The relationship between complement C1q and coronary plaque vulnerability based on optical coherence tomography analysis

To determine the association between complement C1q and vulnerable plaque morphology among coronary artery disease (CAD) patients. We conducted a retrospective observational study of 221 CAD patients admitted to The Second Affiliated Hospital of Xi'an Jiaotong University. Intravascular optical coherence tomography was utilized to describe the culprit plaques' morphology. Using logistic regression analysis to explore the correlation between C1q and vulnerable plaques, and receiver operator characteristic (ROC) analysis assess the predictive accuracy. As reported, the complement C1q level was lower in ACS patients than CCS patients (18.25 ± 3.88 vs. 19.18 ± 4.25, P = 0.045). The low complement-C1q-level group was more prone to develop vulnerable plaques. In lipid-rich plaques, the complement C1q level was positively correlated with the thickness of fibrous cap (r = 0.480, P = 0.041). Univariate and multivariate logistic regression analyses suggested that complement C1q could be an independent contributor to plaques' vulnerability. For plaque rupture, erosion, thrombus, and cholesterol crystals, the areas under the ROC curve of complement C1q level were 0.873, 0.816, 0.785, and 0.837, respectively (P < 0.05 for all). In CAD patients, the complement C1q could be a valuable indicator of plaque vulnerability.

CTRP9 prevents atherosclerosis progression through changing autophagic status of macrophages by activating USP22 mediated-de-ubiquitination on Sirt1 in vitro

BACKGROUND

Atherosclerosis (AS) is commonly regarded as a key driver accounted for the leading causes of morbidity and mortality among cardiovascular and cerebrovascular diseases. A growing body of evidence indicates that autophagy in macrophages involved in AS might be a potential therapeutic target. C1q/TNF-related protein 9 (CTRP9) has been proven to delay the progression of cardiovascular diseases. However, the relations between CTRP9 and Sirt1, as well as their effects on macrophages autophagy have not been fully explored.

METHODS

Macrophages were differentiated from mononuclear cells collected from peripheral blood samples of healthy donors. The in vitro AS models were constructed by ox-LDL treatment. Cell viability was determined by CCK-8 assay. Immunofluorescence assay of LC3 was implemented for evaluating autophagy activity. Oil Red O staining was performed for lipid accumulation detection. ELISA, cholesterol concentration assay and cholesterol efflux analysis were conducted using commercial kits. Cycloheximide assay was implemented for revealing protein stability. RT-qPCR was used for mRNA expression detection, and western blotting was performed for protein level monitoring.

RESULTS

CTRP9 attenuated impaired cell viability, autophagy inhibition and increased lipid accumulation induced by ox-LDL. Moreover, CTRP9 maintained Sirt1 protein level through enhancing its stability through de-ubiquitination, which was mediated by upregulated USP22 level. CRTP9 exerted its protective role in promoting autophagy and reducing lipid accumulation through the USP22/Sirt1 axis.

CONCLUSION

Collectively, CTRP9 alleviates lipid accumulation and facilitated the macrophages autophagy by upregulating USP22 level and maintaining Sirt1 protein expression, thereby exerting a protective role in AS progression in vitro.

Immune proteins C1q and CD47 may contribute to aberrant microglia-mediated synapse loss in the aging monkey brain that is associated with cognitive impairment

Cognitive impairment in learning, memory, and executive function occurs in normal aging even in the absence of Alzheimer's disease (AD). While neurons do not degenerate in humans or monkeys free of AD, there are structural changes including synapse loss and dendritic atrophy, especially in the dorsolateral prefrontal cortex (dlPFC), and these correlate with cognitive age-related impairment. Developmental studies revealed activity-dependent neuronal properties that lead to synapse remodeling by microglia. Microglia-mediated phagocytosis that may eliminate synapses is regulated by immune "eat me" and "don't eat me" signaling proteins in an activity-dependent manner, so that less active synapses are eliminated. Whether this process contributes to age-related synapse loss remains unknown. The present study used a rhesus monkey model of normal aging to investigate the balance between the "eat me" signal, complement component C1q, and the "don't eat me" signal, transmembrane glycoprotein CD47, relative to age-related synapse loss in dlPFC Area 46. Results showed an age-related elevation of C1q and reduction of CD47 at PSD95+ synapses that is associated with cognitive impairment. Additionally, reduced neuronal CD47 RNA expression was found, indicating that aged neurons were less able to produce the protective signal CD47. Interestingly, microglia do not show the hypertrophic morphology indicative of phagocytic activity. These findings suggest that in the aging brain, changes in the balance of immunologic proteins give microglia instructions favoring synapse elimination of less active synapses, but this may occur by a process other than classic phagocytosis such as trogocytosis.

Galectin-3 - A novel ligand of complement protein C1q

In the present study we report a novel interaction of human C1q, a primary activator of the Complement system, with human Galectin-3 (Gal-3). We investigated the potential recognition between C1q and Gal-3 on a solid hydrophobic surface by ELISA, by fluorescence spectroscopy, molecular docking and molecular dynamics (MD). The data showed that C1q and Gal-3 had a pronounced affinity for protein-protein interaction and supramolecular binding, locating the binding sites within the globular domains of C1q (gC1q) and on the backside of the carbohydrate recognition domain (CRD) of Gal-3. Fluorescence spectroscopy gave quantitative assessment of the recognition with KD value of 0.04 μM. MD analysis showed that when the active AAs of the two proteins interacted, electrostatic attraction, aided by a large number of hydrogen bonds, was dominant for the stabilization of the complex. When the contact of C1q and Gal-3 was not limited to active residues, the complex between them was stabilized mainly by Van der Waals interactions and smaller in number but stronger hydrogen bonds. This is the first report analyzing the interaction of Gal-3 with C1q, which could open the way to new applications of this protein-protein complex.

Identification of C1q/TNF-related protein 4 as a novel appetite-regulating peptide that reduces food intake in Siberian sturgeon (Acipenser baerii)

Emerging findings point to a role for C1q/TNF-related protein 4 (CTRP4) in feeding in mammals. However, it remains unknown whether CTRP4 regulates feeding in fish. This study aimed to determine the feeding regulation function of CTRP4 in Siberian sturgeon (Acipenser baerii). In this study, the Siberian sturgeon ctrp4 (Abctrp4) gene was cloned, and Abctrp4 mRNA was shown to be highly expressed in the hypothalamus. In the hypothalamus, Abctrp4 mRNA decreased during fasting and reversed after refeeding. Subsequently, we obtained the AbCTRP4 recombinant protein by prokaryotic expression and optimized the expression and purification conditions. Siberian sturgeon (81.28 ± 14.75 g) were injected intraperitoneally using 30, 100, and 300 ng/g Body weight (BW) AbCTRP4 to investigate its effect on feeding. The results showed that 30, 100, and 300 ng/g BW of the AbCTRP4 significantly reduced the cumulative food intake of Siberian sturgeon at 1, 3, and 6 h. Finally, to investigate the potential mechanism of CTRP4 feeding inhibition, 300 ng/g BW AbCTRP4 was injected intraperitoneally. The findings demonstrated that AbCTRP4 treatment for 1 h significantly promoted the mRNA levels of anorexigenic peptides (pomc, cart, and leptin) while suppressing the mRNA abundances of orexigenic peptides (npy and agrp).In addition, the jak2/stat3 pathway in the hypothalamus was significantly activated after 1 h of AbCTRP4 treatment. In conclusion., this study confirms the anorexigenic effect of CTRP4 in Siberian sturgeon.

C1q/Tumor Necrosis Factor-Related Protein-9 Is a Novel Vasculoprotective Cytokine That Restores High Glucose-Suppressed Endothelial Progenitor Cell Functions by Activating the Endothelial Nitric Oxide Synthase

BACKGROUND

This study investigated whether gCTRP9 (globular C1q/tumor necrosis factor-related protein-9) could restore high-glucose (HG)-suppressed endothelial progenitor cell (EPC) functions by activating the endothelial nitric oxide synthase (eNOS).

METHODS AND RESULTS

EPCs were treated with HG (25 mmol/L) and gCTRP9. Migration, adhesion, and tube formation assays were performed. Adiponectin receptor 1, adiponectin receptor 2, and N-cadherin expression and AMP-activated protein kinase, protein kinase B, and eNOS phosphorylation were measured by Western blotting. eNOS activity was determined using nitrite production measurement. In vivo reendothelialization and EPC homing assays were performed using Evans blue and immunofluorescence in mice. Treatment with gCTRP9 at physiological levels enhanced migration, adhesion, and tube formation of EPCs. gCTRP9 upregulated the phosphorylation of AMP-activated protein kinase, protein kinase B, and eNOS and increased nitrite production in a concentration-dependent manner. Exposure of EPCs to HG-attenuated EPC functions induced cellular senescence and decreased eNOS activity and nitric oxide synthesis; the effects of HG were reversed by gCTRP9. Protein kinase B knockdown inhibited eNOS phosphorylation but did not affect gCTRP9-induced AMP-activated protein kinase phosphorylation. HG impaired N-cadherin expression, but treatment with gCTRP9 restored N-cadherin expression after HG stimulation. gCTRP9 restored HG-impaired EPC functions through both adiponectin receptor 1 and N-cadherin-mediated AMP-activated protein kinase /protein kinase B/eNOS signaling. Nude mice that received EPCs treated with gCTRP9 under HG medium showed a significant enhancement of the reendothelialization capacity compared with those with EPCs incubated under HG conditions.

