear factor kappa B (NF-κB), NLR family pyrin domain containing 3 (NLRP3), activated caspase-1, gasdermin D N-terminal (GSDMD-N), PSD95, synaptophysin (SYP), the transcription levels of interleukin (IL)-1β and IL-18, and the survival rate of astrocytes after UCB treatment. The results showed that an increase in C3 was accompanied by a decrease in S100A10, and that A1-like astrocytes were functionally expressed after UCB stimulation. Meanwhile, the NF-κB and caspase-1 pathways were activated after UCB stimulation. After adding the NF-κB-specific inhibitor trans-activator of transcriptional-NEMO-binding domain (TAT-NBD) and caspase-1 specific inhibitor VX-765, the survival rate of astrocytes and neurons increased, whereas the protein expression of C3, NF-κB, NLRP3, activated caspase-1, and GSDMD-N decreased, and the mRNA levels of IL-1β and IL-18 reduced. Thus, we concluded that UCB stimulates the activation of A1-like astrocytes. Inhibition of NF-κB and caspase-1 alleviated A1-like astrocytes and exerted anti-inflammatory protective effects.

Succinate and inosine coordinate innate immune response to bacterial infection

Macrophages restrict bacterial infection partly by stimulating phagocytosis and partly by stimulating release of cytokines and complement components. Here, we treat macrophages with LPS and a bacterial pathogen, and demonstrate that expression of cytokine IL-1β and bacterial phagocytosis increase to a transient peak 8 to 12 h post-treatment, while expression of complement component 3 (C3) continues to rise for 24 h post-treatment. Metabolomic analysis suggests a correlation between the cellular concentrations of succinate and IL-1β and of inosine and C3. This may involve a regulatory feedback mechanism, whereby succinate stimulates and inosine inhibits HIF-1α through their competitive interactions with prolyl hydroxylase. Furthermore, increased level of inosine in LPS-stimulated macrophages is linked to accumulation of adenosine monophosphate and that exogenous inosine improves the survival of bacterial pathogen-infected mice and tilapia. The implications of these data suggests potential therapeutic tools to prevent, manage or treat bacterial infections.

PD16-06 SHIFT CHANGE OF THE ACTIVATED COMPLEMENT PATHWAY IN THE FIBROTIC PROCESS ASSOCIATED WITH PROGRESSION OF BENIGN PROSTATIC HYPERPLASIA

