Sahu, SK;Ozantürk, AN;Kulkarni, DH;Ma, L;Barve, RA;Dannull, L;Lu, A;Starick, M;McPhatter, J;Garnica, L;Sanfillipo-Burchman, M;Kunen, J;Wu, X;Gelman, AE;Brody, SL;Atkinson, JP;Kulkarni, HS;
PMID: 36735773 | DOI: 10.1126/sciimmunol.abp9547
The complement component C3 is a fundamental plasma protein for host defense, produced largely by the liver. However, recent work has demonstrated the critical importance of tissue-specific C3 expression in cell survival. Here, we analyzed the effects of local versus peripheral sources of C3 expression in a model of acute bacterial pneumonia induced by Pseudomonas aeruginosa. Whereas mice with global C3 deficiency had severe pneumonia-induced lung injury, those deficient only in liver-derived C3 remained protected, comparable to wild-type mice. Human lung transcriptome analysis showed that secretory epithelial cells, such as club cells, express high levels of C3 mRNA. Mice with tamoxifen-induced C3 gene ablation from club cells in the lung had worse pulmonary injury compared with similarly treated controls, despite maintaining normal circulating C3 levels. Last, in both the mouse pneumonia model and cultured primary human airway epithelial cells, we showed that stress-induced death associated with C3 deficiency parallels that seen in Factor B deficiency rather than C3a receptor deficiency. Moreover, C3-mediated reduction in epithelial cell death requires alternative pathway component Factor B. Thus, our findings suggest that a pathway reliant on locally derived C3 and Factor B protects the lung mucosal barrier.
British journal of pharmacology
Bode, M;Diemer, JN;Luu, TV;Ehnert, N;Teigeler, T;Wiech, T;Lindenmeyer, MT;Herrnstadt, GR;Bülow, J;Huber, TB;Tomas, NM;Wenzel, UO;
PMID: 37076314 | DOI: 10.1111/bph.16097
Complement activation may drive hypertension through its effects on immunity and tissue integrity.We examined expression of C3, the central protein of the complement cascade, in hypertension.Increased C3 expression was found in kidney biopsies and microdissected glomeruli of patients with hypertensive nephropathy. Renal single cell RNA seq data from normotensive and hypertensive patients confirmed expression of C3 in different cellular compartments of the kidney. In angiotensin II (Ang II) induced hypertension renal C3 expression was upregulated. C3-/- mice revealed a significant lower albuminuria in the early phase of hypertension. However, no difference was found for blood pressure, renal injury (histology, glomerular filtration rate, inflammation) and cardiac injury (fibrosis, weight, gene expression) between C3-/- and wildtype mice after Ang II infusion. Also, in deoxycorticosterone acetate (DOCA) salt hypertension, a significantly lower albuminuria was found in the first weeks of hypertension in C3 deficient mice but no significant difference in renal and cardiac injury. Downregulation of C3 by C3 targeting GalNAc (n-acetylgalactosamine) small interfering RNA (siRNA) conjugate decreased C3 in the liver by 96% and lowered albuminuria in the early phase but showed no effect on blood pressure and endorgan damage. Inhibition of complement C5 by siRNA showed no effect on albuminuria.Increased C3 expression is found in the kidneys of hypertensive mice and men. Genetic and therapeutic knockdown of C3 improved albuminuria in the early phase of hypertension but did not ameliorate arterial blood pressure nor renal and cardiac injury.This article is protected by
Investigative Ophthalmology & Visual Science
Yang, H;Yuan, M;Gaurang, P;Sun, A;
RESULTS : In rodent eye (both rat and mouse), CFH mRNA is strongly expressed in the retinal pigment epithelium with some expression also found in inner nuclear (INL) and retinal ganglion cell (RGC) layers of the retina. C3 mRNA is expressed mainly in RGC, INL of retina, ciliary body, corneal epithelium with some expression is also found in rodent retinal pigment epithelium layer. However, in human eye, CFH and C3 mRNA are strongly expressed in the choroid. Some expression is also found in RGC, INL layer of retina, ONH, sclera, cornea endothelial and stroma; and ciliary body. There is no C3 or CFH signal detected in RPE cells.
King BC, Kulak K, Krus U, Rosberg R, Golec E, Wozniak K, Gomez MF, Zhang E, O'Connell DJ, Renström E, Blom AM.
