Complement proteins C1q and MBL are pattern recognition molecules that signal immediate and long-term protective immune functions

LYVE-1-expressing Macrophages Modulate the Hyaluronan-containing Extracellular Matrix in the Mammary Stroma and Contribute to Mammary Tumor Growth

Macrophages represent a heterogeneous myeloid population with diverse functions in normal tissues and tumors. While macrophages expressing the cell surface marker lymphatic vessel endothelial hyaluronan receptor 1 (LYVE-1) have been identified in stromal regions of the normal mammary gland and in the peritumoral stroma, their functions within these regions are not well understood. Using a genetic mouse model of LYVE-1+ macrophage depletion, we demonstrate that loss of LYVE-1+ macrophages is associated with altered extracellular matrix remodeling in the normal mammary gland and reduced mammary tumor growth in vivo. In further studies focused on investigating the functions of LYVE-1+ macrophages in the tumor microenvironment, we demonstrate that LYVE-1 expression correlates with an increased ability of macrophages to bind, internalize, and degrade hyaluronan. Consistent with this, we show that depletion of LYVE-1+ macrophages correlates with increased hyaluronan accumulation in both the normal mammary gland and in mammary tumors. Analysis of single-cell RNA sequencing of macrophages isolated from these tumors reveals that depletion of LYVE-1+ macrophages in tumors drives a shift in the majority of the remaining macrophages toward a proinflammatory phenotype, as well as an increase in CD8+ T-cell infiltration. Together, these findings indicate that LYVE-1+ macrophages represent a tumor-promoting anti-inflammatory subset of macrophages that contributes to hyaluronan remodeling in the tumor microenvironment.

SIGNIFICANCE

We have identified a macrophage subset in mouse mammary tumors associated with tumor structural components. When this macrophage subset is absent in tumors, we report a delay in tumor growth and an increase in antitumor immune cells. Understanding the functions of distinct macrophage subsets may allow for improved therapeutic strategies for patients with breast cancer.

Identification of the C1qDC gene family in grass carp (Ctenopharyngodon idellus) and the response of C1qA, C1qB, and C1qC to GCRV infection in vivo and in vitro

Proteins from the C1q domain-containing (C1qDC) family recognize self-, non-self-, and altered-self ligands and serves as an initiator molecule for the classical complement pathway as well as recognizing immune complexes. In this study, C1qDC gene family members were identified and analyzed in grass carp (Ctenopharyngodon idellus). Members of the C1q subfamily were cloned, and their response to infection with the grass carp virus was investigated. In the grass carp genome, 54 C1qDC genes and 67 isoforms have been identified. Most were located on chromosome 3, with 52 shared zebrafish homologies. Seven substantially differentially expressed C1qDC family genes were identified in the transcriptomes of cytokine-induced killer (CIK) cells infected with grass carp reovirus (GCRV), all of which exhibited sustained upregulation. The opening reading frames of grass carp C1qA, C1qB, and C1qC, belonging to the C1q subfamily, were determined to be 738, 732, and 735 base pairs, encoding 245, 243, and 244 amino acids with molecular weights of 25.81 kDa, 25.63 kDa and 26.16 kDa, respectively. Three genes were detected in the nine collected tissues, and their expression patterns were similar, with the highest expression levels observed in the spleen. In vivo after GCRV infection showed expression trends of C1qA, C1qB, and C1qC in the liver, spleen, and kidney. An N-type pattern in the liver and kidney was characterized by an initial increase followed by a decrease, with the highest expression occurring during the recovering period, and a V-type pattern in the spleen with the lowest expression levels during the death period. In vitro, after GCRV infection showed expression trends of C1qA, C1qB, and C1qC, and this gradually increased within the first 24 h, with a notable increase observed at the 24 h time point. After CIK cells incubation with purified recombinant proteins, rC1qA, rC1qB, and rC1qC for 3 h, followed by GCRV inoculation, the GCRV replication indicated that rC1qC exerted a substantial inhibitory effect on viral replication in CIK cells after 24 h of GCRV inoculation. These findings offer valuable insights into the structure, evolution, and function of the C1qDC family genes and provide a foundational understanding of the immune function of C1q in grass carp.

Integrating Bulk RNA and Single-Cell Sequencing Data Unveils Efferocytosis Patterns and ceRNA Network in Ischemic Stroke

Excessive inflammatory response following ischemic stroke (IS) injury is a key factor affecting the functional recovery of patients. The efferocytic clearance of apoptotic cells within ischemic brain tissue is a critical mechanism for mitigating inflammation, presenting a promising avenue for the treatment of ischemic stroke. However, the cellular and molecular mechanisms underlying efferocytosis in the brain after IS and its impact on brain injury and recovery are poorly understood. This study explored the roles of inflammation and efferocytosis in IS with bioinformatics. Three Gene Expression Omnibus Series (GSE) (GSE137482-3 m, GSE137482-18 m, and GSE30655) were obtained from NCBI (National Center for Biotechnology Information) and GEO (Gene Expression Omnibus). Differentially expressed genes (DEGs) were processed for GSEA (Gene Set Enrichment Analysis), GO (Gene Ontology Functional Enrichment Analysis), and KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway analyses. Efferocytosis-related genes were identified from the existing literature, following which the relationship between Differentially Expressed Genes (DEGs) and efferocytosis-related genes was examined. The single-cell dataset GSE174574 was employed to investigate the distinct expression profiles of efferocytosis-related genes. The identified hub genes were verified using the dataset of human brain and peripheral blood sample datasets GSE56267 and GSE122709. The dataset GSE215212 was used to predict competing endogenous RNA (ceRNA) network, and GSE231431 was applied to verify the expression of differential miRNAs. At last, the middle cerebral artery (MCAO) model was established to validate the efferocytosis process and the expression of hub genes. DEGs in two datasets were significantly enriched in pathways involved in inflammatory response and immunoregulation. Based on the least absolute shrinkage and selection operator (LASSO) analyses, we identified hub efferocytosis-related genes (Abca1, C1qc, Ptx3, Irf5, and Pros1) and key transcription factors (Stat5). The scRNA-seq analysis showed that these hub genes were mainly expressed in microglia and macrophages which are the main cells with efferocytosis function in the brain. We then identified miR-125b-5p as a therapeutic target of IS based on the ceRNA network. Finally, we validated the phagocytosis and clearance of dead cells by efferocytosis and the expression of hub gene Abca1 in MCAO mice models.

Complement C1q and von Willebrand factor interaction in atherosclerosis of human carotid artery

Atherosclerosis is an inflammatory disease of the vessel wall, with cholesterol crystal (CC) deposition being a hallmark of the disease. As evidence for a cross-talk between complement activation and hemostasis on CC surfaces has been limited to in vitro data, the aim of this study was to demonstrate the presence of C1q-vWF complexes in human atherosclerosis ex vivo. We used immunofluorescence staining and a proximity ligation assay (PLA, Duolink®) to examine the presence, localization, and co-localization of C1q and vWF in frozen sections of human carotid arteries with atherosclerosis or without atherosclerotic changes as well as material from thrombendarteriectomy. We observed significantly higher levels of C1q and vWF in healthy tissue compared to diseased material and greater co-localization in the PLA in healthy samples than in diseased samples. In diseased samples, fluorescence signals were highest in locations encompassing atheroma and foam cells. While there was overall reduced signal in areas with CCs, the staining was spotty, and there was evidence of co-localization on individual CCs. Thus, we demonstrate the presence of C1q-vWF complexes in human carotid arteries ex vivo, which was most abundant in healthy endothelial and subendothelial space and reduced in diseased tissue. C1q-vWF interaction can also be demonstrated on the CC surface.

Whole-genome sequencing and genomic analysis of Norduz goat (Capra hircus)

Artificial and natural selective breeding of goats has resulted in many different goat breeds all around the world. Norduz goat is one of these breeds, and it is a local goat breed of Turkey. The goats are favorable due to pre-weaning viability and reproduction values compared to the regional breeds. Development in sequencing technologies has let to understand huge genomic structures and complex phenotypes. Until now, such a comprehensive study has not been carried out to understand the genomic structure of the Norduz goats, yet. In the study, the next-generation sequencing was carried out to understand the genomic structure of Norduz goat. Real-time PCR was used to evaluate prominent CNVs in the Norduz goat individuals. Whole genome of the goat was constructed with an average of 33.1X coverage level. In the stringent filtering condition, 9,757,980 SNPs, 1,536,715 InDels, and 290 CNVs were detected in the Norduz goat genome. Functional analysis of high-impact SNP variations showed that the classical complement activation biological process was affected significantly in the goat. CNVs in the goat genome were found in genes related to defense against viruses, immune response, and cell membrane transporters. It was shown that GBP2, GBP5, and mammalian ortholog GBP1, which are INF-stimulated GTPases, were found to be high copy numbers in the goats. To conclude, genetic variations mainly in immunological response processes suggest that Norduz goat is an immunologically improved goat breed and natural selection could take an important role in the genetical improvements of the goats.