You have accessJournal of UrologyCME1 May 2022PD16-06 SHIFT CHANGE OF THE ACTIVATED COMPLEMENT PATHWAY IN THE FIBROTIC PROCESS ASSOCIATED WITH PROGRESSION OF BENIGN PROSTATIC HYPERPLASIA Junya Hata, Yusuke Kirihana, Tomoyuki Kumekawa, Hiroki Natsuya, Yusuke Hakozaki, Syunsuke Yoshioka, Hitomi Imai, Kanako Matsuoka, Tomoyuki Koguchi, Yuichi Sato, Hidenori Akaihata, Masao Kataoka, and Yoshiyuki Kojima Junya HataJunya Hata More articles by this author , Yusuke KirihanaYusuke Kirihana More articles by this author , Tomoyuki KumekawaTomoyuki Kumekawa More articles by this author , Hiroki NatsuyaHiroki Natsuya More articles by this author , Yusuke HakozakiYusuke Hakozaki More articles by this author , Syunsuke YoshiokaSyunsuke Yoshioka More articles by this author , Hitomi ImaiHitomi Imai More articles by this author , Kanako MatsuokaKanako Matsuoka More articles by this author , Tomoyuki KoguchiTomoyuki Koguchi More articles by this author , Yuichi SatoYuichi Sato More articles by this author , Hidenori AkaihataHidenori Akaihata More articles by this author , Masao KataokaMasao Kataoka More articles by this author , and Yoshiyuki KojimaYoshiyuki Kojima More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000002548.06AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: In a previous study, we reported that complement activation by an autoimmune reaction was associated with the growth process of benign prostatic hyperplasia (BPH). On the other hand, BPH was reported to show a histological transition from smooth muscle-dominant type to fibrous-dominant type as it becomes more severe. Therefore, we hypothesized that activation of complement pathways might be associated with the fibrous process of BPH with progression. In this study, to clarify the activated complement pathway in the fibrous process of BPH with progression, we analyzed the histological severity and the expression of complement components using human fibrous BPH tissues. METHODS: The subjects were 56 histological BPH patients who underwent prostate needle biopsy due to high PSA levels in our institutions (mean age 68.6 ± 6.5 years). BPH patients were divided into two histological groups, fibromuscular type and fibrous type, by hematoxylin-eosin and elastica-Masson staining. Complement expression function analysis was performed by immunohistochemical staining using C3, factor B, and C5b-9 antibody, and the occupancy ratio of the stained region was calculated. RESULTS: Twenty-seven cases (48.2%) were classified as fibromuscular type, and 29 cases (51.8%) were classified as fibrous type. The proportion of fibrous components was significantly lower in the fibromuscular type than in the fibrous type (fibromuscular type 36.0 ± 12.9%, fibrous type 61.1 ± 11.7% (p<0.01)). In the expression analyses of complement components, factor B was not significantly different between the two groups, whereas C3 (fibromuscular type 10.7 ± 8.2%, fibrous type 16.4 ± 12.7%) and C5b-9 (fibromuscular type 15.9 ± 6.2%, fibrous type 17.6 ± 9.2%) were significantly upregulated in fibrous type compared to fibromuscular type (p = 0.04, p = 0.04). Furthermore, abundant infiltration of inflammatory cells was observed in the fibromuscular type (p = 0.03). CONCLUSIONS: In the fibrous process of BPH from fibromuscular type to fibrous type histologically, the inflammatory amplification loop enhancement by complement alternative pathway activation promotes the fibrosis of BPH, and finally shifts to fibrotic BPH. These results suggested that shift change to complement late pathway activation was involved in the progression of fibrous BPH. Source of Funding: None © 2022 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 207Issue Supplement 5May 2022Page: e271 Advertisement Copyright & Permissions© 2022 by American Urological Association Education and Research, Inc.MetricsAuthor Information Junya Hata More articles by this author Yusuke Kirihana More articles by this author Tomoyuki Kumekawa More articles by this author Hiroki Natsuya More articles by this author Yusuke Hakozaki More articles by this author Syunsuke Yoshioka More articles by this author Hitomi Imai More articles by this author Kanako Matsuoka More articles by this author Tomoyuki Koguchi More articles by this author Yuichi Sato More articles by this author Hidenori Akaihata More articles by this author Masao Kataoka More articles by this author Yoshiyuki Kojima More articles by this author Expand All Advertisement PDF DownloadLoading ...

Astrocytes display cell autonomous and diverse early reactive states in familial amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis is a rapidly progressive and fatal disease. Although astrocytes are increasingly recognized contributors to the underlying pathogenesis, the cellular autonomy and uniformity of astrocyte reactive transformation in different genetic forms of amyotrophic lateral sclerosis remain unresolved.Here we systematically examine these issues by using highly enriched and human induced pluripotent stem cell-derived astrocytes from patients with VCP and SOD1 mutations.We show that VCP mutant astrocytes undergo cell-autonomous reactive transformation characterized by increased expression of complement component 3 (C3) in addition to several characteristic gene expression changes. We then demonstrate that isochronic SOD1 mutant astrocytes also undergo a cell-autonomous reactive transformation, but that this is molecularly distinct from VCP mutant astrocytes. This is shown through transcriptome-wide analyses, identifying divergent gene expression profiles and activation of different key transcription factors in SOD1 and VCP mutant human induced pluripotent stem cell-derived astrocytes. Finally, we show functional differences in the basal cytokine secretome between VCP and SOD1 mutant human induced pluripotent stem cell-derived astrocytes.Our data therefore reveal that reactive transformation can occur cell autonomously in human amyotrophic lateral sclerosis astrocytes and with a striking degree of early molecular and functional heterogeneity when comparing different disease-causing mutations. These insights may be important when considering astrocyte reactivity as a putative therapeutic target in familial amyotrophic lateral sclerosis.