PMID: - | DOI: 10.1016/j.cmet.2018.09.009
We show here that human pancreatic islets highly express C3, which is both secreted and present in the cytosol. Within isolated human islets, C3 expression correlates with type 2 diabetes (T2D) donor status, HbA1c, and inflammation. Islet C3 expression is also upregulated in several rodent diabetes models. C3 interacts with ATG16L1, which is essential for autophagy. Autophagy relieves cellular stresses faced by β cells during T2D and maintains cellular homeostasis. C3 knockout in clonal β cells impaired autophagy and led to increased apoptosis after exposure of cells to palmitic acid and IAPP. In the absence of C3, autophagosomes do not undergo fusion with lysosomes. Thus, C3 may be upregulated in islets during T2D as a cytoprotective factor against β cell dysfunction caused by impaired autophagy. Therefore, we revealed a previously undescribed intracellular function for C3, connecting the complement system directly to autophagy, with a broad potential importance in other diseases and cell types.
bioRxiv : the preprint server for biology
Wu, M;Zheng, W;Song, X;Bao, B;Wang, Y;Ramanan, D;Yang, D;Liu, R;Macbeth, JC;Do, EA;Andrade, WA;Yang, T;Cho, HS;Gazzaniga, FS;Ilves, M;Coronado, D;Thompson, C;Hang, S;Chiu, IM;Moffitt, JR;Hsiao, A;Mekalanos, JJ;Benoist, C;Kasper, DL;
PMID: 36778396 | DOI: 10.1101/2023.02.02.523770
Canonically, complement is a serum-based host defense system that protects against systemic microbial invasion. Little is known about the production and function of complement components on mucosal surfaces. Here we show gut complement component 3 (C3), central to complement function, is regulated by the composition of the microbiota in healthy humans and mice, leading to host-specific gut C3 levels. Stromal cells in intestinal lymphoid follicles (LFs) are the predominant source of intestinal C3. During enteric infection with Citrobacter rodentium or enterohemorrhagic Escherichia coli, luminal C3 levels increase significantly and are required for protection. C. rodentium is remarkably more invasive to the gut epithelium of C3-deficient mice than of wild-type mice. In the gut, C3-mediated phagocytosis of C. rodentium functions to clear pathogens. Our study reveals that variations in gut microbiota determine individuals†intestinal mucosal C3 levels, dominantly produced by LF stromal cells, which directly correlate with protection against enteric infection.Gut complement component 3 (C3) is induced by the microbiome in healthy humans and mice at a microbiota-specific level.Gut stromal cells located in intestinal lymphoid follicles are a major source of luminal C3 During enteric infections with Citrobacter rodentium or enterohemorrhagic Escherichia coli, gut luminal C3 levels increase and are required for protection. C. rodentium is significantly more invasive of the gut epithelium in C3-deficient mice when compared to WT mice. In the gut, C3-mediated opsonophagocytosis of C. rodentium functions to clear pathogens.
Bourel, J;Planche, V;Dubourdieu, N;Oliveira, A;Séré, A;Ducourneau, EG;Tible, M;Maitre, M;Lesté-Lasserre, T;Nadjar, A;Desmedt, A;Ciofi, P;Oliet, SH;Panatier, A;Tourdias, T;
PMID: 34673149 | DOI: 10.1016/j.nbd.2021.105533
Memory impairment is one of the disabling manifestations of multiple sclerosis (MS) possibly present from the early stages of the disease and for which there is no specific treatment. Hippocampal synaptic dysfunction and dendritic loss, associated with microglial activation, can underlie memory deficits, yet the molecular mechanisms driving such hippocampal neurodegeneration need to be elucidated. In early-stage experimental autoimmune encephalomyelitis (EAE) female mice, we assessed the expression level of molecules involved in microglia-neuron interactions within the dentate gyrus and found overexpression of genes of the complement pathway. Compared to sham immunized mice, the central element of the complement cascade, C3, showed the strongest and 10-fold upregulation, while there was no increase of downstream factors such as the terminal component C5. The combination of in situ hybridization with immunofluorescence showed that C3 transcripts were essentially produced by activated microglia. Pharmacological inhibition of C3 activity, by daily administration of rosmarinic acid, was sufficient to prevent early dendritic loss, microglia-mediated phagocytosis of synapses in the dentate gyrus, and memory impairment in EAE mice, while morphological markers of microglial activation were still observed. In line, when EAE was induced in C3 deficient mice (C3KO), dendrites and spines of the dentate gyrus as well as memory abilities were preserved. Altogether, these data highlight the central role of microglial C3 in early hippocampal neurodegeneration and memory impairment in EAE and, therefore, pave the way toward new neuroprotective strategies in MS to prevent cognitive deficit using complement inhibitors.