The echinoid complement system inferred from genome sequence searches

The vertebrate complement cascade is an essential host protection system that functions at the intersection of adaptive and innate immunity. However, it was originally assumed that complement was present only in vertebrates because it was activated by antibodies and functioned with adaptive immunity. Subsequently, the identification of the key component, SpC3, in sea urchins plus a wide range of other invertebrates significantly expanded the concepts of how complement functions. Because there are few reports on the echinoid complement system, an alternative approach to identify complement components in echinoderms is to search the deduced proteins encoded in the genomes. This approach identified known and putative members of the lectin and alternative activation pathways, but members of the terminal pathway are absent. Several types of complement receptors are encoded in the genomes. Complement regulatory proteins composed of complement control protein (CCP) modules are identified that may control the activation pathways and the convertases. Other regulatory proteins without CCP modules are also identified, however regulators of the terminal pathway are absent. The expansion of genes encoding proteins with Macpf domains is noteworthy because this domain is a signature of perforin and proteins in the terminal pathway. The results suggest that the major functions of the echinoid complement system are detection of foreign targets by the proteins that initiate the activation pathways resulting in opsonization by SpC3b fragments to augment phagocytosis and destruction of the foreign targets by the immune cells.

The case for complement component 5 as a target in neurodegenerative disease

INTRODUCTION

Complement-based drug discovery is undergoing a renaissance, empowered by new advances in structural biology, complement biology and drug development. Certain components of the complement pathway, particularly C1q and C3, have been extensively studied in the context of neurodegenerative disease, and established as key therapeutic targets. C5 also has huge therapeutic potential in this arena, with its druggability clearly demonstrated by the success of C5-inhibitor eculizumab.

AREAS COVERED

We will discuss the evidence supporting C5 as a target in neurodegenerative disease, along with the current progress in developing different classes of C5 inhibitors and the gaps in knowledge that will help progress in the field.

EXPERT OPINION

Validation of C5 as a therapeutic target for neurodegenerative disease would represent a major step forward for complement therapeutics research and has the potential to furnish disease-modifying drugs for millions of patients suffering worldwide. Key hurdles that need to be overcome for this to be achieved are understanding how C5a and C5b should be targeted to bring therapeutic benefit and demonstrating the ability to target C5 without creating vulnerability to infection in patients. This requires greater biological elucidation of its precise role in disease pathogenesis, supported by better chemical/biological tools.

Pharmacokinetic and Target Engagement Measures of ANX007, an Anti-C1q Antibody Fragment, Following Intravitreal Administration in Nonhuman Primates

Purpose

C1q and the classical complement cascade are key regulators of synaptic pruning, and their aberrant activation has been implicated in neurodegenerative ophthalmic diseases including geographic atrophy and glaucoma. The antigen-binding fragment antibody ANX007 specifically recognizes globular head groups of C1q to block substrate binding and functionally inhibit classical complement cascade activation. ANX007 was assessed in nonclinical studies of biodistribution and C1q target engagement in the eye following intravitreal (IVT) administration in cynomolgus monkeys.

Methods

Female juvenile cynomolgus monkeys (n = 12) received a single bilateral dose of 1 or 5 mg ANX007/eye, with vitreous and non-perfused tissue samples collected approximately 4 weeks later. In a separate study, male (n = 6/5) and female (n = 6/5) animals received repeat bilateral dosing of 1, 2.5, or 5 mg ANX007/eye on days 1 and 29, with aqueous and vitreous collections on day 44 or day 59. Tissues from the 5 mg/eye repeat-dose group were perfused, and retina, choroid, and optic nerve samples were collected approximately 2 and 4 weeks post-last dose.

Results

Following a single dose of ANX007, vitreous levels of free drug were measurable through 4 weeks at both the 1 and 5 mg dose levels, with approximately 3-day half-life. With repeat dose of 5 mg/eye, free-ANX007 was measurable 4 weeks post-last dose in perfused retina and choroid and up to approximately 2 weeks post-last dose in optic nerve. There was a strong correlation between C1q target engagement and free drug levels in aqueous and vitreous humors and retinal tissue.

Conclusions

Following IVT administration, ANX007 distributes to sites within the retina that are relevant to neurodegenerative ophthalmic disease with clear evidence of C1q target engagement. Based on its mechanism of action inhibiting C1q and its downstream activity, ANX007 is predicted to mitigate tissue damage driven by classical complement activation in the retina. These data support further clinical evaluation of ANX007.

Single-cell analyses highlight the proinflammatory contribution of C1q-high monocytes to Behçet's disease

Behçet's disease (BD) is a chronic vasculitis characterized by systemic immune aberrations. However, a comprehensive understanding of immune disturbances in BD and how they contribute to BD pathogenesis is lacking. Here, we performed single-cell and bulk RNA sequencing to profile peripheral blood mononuclear cells (PBMCs) and isolated monocytes from BD patients and healthy donors. We observed prominent expansion and transcriptional changes in monocytes in PBMCs from BD patients. Deciphering the monocyte heterogeneity revealed the accumulation of C1q-high (C1q^hi) monocytes in BD. Pseudotime inference indicated that BD monocytes markedly shifted their differentiation toward inflammation-accompanied and C1q^hi monocyte-ended trajectory. Further experiments showed that C1q^hi monocytes enhanced phagocytosis and proinflammatory cytokine secretion, and multiplatform analyses revealed the significant clinical relevance of this subtype. Mechanistically, C1q^hi monocytes were induced by activated interferon-γ (IFN-γ) signaling in BD patients and were decreased by tofacitinib treatment. Our study illustrates the BD immune landscape and the unrecognized contribution of C1q^hi monocytes to BD hyperinflammation, showing their potential as therapeutic targets and clinical assessment indexes.

Proteins of the lectin pathway of the complement system activation: immunobiological functions, genetics and involvement in the pathogenesis of human diseases

The complement system is the most ancient components in the innate immunity, mainly functioning to primarily eliminate bacterial agents intravascularly. Moreover, the complement complex proteins play a role as a bridge between the systems of innate and adaptive immunity providing adequate conditions for maturation and differentiation of B- and T-lymphocytes. The complement system consists of plasma proteins and membrane receptors. Plasma proteins interact with each other via the three described cascade pathways lectin (which is most ancient phylogenetically), alternative and classical. Lectins are proteins comprising a separate superfamily of pattern-recognizing receptors able to sense molecules of oligo- and polysaccharide nature and induce their aggregation. Among all the lectins, ficolins (FCN) (common domain fibrinogen) and collectins (common domain collagen) mannose-binding lectin (MBL), hepatic and renal collectins have exert unique functions by complexing with carbohydrate components of microbial wall. Formation of a compound complex microbial wall polysaccharides + collectin/ficolin + specific mannose-binding lectin-associated serine proteases (MARP) results in the complement system activation, inflammatory reaction and bacterium elimination. Such scenario is proceeded along the lectin pathway compared to the two other pathways called classical and alternative. Examining a role of the complement system and congenital protein defects in the pathogenesis of various diseases is of topical interest because inborn deficiency of the complement components comprises at least 5% out of total primary immunodeficiency rate, whereas the aspects of their prevalence and pathogenesis remain unexplored. Relevance of investigating the complement system components for diverse populations is tremendous, taking into consideration accumulated evidence regarding an important role of the lectin pathway in viral infections. Lectins, the main proteins in the lectin pathway of the complement activation, are encoded by polymorphic genes, wherein single nucleotide polymorphisms (SNPs) result in altered protein conformation and expression, which, in turn, affects functionality and potential to respond to a pathogen. The distribution of the lectin polymorphic gene frequencies and their haplotypes displays extremely marked population differences. According to analyzing available data, population SNP frequencies including those associated with inborn deficiencies for components of the lectin pathway have been currently scarce or unexplored. hence, here we review major lectins and their functions, their functionally significant SNPs in diverse populations and their pathogenetic importance for host defense functions.

Identification of Molecular Correlations Between DHRS4 and Progressive Neurodegeneration in Amyotrophic Lateral Sclerosis By Gene Co-Expression Network Analysis

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease, and its candidate biomarkers have not yet been fully elucidated in previous studies. Therefore, with the present study, we aim to define and verify effective biomarkers of ALS by bioinformatics. Here, we employed differentially expressed gene (DEG) analysis, weighted gene co-expression network analysis (WGCNA), enrichment analysis, immune infiltration analysis, and protein-protein interaction (PPI) to identify biomarkers of ALS. To validate the biomarkers, we isolated the lumbar spinal cord from mice and characterized them using Western blotting and immunofluorescence. The results showed that Dhrs4 expression in the spinal cord was upregulated with the progression of SOD1G93A mice, and the upregulation of DHRS4 and its synergistic DHRS3 might be primarily associated with the activation of the complement cascade in the immune system (C1QA, C1QB, C1QC, C3, and ITGB2), which might be a novel mechanism that induces spinal neurodegeneration in ALS. We propose that DHRS4 and its synergistic DHRS3 are promising molecular markers for detecting ALS progression.