Increased expression of complement components in tuberous sclerosis complex and focal cortical dysplasia type 2B brain lesions.

ObjectiveIncreasing evidence supports the contribution of inflammatory mechanisms to the neurological manifestations of epileptogenic developmental pathologies linked to mammalian target of rapamycin (mTOR) pathway dysregulation (mTORopathies), such as tuberous sclerosis complex (TSC) and focal cortical dysplasia (FCD). In this study, we aimed to investigate the expression pattern and cellular distribution of the complement factors C1q and C3 in resected cortical tissue of clinically well‐characterized patients with TSC and FCD2B.MethodsWe applied immunohistochemistry in TSC (n = 29) and FCD2B (n = 32) samples and compared them to autopsy and biopsy controls (n = 27). Furthermore, protein expression was observed via Western blot, and for descriptive colocalization studies immunofluorescence double labeling was performed.ResultsProtein expression for C3 was significantly upregulated in TSC and FCD2B white and gray matter lesions compared to controls. Staining of the synaptic vesicle protein synaptophysin showed a remarkable increase in the white matter of both TSC and FCD2B. Furthermore, confocal imaging revealed colocalization of complement factors with astroglial, microglial, neuronal, and abnormal cells in various patterns.SignificanceOur results demonstrate that the prominent activation of the complement pathway represents a common pathological hallmark of TSC and FCD2B, suggesting that complement overactivation may play a role in these mTORopathies.

Changes in Expression of Complement Components in the Ovine Spleen during Early Pregnancy.

Simple SummaryComplement regulation is related to fetal growth during early pregnancy in humans. The results show that C1q increased during early pregnancy, and C1r, C1s, C2, C3 and C5b enhanced at day 25 of gestation, and C4a and C9 increased on days 13 and 16 of pregnancy in the ovine maternal spleen. In summary, a complement pathway participates in maternal immune regulation during early gestation.During early gestation in humans, complement regulation is essential for normal fetal growth. It is supposed that a complement pathway participates in maternal splenic immune regulation at the early stage of gestation in ewes. The aim of this study was to analyze the effects of early pregnancy on the expression of complement components in the maternal spleen of ewes. In this study, ovine spleens were sampled on day 16 of nonpregnancy, and days 13, 16 and 25 of gestation. RT-qPCR, Western blot and immunohistochemical analysis were used to detect the changes in expression of complement components in the ovine maternal spleens. Our results reveal that C1q was upregulated during early gestation, C1r, C1s, C2, C3 and C5b increased at day 25 of gestation and C4a and C9 peaked at days 13 and 16 of gestation. In addition, C3 protein was located in the capsule, trabeculae and splenic cords. In conclusion, our results show for the first time that there was modification in the expression of complement components in the ovine spleen at the early stage of gestation, and complement pathways may participate in modulating splenic immune responses at the early stage of gestation.

Transcriptional profiling of equine endometrium before, during and after capsule disintegration during normal pregnancy and after oxytocin-induced luteostasis in non-pregnant mares.

The current study used RNA sequencing to determine transcriptional profiles of equine endometrium collected 14, 22, and 28 days after ovulation from pregnant mares. In addition, the transcriptomes of endometrial samples obtained 20 days after ovulation from pregnant mares, and from non-pregnant mares which displayed and failed to display extended luteal function following the administration of oxytocin, were determined and compared in order to delineate genes whose expressions depend on the presence of the conceptus as opposed to elevated progesterone alone. A mere fifty-five transcripts were differentially expressed between samples collected from mares at Day 22 and Day 28 of pregnancy. This likely reflects the longer-term exposure to a relatively constant, progesterone-dominated environment with little change in factors secreted by the conceptus that would affect endometrial gene expression. The complement system was amongst the canonical pathways significantly enriched in transcripts differentially expressed between Day 14 and Day 22/28 of pregnancy. The expression of complement components 7 and 8 was confirmed using in situ hybridization. The expression of SERPING1, an inhibitor of the complement system, was confirmed by immunohistochemistry. In line with the resumed capacity of the endometrium to produce prostaglandin, prostaglandin G/H synthase 1 was expressed at higher levels at Days 22 and 28 than at Day 14 of pregnancy. Our data suggest that this up-regulation is enhanced by the presence of the conceptus; samples obtained from mares at Day 20 of pregnancy had significantly higher levels of prostaglandin G/H synthase 1 transcript than mares with extended luteal function.