CONCLUSIONS

CTRP9 promotes EPC migration, adhesion, and tube formation and restores these functions under HG conditions through eNOS-mediated signaling mechanisms. Therefore, CTRP9 modulation could eventually be used for vascular healing after injury.

CTRP3 inhibits myocardial fibrosis through the P2X7R-NLRP3 inflammasome pathway in SHR rats

BACKGROUND AND PURPOSE

Reducing hypertensive myocardial fibrosis is the fundamental approach to preventing hypertensive ventricular remodelling. C1q/TNF-related protein-3 (CTRP3) is closely associated with hypertension. However, the role and mechanism of CTRP3 in hypertensive myocardial fibrosis are unclear. In this study, we aimed to explore the effect of CTRP3 on hypertensive myocardial fibrosis and the potential mechanism.

METHODS AND RESULTS

WKY and SHR rats were employed, blood pressure, body weight, heart weight, H/BW were measured, and fibrotic-related proteins, CTRP3 and Collagen I were tested in myocardium at 12 and 20 weeks by immunohistochemical staining and Western blotting, respectively. The results showed that compared with the WKY, SBP, DBP, mean arterial pressure and heart rate (HR) were all significantly increased in SHR at 12 and 20 weeks, while heart weight and H/BW were only increased at 20 weeks. Meanwhile, CTRP3 decreased, while Collagen I increased significantly in the SHR rat myocardium at 20 weeks, which compared to the WKY. Moreover, the expression of α-SMA increased from 12 weeks, Collagen I/III and MMP2/9 increased and TIMP-2 decreased until 20 weeks. In order to explore the function and mechanism of CTRP3 in hypertensive fibrosis, Angiotensin II (Ang II) was used to induce hypertension in primary neonatal rat cardiac fibroblasts in vitro . CTRP3 significantly inhibited the Ang II induced activation of fibrotic proteins, purinergic 2X7 receptor (P2X7R)-NLRP3 inflammasome pathway. The P2X7R agonist BzATP significantly exacerbated Ang II-induced NLRP3 inflammasome activation, which was decreased by the P2X7R antagonists A43079, CTRP3 and MCC950.

CONCLUSION

CTRP3 expression was decreased in the myocardium of SHR rats, and exogenous CTRP3 inhibited Ang II-induced fibrosis in cardiac fibroblasts by regulating the P2X7R-NLRP3 inflammasome pathway, suggesting that CTRP3 is a potential drug for alleviating myocardial fibrosis in hypertensive conditions.

Novel tumor-associated macrophage populations and subpopulations by single cell RNA sequencing

Tumor-associated macrophages (TAMs) are present in almost all solid tumor tissues. 16They play critical roles in immune regulation, tumor angiogenesis, tumor stem cell activation, tumor invasion and metastasis, and resistance to therapy. However, it is unclear how TAMs perform these functions. With the application of single-cell RNA sequencing (scRNA-seq), it has become possible to identify TAM subpopulations associated with distinct functions. In this review, we discuss four novel TAM subpopulations in distinct solid tumors based on core gene signatures by scRNA-seq, including FCN1 +, SPP1 +, C1Q + and CCL18 + TAMs. Functional enrichment and gene expression in scRNA-seq data from different solid tumor tissues found that FCN1 + TAMs may induce inflammation; SPP1 + TAMs are potentially involved in metastasis, angiogenesis, and cancer cell stem cell activation, whereas C1Q + TAMs participate in immune regulation and suppression; And CCL18 + cells are terminal immunosuppressive macrophages that not only have a stronger immunosuppressive function but also enhance tumor metastasis. SPP1 + and C1Q + TAM subpopulations can be further divided into distinct populations with different functions. Meanwhile, we will also present emerging evidence highlighting the separating macrophage subpopulations associated with distinct functions. However, there exist the potential disconnects between cell types and subpopulations identified by scRNA-seq and their actual function.

A distinct variant of the SzM protein of Streptococcus equi subsp. zooepidemicus recruits C1q independent of IgG binding and inhibits activation of the classical complement pathway

Streptococcus equi subsp. zooepidemicus (SEZ) is a major equine pathogen that causes pneumonia, abortion, and polyarthritis. It can also cause invasive infections in humans. SEZ expresses the M-like protein SzM, which recruits host proteins such as fibrinogen to the bacterial surface. Equine SEZ strain C2, which binds only comparably low amounts of human fibrinogen in comparison to human SEZ strain C33, was previously shown to proliferate in equine and human blood. As the expression of SzM_C2 was necessary for survival in blood, this study investigated the working hypothesis that SzM_C2 inhibits complement activation through a mechanism other than fibrinogen and non-immune immunoglobulin binding. Loss-of-function experiments showed that SEZ C2, but not C33, binds C1q via SzM in IgG-free human plasma. Furthermore, SzM C2 expression is necessary for recruiting purified human or equine C1q to the bacterial surface. Flow cytometry analysis demonstrated that SzM expression in SEZ C2 is crucial for the significant reduction of C3b labelling in human plasma. Addition of human plasma to immobilized rSzM_C2 and immobilized aggregated IgG led to binding of C1q, but only the latter activated the complement system, as shown by the detection of C4 deposition. Complement activation induced by aggregated IgG was significantly reduced if human plasma was pre-incubated with rSzM_C2. Furthermore, rSzM_C2, but not rSzM_C33, inhibited the activation of the classical complement pathway in human plasma, as determined in an erythrocyte lysis experiment. In conclusion, the immunoglobulin-independent binding of C1q to SzM_C2 is associated with complement inhibition.

Responses of multifunctional immune complement component 1q (C1q) and apoptosis-related genes in Macrophthalmus japonicus tissues and human cells following exposure to environmental pollutants

Apoptosis is a key defense process for multiple immune system functions, playing a central role in maintaining homeostasis and cell development. The purpose of this study was to evaluate the effects of environmental pollutant exposure on immune-related apoptotic pathways in crab tissues and human cells. To do this, we characterized the multifunctional immune complement component 1q (C1q) gene and analyzed C1q expression in Macrophthalmus japonicus crabs after exposure to di(2-ethylhexyl) phthalate (DEHP) or hexabromocyclododecanes (HBCDs). Moreover, the responses of apoptotic signal-related genes were observed in M. japonicus tissues and human cell lines (HEK293T and HCT116). C1q gene expression was downregulated in the gills and hepatopancreas of M. japonicus after exposure to DEHP or HBCD. Pollutant exposure also increased antioxidant enzyme activities and altered transcription of 15 apoptotic signaling genes in M. japonicus. However, patterns in apoptotic signaling in response to these pollutants differed in human cells. HBCD exposure generated an apoptotic signal (cleaved caspase-3) and inhibited cell growth in both cell lines, whereas DEHP exposure did not produce such a response. These results suggest that exposure to environmental pollutants induced different levels of immune-related apoptosis depending on the cell or tissue type and that this induction of apoptotic signaling may trigger an initiation of carcinogenesis in M. japonicus and in humans as consumers.

Complement C1q essential for aeroallergen sensitization via CSF1R+ conventional dendritic cells type 2

BACKGROUND

Dendritic cells (DCs) are heterogeneous, comprising multiple subsets with unique functional specifications. Our previous work has demonstrated that the specific conventional type 2 DC subset, CSF1R+cDC2s, plays a critical role in sensing aeroallergens.

OBJECTIVE

It remains to be understood how CSF1R+cDC2s recognize inhaled allergens. We sought to elucidate the transcriptomic programs and receptor-ligand interactions essential for function of this subset in allergen sensitization.

METHODS

We applied single-cell RNA sequencing to mouse lung DCs. Conventional DC-selective knockout mouse models were employed, and mice were subjected to inhaled allergen sensitization with multiple readouts of asthma pathology. Under the clinical arm of this work, human lung transcriptomic data were integrated with mouse data, and bronchoalveolar lavage (BAL) specimens were collected from subjects undergoing allergen provocation, with samples assayed for C1q.

RESULTS

We found that C1q is selectively enriched in lung CSF1R+cDC2s, but not in other lung cDC2 or cDC1 subsets. Depletion of C1q in conventional DCs significantly attenuates allergen sensing and features of asthma. Additionally, we found that C1q binds directly to human dust mite allergen, and the C1q receptor CD91 (LRP1) is required for lung CSF1R+cDC2s to recognize the C1q-allergen complex and induce allergic lung inflammation. Lastly, C1q is enriched in human BAL samples following subsegmental allergen challenge, and human RNA sequencing data demonstrate close homology between lung IGSF21+DCs and mouse CSF1R+cDC2s.

CONCLUSIONS

C1q is secreted from the CSF1R+cDC2 subset among conventional DCs. Our data indicate that the C1q-LRP1 axis represents a candidate for translational therapeutics in the prevention and suppression of allergic lung inflammation.

Mapping and targeting of C1ql1-expressing cells in the mouse

The C1Q complement protein C1QL1 is highly conserved in mammals where it is expressed in various tissues including the brain. This secreted protein interacts with Brain-specific Angiogenesis Inhibitor 3, BAI3/ADGRB3, and controls synapse formation and maintenance. C1ql1 is expressed in the inferior olivary neurons that send projections to cerebellar Purkinje cells, but its expression in the rest of the brain is less documented. To map C1ql1 expression and enable the specific targeting of C1ql1-expressing cells, we generated a knockin mouse model expressing the Cre recombinase under the control of C1ql1 regulatory sequences. We characterized the capacity for Cre-driven recombination in the brain and mapped Cre expression in various neuron types using reporter mouse lines. Using an intersectional strategy with viral particle injections, we show that this mouse line can be used to target specific afferents of Purkinje cells. As C1ql1 is also expressed in other regions of the brain, as well as in other tissues such as adrenal glands and colon, our mouse model is a useful tool to target C1ql1-expressing cells in a broad variety of tissues.