Comparative analysis of the Mercenaria mercenaria genome provides insights into the diversity of transposable elements and immune molecules in bivalve mollusks

BACKGROUND

The hard clam Mercenaria mercenaria is a major marine resource along the Atlantic coasts of North America and has been introduced to other continents for resource restoration or aquaculture activities. Significant mortality events have been reported in the species throughout its native range as a result of diseases (microbial infections, leukemia) and acute environmental stress. In this context, the characterization of the hard clam genome can provide highly needed resources to enable basic (e.g., oncogenesis and cancer transmission, adaptation biology) and applied (clam stock enhancement, genomic selection) sciences.

RESULTS

Using a combination of long and short-read sequencing technologies, a 1.86 Gb chromosome-level assembly of the clam genome was generated. The assembly was scaffolded into 19 chromosomes, with an N50 of 83 Mb. Genome annotation yielded 34,728 predicted protein-coding genes, markedly more than the few other members of the Venerida sequenced so far, with coding regions representing only 2% of the assembly. Indeed, more than half of the genome is composed of repeated elements, including transposable elements. Major chromosome rearrangements were detected between this assembly and another recent assembly derived from a genetically segregated clam stock. Comparative analysis of the clam genome allowed the identification of a marked diversification in immune-related proteins, particularly extensive tandem duplications and expansions in tumor necrosis factors (TNFs) and C1q domain-containing proteins, some of which were previously shown to play a role in clam interactions with infectious microbes. The study also generated a comparative repertoire highlighting the diversity and, in some instances, the specificity of LTR-retrotransposons elements, particularly Steamer elements in bivalves.

CONCLUSIONS

The diversity of immune molecules in M. mercenaria may allow this species to cope with varying and complex microbial and environmental landscapes. The repertoire of transposable elements identified in this study, particularly Steamer elements, should be a prime target for the investigation of cancer cell development and transmission among bivalve mollusks.

Involvement of enhanced expression of classical complement C1q in atherosclerosis progression and plaque instability: C1q as an indicator of clinical outcome

Activation of the classical complement pathway plays a major role in regulating atherosclerosis progression, and it is believed to have both proatherogenic and atheroprotective effects. This study focused on C1q, the first protein in the classical pathway, and examined its potentialities of plaque progression and instability and its relationship with clinical outcomes. To assess the localization and quantity of C1q expression in various stages of atherosclerosis, immunohistochemistry, western blotting, and real-time polymerase chain reaction (PCR) were performed using abdominal aortas from eight autopsy cases. C1q immunoreactivity in relation to plaque instability and clinical outcomes was also examined using directional coronary atherectomy (DCA) samples from 19 patients with acute coronary syndromes (ACS) and 18 patients with stable angina pectoris (SAP) and coronary aspirated specimens from 38 patients with acute myocardial infarction. C1q immunoreactivity was localized in the extracellular matrix, necrotic cores, macrophages and smooth muscle cells in atherosclerotic lesions. Western blotting and real-time PCR illustrated that C1q protein and mRNA expression was significantly higher in advanced lesions than in early lesions. Immunohistochemical analysis using DCA specimens revealed that C1q expression was significantly higher in ACS plaques than in SAP plaques. Finally, immunohistochemical analysis using thrombus aspiration specimens demonstrated that histopathological C1q in aspirated coronary materials could be an indicator of poor medical condition. Our results indicated that C1q is significantly involved in atherosclerosis progression and plaque instability, and it could be considered as one of the indicators of cardiovascular outcomes.

Modulation of the Complement System by Neoplastic Disease of the Central Nervous System

The complement system is a highly conserved component of innate immunity that is involved in recognizing and responding to pathogens. The system serves as a bridge between innate and adaptive immunity, and modulation of the complement system can affect the entire host immune response to a foreign insult. Neoplastic diseases have been shown to engage the complement system in order to evade the immune system, gain a selective growth advantage, and co-opt the surrounding environment for tumor proliferation. Historically, the central nervous system has been considered to be an immune-privileged environment, but it is now clear that there are active roles for both innate and adaptive immunity within the central nervous system. Much of the research on the role of immunological modulation of neoplastic disease within the central nervous system has focused on adaptive immunity, even though innate immunity still plays a critical role in the natural history of central nervous system neoplasms. Here, we review the modulation of the complement system by a variety of neoplastic diseases of the central nervous system. We also discuss gaps in the current body of knowledge and comment on future directions for investigation.

Characterisation and functional role of a novel C1qDC protein from a colonial ascidian

As an invertebrate, the compound ascidian Botryllus schlosseri faces nonself only with innate immunity. In this species, we already identified the key components of the lectin and alternative complement activation pathways. In the present work, by mining the transcriptome, we identified a single transcript codifying for a protein, member of the C1q-domain-containing protein family, with a signal peptide followed by two globular C1q (gC1q) domains. It shares a similar domain organisation with C1q/TNF-related proteins 4, the only vertebrate protein family with two gC1q domains. Our gC1q domain-containing protein, called BsC1qDC, is actively transcribed by immunocytes. The transcription is modulated during the Botryllus blastogenetic cycle and is upregulated following the injection of Bacillus clausii cells in the circulation. Furthermore, the injection of bsc1qdc iRNA in the vasculature results in decreased transcription of the gene and a significant impairment of phagocytosis and degranulation, suggesting the involvement of this molecule in immune responses.

Differential expression of complement receptors CR1/2 and CR4 by murine M1 and M2 macrophages

Macrophages polarize into functionally divergent phenotypes - M1 and M2 - which express distinct receptors. These cells are known to express complement receptors, including CR1, CR3, and CR4. However, whether these complement receptors are differentially expressed on M1 and M2 macrophages is not yet known. Herein, we have examined the expression of CR1 to CR4 on murine bone marrow-derived M1 (stimulated with IFN-γ or LPS) and M2 (stimulated with IL-4 or IL-4 + IL-13) macrophages. We show that M1 cells exhibit increased expression of CR1/2, whereas M2 cells display the higher expression of CR4; CR3 is equally expressed on both the phenotypes. Thus, M1 cells are CR1/2⁺CR4⁺, and M2 are CR1/2^-CR4⁺. Functional probing of these cells for their phagocytic ability indicates that M1 cells, which express higher CR1/2, internalize a significantly greater number of C3b-opsonized erythrocytes. Both M1 and M2 cells, on the other hand, internalize iC3b-opsonized erythrocytes to a similar extent. Interestingly, the phagocytic receptor involved in phagocytosis of iC3b-opsonized erythrocytes is only CR3 with no contribution of CR4. We, thus, propose that complement receptor expression can be used in combination with the expression of other known polarization markers to better locate a macrophage along its phenotypic spectrum.

A systematic review of anti-Entamoeba histolytica activity of medicinal plants published in the last 20 years

Amoebiasis has emerged as a major health problem worldwide. It is endemic in the present scenario is different and sub-tropical regions especially in Asia, Latin America and also in Africa. Causative of amoebiasis is a protozoan known as Entamoeba histolytica. We screened all the databases such as PubMed, Science Direct, Medline and Google Scholar by using the keywords ‘anti-Entamoeba histolytica activity of medicinal plants, anti-Entamoeba histolytica activity of herbal drugs, the anti-amoebic activity of natural drugs’. In the present study, we found 7861 articles, where all articles were screened for bias analysis and included 32 full-matching articles in total reporting the use of medicinal plants as a remedy for amoebiasis. Through these articles, we found 42 herbs having anti-amoebic activity. In bias analysis, we also found four articles under high bias risk. In our study, seven medicinal plants were concluded to possess the most potent anti-amoebic activity based on their IC50 value, which was less than 1 μg mL−1. On bias analysis, we found four articles with high bias risk, hence these studies can be repeated for better results.

Transcriptomic analysis of Manila clam Ruditapes philippinarum under lipopolysaccharide challenge provides molecular insights into immune response

The Manila clam, Ruditapes philippinarum, is an economically important shellfish in marine aquaculture. A better understanding of the immune system in R. philippinarum will provide the basis for the development of strategies to mitigate the impact of infectious diseases affecting this species but can also be of relevance for other bivalves of commercial interest. In this study, the transcriptional response of the Manila clam under lipopolysaccharide (LPS) challenge was characterized using RNA sequencing. The transcriptomes of LPS challenged group of clams (LH1, LH2 and LH3), and the PBS control group (CH1, CH2 and CH3), were sequenced with the Illumina HiSeq platform. Compared with the unigene expression profile of the control group, 223 unigenes were up-regulated and 389 unigenes were down-regulated in the LPS challenged group. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses revealed that signal transduction, defense response, and immune-related pathways such as Chemokine signaling pathway, Complement and coagulation cascades, NOD-like receptor signaling pathway, and Inflammatory mediator regulation of TRP channels in sensory system were the most highly enriched pathways among the genes that were differentially expressed under LPS challenge. This study present understanding of the molecular basis underpinning response to LPS challenge and provides useful information for future work on the molecular mechanism of pathogen resistance and immunity in Manila clam.