Analysis of gut microbiota and immune-related genes during sea cucumber (Apostichopus japonicus) response to dietary supplementation with Codonopsis pilosula

The gut microbiota composition of sea cucumber (Apostichopus japonicas) was investigated using high-throughput sequencing techniques. The mRNA expression of complement component 3 and lysozyme genes was evaluated using quantitative fluorescence PCR. Sea cucumbers were fed with a basal diet (control group) and an experimental diet supplemented with Codonopsis pilosula (experimental group) for 30 days. The results showed that the alpha diversity of the gut microbiota was changed in different indices, including Chao1, the abundance-based coverage estimator, the Shannon index, and Good’s coverage. Dietary C. pilosula promoted the proliferation of the Flavobacteriaceae family of the Proteobacteria phylum and reduced the relative abundance of the Verrucomicrobiaceae family of the Verrucomicrobia phylum. We concluded that dietary C. pilosula supplementation could alter the network interactions among different microbial functional groups by changing the ecological network’s microbial community composition and biological evolution. A positive effect on A. japonicus immune responses in the gut was seen via increasing the mRNA expression of the complement component 3 and lysozyme genes. It seems to happen via modulating the balance in gut microbiota.

Complement C4 Is Reduced in iPSC-Derived Astrocytes of Autism Spectrum Disorder Subjects.

In recent years, accumulating evidence has shown that the innate immune complement system is involved in several aspects of normal brain development and in neurodevelopmental disorders, including autism spectrum disorder (ASD). Although abnormal expression of complement components was observed in post-mortem brain samples from individuals with ASD, little is known about the expression patterns of complement molecules in distinct cell types in the developing autistic brain. In the present study, we characterized the mRNA and protein expression profiles of a wide range of complement system components, receptors and regulators in induced pluripotent stem cell (iPSC)-derived neural progenitor cells, neurons and astrocytes of individuals with ASD and neurotypical controls, which constitute in vitro cellular models that recapitulate certain features of both human brain development and ASD pathophysiology. We observed that all the analyzed cell lines constitutively express several key complement molecules. Interestingly, using different quantification strategies, we found that complement C4 mRNA and protein are expressed in significantly lower levels by astrocytes derived from ASD individuals compared to control astrocytes. As astrocytes participate in synapse elimination, and diminished C4 levels have been linked to defective synaptic pruning, our findings may contribute to an increased understanding of the atypically enhanced brain connectivity in ASD.

Complement cascade functions during brain development and neurodegeneration.

The complement system, an essential tightly regulated innate immune system, is a key regulator of normal central nervous system (CNS) development and function. However, aberrant complement component expression and activation in the brain may culminate into marked neuroinflammatory response, neurodegenerative processes and cognitive impairment. Over the years, complement-mediated neuroinflammatory responses and complement-driven neurodegeneration have been increasingly implicated in the pathogenesis of a wide spectrum of CNS disorders. This review describes how complement system contributes to normal brain development and function. We also discuss how pathologic insults such as misfolded proteins, lipid droplet/lipid droplet-associated protein or glycosaminoglycan accumulation could trigger complement-mediated neuroinflammatory responses and neurodegenerative process in neurodegenerative proteinopathies, age-related macular degeneration and neurodegenerative lysosomal storage disorders.

Arginine Methylation of Hepatic hnRNPH Suppresses Complement Activation and Systemic Inflammation in Alcohol-Fed Mice.