TREM2 receptor protects against complement-mediated synaptic loss by binding to complement C1q during neurodegeneration

Triggering receptor expressed on myeloid cells 2 (TREM2) is strongly linked to Alzheimer's disease (AD) risk, but its functions are not fully understood. Here, we found that TREM2 specifically attenuated the activation of classical complement cascade via high-affinity binding to its initiator C1q. In the human AD brains, the formation of TREM2-C1q complexes was detected, and the increased density of the complexes was associated with lower deposition of C3 but higher amounts of synaptic proteins. In mice expressing mutant human tau, Trem2 haploinsufficiency increased complement-mediated microglial engulfment of synapses and accelerated synaptic loss. Administration of a 41-amino-acid TREM2 peptide, which we identified to be responsible for TREM2 binding to C1q, rescued synaptic impairments in AD mouse models. We thus demonstrate a critical role for microglial TREM2 in restricting complement-mediated synaptic elimination during neurodegeneration, providing mechanistic insights into the protective roles of TREM2 against AD pathogenesis.

Complement is activated by elevated IgG3 hexameric platforms and deposits C4b onto distinct antibody domains

IgG3 is unique among the IgG subclasses due to its extended hinge, allotypic diversity and enhanced effector functions, including highly efficient pathogen neutralisation and complement activation. It is also underrepresented as an immunotherapeutic candidate, partly due to a lack of structural information. Here, we use cryoEM to solve structures of antigen-bound IgG3 alone and in complex with complement components. These structures reveal a propensity for IgG3-Fab clustering, which is possible due to the IgG3-specific flexible upper hinge region and may maximise pathogen neutralisation by forming high-density antibody arrays. IgG3 forms elevated hexameric Fc platforms that extend above the protein corona to maximise binding to receptors and the complement C1 complex, which here adopts a unique protease conformation that may precede C1 activation. Mass spectrometry reveals that C1 deposits C4b directly onto specific IgG3 residues proximal to the Fab domains. Structural analysis shows this to be caused by the height of the C1-IgG3 complex. Together, these data provide structural insights into the role of the unique IgG3 extended hinge, which will aid the development and design of upcoming immunotherapeutics based on IgG3.

CX3CR1+ Macrophage Facilitates the Resolution of Allergic Lung Inflammation via Interacting CCL26

Rationale: The resolution of inflammation is an active process coordinated by mediators and immune cells to restore tissue homeostasis. However, the mechanisms for resolving eosinophilic allergic lung inflammation triggered by inhaled allergens have not been fully elucidated. Objectives: Our objectives were to investigate the cellular mechanism of tissue-resident macrophages involved in the resolution process of eosinophilic lung inflammation. Methods: For the study, we used the institutional review board-approved protocol for human subsegmental bronchoprovocation with allergen, mouse models for allergic lung inflammation, and novel transgenic mice, including a conditional CCL26 knockout. The samples were analyzed using mass cytometry, single-cell RNA sequencing, and biophysical and immunological analyses. Measurements and Main Results: We compared alveolar macrophage (AM) subsets in the BAL before and after allergen provocation. In response to provocation with inhaled allergens, the subsets of AMs are dynamically changed in humans and mice. In the steady state, the AM subset expressing CX3CR1 is a relatively small fraction in bronchoalveolar space and lung tissue but drastically increases after allergen challenges. This subset presents unique patterns of gene expression compared with classical AMs, expressing high C1q family genes. CX3CR1+ macrophages are activated by airway epithelial cell-derived CCL26 via a receptor-ligand interaction. The binding of CCL26 to the CX3CR1+ receptor induces CX3CR1+ macrophages to secrete C1q, subsequently facilitating the clearance of eosinophils. Furthermore, the depletion of CX3CR1 macrophages or CCL26 in airway epithelial cells delays the resolution of allergic lung inflammation displaying prolonged tissue eosinophilia. Conclusions: These findings indicate that the CCL26-CX3CR1 pathway is pivotal in resolving eosinophilic allergic lung inflammation.

C1q/TNF-related protein 3 alleviates heart failure via attenuation of oxidative stress in myocardial infarction rats

C1q-tumor necrosis factor-related protein 3 (CTRP3), an adipokine, has been reported to be closely related to cardiovascular diseases (CVDs). However, the effect of CTRP3 on heart failure (HF) remains dimness. This study was to explore the role of CTRP3 in HF and its potential interaction mechanism. Heart failure model was established by inducing ischemia myocardial infarction (MI) through ligation of the left anterior descending artery in Sprague-Dawley rats. Four weeks later, the rats were detected by transthoracic echocardiography and masson staining. Atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), cardiac troponin I (cTnI) levels, creatine kinase-MB (CK-MB) and oxidative stress levels were recorded. The level of CTRP3 was reduced in the cardiomyocytes (CMs) treated with oxygen-glucose deprivation (OGD) and in the heart of MI rats. CTRP3 overexpression alleviated cardiac dysfunction, attenuated the cardiac fibrosis, and inhibited the increases of ANP, BNP, cTnI and CK-MB in the serum of MI rats. The increases of ANP and BNP in the CMs, and the collagen I and collagen III in the cardiac fibroblasts (CFs) induced by OGD were inhibited by CTRP3 overexpression. The enhancement of oxidative stress in the heart of MI rats was inhibited by CTRP3 overexpression. These results indicated that overexpression of CTRP3 could improve cardiac function and the related cardiac fibrosis in MI-induced HF rats via inhibition of oxidative stress. Upregulation of CTRP3 may be a strategy for HF therapy in the future.

The neuronal pentraxin Nptx2 regulates complement activity and restrains microglia-mediated synapse loss in neurodegeneration

Complement overactivation mediates microglial synapse elimination in neurological diseases such as Alzheimer's disease (AD) and frontotemporal dementia (FTD), but how complement activity is regulated in the brain remains largely unknown. We identified that the secreted neuronal pentraxin Nptx2 binds complement C1q and thereby regulates its activity in the brain. Nptx2-deficient mice show increased complement activity, C1q-dependent microglial synapse engulfment, and loss of excitatory synapses. In a neuroinflammation culture model and in aged TauP301S mice, adeno-associated virus (AAV)-mediated neuronal overexpression of Nptx2 was sufficient to restrain complement activity and ameliorate microglia-mediated synapse loss. Analysis of human cerebrospinal fluid (CSF) samples from a genetic FTD cohort revealed reduced concentrations of Nptx2 and Nptx2-C1q protein complexes in symptomatic patients, which correlated with elevated C1q and activated C3. Together, these results show that Nptx2 regulates complement activity and microglial synapse elimination in the brain and that diminished Nptx2 concentrations might exacerbate complement-mediated neurodegeneration in patients with FTD.

Blockade of Type 2A Protein Phosphatase Signaling Attenuates Complement C1q-Mediated Microglial Phagocytosis of Glutamatergic Synapses Induced by Amyloid Fibrils

We previously reported the critical involvement of metabotropic GluR1 (mGluR1) signaling in complement C1q-dependent microglial phagocytosis of glutamatergic synapses in a rat model of Alzheimer's disease (AD) injected with amyloid fibrils. Here, we explored the role of type 2A protein phosphatase (type 2A PPase), a key enzyme downstream of mGluR1 signaling, in the pathogenesis of AD in rats. Significant local upregulation of PP2A expression was observed in the hippocampal CA1 after bilateral microinjection of amyloid-beta (Aβ1-40) fibrils. Amyloid fibrils induced remarkable dephosphorylation of pFMRP (fragile X mental retardation protein) and C1q upregulation in hippocampal glutamatergic synapses, which was ameliorated by microinjection of type 2A PPase inhibitor okadaic acid (OA). Microinjection of OA further attenuated the microglial phagocytosis of glutamatergic synapses, recovered the hippocampal glutamatergic transmission, and improved the performance in Morris water maze test. These findings demonstrated that dysfunction of type 2A PPase signaling contributed to complement C1q-dependent microglial phagocytosis of glutamatergic synapses and the cognitive impairments in the rat model of AD.

The immune-metabolic crosstalk between CD3+C1q+TAM and CD8+T cells associated with relapse-free survival in HCC

Introduction

Although multiple targeted treatments have appeared, hepatocellular carcinoma (HCC) is still one of the most common causes of cancer-related deaths. The immunosuppressive tumor microenvironment (TME) is a critical factor in the oncogenesis and progression of HCC. The emerging scRNA-seq makes it possible to explore the TME at a high resolution. This study was designed to reveal the immune-metabolic crosstalk between immune cells in HCC and provide novel strategies to regulate immunosuppressive TME.

Method

In this study, we performed scRNA-seq on paired tumor and peri-tumor tissues of HCC. The composition and differentiation trajectory of the immune populations in TME were portrayed. Cellphone DB was utilized to calculate interactions between the identified clusters. Besides, flow cytometry, RT-PCR and seahorse experiments were implemented to explore potential metabolic and epigenetic mechanisms of the inter-cellular interaction.

Result

A total of 19 immune cell clusters were identified and 7 were found closely related to HCC prognosis. Besides, differentiation trajectories of T cells were also presented. Moreover, a new population, CD3+C1q+ tumor-associated macrophages (TAM) were identified and found significantly interacted with CD8+ CCL4+T cells. Compared to the peri-tumor tissue, their interaction was attenuated in tumor. Additionally, the dynamic presence of this newly found cluster was also verified in the peripheral blood of patients with sepsis. Furthermore, we found that CD3+C1q+TAM affected T cell immunity through C1q signaling-induced metabolic and epigenetic reprogramming, thereby potentially affecting tumor prognosis.