Roles of the complement system in alcohol-induced liver disease

Alcohol-induced liver disease (ALD) is a complex disorder, with a disease spectrum ranging from steatosis to steatohepatitis, cirrhosis, and hepatocellular carcinoma. Although the pathogenesis of ALD is incompletely understood and currently no effective drugs are available for ALD, several lines of evidence suggest that complement activation and oxidative stress play crucial roles in the pathogenesis of ALD. Complement activation can regulate the production of ROS and influence oxidative stress in ALD. Precise regulation of the complement system in ALD may be a rational and novel avenue to postpone and even reverse the progression of disease and simultaneously promote the repair of liver injury. In this mini-review, we briefly summarize the recent research progress, especially focusing on the role of complement and oxidative stress-induced transfer RNA-derived fragments, which might help us to better understand the pathogenesis of ALD and provide aid in the development of novel therapeutic strategies for ALD.

Complement C5a Induces Pro-inflammatory Microvesicle Shedding in Severely Injured Patients

Initially underestimated as platelet dust, extracellular vesicles are continuously gaining interest in the field of inflammation. Various studies addressing inflammatory diseases have shown that microvesicles (MVs) originating from different cell types are systemic transport vehicles carrying distinct cargoes to modulate immune responses. In this study, we focused on the clinical setting of multiple trauma, which is characterized by activation and dysfunction of both, the fluid-phase and the cellular component of innate immunity. Given the sensitivity of neutrophils for the complement anaphylatoxin C5a, we hypothesized that increased C5a production induces alterations in MV shedding of neutrophils resulting in neutrophil dysfunction that fuels posttraumatic inflammation. In a mono-centered prospective clinical study with polytraumatized patients, we found significantly increased granulocyte-derived MVs containing the C5a receptor (C5aR1, CD88) on their surface. This finding was accompanied by a concomitant loss of C5aR1 on granulocytes indicative of an impaired cellular chemotactic and pro-inflammatory neutrophil functions. Furthermore, in vitro exposure of human neutrophils (from healthy volunteers) to C5a significantly increased MV shedding and C5aR1 loss on neutrophils, which could be blocked using the C5aR1 antagonist PMX53. Mechanistic analyses revealed that the interaction between C5aR1 signaling and the small GTPase Arf6 acts as a molecular switch for MV shedding. When neutrophil derived, C5a-induced MV were exposed to a complex ex vivo whole blood model significant pro-inflammatory properties (NADPH activity, ROS and MPO generation) of the MVs became evident. C5a-induced MVs activated resting neutrophils and significantly induced IL-6 secretion. These data suggest a novel role of the C5a-C5aR1 axis: C5a-induced MV shedding from neutrophils results in decreased C5aR1 surface expression on the one hand, on the other hand it leads to profound inflammatory signals which likely are both key drivers of the neutrophil dysfunction which is regularly observed in patients suffering from multiple traumatic injuries.

Opsonic character of the plasma proteins in phagocytosis-dependent host response to bacterial infection in a marine invertebrate, Crassostrea gigas

Phagocytosis is an evolutionarily conserved immune response, whose efficiency is fundamentally coupled with opsonization of extracellular microbes. How marine mollusks cells recognize and selectively capture pathogens during phagocytosis to clear them is not completely understood. In this study, we observed that plasma is extremely effective for oyster hemocyte phagocytosis, so we investigated candidate proteins among plasma proteins with binding affinity for Vibrio parahaemolyticus in Pacific oyster (Crassostrea gigas) by subjecting them to mass spectroscopy analysis for protein identification and characterization, and address the complex regulatory network to engulf invaders. There were 620 identified proteins potentially associated with bacteria binding and phagocytosis which could be quantified. Our results showed that C1q and lectins identified in Pacific oyster plasma held binding ability to bacteria, clearly suggesting their potent to be opsonins. The dominant expressed plasma protein p1-CgC1q (Complement component 1q)-like protein was identified and its opsonic role was confirmed in this study. The cell surface receptor Cgintegrin interacts directly with p1-CgC1q to mediate phagocytosis. We further confirmed that the interaction between C1q and integrin not rely on the typical recognition site RGD but on the RGE. Evidence exist revealed that p1-CgC1q could coat bacteria via the endotoxin LPS (lipopolysaccharide) and subsequently bind the receptor integrin to significantly enhance hemocytic phagocytosis and bacteria clearance. This study has thus furnished clear evidence for the importance of plasma proteins in mollusk, shedding light on the humoral immunity and an underappreciated strategy in marine host-pathogen interactions.

The role of miR-155 in cigarette smoke-induced pulmonary inflammation and COPD

Chronic obstructive pulmonary disease (COPD) is a highly prevalent respiratory disease characterized by airflow limitation and chronic inflammation. MiR-155 is described as an ancient regulator of the immune system. Our objective was to establish a role for miR-155 in cigarette smoke (CS)-induced inflammation and COPD. We demonstrate increased miR-155 expression by RT-qPCR in lung tissue of smokers without airflow limitation and patients with COPD compared to never smokers and in lung tissue and alveolar macrophages of CS-exposed mice compared to air-exposed mice. In addition, we exposed wild type and miR-155 deficient mice to CS and show an attenuated inflammatory profile in the latter. Alveolar macrophages were sorted by FACS from the different experimental groups and their gene expression profile was analyzed by RNA sequencing. This analysis revealed increased expression of miR-155 targets and an attenuation of the CS-induced increase in inflammation-related genes in miR-155 deficient mice. Moreover, intranasal instillation of a specific miR-155 inhibitor attenuated the CS-induced pulmonary inflammation in mice. Finally, elastase-induced emphysema and lung functional changes were significantly attenuated in miR-155 deficient mice. In conclusion, we highlight a role for miR-155 in CS-induced inflammation and the pathogenesis of COPD, implicating miR-155 as a new therapeutic target in COPD.

Complement C1q subunit molecules from Xenopus laevis possess conserved function in C1q-immunoglobulin interaction

Complement component 1q (C1q), together with C1r and C1s to form C1, recognize and bind immune complex to initiate the classical complement pathway. In this study, C1q subunit molecules (XlC1qA, XlC1qB, XlC1qC) were cloned and analyzed from Xenopus laevis (X. laevis). The open reading frame (ORF) of XlC1qA is 819 bp of nucleotide sequence encoding 272 amino acids, the ORF of XlC1qB is 711 bp encoding 236 aa, and the XlC1qC is consists of 732 bp encoding 243 aa. The deduced amino acid sequences contain a collagen-like region (CLR), Gly-X-Y repeats in the N-terminus and a C1q family domain at the C-terminus. Phylogenetic analysis revealed that the XlC1qs are clustered with the amphibian clade. Expression analysis indicated that the XlC1qs exhibited constitutive expression in all examined tissues, with the highest expression in liver. Additionally, XlC1q could interact with heat-aggregated mouse IgG and IgM, Xenopus IgM and Nile tilapia IgM, respectively, indicating the functional conservation of XlC1q binding to immunoglobulins. Further, XlC1qs can inhibit C1q-dependent hemolysis of sensitized sheep red blood cells with concentration-dependent manner. These data collectively suggest that the function of C1qs in X. laevis may be conserved in interaction with immunoglobulins, as that of mammals and teleosts.

An inhibitor of complement C5 provides structural insights into activation

The complement system is a crucial antimicrobial system in the human body. However, controlling its regulation is essential, and failure to do so is implicated in a number of clinical inflammatory pathologies leading to great interest in therapeutic complement inhibition. We have identified and characterized a class of complement inhibitors from biting ticks. Utilizing both cryoelectron microscopy and X-ray crystallography we provide a comprehensive understanding of their mechanism of inhibition at the level of the terminal pathway of complement. We present a high-resolution cryoelectron microscopy structure of complement C5, the molecule targeted by the major therapeutic Eculizumab. In addition, we reveal the fold of the CirpT family of tick inhibitors and their unique mode of inhibition.

The complement system is a crucial part of innate immune defenses against invading pathogens. The blood-meal of the tick Rhipicephalus pulchellus lasts for days, and the tick must therefore rely on inhibitors to counter complement activation. We have identified a class of inhibitors from tick saliva, the CirpT family, and generated detailed structural data revealing their mechanism of action. We show direct binding of a CirpT to complement C5 and have determined the structure of the C5–CirpT complex by cryoelectron microscopy. This reveals an interaction with the peripheral macro globulin domain 4 (C5_MG4) of C5. To achieve higher resolution detail, the structure of the C5_MG4–CirpT complex was solved by X-ray crystallography (at 2.7 Å). We thus present the fold of the CirpT protein family, and provide detailed mechanistic insights into its inhibitory function. Analysis of the binding interface reveals a mechanism of C5 inhibition, and provides information to expand our biological understanding of the activation of C5, and thus the terminal complement pathway.

