Project description:Tumorigenesis in different segments of the intestinal tract involves tissue-specific oncogenic drivers. In the colon, complement component 3 (C3) activation is a major contributor to inflammation and malignancies. By contrast, tumorigenesis in the small intestine involves fatty acid–binding protein 1. However, little is known of the upstream mechanisms driving their expressions in different segments of the intestinal tract. Here, we report that the RNA-binding protein DDX5 binds to the mRNA transcripts of C3 and fatty acid–binding protein 1 to augment their expressions posttranscriptionally. Knocking out DDX5 in epithelial cells protected mice from intestinal tumorigenesis and dextran sodium sulfate–induced col- itis. Identification of DDX5 as a common upstream regulator of tissue-specific oncogenic molecules provides an excellent therapeutic target for intestinal diseases.
Project description: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 bacterial pneumonia. While mice with global C3 deficiency had severe pneumonia-induced lung injury, those deficient in liver-deficient C3 remain protected, comparable to wildtype mice. Human lung transcriptome analysis showed that secretory epithelial cells, such as club cells, are a major source of C3. Mice with a tamoxifen-induced C3 gene ablation from club cells in the lung had worse pulmonary injury compared to similarly treated controls, despite maintaining normal circulating C3 levels. Finally, in human cellular and mouse pneumonia models, we show that C3 reduces epithelial cell death mediated through the alternative pathway component Factor B, rather than the C3aR. Thus, our findings suggest that a locally-derived C3-Factor B pathway protects the lung mucosal barrier.
Project description:Complement has emerged as a component of tumor promoting inflammation. We conducted a systematic assessment of the role of complement activation and effector pathways in sarcomas. C3-/-, MBL1/2-/- and C4-/- mice showed reduced susceptibility to 3-methylcholanthrene sarcomagenesis and transplanted sarcomas, whereas C1q and factor B deficiency had marginal effects. Complement 3a receptor (C3aR), but not C5aR1 and C5aR2, deficiency mirrored the phenotype of C3-/- mice. C3 and C3aR deficiency were associated with reduced accumulation and functional skewing of tumor-associated macrophages, increased T cell activation and response to anti-PD-1 therapy. Transcriptional profiling of sarcoma infiltrating macrophages and monocytes revealed the enrichment of MHC II-dependent antigen presentation pathway in C3-deficient cells. In patients, C3aR expression correlated with a macrophage population signature and C3 deficiency-associated signatures predicted better clinical outcome. These results suggest that the lectin pathway and C3a/C3aR axis are key components of complement and macrophage-mediated sarcoma promotion and immunosuppression.
Project description:Rhabdomyolysis is a severe condition caused by skeletal muscle damage, leading to acute kidney injury (AKI). We demonstrate that complement has a direct pathogenic role in rhabdomyolysis-induced AKI. Deposition of C3d in the tubules of patients and mice correlated with rhabdomyolysis-induced AKI. Moreover, C3-defiient mice with rhabdomyolysis had preserved renal function. Mechanistically, C3-deficiency attenuated strongly inflammatory and apoptotic components of the renal transcriptome, perturbed by rhabdomyolysis. Complement was activated intrarenal by the lectin pathway via collectin-11. It proceeded in a C4-bypass manner and was amplified by heme-activated alternative pathway. Therefore, complement and heme are promising therapeutic targets for rhabdomyolysis-induced AKI.