Conclusion

Our study revealed the interaction between CD3+C1q+TAM and CD8+ CCL4+T cells and may provide implications for tackling the immunosuppressive TME in HCC.

C1q and Tumor Necrosis Factor Related Protein 9 Protects from Diabetic Cardiomyopathy by Alleviating Cardiac Insulin Resistance and Inflammation

(1) Background: Diabetic cardiomyopathy is a major health problem worldwide. CTRP9, a secreted glycoprotein, is mainly expressed in cardiac endothelial cells and becomes downregulated in mouse models of diabetes mellitus; (2) Methods: In this study, we investigated the impact of CTRP9 on early stages of diabetic cardiomyopathy induced by 12 weeks of high-fat diet; (3) Results: While the lack of CTRP9 in knock-out mice aggravated insulin resistance and triggered diastolic left ventricular dysfunction, AAV9-mediated cardiac CTRP9 overexpression ameliorated cardiomyopathy under these conditions. At this early disease state upon high-fat diet, no fibrosis, no oxidative damage and no lipid deposition were identified in the myocardium of any of the experimental groups. Mechanistically, we found that CTRP9 is required for insulin-dependent signaling, cardiac glucose uptake in vivo and oxidative energy production in cardiomyocytes. Extensive RNA sequencing from myocardial tissue of CTRP9-overexpressing and knock-out as well as respective control mice revealed that CTRP9 acts as an anti-inflammatory mediator in the myocardium. Hence, CTRP9 knock-out exerted more, while CTRP9-overexpressing mice showed less leukocytes accumulation in the heart during high-fat diet; (4) Conclusions: In summary, endothelial-derived CTRP9 plays a prominent paracrine role to protect against diabetic cardiomyopathy and might constitute a therapeutic target.

A C1q domain-containing protein in Pinctada fucata contributes to the innate immune response and elimination of the pathogen

The C1q domain-containing proteins (C1qDCs) in bivalve mollusks primarily exist as the globular head C1q proteins (ghC1qs), for the N-terminal collagen domains were very rare in bivalves, although widespread in C1qDCs of vertebrates. In this work, the C1qDC protein with only a ghC1q domain (named as Pf-ghC1q) was identified from Pinctada fucata, and molecular characterization, gene expression, and functional studies were also conducted. The full-length cDNA sequence of Pf-ghC1q was 738 bp long, containing a signal peptide of 23 residues encoded. Pf-ghC1q was clustered with some C1qDCs from other invertebrates in the phylogenetic tree analysis, rather than vertebrates. Pf-ghC1q was detected in all tested tissues, including the mantle, hemocyte, digestive gland, gill, and adductor muscle. Moreover, the expression levels of Pf-ghC1q were up-regulated in all tested tissues after the challenge with Vibrio alginolyticus 4 h later. The expression level of Pf-ghC1q was inhibited by specific si-276, and the low level of Pf-ghC1q affected the phagocytosis efficiency of V. alginolyticus by hemocytes. These results indicated that Pf-ghC1q may participate in the target recognition of V. alginolyticus and the phagocytosis process in the immune response of P. fucata.

Complement C1s as a diagnostic marker and therapeutic target: Progress and propective

The molecules of the complement system connect the effectors of innate and adaptive immunity and play critical roles in maintaining homeostasis. Among them, the C1 complex, composed of C1q, C1r, and C1s (C1qr₂s₂), is the initiator of the classical complement activation pathway. While deficiency of C1s is associated with early-onset systemic lupus erythematosus and increased susceptibility to bacteria infections, the gain-of- function variants of C1r and C1s may lead to periodontal Ehlers Danlos syndrome. As C1s is activated under various pathological conditions and associated with inflammation, autoimmunity, and cancer development, it is becoming an informative biomarker for the diagnosis and treatment of a variety of diseases. Thus, more sensitive and convenient methods for assessing the level as well as activity of C1s in clinic samples are highly desirable. Meanwhile, a number of small molecules, peptides, and monoclonal antibodies targeting C1s have been developed. Some of them are being evaluated in clinical trials and one of the antibodies has been approved by US FDA for the treatment of cold agglutinin disease, an autoimmune hemolytic anemia. In this review, we will summarize the biological properties of C1s, its association with development and diagnosis of diseases, and recent progress in developing drugs targeting C1s. These progress illustrate that the C1s molecule is an effective biomarker and promising drug target.

CTRP1 prevents high fat diet-induced obesity and improves glucose homeostasis in obese and STZ-induced diabetic mice

BACKGROUND

C1q/tumor necrosis factor-related protein 1 (CTRP1) is an adipokine secreted by adipose tissue, related to chondrocyte proliferation, inflammation, and glucose homeostasis. However, the therapeutic effects on metabolic disorders and the underlying mechanism were unclear. Here, we investigated the functions and mechanisms of CTRP1 in treating obesity and diabetes.

METHODS

The plasmid containing human CTRP1 was delivered to mice by hydrodynamic injection, which sustained expression of CTRP1 in the liver and high protein level in the blood. High-fat diet (HFD) fed mice and STZ-induced diabetes model were used to study the effects of CTRP1 on obesity, glucose homeostasis, insulin resistance, and hepatic lipid accumulation. The lipid accumulation in liver and adipose tissue, glucose tolerance, insulin sensitivity, food intake, and energy expenditure were detected by H&E staining, Oil-Red O staining, glucose tolerance test, insulin tolerance test, and metabolic cage, respectively. The metabolic-related genes and signal pathways were determined using qPCR and western blotting.

RESULTS

With high blood circulation, CTRP1 prevented obesity, hyperglycemia, insulin resistance, and fatty liver in HFD-fed mice. CTRP1 also improved glucose metabolism and insulin resistance in obese and STZ-induced diabetic mice. The metabolic cage study revealed that CTRP1 reduced food intake and enhanced energy expenditure. The mechanistic study demonstrated that CTRP1 upregulated the protein level of leptin in blood, thermogenic gene expression in brown adipose tissue, and the gene expression responsible for lipolysis and glycolysis in white adipose tissue (WAT). CTRP1 also downregulated the expression of inflammatory genes in WAT. Overexpression of CTRP1 activated AMPK and PI3K/Akt signaling pathways and inhibited ERK signaling pathway.

CONCLUSION

These results demonstrate that CTRP1 could improve glucose homeostasis and prevent HFD-induced obesity and fatty liver through upregulating the energy expenditure and reducing food intake, suggesting CTRP1 may serve as a promising target for treating metabolic diseases.

[C1q or IgA deposition in glomeruli of children with primary membranous nephropathy]

Objective: To assess the correlation of glomerular C1q or IgA deposition with clinical and pathological features of primary membranous nephropathy (PMN) in children. Methods: The clinical and pathological manifestations including (phospholipase A2 receptor, PLA2R) and IgG subclasses staining in renal biopsies, serum anti-PLA2R antibody and therapeutic response of 33 children diagnosed with PMN in Peking University First Hospital from December 2012 to December 2020 were retrospectively summarized and analyzed. According to results of PLA2R test and findings renal pathological, the patients were divided into PLA2R-related group and non-PLA2R-related group, typical MN group and atypical MN group, C1q deposit group and non-C1q deposit group, as well as IgA deposit group and non-IgA deposit group respectively. T-test, Mann-Whitney U test and Fisher's exact probability test were used for comparison between the groups. Results: Among the 33 children with PMN, there were 20 males and 13 females, of that the age of onset was 11 (8, 13) years, and 32 patients had nephrotic level proteinuria. Renal biopsies were performed at 4.6 (2.1, 11.6) months after onset, and 28 patients (85%) received glucocorticoid or immunosuppressive therapy prior to renal biopsy. There were 20 cases (61%) with PLA2R-related MN and 13 cases (39%) with non-PLA2R-related MN. Compared with the non-PLA2R-related group, the PLA2R-related group had an older age of onset (12 (10, 13) vs. 7 (3, 12) years, Z=-2.52, P=0.011), a lower preceding infection rate (45% (9/20) vs. 11/13, P=0.032) and lower spontaneous remission rate (0 vs. 4/13, P=0.017). Renal PLA2R positivity was significantly associated with predominant or co-deposition of IgG4 (13/17 vs. 5/15, P=0.031) and low albumin levels at renal biopsy ((25±6) vs. (29±7) g/L, t=2.14, P=0.041). There were 12 patients with typical PMN and 21 patients with atypical PMN, and no significant difference in clinical and pathological manifestations was found between these 2 groups (all P>0.05). There were 10 cases (32.3%) with glomerular C1q deposition, and their disease course before renal biopsy was significantly shorter than those without C1q deposition (1.8 (0.8, 5.9) vs. 6.0 (2.5, 22.3) months, Z=-2.27, P=0.023). Twelve cases (36.4%) had glomerular IgA deposition, and their course of disease,clinical and pathological manifestations were not significantly different from those without IgA deposition (all P>0.05). Conclusion: Glomerular C1q or IgA deposition may not affect the clinical manifestations, glomerular PLA2R and IgG subclasses staining pattern, or the response to treatment of PMN in children.