Binding of von Willebrand Factor to Complement C1q Decreases the Phagocytosis of Cholesterol Crystals and Subsequent IL-1 Secretion in Macrophages

Complement C1q, the initiation molecule of the classical pathway, exerts various immunomodulatory functions independent of complement activation. Non-classical functions of C1q include the clearance of apoptotic cells and cholesterol crystals (CC), as well as the modulation of cytokine secretion by immune cells such as macrophages. Moreover, C1q has been shown to act as a binding partner for von Willebrand factor (vWF), initiation molecule of primary hemostasis. However, the consequences of this C1q-vWF interaction on the phagocytosis of CC by macrophages has remained elusive until now. Here, we used CC-C1q-vWF complexes to study immunological effects on human monocyte-derived macrophages (HMDMs). HMDMs were investigated by analyzing surface receptor expression, phagocytosis of CC complexes, cytokine secretion, and caspase-1 activity. We found that vWF only bound to CC in a C1q-dependent manner. Exposure of macrophages to CC-C1q-vWF complexes resulted in an upregulated expression of phagocytosis-mediating receptors MerTK, LRP-1, and SR-A1 as well as CD14, LAIR1, and PD-L1 when compared to CC-C1q without vWF, whereas phagocytosis of CC-C1q complexes was hampered in the presence of vWF. In addition, we observed a diminished caspase-1 activation and subsequent reduction in pro-inflammatory IL-1β cytokine secretion, IL-1β/IL-1RA ratio and IL-1α/IL-1RA ratio. In conclusion, our results demonstrate that vWF binding to C1q substantially modulates the effects of C1q on HMDMs. In this way, the C1q-vWF interaction might be beneficial in dampening inflammation, e.g., in the context of atherosclerosis.

Recombinant C1q variants modulate macrophage responses but do not activate the classical complement pathway

Complement protein C1q plays a dual role in a number of inflammatory diseases such as atherosclerosis. While in later stages classical complement pathway activation by C1q exacerbates disease progression, C1q also plays a beneficial role in early disease. Independent of its role in complement activation, we and others have identified a number of potentially beneficial interactions of C1q with phagocytes in vitro, including triggering phagocytosis of cellular and molecular debris and polarizing macrophages toward an anti-inflammatory phenotype. These interactions may also be important in preventing autoimmunity. Here, we characterize variants of recombinant human C1q (rC1q) which no longer initiate complement activation, through mutation of the C1r₂C1s₂ interaction site. For insight into the structural location of the site of C1q that is important for interaction with phagocytes, we investigated the effect of these mutations on phagocytosis and macrophage inflammatory polarization, as compared to wild-type C1q. Phagocytosis of antibody coated sheep erythrocytes and oxidized LDL was measured in human monocytes and monocyte-derived macrophages (HMDM) respectively that had interacted with rC1q wild-type or variants. Secreted levels of cytokines were also measured in C1q stimulated HMDM. All variants of C1q increased phagocytosis in HMDM compared to controls, similar to native or wild-type rC1q. In addition, levels of certain pro-inflammatory cytokines and chemokines secreted by HMDM were modulated in cells that interacted with C1q variants, similar to wild-type rC1q and native C1q. This includes downregulation of IL-1α, IL-1β, TNFα, MIP-1α, and IL-12p40 by native and rC1q in both resting and M1-polarized HMDM. This suggests that the site responsible for C1q interaction with phagocytes is independent of the C1r₂C1s₂ interaction site. Further studies with these classical pathway-null variants of C1q should provide greater understanding of the complement-independent role of C1q, and allow for potential therapeutic exploitation.

A sialic acid-binding lectin with bactericidal and opsonic activities from Ruditapes philippinarum

In the present study, a sialic acid-binding lectin was cloned and characterized from Manila clam Ruditapes philippinarum (designed as RpSabl). The open reading frame of RpSabl encoded a polypeptide of 162 amino acids with a calculated molecular mass of 17.7 kDa. Analysis of the conserved domain suggested that RpSabl was a new member of the sialic acid-binding lectins family. In non-stimulated clams, RpSabl transcripts were constitutively expressed in all five tested tissues, especially in hepatopancreas. After Vibrio anguillarum challenge, the expression of RpSabl mRNA in hepatopancreas was significantly up-regulated at 3 h (3.8-fold, P < 0.05), 6 h (4.9-fold, P < 0.05), 12 h (12.3-fold, P < 0.01) and 24 h (9.7-fold, P < 0.01), while RpSabl transcripts in hemocytes was only significantly up-regulated at 6 h (8.5-Fold, P < 0.01). RNAi-mediated knockdown of RpSabl transcripts affected the survival rates of Manila clam against V. anguillarum, perhaps mainly due to the inhibited expression of antibacterial effectors (e.g. lysozyme and defensin). Moreover, recombinant protein of RpSabl (rRpSabl) possessed binding activities towards lipopolysaccharides (LPS), peptidoglycan (PGN) and glucan in vitro. Coinciding with the Pathogen-associated molecular patterns (PAMPs) binding assay, rRpSabl displayed broad bacterial-agglutination properties towards Vibrio harveyi, Vibrio splendidus, V. anguillarum, Enterobacter cloacae and Aeromonas hydrophila. Meanwhile, the phagocytosis and encapsulation ability of hemocytes could be significantly enhanced by rRpSabl incubation. All these results showed that RpSabl could function as a versatile molecule involved in the innate immune responses of R. philippinarum.

Role of mannose-binding lectin in regulating monocytes/macrophages functions during Aeromonas hydrophila infection in grass carp, Ctenopharyngodon idella

Mannose-binding lectin (MBL) is a vital component in host's innate immune system and the initiator of the lectin pathway of complement cascade. However, its opsonic role has rarely been reported. In this study, we revealed the biological function of Ctenopharyngodon idella MBL (CiMBL) in regulating monocytes/macrophages (MO/MФ) in the grass carp (C. idella). Flow cytometry results indicated that recombinant CiMBL (rCiMBL) significantly enhanced the phagocytotic activity of MO/MФ. Recombinant CiMBL also enhanced bactericidal activity and respiratory burst capacity in Aeromonas hydrophila-infected MO/MФ, regulated A. hydrophila-induced polarization of MO/MФ including down- and up-regulated pro- and anti-inflammatory cytokines, respectively, suppressed the inducible nitric oxide synthase activity, and enhanced the arginase activity. In addition, rCiMBL suppressed the bacteria burden in tissues and blood in vivo and enhanced the survival rate of juvenile A. hydrophila-infected grass carp. We provide evidence that CiMBL was synthesized by MO/MФ, regulating the biological function of MO/MФ against A. hydrophila infection.

Plasma membrane damage repair is mediated by an acid sphingomyelinase in Entamoeba histolytica

Entamoeba histolytica is a pathogen that during its infective process confronts the host defenses, which damages the amoebic plasma membrane (PM), resulting in the loss of viability. However, it is unknown whether amoebic trophozoites are able to repair their PM when it is damaged. Acid sphingomyelinases (aSMases) have been reported in mammalian cells to promote endocytosis and removal of PM lesions. In this work, six predicted amoebic genes encoding for aSMases were found to be transcribed in the HM1:IMSS strain, finding that the EhaSM6 gene is the most transcribed in basal growth conditions and rendered a functional protein. The secreted aSMase activity detected was stimulated by Mg⁺² and inhibited by Co⁺². Trophozoites that overexpress the EhaSM6 gene (HM1-SM6HA) exhibit an increase of 2-fold in the secreted aSMase activity. This transfectant trophozoites exposed to pore-forming molecules (SLO, Magainin, β-Defensin 2 and human complement) exhibited an increase from 6 to 25-fold in the secreted aSMase activity which correlated with higher amoebic viability in a Ca⁺² dependent process. However, other agents that affect the PM such as hydrogen peroxide also induced an increase of secreted aSMase, but to a lesser extent. The aSMase6 enzyme is N- and C-terminal processed. Confocal and transmission electron microscopy showed that trophozoites treated with SLO presented a migration of lysosomes containing the aSMase towards the PM, inducing the formation of membrane patches and endosomes in the control strain. These cellular structures were increased in the overexpressing strain, indicating the involvement of the aSMase6 in the PM injury repair. The pore-forming molecules induced an increase in the expression of EhaSM1, 2, 5 and 6 genes, meanwhile, hydrogen peroxide induced an increase in all of them. In all the conditions evaluated, the EhaSM6 gene exhibited the highest levels of induction. Overall, these novel findings show that the aSMase6 enzyme from E. histolytica promotes the repair of the PM damaged with pore-forming molecules to prevent losing cell integrity. This novel system could act when encountered with the lytic defense systems of the host.

