Complement anaphylatoxins C3a and C5a: Emerging roles in cancer progression and treatment

Complement C3a/C3aR and C5a/C5aR deposits accelerate the progression of advanced IgA nephropathy to end-stage renal disease

IgA nephropathy (IgAN) is still one of the leading causes of end-stage kidney disease (ESRD), and complement system activation is a key to the pathogenesis of IgAN. The role of complement C3a/C3aR and C5a/C5aR in late stage of IgAN remains unknown. Renal specimens of 75 IgAN patients at the stage 4 CKD were stained using immunofluorescence and immunohistochemistry. The primary outcome was a composite of end-stage renal disease (ESRD) and death. Associations of complement components with baseline clinicopathological characteristics and outcomes were assessed using multivariable Cox regression and Spearman analyses. During a median follow-up of 15.0 months, 27 patients progressed to ESRD and none died. Lower eGFR [hazards ratio (HR), 0.827, 95% confidence interval (CI), 0.732-0.935; P = 0.002] and glomerular C3 deposition (HR, 3.179, 95% CI, 1.079-9.363; P = 0.036) were predictive of time to ESRD in stage 4 CKD IgAN. Higher expression of C3a (P = 0.010), C3aR (P = 0.005), C5a (P = 0.015), and C5aR (P < 0.001) was identified in ESRD group than in non-ESRD group. Glomerular C3a/C3aR and C5a/C5aR deposits were both correlated with a lower baseline eGFR, higher baseline 24 h-urinary protein (24 h-UP) and faster decline of eGFR. Besides, C3a and C5a deposits were found in patients with high S (S1) and T (T1/2) scores, respectively. Complement C3a/C3aR and C5a/C5aR in IgAN patients with stage 4 CKD may portend a faster deterioration of kidney function.

Mass Spectrometry Proteomics Characterization of Plasma Biomarkers for Colorectal Cancer Associated With Inflammation

Background

Colorectal cancer (CRC) prognosis is determined by the disease stage with low survival rates for advanced stages. Current CRC screening programs are mainly using colonoscopy, limited by its invasiveness and high cost. Therefore, non-invasive, cost-effective, and accurate alternatives are urgently needed.

Objective and design

This retrospective multi-center plasma proteomics study was performed to identify potential blood-based biomarkers in 36 CRC patients and 26 healthy volunteers by high-resolution mass spectrometry proteomics followed by the validation in an independent CRC cohort (60 CRC patients and 44 healthy subjects) of identified selected biomarkers.

Results

Among the 322 identified plasma proteins, 37 were changed between CRC patients and healthy volunteers and were associated with the complement cascade, cholesterol metabolism, and SERPIN family members. Increased levels in CRC patients of the complement proteins C1QB, C4B, and C5 as well as pro-inflammatory proteins, lipopolysaccharide-binding protein (LBP) and serum amyloid A4, constitutive (SAA4) were revealed for first time. Importantly, increased level of C5 was verified in an independent validation CRC cohort. Increased C4B and C8A levels were correlated with cancer-associated inflammation and CRC progression, while cancer-associated inflammation was linked to the acute-phase reactant leucine-rich alpha-2-glycoprotein 1 (LRG1) and ceruloplasmin. Moreover, a 4-protein signature including C4B, C8A, apolipoprotein C2 (APO) C2, and immunoglobulin heavy constant gamma 2 was changed between early and late CRC stages.

Conclusion

Our results suggest that C5 could be a potential biomarker for CRC diagnosis. Further validation studies will aid the application of these new potential biomarkers to improve CRC diagnosis and patient care.

Complement factor H: a novel innate immune checkpoint in cancer immunotherapy

The elimination of cancer cells critically depends on the immune system. However, cancers have evolved a variety of defense mechanisms to evade immune monitoring, leading to tumor progression. Complement factor H (CFH), predominately known for its function in inhibiting the alternative pathway of the complement system, has recently been identified as an important innate immunological checkpoint in cancer. CFH-mediated immunosuppression enhances tumor cells' ability to avoid immune recognition and produce an immunosuppressive tumor microenvironment. This review explores the molecular underpinnings, interactions with immune cells, clinical consequences, and therapeutic possibilities of CFH as an innate immune checkpoint in cancer control. The difficulties and opportunities of using CFH as a target in cancer immunotherapy are also explored.

Innate and adaptive immune-directed tumour microenvironment in pancreatic ductal adenocarcinoma

One of the most deadly and aggressive cancers in the world, pancreatic ductal adenocarcinoma (PDAC), typically manifests at an advanced stage. PDAC is becoming more common, and by the year 2030, it is expected to overtake lung cancer as the second greatest cause of cancer-related death. The poor prognosis can be attributed to a number of factors, including difficulties in early identification, a poor probability of curative radical resection, limited response to chemotherapy and radiotherapy, and its immunotherapy resistance. Furthermore, an extensive desmoplastic stroma that surrounds PDAC forms a mechanical barrier that prevents vascularization and promotes poor immune cell penetration. Phenotypic heterogeneity, drug resistance, and immunosuppressive tumor microenvironment are the main causes of PDAC aggressiveness. There is a complex and dynamic interaction between tumor cells in PDAC with stromal cells within the tumour immune microenvironment. The immune suppressive microenvironment that promotes PDAC aggressiveness is contributed by a range of cellular and humoral factors, which itself are modulated by the cancer. In this review, we describe the role of innate and adaptive immune cells, complex tumor microenvironment in PDAC, humoral factors, innate immune-mediated therapeutic advances, and recent clinical trials in PDAC.