Prevention of intrauterine fetal growth restriction by administrating C1q/TNF-related protein 6, a specific inhibitor of the alternative complement pathway

PURPOSE

The latest treatments do not sufficiently prevent miscarriage and fetal growth restriction (FGR) in pregnant women. Here, we assessed the effects of a human protein, CTRP6, that specifically inhibits the activation of the alternative complement pathway on miscarriage, fetal and placental development.

METHODS

Pregnant CBA/J mice mated with DBA/2 male mice as a model of spontaneous abortion and FGR were randomly divided into the control and CTRP6 groups. In the CTRP6 group, the mice were intravenously administered CTRP6 on days 4.5 and 6.5 post-conception (dpc). The abortion rate and fetal and placental weights on 14.5 dpc were examined. Remodeling of the spiral artery was also assessed.

RESULTS

The abortion rate in the CTRP6 group (13%) was reduced compared to the control group (21%), but there was no statistical difference. The placental and fetal weights in the CTRP6 group were also heavier than those in the control (P < 0.05). Moreover, the thickness of the blood vessel wall in the CTRP6 group was significantly thinner than that in the control (P < 0.05) and comparable to that in the non-abortion model (CBA/J x BALB). The ratio of the inner-per-the-outer diameter of the spiral artery increased more in the CTRP6 group than that in the control (P < 0.05). As well, the Th1/Th2 cytokine ratio was significantly reduced by CTRP6 treatment.

CONCLUSIONS

Taken together, the supplementation with a protein that regulates the alternative complement pathway in vivo improves FGR and promotes spiral artery remodeling in a mouse model of miscarriage and FGR.

Crosstalk between CD93, C1q and GIPC in the Regulation of Pneumococcal Meningitis Inflammation

OBJECTIVE

Pneumococcal meningitis is a common and serious infectious disease that threatens human health worldwide. Recent studies have shown that various regulatory proteins of the immune system may be potential targets for adjuvant therapy. The aim of this study was to investigate CD93 expression and potential signaling pathways in rat models of pneumococcal meningitis.

METHODS

The levels of sCD93 (soluble CD93), IL-6 (Interleukin-6) and TNF-α (tumor necrosis factor-α) in cerebrospinal fluid were assessed by ELISA, and the levels of iNOS (inducible nitric oxide synthase), CD93, complement C1q, and GIPC (C-terminal of the regulator of G protein signaling-G alpha interacting protein) in the brain tissue were evaluated by Western Blotting. The interaction between CD93 and complement C1q was investigated by co-immunoprecipitation, and the interaction between CD93 and GIPC was detected by immunofluorescence colocalization.

RESULTS

Our results showed a significant increase in the levels of IL-6, TNF-α, sCD93, CD93, complement C1q, GIPC, and iNOS in the Streptococcus pneumoniae infection group. CD93 interacted with complement C1q, and CD93 and GIPC colocalized on the cell membrane of the cerebral cortex.

CONCLUSIONS

This study suggests that CD93 may be a new inflammatory factor in pneumococcal meningitis. C1q and GIPC may mediate downstream signaling pathways of CD93 in pneumococcal meningitis.

[Effect of electroacupuncture on complement C1q and microglia phagocytosis in hippocampus of SAMP8 mice]

OBJECTIVE

To observe the effect of electroacupuncture (EA) on the expression of Iba-1, complement C1q and CD68 in hippocampus of SAMP8 mice, so as to explore its mechanisms underlying improvement of Alzheimer's disease (AD).

METHODS

Twenty-four male SAMP8 mice were randomly and equally divided into model and EA groups, and 12 SAMR1 mice were used as the control group. EA (2 Hz, 1.5-2.0 mA) was applied to "Baihui" (GV20), "Dazhui"(GV14) and "Shen-shu"(BL23) for 20 min once daily in the EA group, each course of treatment was 8 days, with an interval of 2 days between two courses, and the mice were treated for 3 courses. Morris water maze test was performed to assess the learning-memory ability of mice. The positive expression levels of Iba-1 and CD68 proteins in the hippocampus CA1 region were detected by immunohistochemistry. The mRNA and protein expression levels of Iba-1,C1q and CD68 in the hippocampus were detected by real-time PCR and Western blot, separately.

RESULTS

Compared with the control group, the average escape latency of Morris water maze test was prolonged in the model group (P<0.01), duration of swimming in the original platform quadrant and the number of original platform crossing were significantly shorter and decreased respectively (P<0.01). Compared with the model group, the average escape latency in the EA group was shortened (P<0.05, P<0.01), the duration of swimming in the original platform quadrant and the number of original platform crossing were significantly prolonged and increased (P<0.01). The immunoactivity of Iba-1 and CD68 in hippocampal CA1 region, and mRNA and protein expression levels of hippocampal Iba-1,C1q and CD68 were significantly up-regulated in the model group in contrast to the control group (P<0.01, P<0.05), and obviously down-regulated except the mRNA expression level of hippocampal Iba-1 in the EA group relevant to the model group (P<0.01, P<0.05).

CONCLUSION

EA can improve the learning and memory ability of SAMP8 mice, which may be associated with its effect in inhibiting of complement C1q-dependent microglial phagocytosis in the hippocampus.

Plasma Complement C1q/tumor necrosis factor-related protein 15 concentration is associated with polycystic ovary syndrome

Polycystic ovarian syndrome (PCOS) is a common poignant endocrine disorder affecting women, posing a close association with metabolic syndrome and obesity. Existing literature characterizes PCOS with deranged levels of several adipokines and myokines. CTRP15 is a paralogue of adiponectin, mainly expressed by skeletal muscles, and plays a key role in insulin, glucose, and lipid metabolism. In the current study, we aim to determine the circulating levels of CTRP15 and evaluate its association with cardiometabolic and inflammatory parameters in PCOS women. This case-control study included 120 PCOS patients (60 Recurrent pregnancy loss (RPL) and 60 infertile (inf) PCOS) and 60 healthy non-PCOS controls. Serum levels of hs-CRP were measured by commercial kits, while serum levels of adiponectin and CTRP15 were determined using the ELISA technique. Serum levels of CTRP15 were significantly elevated in PCOS-RPL and PCOS-inf subgroups when compared to controls (94.80 ± 27.08 and 87.77 ± 25.48 vs. 54.78 ± 15.45, both P < 0.001). Moreover, serum adiponectin was considerably lower in the PCOS group and subgroups (P < 0.001), while serum hs-CRP, fasting insulin, HOMA-IR, and free testosterone were significantly higher when compared to the non-PCOS group (P < 0.05). Furthermore, CTRP15 closely associated with FSH, HOMA-IR, hs-CRP, and BMI. These results highlight a possible involvement of CTRP15 in the pathogenesis of PCOS. The elevated levels of CTRP15 might be a compensatory mechanism for the metabolic dysregulations (excess adiposity, insulin resistance, metaflammation) associated with the syndrome. Nevertheless, future studies are necessary to unravel the underlying mechanism.

Effect of rottlerin on astrocyte phenotype polarization after trimethyltin insult in the dentate gyrus of mice

BACKGROUND

It has been demonstrated that reactive astrocytes can be polarized into pro-inflammatory A1 phenotype or anti-inflammatory A2 phenotype under neurotoxic and neurodegenerative conditions. Microglia have been suggested to play a critical role in astrocyte phenotype polarization by releasing pro- and anti-inflammatory mediators. In this study, we examined whether trimethyltin (TMT) insult can induce astrocyte polarization in the dentate gyrus of mice, and whether protein kinase Cδ (PKCδ) plays a role in TMT-induced astrocyte phenotype polarization.

METHODS

Male C57BL/6 N mice received TMT (2.6 mg/kg, i.p.), and temporal changes in the mRNA expression of A1 and A2 phenotype markers were evaluated in the hippocampus. In addition, temporal and spatial changes in the protein expression of C3, S100A10, Iba-1, and p-PKCδ were examined in the dentate gyrus. Rottlerin (5 mg/kg, i.p. × 5 at 12-h intervals) was administered 3-5 days after TMT treatment, and the expression of A1 and A2 transcripts, p-PKCδ, Iba-1, C3, S100A10, and C1q was evaluated 6 days after TMT treatment.

RESULTS

TMT treatment significantly increased the mRNA expression of A1 and A2 phenotype markers, and the increased expression of A1 markers remained longer than that of A2 markers. The immunoreactivity of the representative A1 phenotype marker, C3 and A2 phenotype marker, S100A10 peaked 6 days after TMT insult in the dentate gyrus. While C3 was expressed evenly throughout the dentate gyrus, S100A10 was highly expressed in the hilus and inner molecular layer. In addition, TMT insult induced microglial p-PKCδ expression. Treatment with rottlerin, a PKCδ inhibitor, decreased Iba-1 and C3 expression, but did not affect S100A10 expression, suggesting that PKCδ inhibition attenuates microglial activation and A1 astrocyte phenotype polarization. Consistently, rottlerin significantly reduced the expression of C1q and tumor necrosis factor-α (TNFα), which has been suggested to be released by activated microglia and induce A1 astrocyte polarization.

CONCLUSION

We demonstrated the temporal and spatial profiles of astrocyte polarization after TMT insult in the dentate gyrus of mice. Taken together, our results suggest that PKCδ plays a role in inducing A1 astrocyte polarization by promoting microglial activation and consequently increasing the expression of pro-inflammatory mediators after TMT insult.