The host-amoeba relationship is based on a series of interplays between host defense mechanisms and parasite survival strategies. While host cells elaborate diverse mechanisms for pathogen elimination, Entamoeba histolytica trophozoites have also developed complex strategies to counteract host immune response and facilitate its own survival while confronting host defenses. E. histolytica exposed to pore-forming proteins such as β-Defensin 2, human complement and Streptolysin O (SLO), increases the activity of secreted aSMase, which is related to greater amoebic viability. Other agents that affect plasma membrane (PM) may also increase secreted aSMase but to a lesser extent. SLO form pores in the PM of E. histolytica trophozoites that initiates the uncontrolled entry of Ca²⁺, recognized as the primary trigger for cell responses which favors the migration of the lysosomes to the periphery of the cell, fuses with the PM and release their content, including aSMase to the external side of the cell. The secreted aSMase favoring the internalization of the lesion for its degradation in phagolysosomes. During the early stages of PM damage, the pores are rapidly blocked by patch-like structures that prevent the lysis of the trophozoite and immediately begin internalizing the lesion. The aSMase6 overexpression favors the repair of the lesion and the survival of E. histolytica trophozoites. Pore-forming proteins induced an increase in the expression of EhaSM1, 2, 5 and 6 genes, meanwhile oxidative stress induced an increase in all of them. Here we report, for the first time, that E. histolytica possess a mechanism for PM damage repair mediated by aSMase similar to the system described in mammalian cells.

Transcriptomic analysis reveals insights into deep-sea adaptations of the dominant species, Shinkaia crosnieri (Crustacea: Decapoda: Anomura), inhabiting both hydrothermal vents and cold seeps

Background

Hydrothermal vents and cold seeps are typical deep-sea chemosynthetically-driven ecosystems that allow high abundance of specialized macro-benthos. To gather knowledge about the genetic basis of adaptation to these extreme environments, species shared between different habitats, especially for the dominant species, are of particular interest. The galatheid squat lobster, Shinkaia crosnieri Baba and Williams, 1998, is one of the few dominant species inhabiting both deep-sea hydrothermal vents and cold seeps. In this study, we performed transcriptome analyses of S. crosnieri collected from the Iheya North hydrothermal vent (HV) and a cold seep in the South China Sea (CS) to provide insights into how this species has evolved to thrive in different deep-sea chemosynthetic ecosystems.

Results

We analyzed 5347 orthologs between HV and CS to identify genes under positive selection through the maximum likelihood approach. A total of 82 genes were identified to be positively selected and covered diverse functional categories, potentially indicating their importance for S. crosnieri to cope with environmental heterogeneity between deep-sea vents and seeps. Among 39,806 annotated unigenes, a large number of differentially expressed genes (DEGs) were identified between HV and CS, including 339 and 206 genes significantly up-regulated in HV and CS, respectively. Most of the DEGs associated with stress response and immunity were up-regulated in HV, possibly allowing S. crosnieri to increase its capability to manage more environmental stresses in the hydrothermal vents.

Conclusions

We provide the first comprehensive transcriptomic resource for the deep-sea squat lobster, S. crosnieri, inhabiting both hydrothermal vents and cold seeps. A number of stress response and immune-related genes were positively selected and/or differentially expressed, potentially indicating their important roles for S. crosnieri to thrive in both deep-sea vents and cold seeps. Our results indicated that genetic adaptation of S. crosnieri to different deep-sea chemosynthetic environments might be mediated by adaptive evolution of functional genes related to stress response and immunity, and alterations in their gene expression that lead to different stress resistance. However, further work is required to test these proposed hypotheses. All results can constitute important baseline data for further studies towards elucidating the adaptive mechanisms in deep-sea crustaceans.

Electronic supplementary material

The online version of this article (10.1186/s12864-019-5753-7) contains supplementary material, which is available to authorized users.

Complement Evasion: An Effective Strategy That Parasites Utilize to Survive in the Host

Parasitic infections induce host immune responses that eliminate the invading parasites. However, parasites have evolved to develop many strategies to evade host immune attacks and survive in a hostile environment. The complement system acts as the first line of immune defense to eliminate the invading parasites by forming the membrane attack complex (MAC) and promoting an inflammatory reaction on the surface of invading parasites. To date, the complement activation pathway has been precisely delineated; however, the manner in which parasites escape complement attack, as a survival strategy in the host, is not well understood. Increasing evidence has shown that parasites develop sophisticated strategies to escape complement-mediated killing, including (i) recruitment of host complement regulatory proteins on the surface of the parasites to inhibit complement activation; (ii) expression of orthologs of host RCA to inhibit complement activation; and (iii) expression of parasite-encoded proteins, specifically targeting different complement components, to inhibit complement function and formation of the MAC. In this review, we compiled information regarding parasitic abilities to escape host complement attack as a survival strategy in the hostile environment of the host and the mechanisms underlying complement evasion. Effective escape of host complement attack is a crucial step for the survival of parasites within the host. Therefore, those proteins expressed by parasites and involved in the regulation of the complement system have become important targets for the development of drugs and vaccines against parasitic infections.

Mannose binding lectin 2 gene polymorphisms in patients after renal transplantation with acute graft rejection

Mannose binding lectin 2 (MBL2) is one of the pattern-recognition soluble receptors and is responsible for complement activation via the lectin pathway, so it plays an important role in kidney transplantation. The aim of the study was to examine the association between MBL2 gene polymorphisms and acute rejection of the kidney allograft. This study enrolled 266 Caucasian deceased-donor renal transplant recipients - 69 with diagnosed acute graft rejection, 197 with stable graft function. A 969 bp DNA fragment, from chromosome 10, including promoter region and exon 1 of MBL2 gene was sequenced. The DNA fragment obtained contained 122 SNPs accordingly to the NCBI dbSNP database. Of this number only nine showed variation within our population (rs36014597, rs5030737, rs1800450, rs7095891, rs11003123, rs7096206, rs7084554, rs11003124, rs11003125), and only these were subjected to further analysis. Among the studied polymorphisms in the MBL2 gene only rs1800450 polymorphism was statistically significantly associated with kidney allograft rejection. The AA genotype was significantly associated with an increased risk of acute kidney allograft rejection. (AA vs GA+GG: OR=9.29 (95%CI: 1.83-47.17), p=0.005). The results of our study indicate that MBL2 gene rs1800450 polymorphism may be associated with the risk of acute kidney allograft rejection. The AA genotype, associated with lower MBL2 expression, may be associated with an increased risk of acute kidney allograft rejection.

Is complement C1q a potential marker for tumor burden and immunodeficiency in multiple myeloma?

Multiple myeloma (MM) patients are immunodeficient. Complement C1q is an important cofactor of both nonspecific and humoral immunity, and it participates in the immunomodulation of multiple tumors. Thus, this study aimed to determine the risk factors and clinical significance of C1q expression in MM patients. In total, 193 MM patients were examined. The mean value of C1q in the patient group (130.46 ± 36.17 mg/L), was lower than that in the control group (anemia and nonmalignant hematologic disease). C1q dynamically changed with different MM stages and was recovered to normal levels when the disease was in remission; however, it decreased again after disease progression. The risk factors of C1q reduction included Durie-Salmon stage and the immunoglobulin type of the disease. In conclusion, C1q appears to be a useful biomarker of tumor burden and a prognostic factor of disease relapse. C1q is a potential marker of the immunodeficiency status in MM patients.

Complement Activation as a Helping Hand for Inflammophilic Pathogens and Cancer

The complement system, an evolutionarily ancient component of innate immunity, is capable of protecting hosts from invading pathogens, either directly, by lysis of target cells, or indirectly, by mobilization of host immune mechanisms. However, this potentially cytotoxic cascade must be tightly regulated, since improperly controlled complement can damage healthy cells and tissues. The practical importance of this axis is highlighted when impairment of complement regulators or bacterial mechanisms of complement evasion result in pathogenic conditions. Recognition of complement as a "double-edged sword" is widely acknowledged, but another, currently underappreciated aspect of complement function has emerged as an important player in homeostatic balance-the dual outcome of complement-mediated inflammation. In most cases, the proinflammatory properties of complement are beneficial to the host. However, certain pathogens have developed the ability to utilize local inflammation as a source of nutrients and as a way to establish a niche for further colonization. Such a strategy can be illustrated in the example of periodontitis. Interestingly, certain tumors also seem to benefit from complement activation products, which promote a proangiogenic and immunosuppressive microenvironment.

Subretinal macrophages produce classical complement activator C1q leading to the progression of focal retinal degeneration

BACKGROUND

The role of the alternative complement pathway and its mediation by retinal microglia and macrophages, is well-established in the pathogenesis of Age-Related Macular Degeneration (AMD). However, the contribution of the classical complement pathway towards the progression of retinal degenerations is not fully understood, including the role of complement component 1q (C1q) as a critical activator molecule of the classical pathway. Here, we investigated the contribution of C1q to progressive photoreceptor loss and neuroinflammation in retinal degenerations.