Zaizen, Y;Okamoto, M;Azuma, K;Fukuoka, J;Hozumi, H;Sakamoto, N;Suda, T;Mukae, H;Hoshino, T;
PMID: 36934274 | DOI: 10.1186/s12931-023-02362-0
Interstitial lung disease is frequently comorbid with dermatomyositis and has a poor prognosis, especially in patients with the anti-melanoma differentiation-associated gene 5 (MDA5) autoantibody. However, the pathogenesis of dermatomyositis-related interstitial lung disease remains unclear.We examined 18 and 19 patients with dermatomyositis-related interstitial lung disease and idiopathic pulmonary fibrosis (control), respectively. Lung tissues obtained from these patients were semi-quantitatively evaluated by immunohistochemical staining with in-house anti-human MDA5 monoclonal antibodies, as well as anti-human immunoglobulin (Ig) G, IgM, IgA, and complement component 3(C3) antibodies. We established human MDA5 transgenic mice and treated them with rabbit anti-human MDA5 polyclonal antibodies, and evaluated lung injury and Ig and C3 expression.MDA5 was moderately or strongly expressed in the lungs of patients in both groups, with no significant differences between the groups. However, patients with dermatomyositis-related interstitial lung disease showed significantly stronger expression of C3 (p < 0.001), IgG (p < 0.001), and IgM (p = 0.001) in the lungs than control. Moreover, lung C3, but IgG, IgA, nor IgM expression was significantly stronger in MDA5 autoantibody-positive dermatomyositis-related interstitial lung disease (n = 9) than in MDA5 autoantibody-negative dermatomyositis-related interstitial lung disease (n = 9; p = 0.022). Treatment with anti-MDA5 antibodies induced lung injury in MDA5 transgenic mice, and strong immunoglobulin and C3 expression was observed in the lungs of the mice.Strong immunoglobulin and C3 expression in the lungs involve lung injury related to dermatomyositis-related interstitial lung disease. Enhanced immune complex formation in the lungs may contribute to the poor prognosis of MDA5 autoantibody-positive dermatomyositis-related interstitial lung disease.
Ng, ESY;Kady, N;Hu, J;Dave, A;Jiang, Z;Pei, J;Gorin, MB;Matynia, A;Radu, RA;
PMID: 36359858 | DOI: 10.3390/cells11213462
Recessive Stargardt disease (STGD1) is an inherited retinopathy caused by mutations in the ABCA4 gene. The ABCA4 protein is a phospholipid-retinoid flippase in the outer segments of photoreceptors and the internal membranes of retinal pigment epithelial (RPE) cells. Here, we show that RPE cells derived via induced pluripotent stem-cell from a molecularly and clinically diagnosed STGD1 patient exhibited reduced ABCA4 protein and diminished activity compared to a normal subject. Consequently, STGD1 RPE cells accumulated intracellular autofluorescence-lipofuscin and displayed increased complement C3 activity. The level of C3 inversely correlated with the level of CD46, an early negative regulator of the complement cascade. Persistent complement dysregulation led to deposition of the membrane attack complex on the surface of RPE cells, decrease in transepithelial resistance, and subsequent cell death. These findings are strong evidence of complement-mediated RPE cell damage in STGD1, in the absence of photoreceptors, caused by reduced CD46 regulatory protein.
Retinal Ganglion Cell Axon Regeneration Requires Complement and Myeloid Cell Activity within the Optic Nerve
The Journal of neuroscience : the official journal of the Society for Neuroscience
Peterson, SL;Li, Y;Sun, CJ;Wong, KA;Leung, KS;de Lima, S;Hanovice, NJ;Yuki, K;Stevens, B;Benowitz, LI;
PMID: 34417332 | DOI: 10.1523/JNEUROSCI.0555-21.2021
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 optic nerve injury, 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 neuro-immune role for complement and microglia/monocytes in CNS repair.SIGNIFICANCE STATEMENTDespite 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.