Project description:We performed scRNAseq analysis of CD45- cells sorted from murine brains on the presence or absence of a fluorescent reporter for complement component C3 at peak of experimental autoimmune encephalomyelitis to study the non-immune cellular sources of C3
Project description:Perioperative neurocognitive disorder (PNDs) can commonly occur after major surgery in at risk patients and its occurrence increases medical healthcare burdens and even mortality. Accumulating evidence points to neuroinflammation being pivotal to the pathogenesis of these conditions. The complement cascade contributes to neuroinflammatory responses in the central nervous system (CNS) and complement C3 has been implicated in the manifestation of cognitive deficits in several neurological conditions. Neurotoxic reactive astrocytes function differently to their non-activated counterparts and release complement components in response to pathological triggers. We observed previously that surgery induces a rapid rise and then fall in cytokines but a more sustained glial activation response that coincided with postoperative cognitive impairment. In this study, we explored the relationship between the expression of complement C3, glial activation, and cognitive deficits. Using a murine model of surgery, we characterized the transcriptional profiles of hippocampal astrocytes after surgery and examined the effects of C3 suppression on the neuroinflammatory response and cognitive performance. There was a delayed but sustained rise in hippocampal C3 of astrocytic in origin after surgery which corresponded with the onset of cognitive decline. Furthermore, the A1 or the neurotoxic phenotype predominated in this postoperative astrocytic activation, and these cells have a distinct transcriptional profile including C3 upregulation. Suppression of C3 inhibited synaptic phagocytosis by microglia and attenuated postoperative cognitive impairment. Therefore, C3 from reactive astrocytes appear central to the development of cognitive dysfunction associated with postoperative neuroinflammation.
Project description:Mounting evidence has highlighted the importance of complement in the construction of an immunosuppressive tumor microenvironment (TME). Tumor cell-derived C3 has been previously reported, however, whether and how it acts on anti-tumor immunity remains to be elucidated. Here, we describe a unique role of tumor cell-derived C3 in suppressing anti-tumor immunity. Tumor cell-derived C3 was activated intracellularly, which results in generation of C3a. C3a could modulate tumor-associated macrophages (TAMs) via C3a-C3aR-PI3Kγ signaling, thereby repressing anti-tumor immunity. More importantly, deletion of C3 in tumor cells with high C3 expression is sufficient to enhance the efficacy of ɑPD-L1 treatment. Collectively, our present results suggest tumor cell-derived C3 may serve as a novel target in cancer immunotherapy, specifically targeting C3 in tumor cells to enhance anti-tumor immunity.
Project description:Systemic lupus erythematosus is a chronic autoimmune disease with multifactorial ethiopathogenesis. The complement system is involved in both the early and late stages of disease development and organ damage. To better understand autoantibody mediated complement consumption the GAPAID consortium examined ex vivo immune complex formation on autoantigen arrays. We recruited patients with SLE (n=211), with other systemic autoimmune diseases (n=65) and non-autoimmune control subjects (n=149) in two rheumatology tertiary care centers. Standard clinical and laboratory data were collected from all subjects and serum complement levels were determined in SLE patients. The genotype of SNP rs1143679 in the ITGAM gene was also determined. On-chip formation of immune complexes was examined using a functional immunoassay on autoantigen microarray. The amount of antigen-bound IgM, IgG and complement C4 and C3 was quantified on autoantigens comprising nucleic acids, proteins and lipids. Our results show that the relatively high complement consumption of nucleic acids is further increased upon binding of IgM and IgG. This is true even when serum complement levels are decreased due to complement consumption in SLE patients. A negative correlation between serum complement levels and ex vivo complement deposition on nucleic acid autoantigens is demonstrated. On the contrary, most protein and lipid autoantigens show positive correlation with C4 and C3 levels. Genetic analysis reveals that the non-synonymous variant rs1143679 in complement receptor type 3 is associated with an increased production of anti-dsDNA IgG antibodies. Notwithstanding, homozygous carriers of the previously reported susceptible allele (AA) have lower levels of dsDNA specific IgM among SLE patients. Regarding organ involvement we find that besides anti-C1q IgG, low levels of dsDNA specific IgM and low complement C4 binding to C1q are also associated with renal injury. In summary, nucleic acids maintain a skewed complement deposition balance when bound by IgG and IgM, depleting the early classical complement pathway from other physiological processes. Dysfunction of the receptor responsible for complement-mediated apoptotic debris removal promotes the development of autoantibodies targeting nucleic acids. These observations provide serological and genetic evidence for complement-mediated clearance deficiency of apoptotic debris in lupus.
Project description:We developed a novel, rapidly-progressing, severe murine model of C3G by replacing the mouse C3 gene with the human C3 homologue using Velocigene® technology. We conducted functional, histological, molecular and pharmacologic assays to characterize the presentation of renal disease and useful pharmacologic interventions in the humanized C3 (C3hu/hu) mice.