Deficiency of C1QL1 Reduced Murine Ovarian Follicle Reserve Through Intraovarian and Endocrine Control

Ovarian aging is associated with depletion of the ovarian follicle reserve, which is the key determinant of fertility potential in females. In this study, we found that the small, secreted protein complement 1Q-like (C1QL1) is involved in the regulation of follicle depletion through intraovarian and endocrine control in a multidimensional collaborative manner. C1ql1 was detected to be conserved in the ovary and showed high transcript levels during folliculogenesis. Blockade of C1QL1 by IP and ovarian intrabursal injection of C1QL1 antiserum into prepubertal mice impaired folliculogenesis accompanied by reductions in body weight, fat mass, and intraovarian lipid accumulation. An elevation of circulating estradiol levels, reduction of hypothalamic KISS1 and GnRH expression, and a decrease in serum FSH levels were found in C1QL1-deficient mice. In C1QL1-deficient ovaries, many primordial follicles were recruited and developed into medium follicles but underwent atresia at the large follicle stages, which resulted in depletion of follicle reserve. Depletion of C1QL1 alleviated the inhibitory effect of C1QL1 on granulosa cell apoptosis and the stimulatory effect of C1QL1 on granulosa cell autophagy, which resulted in accumulation in the preantral and early antral follicles and an increase in the atretic follicles. The abnormal profile of endocrine hormones accelerated the intraovarian effect of C1QL1 deficiency and further led to depletion of ovarian reserve. Altogether, this study revealed the expression patterns and the mechanism of action of C1QL1 during folliculogenesis and demonstrated that deficiency of C1QL1 caused ovarian follicular depletion.

Distinct Roles of Classical and Lectin Pathways of Complement in Preeclamptic Placentae

Pre-eclampsia is a pregnancy complication characterized by defective vascular remodeling in maternal decidua responsible for reduced blood flow leading to functional and structural alterations in the placenta. We have investigated the contribution of the complement system to decidual vascular changes and showed that trophoblasts surrounding unremodeled vessels prevalent in preeclamptic decidua fail to express C1q that are clearly detected in cells around remodeled vessels predominant in control placenta. The critical role of C1q is supported by the finding that decidual trophoblasts of female C1qa^-/- pregnant mice mated to C1qa^+/+ male mice surrounding remodeled vessels express C1q of paternal origin. Unlike C1qa^-/- pregnant mice, heterozygous C1qa^+/- and wild type pregnant mice share a high percentage of remodeled vessels. C1q was also found in decidual vessels and stroma of normal placentae and the staining was stronger in preeclamptic placentae. Failure to detect placental deposition of C1r and C1s associated with C1q rules out complement activation through the classical pathway. Conversely, the intense staining of decidual endothelial cells and villous trophoblast for ficolin-3, MASP-1 and MASP-2 supports the activation of the lectin pathway that proceeds with the cleavage of C4 and C3 and the assembly of the terminal complex. These data extend to humans our previous findings of complement activation through the lectin pathway in an animal model of pre-eclampsia and provide evidence for an important contribution of C1q in decidual vascular remodeling.

Activation of complement C1q and C3 in glomeruli might accelerate the progression of diabetic nephropathy: Evidence from transcriptomic data and renal histopathology

AIMS/INTRODUCTION

It is not unclear whether the complement system is involved in the pathogenesis of diabetic nephropathy (DN). We explored the role of the complement system in glomeruli from patients with DN using integrated transcriptomic bioinformatics analysis and renal histopathology.

MATERIALS AND METHODS

Four datasets (GSE30528, GSE104948, GSE96804 and GSE99339) from the Gene Expression Omnibus database were integrated. We used a protein-protein interaction network and the Molecular Complex Detection App to obtain hub genes. Gene ontology and the Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses were carried out to identify significant pathways. We also investigated the associations of C1q and C3 deposition on renal histopathology with clinical data, pathological parameters and renal survival in DN patients.

RESULTS

We identified 47 up- and 48 downregulated genes associated with DN. C3, C1QB and C1QA were found to be complement-related hub genes. The gene ontology and Kyoto Encyclopedia of Genes and Genomes analyses identified complement activation and humoral immune response as the significant oncology terms, with C1QB and C3 positioned at the center of the pathway. Regarding renal histopathology, patients with both C1q and C3 deposition had more severe glomerular classes. Multivariate Cox proportional hazards regression showed that the deposition of glomerular C1q and C3 was an independent risk factor for kidney failure. Patients with high C1q, C3 or C4d expression in glomeruli were more likely to progress to kidney failure, whereas glomerular mannose-binding lectin was rare.

CONCLUSIONS

Complement activation is involved in the development of DN, and activation of the classical complement pathway in glomeruli might accelerate disease progression.

Profibrotic properties of C1q+ interstitial macrophages in silica-induced pulmonary fibrosis in mice

Pulmonary fibrosis (PF) is a progressive fibrotic disease with poor prognosis and suboptimal therapeutic options. Although macrophages have been implicated in PF, the role of macrophage subsets, particularly interstitial macrophages (IMs), remains unknown. We performed a time-series single-cell RNA sequencing analysis of the silica-induced mouse PF model. Among the macrophage subsets in fibrotic lungs, Lyve1lo MHC IIhi IMs increased with fibrosis, and highly expressed profibrotic genes. Additionally, we identified C1q as an IM-specific marker. Experiments with C1q-diphtheria toxin receptor-GFP knock-in (C1qKI) mice revealed that IMs are distributed around fibrotic nodules. Depletion of C1q+ IMs in C1qKI mice decreased activated fibroblasts and epithelial cells; however, bodyweight loss and neutrophil infiltration were exacerbated in silica-induced PF. Collectively, these results suggest that IMs have profibrotic and anti-inflammatory properties and that the selective inhibition of the profibrotic function of IMs without compromising their anti-inflammatory effects is a potential novel therapeutic strategy for PF.

Globular C1q domain-containing protein from Pinctada fucata martensii participates in the immune defense process

The globular C1q domain-containing (C1qDC) protein can recognize a variety of ligands, such as pathogen-associated molecular patterns, and plays an important role in the innate immune response. Our previous studies showed that a novel globular C1q domain-containing protein (PmC1qDC-1) is involved in the damage repair process of pearl oyster shells. However, the function of PmC1qDC-1 in pearl oyster innate immunity remains unknown. In the present study, the high-level structural analysis showed that PmC1qDC-1 was a spherical structure composed of 10 strands and was similar to the AiC1qDC-2 of bay scallop (Argopecten irradians). In situ hybridization indicated that PmC1qDC-1 had strong fluorescence signal in gills. Furthermore, the mRNA expression of PmC1qDC-1 was highly induced at 6-48 h in gill after lipopolysaccharide, peptidoglycan and polyinosinic-polycytidylic acid stimulation. Additionally, we obtained the recombinant protein of PmC1qDC-1 (rPmC1qDC-1) and found that rPmC1qDC-1 had antibacterial activity against Gram-negative (i.e., Pseudomonas aeruginosa, Vibrio parahaemolyticus, Escherichia coli, and Aeromonas hydrophila) and Gram-positive (i.e., Staphylococcus aureus and Bacillus subtilis) bacteria. These results indicated that PmC1qDC-1 might play an important role in the immune response against bacteria and viruses. This study provides clues for further studying the immune defense of Pinctada fucata martensii against pathogens and exploring the evolution of the classic pathway of complement system.

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.

Periodontal Infection Aggravates C1q-Mediated Microglial Activation and Synapse Pruning in Alzheimer's Mice

Periodontitis is a dysbiotic infectious disease that leads to the destruction of tooth supporting tissues. There is increasing evidence that periodontitis may affect the development and severity of Alzheimer's disease (AD). However, the mechanism(s) by which periodontal infection impacts the neurodegenerative process in AD remains unclear. In the present study, using an amyloid precursor protein (APP) knock-in (App KI) AD mouse model, we showed that oral infection with Porphyromonas gingivalis (Pg), a keystone pathogen of periodontitis, worsened behavioral and cognitive impairment and accelerated amyloid beta (Aβ) accumulation in AD mice, thus unquestionably and significantly aggravating AD. We also provide new evidence that the neuroinflammatory status established by AD, is greatly complicated by periodontal infection and the consequential entry of Pg into the brain via Aβ-primed microglial activation, and that Pg-induced brain overactivation of complement C1q is critical for periodontitis-associated acceleration of AD progression by amplifying microglial activation, neuroinflammation, and tagging synapses for microglial engulfment. Our study renders support for the importance of periodontal infection in the innate immune regulation of AD and the possibility of targeting microbial etiology and periodontal treatment to ameliorate the clinical manifestation of AD and lower AD prevalence.

Fc-engineered antibodies with immune effector functions completely abolished

Elimination of the binding of immunoglobulin Fc to Fc gamma receptors (FcγR) is highly desirable for the avoidance of unwanted inflammatory responses to therapeutic antibodies and fusion proteins. Many different approaches have been described in the literature but none of them completely eliminates binding to all of the Fcγ receptors. Here we describe a set of novel variants having specific amino acid substitutions in the Fc region at L234 and L235 combined with the substitution G236R. They show no detectable binding to Fcγ receptors or to C1q, are inactive in functional cell-based assays and do not elicit inflammatory cytokine responses. Meanwhile, binding to FcRn, manufacturability, stability and potential for immunogenicity are unaffected. These variants have the potential to improve the safety and efficacy of therapeutic antibodies and Fc fusion proteins.