METHODS

Wild-type (WT), C1qa knockout (C1qa^-/-) and mice treated with a C1q inhibitor (ANX-M1; Annexon Biosciences), were exposed to photo-oxidative damage (PD) and were observed for progressive lesion development. Retinal function was assessed by electroretinography, followed by histological analyses to assess photoreceptor degeneration. Retinal inflammation was investigated through complement activation, macrophage recruitment and inflammasome expression using western blotting, qPCR and immunofluorescence. C1q was localised in human AMD donor retinas using immunohistochemistry.

RESULTS

PD mice had increased levels of C1qa which correlated with increasing photoreceptor cell death and macrophage recruitment. C1qa^-/- mice did not show any differences in photoreceptor loss or inflammation at 7 days compared to WT, however at 14 days after the onset of damage, C1qa^-/- retinas displayed less photoreceptor cell death, reduced microglia/macrophage recruitment to the photoreceptor lesion, and higher visual function. C1qa^-/- mice displayed reduced inflammasome and IL-1β expression in microglia and macrophages in the degenerating retina. Retinal neutralisation of C1q, using an intravitreally-delivered anti-C1q antibody, reduced the progression of retinal degeneration following PD, while systemic delivery had no effect. Finally, retinal C1q was found to be expressed by subretinal microglia/macrophages located in the outer retina of early AMD donor eyes, and in mouse PD retinas.

CONCLUSIONS

Our data implicate subretinal macrophages, C1q and the classical pathway in progressive retinal degeneration. We demonstrate a role of local C1q produced by microglia/macrophages as an instigator of inflammasome activation and inflammation. Crucially, we have shown that retinal C1q neutralisation during disease progression may slow retinal atrophy, providing a novel strategy for the treatment of complement-mediated retinal degenerations including AMD.

Usefulness of Complement C1q to Predict 10-Year Mortality in Men With Diabetes Mellitus Referred for Coronary Angiography

The complement system consists of a family of proteins that play a critical role in the innate immune system. Complement activation has been implicated in many chronic inflammatory diseases, including atherosclerosis. However, a number of experimental studies have highlighted a beneficial role of component C1q in early atherosclerosis and in diabetes mellitus (DM). Despite these data, there have been no studies that have specifically examined the utility of plasma complement C1q as a clinical biomarker in patients with known or suspected coronary artery disease. In this study, baseline plasma complement C1q levels were measured in 159 men with DM who were referred for coronary angiography and who were followed up prospectively for the development of all-cause mortality for 10 years. After adjustment for baseline clinical, angiographic, and laboratory parameters, reduced plasma complement C1q levels were an independent predictor of all-cause mortality at 10 years (hazard ratio 0.66, 95% confidence interval 0.52 to 0.84, p = 0.0006). In additional multivariate models that adjusted for a variety of biomarkers with established prognostic efficacy, complement C1q remained an independent predictor of all-cause mortality at 10 years. In conclusion, reduced levels of complement C1q are associated with an increased risk of all-cause mortality at 10 years in patients with DM referred for coronary angiography. Furthermore, this association is independent of a variety of clinical, angiographic, laboratory variables, including biomarkers with established prognostic efficacy in the prediction of adverse cardiovascular outcomes.

Classical Pathway of Complement Activation: Longitudinal Associations of C1q and C1-INH With Cardiovascular Outcomes: The CODAM Study (Cohort on Diabetes and Atherosclerosis Maastricht)-Brief Report

OBJECTIVE

The classical complement pathway has been assigned both protective and pathological effects in cardiovascular disease (CVD), but human data are lacking. We determined the associations of the pattern recognition factor C1q and the regulator C1-INH (C1-inhibitor) with incident CVD, carotid intima-media thickness, endothelial dysfunction, and low-grade inflammation.

APPROACH AND RESULTS

Baseline concentrations of C1q and C1-INH were measured in the CODAM study (Cohort on Diabetes and Atherosclerosis Maastricht; n=574; 61% men; age, 60±7 years). The 7-year incidence of CVD in participants free of CVD at baseline was evaluated using logistic regression analyses (n=342; 73 cases). The lowest incidence of CVD was observed in the middle tertile of C1q (T_low compared with T_middle: odds ratio, 2.38 [95% confidence interval, 1.14-4.95]; T_high compared with T_middle: odds ratio, 1.96 [95% confidence interval, 0.94-4.07]). C1-INH was not associated with CVD. During the 7-year follow-up period, C1q and C1-INH were not, or inconsistently, associated with carotid intima-media thickness or with biomarker scores reflecting endothelial dysfunction and low-grade inflammation.

CONCLUSIONS

Our results suggest a nonlinear association between C1q and incident CVD. This supports the concept that early steps in classical pathway activation may have both protective and pathological effects on human CVD.

C1q and Mannose-Binding Lectin Interact with CR1 in the Same Region on CCP24-25 Modules

Complement receptor type 1 (CR1) is a multi modular membrane receptor composed of 30 homologous complement control protein modules (CCP) organized in four different functional regions called long homologous repeats (LHR A, B, C, and D). CR1 is a receptor for complement-opsonins C3b and C4b and specifically interacts through pairs of CCP modules located in LHR A, B, and C. Defense collagens such as mannose-binding lectin (MBL), ficolin-2, and C1q also act as opsonins and are involved in immune clearance through binding to the LHR-D region of CR1. Our previous results using deletion variants of CR1 mapped the interaction site for MBL and ficolin-2 on CCP24-25. The present work aimed at deciphering the interaction of C1q with CR1 using new CR1 variants concentrated around CCP24-25. CR1 bimodular fragment CCP24-25 and CR1 CCP22-30 deleted from CCP24-25 produced in eukaryotic cells enabled to highlight that the interaction site for both MBL and C1q is located on the same pair of modules CCP24-25. C1q binding to CR1 shares with MBL a main common interaction site on the collagen stalks but also subsidiary sites most probably located on C1q globular heads, contrarily to MBL.

The oyster immunity

Oysters, the common name for a number of different bivalve molluscs, are the worldwide aquaculture species and also play vital roles in the function of ecosystem. As invertebrate, oysters have evolved an integrated, highly complex innate immune system to recognize and eliminate various invaders via an array of orchestrated immune reactions, such as immune recognition, signal transduction, synthesis of antimicrobial peptides, as well as encapsulation and phagocytosis of the circulating haemocytes. The hematopoietic tissue, hematopoiesis, and the circulating haemocytes have been preliminary characterized, and the detailed annotation of the Pacific oyster Crassostrea gigas genome has revealed massive expansion and functional divergence of innate immune genes in this animal. Moreover, immune priming and maternal immune transfer are reported in oysters, suggesting the adaptability of invertebrate immunity. Apoptosis and autophagy are proved to be important immune mechanisms in oysters. This review will summarize the research progresses of immune system and the immunomodulation mechanisms of the primitive catecholaminergic, cholinergic, neuropeptides, GABAergic and nitric oxidase system, which possibly make oysters ideal model for studying the origin and evolution of immune system and the neuroendocrine-immune regulatory network in lower invertebrates.

A novel C1q-domain-containing protein from razor clam Sinonovacula constricta mediates G-bacterial agglutination as a pattern recognition receptor

Complement component 1q (C1q) with a characteristic C1q globular domain is an important pattern recognition molecule in the classical complement systems and plays a major role in the crosslinking between innate immunity and specific immunity in vertebrates. In this study, a homologous gene encoding typically C1q domains was obtained from the razor clam Sinonovacula constricta (designated ScC1qDC) by rapid amplification of the cDNA end. The full-length cDNA of ScC1qDC was 1225 bp in length with a 5'UTR of 258 bp, a 3'UTR of 223 bp, and an open reading frame of 744 bp encoding a polypeptide of 247 amino acids containing a typical C1q globular domain. The mRNA transcripts of ScC1qDC were constitutively transcribed in all examined tissues with higher expression in the hepatopancreas. Time-course expression analysis indicated that ScC1qDC was significantly up-regulated both in hepatopancreas and gills after Vibrio parahaemolyticus challenge. The recombinant ScC1qDC (rScC1qDC) displayed high binding activities to various pathogen-associated molecular patterns, including LPS, PGN, and MAN. Recombinant ScC1qDC showed no agglutinating activity to Gram-positive bacterium of Micrococcus luteus but showed obvious activities towards all the three examined Gram-negative bacteria. All our results indicated that ScC1qDC might be served as a pattern recognition receptor and promoted Gram-negative bacteria agglutination during the pathogen challenge.