Fan, W;Huang, W;Chen, J;Li, N;Mao, L;Hou, S;
PMID: 35403700 | DOI: 10.1111/imm.13479
Microglia, the resident immune cells in the retina and nervous system, make irreplaceable contributions to the maintenance of normal homeostasis and immune surveillance of these systems. Recently, great progress has been made in determining the origin, distribution, features and functions of retinal microglia and in identifying their roles in retinal diseases. In the retinal microenvironment, microglia constantly monitor changes in their surroundings and maintain balanced functions by communicating with other retinal cells. When disturbed, activated microglia may kill degenerated neurons and photoreceptors through phagocytosis and exacerbate retinal injury by producing multiple proinflammatory mediators. Numerous animal studies and in situ analyses of human tissue have shown that retinal microglia are involved in multiple retinal diseases. The functions and mechanisms of activated microglia in retinal disorders are gradually being elucidated. Increasing evidence points towards the dual roles of microglia in the retina and they are regulated by many factors. How to inhibit the detrimental effects of microglia and promote beneficial effects are worth studying. This review focuses primarily on the features and functions of microglia and how they participate in retinal diseases based on existing research findings. We also discuss current opinions about microglial transdifferentiation.
The complement system drives local inflammatory tissue priming by metabolic reprogramming of synovial fibroblasts
Friščić, J;Böttcher, M;Reinwald, C;Bruns, H;Wirth, B;Popp, SJ;Walker, KI;Ackermann, JA;Chen, X;Turner, J;Zhu, H;Seyler, L;Euler, M;Kirchner, P;Krüger, R;Ekici, AB;Major, T;Aust, O;Weidner, D;Fischer, A;Andes, FT;Stanojevic, Z;Trajkovic, V;Herrmann, M;Korb-Pap, A;Wank, I;Hess, A;Winter, J;Wixler, V;Distler, J;Steiner, G;Kiener, HP;Frey, B;Kling, L;Raza, K;Frey, S;Kleyer, A;Bäuerle, T;Hughes, TR;Grüneboom, A;Steffen, U;Krönke, G;Croft, AP;Filer, A;Köhl, J;Klein, K;Buckley, CD;Schett, G;Mougiakakos, D;Hoffmann, MH;
PMID: 33761330 | DOI: 10.1016/j.immuni.2021.03.003
Arthritis typically involves recurrence and progressive worsening at specific predilection sites, but the checkpoints between remission and persistence remain unknown. Here, we defined the molecular and cellular mechanisms of this inflammation-mediated tissue priming. Re-exposure to inflammatory stimuli caused aggravated arthritis in rodent models. Tissue priming developed locally and independently of adaptive immunity. Repeatedly stimulated primed synovial fibroblasts (SFs) exhibited enhanced metabolic activity inducing functional changes with intensified migration, invasiveness and osteoclastogenesis. Meanwhile, human SF from patients with established arthritis displayed a similar primed phenotype. Transcriptomic and epigenomic analyses as well as genetic and pharmacological targeting demonstrated that inflammatory tissue priming relies on intracellular complement C3- and C3a receptor-activation and downstream mammalian target of rapamycin- and hypoxia-inducible factor 1α-mediated metabolic SF invigoration that prevents activation-induced senescence, enhances NLRP3 inflammasome activity, and in consequence sensitizes tissue for inflammation. Our study suggests possibilities for therapeutic intervention abrogating tissue priming without immunosuppression.
American journal of physiology. Gastrointestinal and liver physiology
Yuan, T;Orock, A;Greenwood-Van Meerveld, B;
PMID: 34877892 | DOI: 10.1152/ajpgi.00307.2021
Cognitive behavioral therapy (CBT) improves the quality of life for patients with brain-gut disorders, however, the underlying mechanisms of CBT remain to be explored. Previously we showed that environmental enrichment (EE), an experimental paradigm that mirrors positive behavioral intervention, ameliorates chronic stress-induced visceral hypersensitivity in a rodent model via mechanisms involving altered activity in the central nucleus of amygdala (CeA). In the present study, we investigated whether microglia-mediated synaptic plasticity in the CeA is a potential mechanism underlying the protective effects of EE against stress-induced visceral hypersensitivity. We sterotaxically implanted corticosterone (CORT) micropellets onto the dorsal margin of the CeA shown previously to induce colonic hypersensitivity. Animals were housed in EE cages or standard cages for 14 days following CORT implantation. Visceral sensitivity was assessed via visceromotor behavioral response to colorectal distension. Microglial morphology, microglia-mediated synaptic engulfment and the expression of synaptic pruning-related signals C1q, C3 and C3R were measured using immunofluorescence and RNAscope assay. We found that housing CORT implanted rats in EE cages for 14 days attenuated visceral hypersensitivity in both male and female rats as compared to control rats maintained in standard housing. EE reduced CORT-induced microglial remodeling and microglia-mediated synaptic pruning with reduced C1q and CR3, but not C3, expression. Our data suggest that exposure to EE is sufficient to ameliorate stress-induced visceral pain via reducing amygdala microglia-modulated neuronal plasticity.