C1q inhibits differentiation of oligodendrocyte progenitor cells via Wnt/β-catenin signaling activation in a cuprizone-induced mouse model of multiple sclerosis

Multiple sclerosis (MS) is a chronic central nervous system demyelinating disease of autoimmune originate. Complement C1q, a complex glycoprotein, mediates a variety of immunoregulatory functions considered important in the prevention of autoimmunity. Although we found that the increased serum C1q level was highly associated with the Fazekas scores and T2 lesion volume of MS patients, the effect and mechanism of C1q on demyelination remains unclear. Cluster analysis and protein array results showed that serum Wnt receptors Frizzled-6 and LRP-6 levels in MS patients were both increased, we proposed that C1q may be involved in demyelination via Wnt signaling. The increased C1q protein levels in the serum and brain tissue were confirmed in a cuprizone (CPZ)-induced demyelination mice model. Moreover, CPZ treatment induced significant increase of LRP-6 and Frizzled-6 protein in mice corpus callosum. LRP-6 extra-cellular domain (LRP-6-ECD) level in the serum and cerebrospinal fluid (CSF) of CPZ mice also significantly increased. Knockdown of the subunit C1s of C1 not only substantially attenuated demyelination, promoted M2 microglia polarization and improved neurological function, but inhibited β-catenin expression and its nuclear translocation in oligodendrocyte progenitor cells (OPCs). In vitro, C1s silence reversed the increased level of LRP-6-ECD in the medium and β-catenin expression in OPCs induced by C1q treatment. Meanwhile, inhibition of C1s also markedly lowered the number of EDU positive OPCs, but enhanced the number of CNPase positive oligodendrocyte and the protein of MBP. The present study indicated that C1q was involved in demyelination in response to CPZ in mice by preventing OPC from differentiating into mature oligodendrocyte via Wnt/β-catenin signaling activation.

Clinical relevance of glomerular IgM deposition in patients with lupus nephritis

BACKGROUND

The aim of the study was to investigate the clinical relevance of IgM deposition in patients with lupus nephritis (LN) in a large cohort.

RESULTS

217 patients with renal biopsy-proven active LN were enrolled. The associations between glomerular IgM deposition and clinicopathological parameters were further analyzed. IgM deposition was positively correlated with glomerular C1q and C3 deposition moderately (r = 0.436, P < 0.001; r = 0.408, P < 0.001, respectively), and inversely correlated with plasma levels of C3 and CFH mildly (r =  - 0.138, P = 0.043; r =  - 0.147, P = 0.037, respectively). By multivariate analysis, we found that glomerular IgM deposition independently contributed to glomerular C3 deposition in patients with LN (OR = 2.002, 95% CI 1.295-3.094, P = 0.002). In addition, we also found that patients with IgM 0-2+ had similar plasma CFH levels, but in patients with IgM3+-4+, plasma CFH levels were significantly lower (300.4 ± 155.8 μg/mL vs. 429.9 ± 187.5 μg/mL, P < 0.001). Furthermore, patients with high density of glomerular IgM and low levels of CFH had heavier proteinuria, higher serum creatinine and lower plasma C3 levels (5.7 ± 3.1 g/d vs. 4.7 ± 3.5 g/d, P = 0.037; 150.1 ± 121.0 μmol/L vs. 105.6 ± 97.1 μmol/L, P = 0.005; 0.3 ± 0.2 μg/L vs. 0.4 ± 0.2 μg/L, P = 0.04, respectively), comparing with those with low density of glomerular IgM and low levels of CFH.

CONCLUSIONS

Our results suggested the involvement of glomerular deposited IgM in complement activation and renal injury in LN.

RTN4/NoGo-receptor binding to BAI adhesion-GPCRs regulates neuronal development

RTN4-binding proteins were widely studied as "NoGo" receptors, but their physiological interactors and roles remain elusive. Similarly, BAI adhesion-GPCRs were associated with numerous activities, but their ligands and functions remain unclear. Using unbiased approaches, we observed an unexpected convergence: RTN4 receptors are high-affinity ligands for BAI adhesion-GPCRs. A single thrombospondin type 1-repeat (TSR) domain of BAIs binds to the leucine-rich repeat domain of all three RTN4-receptor isoforms with nanomolar affinity. In the 1.65 Å crystal structure of the BAI1/RTN4-receptor complex, C-mannosylation of tryptophan and O-fucosylation of threonine in the BAI TSR-domains creates a RTN4-receptor/BAI interface shaped by unusual glycoconjugates that enables high-affinity interactions. In human neurons, RTN4 receptors regulate dendritic arborization, axonal elongation, and synapse formation by differential binding to glial versus neuronal BAIs, thereby controlling neural network activity. Thus, BAI binding to RTN4/NoGo receptors represents a receptor-ligand axis that, enabled by rare post-translational modifications, controls development of synaptic circuits.

Retinal Ganglion Cell Axon Regeneration Requires Complement and Myeloid Cell Activity within the Optic Nerve

Axon regenerative failure in the mature CNS contributes to functional deficits following many traumatic injuries, ischemic injuries, and neurodegenerative diseases. The complement cascade of the innate immune system responds to pathogen threat through inflammatory cell activation, pathogen opsonization, and pathogen lysis, and complement is also involved in CNS development, neuroplasticity, injury, and disease. Here, we investigated the involvement of the classical complement cascade and microglia/monocytes in CNS repair using the mouse optic nerve injury (ONI) model, in which axons arising from retinal ganglion cells (RGCs) are disrupted. We report that central complement C3 protein and mRNA, classical complement C1q protein and mRNA, and microglia/monocyte phagocytic complement receptor CR3 all increase in response to ONI, especially within the optic nerve itself. Importantly, genetic deletion of C1q, C3, or CR3 attenuates RGC axon regeneration induced by several distinct methods, with minimal effects on RGC survival. Local injections of C1q function-blocking antibody revealed that complement acts primarily within the optic nerve, not retina, to support regeneration. Moreover, C1q opsonizes and CR3+ microglia/monocytes phagocytose growth-inhibitory myelin debris after ONI, a likely mechanism through which complement and myeloid cells support axon regeneration. Collectively, these results indicate that local optic nerve complement-myeloid phagocytic signaling is required for CNS axon regrowth, emphasizing the axonal compartment and highlighting a beneficial neuroimmune role for complement and microglia/monocytes in CNS repair.SIGNIFICANCE STATEMENT Despite the importance of achieving axon regeneration after CNS injury and the inevitability of inflammation after such injury, the contributions of complement and microglia to CNS axon regeneration are largely unknown. Whereas inflammation is commonly thought to exacerbate the effects of CNS injury, we find that complement proteins C1q and C3 and microglia/monocyte phagocytic complement receptor CR3 are each required for retinal ganglion cell axon regeneration through the injured mouse optic nerve. Also, whereas studies of optic nerve regeneration generally focus on the retina, we show that the regeneration-relevant role of complement and microglia/monocytes likely involves myelin phagocytosis within the optic nerve. Thus, our results point to the importance of the innate immune response for CNS repair.

Classical complement pathway inhibition reduces brain damage in a hypoxic ischemic encephalopathy animal model

Perinatal hypoxic ischemic encephalopathy (HIE) remains a major contributor of infant death and long-term disability worldwide. The role played by the complement system in this ischemia-reperfusion injury remains poorly understood. In order to better understand the role of complement activation and other modifiable mechanisms of injury in HIE, we tested the dual-targeting anti-inflammatory peptide, RLS-0071 in an animal model of HIE. Using the well-established HIE rat pup model we measured the effects of RLS-0071 during the acute stages of the brain injury and on long-term neurocognitive outcomes. Rat pups subject to hypoxia-ischemia insult received one of 4 interventions including normothermia, hypothermia and RLS-0071 with and without hypothermia. We measured histopathological effects, brain C1q levels and neuroimaging at day 1 and 21 after the injury. A subset of animals was followed into adolescence and evaluated for neurocognitive function. On histological evaluation, RLS-0071 showed neuronal protection in combination with hypothermia (P = 0.048) in addition to reducing C1q levels in the brain at 1hr (P = 0.01) and at 8 hr in combination with hypothermia (P = 0.005). MRI neuroimaging demonstrated that RLS-0071 in combination with hypothermia reduced lesion volume at 24 hours (P<0.05) as well as decreased T2 signal at day 21 in combination with hypothermia (P<0.01). RLS-0071 alone or in combination with hypothermia improved both short-term and long-term memory. These findings suggest that modulation by RLS-0071 can potentially decrease brain damage resulting from HIE.

Effects of early pregnancy on the complement system in the ovine thymus

The complement system is crucial for the innate immune system, and complement activation is related to abnormal pregnancy in mice and humans. It is hypothesized that the complement system participates in maternal thymic immune regulation during early pregnancy in sheep. In this study, maternal thymuses were sampled on day 16 of the estrous cycle, and days 13, 16 and 25 of gestation in sheep. Quantitative real-time PCR, Western blot and immunohistochemistry analyses were used to analyze the expression of the complement components C1q, C1r, C1s, C2, C3, C4a, C5b and C9 in the maternal thymus. The results revealed that the mRNA and protein expression of C1r, C1s, C2, C3 and C4a was inhibited by early pregnancy, and the pregnancy recognition signal induced upregulation of C1q, C5b and C9 expression at day 16 of gestation. Furthermore, C3 protein was mostly located in epithelial reticular cells and thymic corpuscles, which may be involved in immune regulation. In summary, early pregnancy inhibits the complement system in the maternal thymus, which may be essential for the maternal immune regulation and successful pregnancy in sheep.