The Whole-Genome and Transcriptome of the Manila Clam (Ruditapes philippinarum)

The manila clam, Ruditapes philippinarum, is an important bivalve species in worldwide aquaculture including Korea. The aquaculture production of R. philippinarum is under threat from diverse environmental factors including viruses, microorganisms, parasites, and water conditions with subsequently declining production. In spite of its importance as a marine resource, the reference genome of R. philippinarum for comprehensive genetic studies is largely unexplored. Here, we report the de novo whole-genome and transcriptome assembly of R. philippinarum across three different tissues (foot, gill, and adductor muscle), and provide the basic data for advanced studies in selective breeding and disease control in order to obtain successful aquaculture systems. An approximately 2.56 Gb high quality whole-genome was assembled with various library construction methods. A total of 108,034 protein coding gene models were predicted and repetitive elements including simple sequence repeats and noncoding RNAs were identified to further understanding of the genetic background of R. philippinarum for genomics-assisted breeding. Comparative analysis with the bivalve marine invertebrates uncover that the gene family related to complement C1q was enriched. Furthermore, we performed transcriptome analysis with three different tissues in order to support genome annotation and then identified 41,275 transcripts which were annotated. The R. philippinarum genome resource will markedly advance a wide range of potential genetic studies, a reference genome for comparative analysis of bivalve species and unraveling mechanisms of biological processes in molluscs. We believe that the R. philippinarum genome will serve as an initial platform for breeding better-quality clams using a genomic approach.

A C1qDC Protein (HcC1qDC6) with Three Tandem C1q Domains Is Involved in Immune Response of Triangle-Shell Pearl Mussel (Hyriopsis cumingii)

C1q-domain-containing (C1qDC) proteins are a family of proteins with a globular C1q (gC1q) domain and participate in several immune responses. In this study, a C1qDC gene was identified from the triangle-shell pearl mussel Hyriopsis cumingii (designated as HcC1qDC6). This gene has a full-length cDNA of 1782 bp and an open reading frame of 1,335 bp that encodes a 444-amino acid polypeptide containing three gC1q domains. HcC1qDC6 contains at least five exons and four introns. The mRNA transcripts of HcC1qDC6 were found to have the highest expression levels in the mantle tissue. The expression levels in the mantle and hepatopancreas were significantly upregulated by Staphylococcus aureus and Vibrio parahaemolyticus challenges. Moreover, knockdown of HcC1qDC6 inhibits the expression of two immune-related genes (tumor necrosis factor and whey acidic protein). The recombinant proteins of C1q1, C1q2, and C1q3 all exhibit a binding activity against seven bacterial species and directly bind to peptidoglycan and lipopolysaccharide. The results indicate that HcC1qDC6 is involved in the innate immunity of H. cumingii.

Transcription of immune related genes in Solea senegalensis vaccinated against Photobacterium damselae subsp. piscicida. Identification of surrogates of protection

Solea senegalensis is a flatfish with a great potential for aquaculture, but infectious diseases restrict its production, being this fish species highly susceptible to Photobacterium damselae subsp. piscicida (Phdp) infections. A better understanding of the mechanisms related to fish immune response is crucial for the development of effective approaches in disease management. In the present work, transcriptional changes of immune related genes have been evaluated in farmed S. senegalensis specimens vaccinated against Phdp by intraperitoneal injection (IP) and immersion (IM). IP fish showed higher antibody levels and increased transcription of genes encoding lysozyme C1, complement factors involved in the classical pathway and components involved in the opsonization and the limitation of free iron availability, all of them facilitating the faster elimination of the pathogen and promoting higher RPS after the infection with Phdp. The results of this study seem to support a different intensity of the specimens immune response in the head kidney. Analysis of the immune response in 15 day post-challenged fish showed up-regulation of genes involved in all stages of S. senegalensis immune response, but especially those genes encoding proteins related to the innate response such as complement, lysozyme and iron homeostasis in the head kidney. On the other hand, liver transcription was higher for genes related to inflammation, apoptosis and cell mediated cytotoxicity (CMC). Furthermore, comparison of the differential response of S. senegalensis genes in vaccinated and unvaccinated fish to Phdp infection allowed the identification of a potential biosignature, consisting in 10 genes, as a surrogate of protection and therefore, as indicator of vaccine success against fotobacteriosis after IP vaccination. These results provide important insights into the S. senegalensis protection against Phdp induced by vaccination.

C1q: A fresh look upon an old molecule

Originally discovered as part of C1, the initiation component of the classical complement pathway, it is now appreciated that C1q regulates a variety of cellular processes independent of complement activation. C1q is a complex glycoprotein assembled from 18 polypeptide chains, with a C-terminal globular head region that mediates recognition of diverse molecular structures, and an N-terminal collagen-like tail that mediates immune effector mechanisms. C1q mediates a variety of immunoregulatory functions considered important in the prevention of autoimmunity such as the enhancement of phagocytosis, regulation of cytokine production by antigen presenting cells, and subsequent alteration in T-lymphocyte maturation. Furthermore, recent advances indicate additional roles for C1q in diverse physiologic and pathologic processes including pregnancy, tissue repair, and cancer. Finally, C1q is emerging as a critical component of neuronal network refinement and homeostatic regulation within the central nervous system. This review summarizes the classical functions of C1q and reviews novel discoveries within the field.

Complement Protein C1q Enhances Macrophage Foam Cell Survival and Efferocytosis

In the atherosclerotic lesion, macrophages ingest high levels of damaged modified low-density lipoproteins (LDLs), generating macrophage foam cells. Foam cells undergo apoptosis and, if not efficiently cleared by efferocytosis, can undergo secondary necrosis, leading to plaque instability and rupture. As a component of the innate immune complement cascade, C1q recognizes and opsonizes modified forms of LDL, such as oxidized or acetylated LDL, and promotes ingestion by macrophages in vitro. C1q was shown to be protective in an atherosclerosis model in vivo. Therefore, this study aimed to investigate whether ingestion of modified LDL in the presence of C1q alters macrophage foam cell survival or function. In an unbiased transcriptome analysis, C1q was shown to modulate expression of clusters of genes involved in cell death and apoptosis pathways in human monocyte-derived macrophages ingesting modified LDL; this was validated by quantitative PCR in human and murine macrophages. C1q downregulated levels and activity of active caspase-3 and PARP-1 in human and mouse macrophages during ingestion of modified LDL. This led to a measurable increase in survival and decrease in cell death, as measured by alamarBlue and propidium iodide assays, respectively. C1q opsonization also increased phagocytosis and efferocytosis in macrophage foam cells. These data suggest that C1q promotes macrophage survival during ingestion of excess cholesterol, as well as improves foam cell efferocytic function. This may be important in slowing disease progression and provides insight into the protective role of C1q in early atherosclerosis.

Identification and function of a novel C1q domain-containing (C1qDC) protein in triangle-shell pearl mussel (Hyriopsis cumingii)

C1q is the target recognition sequence of the classical complement pathway and a major link that connects innate and acquired immunity. In this study, a C1qDC homolog, HcC1qDC5, from the triangle-shell pearl mussel (Hyriopsis cumingii) was identified. The complete nucleotide sequence of HcC1qDC5 cDNA consists of a 5'-untranslated terminal region (UTR) of 123 bp, a 3'-UTR of 105 bp with a poly(A) tail, and an open reading frame (ORF) of 1344 bp, which encodes a polypeptide of 447 amino acids. HcC1qDC5 contains a signal peptide and three typical C1q domains. The HcC1qDC5 gene was expressed in all tested tissues, with the highest expression in the mantle. Staphylococcus aureus or Vibrio parahaemolyticus infection increased the mRNA transcript levels of HcC1qDC5 in the hepatopancreas and mantle. The recombinant HcC1qDC5 protein could bind to Gram-negative and Gram-positive bacteria as well as to different PAMPs (LPS and PGN). RNAi results showed that HcC1qDC5 was involved in V. parahaemolyticus-induced HcTNF and HcWAP expression. The combined results demonstrated that HcC1qDC5 participates in the innate immunity of H. cumingii.

Domain structure of human complement C4b extends with increasing NaCl concentration: implications for its regulatory mechanism

During the activation of complement C4 to C4b, the exposure of its thioester domain (TED) is crucial for the attachment of C4b to activator surfaces. In the C4b crystal structure, TED forms an Arg¹⁰⁴-Glu¹⁰³² salt bridge to tether its neighbouring macroglobulin (MG1) domain. Here, we examined the C4b domain structure to test whether this salt bridge affects its conformation. Dual polarisation interferometry of C4b immobilised at a sensor surface showed that the maximum thickness of C4b increased by 0.46 nm with an increase in NaCl concentration from 50 to 175 mM NaCl. Analytical ultracentrifugation showed that the sedimentation coefficient s_20,w of monomeric C4b of 8.41 S in 50 mM NaCl buffer decreased to 7.98 S in 137 mM NaCl buffer, indicating that C4b became more extended. Small angle X-ray scattering reported similar R_G values of 4.89-4.90 nm for C4b in 137-250 mM NaCl. Atomistic scattering modelling of the C4b conformation showed that TED and the MG1 domain were separated by 4.7 nm in 137-250 mM NaCl and this is greater than that of 4.0 nm in the C4b crystal structure. Our data reveal that in low NaCl concentrations, both at surfaces and in solution, C4b forms compact TED-MG1 structures. In solution, physiologically relevant NaCl concentrations lead to the separation of the TED and MG1 domain, making C4b less capable of binding to its complement regulators. These conformational changes are similar to those seen previously for complement C3b, confirming the importance of this salt bridge for regulating both C4b and C3b.