Protein arginine methyl transferase 1 (PRMT1) is the main enzyme for cellular arginine methylation. It regulates many aspects of liver biology including inflammation, lipid metabolism, and proliferation. Previously we identified that PRMT1 is necessary for protection from alcohol‐induced liver injury. However, many PRMT1 targets in the liver after alcohol exposure are not yet identified. We studied the changes in the PRMT1‐dependent arginine methylated proteome after alcohol feeding in mouse liver using mass spectrometry. We found that arginine methylation of the RNA‐binding protein (heterogeneous nuclear ribonucleoprotein [hnRNP]) H1 is mediated by PRMT1 and is altered in alcohol‐fed mice. PRMT1‐dependent methylation suppressed hnRNP H1 binding to several messenger RNAs of complement pathway including complement component C3. We found that PRMT1‐dependent hnRNP H methylation suppressed complement component expression in vitro, and phosphorylation is required for this function of PRMT1. In agreement with that finding, hepatocyte‐specific PRMT1 knockout mice had an increase in complement component expression in the liver. Excessive complement expression in alcohol‐fed PRMT1 knockout mice resulted in further complement activation and an increase in serum C3a and C5a levels, which correlated with inflammation in multiple organs including lung and adipose tissue. Using specific inhibitors to block C3aR and C5aR receptors, we were able to prevent lung and adipose tissue inflammation without affecting inflammation in the liver or liver injury. Conclusion: Taken together, these data suggest that PRMT1‐dependent suppression of complement production in the liver is necessary for prevention of systemic inflammation in alcohol‐fed mice. C3a and C5a play a role in this liver–lung and liver–adipose interaction in alcohol‐fed mice deficient in liver arginine methylation.

Early pregnancy regulates expression of complement components in ovine liver.

Complement pathways participate in the regulation of innate immune system, and complement activation is inhibited in normal pregnancy. The liver plays key roles in the modulation of immunity and tolerance, but it is unclear that early pregnancy induces the changes in expression of complement components in the ovine maternal liver. The aim of the present study was to explore the expression of complement components in the liver using quantitative real-time polymerase chain reaction (PCR), Western blot, and immunohistochemistry. Maternal livers were collected on Day 16 of the estrous cycle and Days 13, 16, and 25 of gestation. The results indicated that early pregnancy suppressed the expression of C1q, C1r, C1s, C2, C4a, C5b, and C9 in the maternal liver, but C3 expression was increased. In addition, C3 protein was located in the endothelial cells of the proper hepatic arteries and portal veins and hepatocytes. In summary, the downregulaltion of C1q, C1r, C1s, C2, C4a, C5b, and C9 may be involved in the suppression of complement activation, and upregulation of C3 is related to the modulation of maternal immune tolerance in ovine liver.

Properdin Modulates Complement Component Production in Stressed Human Primary Retinal Pigment Epithelium Cells.

The retinal pigment epithelium (RPE) maintains visual function and preserves structural integrity of the retina. Chronic dysfunction of the RPE is associated with retinal degeneration, including age-related macular degeneration (AMD). The AMD pathogenesis includes both increased oxidative stress and complement dysregulation. Physiological sources of oxidative stress in the retina are well known, while complement sources and regulation are still under debate. Using human primary RPE (hpRPE) cells, we have established a model to investigate complement component expression on transcript and protein level in AMD-risk and non-risk hpRPE cells. We evaluated the effect of properdin, a complement stabilizer, on the hpRPE cell-dependent complement profile exposed to oxidative stress. hpRPE cells expressed complement components, receptors and regulators. Complement proteins were also stored and secreted by hpRPE cells. We associated AMD-risk single nucleotide polymorphisms with an increased secretion of complement factors D (CFD) and I (CFI). Furthermore, we detected hpRPE cell-associated complement activation products (C3a, C5a) independent of any extracellularly added complement system. Exogenous properdin increased the mRNA expression of CFI and CFD, but decreased levels of complement components (C1Q, C3), receptors (C3AR, C5AR1, CD11B) and inflammation-associated transcripts (NLRP3, IL1B) in hpRPE cells exposed to oxidative stress. This properdin effect was time-dependently counter regulated. In conclusion, our data unveiled a local, genotype-associated complement component production in hpRPE cells, regulated by exogenous properdin. The local complement production and activation via blood-independent mechanisms can be a new therapeutic target for AMD.