A lymphocyte-microglia-astrocyte axis in chronic active multiple sclerosis

Multiple sclerosis (MS) lesions that do not resolve in the months after they form harbour ongoing demyelination and axon degeneration, and are identifiable in vivo by their paramagnetic rims on MRI scans1-3. Here, to define mechanisms underlying this disabling, progressive neurodegenerative state4-6 and foster development of new therapeutic agents, we used MRI-informed single-nucleus RNA sequencing to profile the edge of demyelinated white matter lesions at various stages of inflammation. We uncovered notable glial and immune cell diversity, especially at the chronically inflamed lesion edge. We define 'microglia inflamed in MS' (MIMS) and 'astrocytes inflamed in MS', glial phenotypes that demonstrate neurodegenerative programming. The MIMS transcriptional profile overlaps with that of microglia in other neurodegenerative diseases, suggesting that primary and secondary neurodegeneration share common mechanisms and could benefit from similar therapeutic approaches. We identify complement component 1q (C1q) as a critical mediator of MIMS activation, validated immunohistochemically in MS tissue, genetically by microglia-specific C1q ablation in mice with experimental autoimmune encephalomyelitis, and therapeutically by treating chronic experimental autoimmune encephalomyelitis with C1q blockade. C1q inhibition is a potential therapeutic avenue to address chronic white matter inflammation, which could be monitored by longitudinal assessment of its dynamic biomarker, paramagnetic rim lesions, using advanced MRI methods.

The Spectrum of C4d Deposition in Renal Biopsies of Lupus Nephritis Patients

Objectives

This study aimed to determine the prevalence and localization of complement factor C4d in renal biopsies from patients with lupus nephritis (LN), as well as its associations with the disease's clinico-pathological features. The correlation between arteriolar C4d deposition and renal microvascular lesions (RVLs) was further analyzed.

Methods

A total of 325 biopsy-proven LN patients were enrolled, and their clinico-pathological data were collected. C4d staining of renal biopsies was performed by immunohistochemistry. The associations between C4d deposition and the clinico-pathological features were further analyzed.

Results

C4d deposition was present in most (98.8%) renal specimens in our cohort. These deposits were localized in the glomeruli (98.2%), tubular basement membrane (TBM) (43.7%), arterioles (31.4%), and peritubular capillary (33.8%). Patients with TBM C4d staining had higher disease activity (measured with the Systemic Lupus Erythematous Disease Activity Index) and higher National Institutes of Health pathological activity and chronicity indices (all P < 0.01). Patients with arteriolar C4d deposition were more likely to develop RVLs (91.2%) compared to those with no arteriolar C4d deposition (78.0%; P = 0.004), especially with two or more types of RVLs (P < 0.001). During the mean follow-up of 55.8 months, arteriolar C4d was related to worse renal outcomes [hazard ration (HR): 2.074, 95% confidence interval (CI) 1.056-4.075, P = 0.034]. Multivariate Cox hazard analysis showed that co-deposition of arteriolar C4d and C3c was an independent risk factor (HR: 3.681, 95% CI 1.519-8.921, P = 0.004) for predicting renal outcomes.

Conclusions

C4d deposition was common in renal tissues from LN patients. TBM C4d deposition was related to the disease activity, and arteriolar C4d deposition was associated with RVLs and worse renal outcomes.

Inflammatory and Oxidative Pathways Are New Drug Targets in Multiple Episode Schizophrenia and Leaky Gut, Klebsiella pneumoniae, and C1q Immune Complexes Are Additional Drug Targets in First Episode Schizophrenia

Breakdown of paracellular and vascular pathways and activated neuroimmune and oxidative pathways was established in (deficit) schizophrenia. The aim of this study was to delineate (a) the differences in these pathways between stable-phase, first (FES) and multiple (MES) episode schizophrenia and (b) the pathways that determine the behavioral-cognitive-physical-psychosocial (BCPS) deterioration in FES/MES. This study included 21 FES and 58 FES patients and 40 healthy controls and measured indicants of serum C1q circulating immune complexes (CIC), leaky gut, immune activation, and oxidative stress toxicity (OSTOX). We constructed a BCPS-worsening index by extracting a latent vector from symptomatic, neurocognitive, and quality of life data. FES was associated with higher IgA CIC-C1q, IgA directed to cadherin, catenin, and plasmalemma vesicle-associated protein, and IgA/IgM to Gram-negative bacteria as compared with FES and controls. In FES patients, the BCPS-worsening score was predicted (48.7%) by IgA to Klebsiella pneumoniae and lowered paraoxonase 1 activity. In MES patients, the BCPS-worsening score was explained (42.7%) by increased tumor necrosis factor-α, OSTOX, and number of episodes. In schizophrenia, 34.0% of the variance in the BCPS-worsening score was explained by IgA to K. pneumoniae, OSTOX, and number of episodes. Increased IgA to K. pneumoniae was the single best predictor of residual psychotic symptoms in FES and MES. This study delineated different mechanistic processes in FES, including breakdown of adherens junctions, bacterial translocation, and IgA CIC-C1q formation, and MES, including immune and oxidative neurotoxic pathways. FES and MES comprise different staging subtypes, i.e., FES and MES with and without worsening.

C1ql1 is expressed in adult outer hair cells of the cochlea in a tonotopic gradient

Hearing depends on the transduction of sounds into neural signals by the inner hair cells of the cochlea. Cochleae also have outer hair cells with unique electromotile properties that increase auditory sensitivity, but they are particularly susceptible to damage by intense noise exposure, ototoxic drugs, and aging. Although the outer hair cells have synapses on afferent neurons that project to the brain, the function of this neuronal circuit is unclear. Here, we created a novel mouse allele that inserts a fluorescent reporter at the C1ql1 locus which revealed gene expression in the outer hair cells and allowed creation of outer hair cell-specific C1ql1 knockout mice. We found that C1ql1 expression in outer hair cells corresponds to areas with the most sensitive frequencies of the mouse audiogram, and that it has an unexpected adolescence-onset developmental timing. No expression was observed in the inner hair cells. Since C1QL1 in the brain is made by neurons, transported anterogradely in axons, and functions in the synaptic cleft, C1QL1 may serve a similar function at the outer hair cell afferent synapse. Histological analyses revealed that C1ql1 conditional knockout cochleae may have reduced outer hair cell afferent synapse maintenance. However, auditory behavioral and physiological assays did not reveal a compelling phenotype. Nonetheless, this study identifies a potentially useful gene expressed in the cochlea and opens the door for future studies aimed at elucidating the function of C1QL1 and the function of the outer hair cell and its afferent neurons.

Host-Specific Serum Factors Control the Development and Survival of Schistosoma mansoni

Introduction

Schistosomiasis is a neglected tropical disease (NTD) caused by blood-dwelling flatworms which develop from skin-penetrating cercariae, the freely swimming water-borne infective stage of Schistosoma mansoni, into adult worms. This natural course of infection can be mimicked in experimental mouse models of schistosomiasis. However, only a maximum of 20-30% of penetrated cercariae mature into fecund adults. The reasons for this are unknown but could potentially involve soluble factors of the innate immune system, such as complement factors and preexisting, natural antibodies.

Materials and Methods

Using our recently developed novel serum- and cell-free in vitro culture system for newly transformed schistosomula (NTS), which supports long-term larval survival, we investigated the effects of mouse serum and its major soluble complement factors C1q, C3, C4 as well as preexisting, natural IgM in vitro and assessed worm development in vivo by infecting complement and soluble (s)IgM-deficient animals.

Results

In contrast to sera from humans and a broad variety of mammalian species, serum from mice, surprisingly, killed parasites already at skin stage in vitro. Interestingly, the most efficient killing component(s) were heat-labile but did not include important members of the perhaps best known family of heat-labile serum factors, the complement system, nor consisted of complement-activating natural immunoglobulins. Infection of complement C1q and sIgM-deficient mice with S. mansoni as well as in vitro tests with sera from mice deficient in C3 and C4 revealed no major role for these soluble factors in vivo in regard to parasite maturation, fecundity and associated immunopathology. Rather, the reduction of parasite maturation from cercariae to adult worms was comparable to wild-type mice.

Conclusion

This study reveals that not yet identified heat-labile serum factors are major selective determinants of the host-specificity of schistosomiasis, by directly controlling schistosomal development and survival.

Cuprizone and EAE mouse frontal cortex proteomics revealed proteins altered in multiple sclerosis

Two pathophysiological different experimental models for multiple sclerosis were analyzed in parallel using quantitative proteomics in attempts to discover protein alterations applicable as diagnostic-, prognostic-, or treatment targets in human disease. The cuprizone model reflects de- and remyelination in multiple sclerosis, and the experimental autoimmune encephalomyelitis (EAE, MOG1-125) immune-mediated events. The frontal cortex, peripheral to severely inflicted areas in the CNS, was dissected and analyzed. The frontal cortex had previously not been characterized by proteomics at different disease stages, and novel protein alterations involved in protecting healthy tissue and assisting repair of inflicted areas might be discovered. Using TMT-labelling and mass spectrometry, 1871 of the proteins quantified overlapped between the two experimental models, and the fold change compared to controls was verified using label-free proteomics. Few similarities in frontal cortex between the two disease models were observed when regulated proteins and signaling pathways were compared. Legumain and C1Q complement proteins were among the most upregulated proteins in cuprizone and hemopexin in the EAE model. Immunohistochemistry showed that legumain expression in post-mortem multiple sclerosis brain tissue (n = 19) was significantly higher in the center and at the edge of white matter active and chronic active lesions. Legumain was associated with increased lesion activity and might be valuable as a drug target using specific inhibitors as already suggested for Parkinson's and Alzheimer's disease. Cerebrospinal fluid levels of legumain, C1q and hemopexin were not significantly different between multiple sclerosis patients, other neurological diseases, or healthy controls.