A guide to complement biology, pathology and therapeutic opportunity

Complement has long been considered a key innate immune effector system that mediates host defence and tissue homeostasis. Yet, growing evidence has illuminated a broader involvement of complement in fundamental biological processes extending far beyond its traditional realm in innate immunity. Complement engages in intricate crosstalk with multiple pattern-recognition and signalling pathways both in the extracellular and intracellular space. Besides modulating host-pathogen interactions, this crosstalk guides early developmental processes and distinct cell trajectories, shaping tissue immunometabolic and regenerative programmes in different physiological systems. This Review provides a guide to the system-wide functions of complement. It highlights illustrative paradigm shifts that have reshaped our understanding of complement pathobiology, drawing examples from evolution, development of the central nervous system, tissue regeneration and cancer immunity. Despite its tight spatiotemporal regulation, complement activation can be derailed, fuelling inflammatory tissue pathology. The pervasive contribution of complement to disease pathophysiology has inspired a resurgence of complement therapeutics with major clinical developments, some of which have challenged long-held dogmas. We thus highlight major therapeutic concepts and milestones in clinical complement intervention.

The Role of the Complement in Clear Cell Renal Carcinoma (ccRCC)-What Future Prospects Are There for Its Use in Clinical Practice?

In recent years, the first-line available therapeutic options for metastatic renal cell carcinoma (mRCC) have radically changed with the introduction into clinical practice of new immune checkpoint inhibitor (ICI)-based combinations. Many efforts are focusing on identifying novel prognostic and predictive markers in this setting. The complement system (CS) plays a central role in promoting the growth and progression of mRCC. In particular, mRCC has been defined as an "aggressive complement tumor", which encompasses a group of malignancies with poor prognosie and highly expressed complement components. Several preclinical and retrospective studies have demonstrated the negative prognostic role of the complement in mRCC; however, there is little evidence on its possible role as a predictor of the response to ICIs. The purpose of this review is to explore more deeply the physio-pathological role of the complement in the development of RCC and its possible future use in clinical practice as a prognostic and predictive factor.

Serum sPD-L1 levels are elevated in patients with viral diseases, bacterial sepsis or in patients with impaired renal function compared to healthy blood donors

OBJECTIVES

Immune checkpoints play an important role in maintaining the balance of the immune system and in the development of autoimmune diseases. A central checkpoint molecule is the programmed cell death protein 1 (PD-1, CD279) which is typically located on the surface of T cells. Its primary ligand PD-L1 is expressed on antigen presenting cells and on cancer cells. Several variants of PD-L1 exist, among these soluble molecules (sPD-L1) present in serum at low concentrations. sPD-L1 was found elevated in cancer and several other diseases. sPD-L1 in infectious diseases has received relatively little attention so far and is therefore subject of this study.

METHODS

sPD-L1 serum levels were determined in 170 patients with viral infections (influenza, varicella, measles, Dengue fever, SARS-CoV2) or bacterial sepsis by ELISA and compared to the levels obtained in 11 healthy controls.

RESULTS

Patients with viral infections and bacterial sepsis generally show significantly higher sPD-L1 serum levels compared to healthy donors, except for varicella samples where results do not reach significance. sPD-L1 is increased in patients with impaired renal function compared to those with normal renal function, and sPD-L1 correlates significantly with serum creatinine. Among sepsis patients with normal renal function, sPD-L1 serum levels are significantly higher in Gram-negative sepsis compared to Gram-positive sepsis. In addition, in sepsis patients with impaired renal function, sPD-L1 correlates positively with ferritin and negatively with transferrin.

CONCLUSIONS

sPD-L1 serum levels are significantly elevated in patients with sepsis, influenza, mesasles, Dengue fever or SARS-CoV2. Highest levels are detectable in patients with measles and Dengue fever. Also impaired renal function causes an increase in levels of sPD-L1. As a consequence, renal function has to be taken into account in the interpretation of sPD-L1 levels in patients.

Complement System and the Kidney: Its Role in Renal Diseases, Kidney Transplantation and Renal Cell Carcinoma

The crosstalk among the complement system, immune cells, and mediators of inflammation provides an efficient mechanism to protect the organism against infections and support the repair of damaged tissues. Alterations in this complex machinery play a role in the pathogenesis of different diseases. Core complement proteins C3 and C5, their activation fragments, their receptors, and their regulators have been shown to be active intracellularly as the complosome. The kidney is particularly vulnerable to complement-induced damage, and emerging findings have revealed the role of complement system dysregulation in a wide range of kidney disorders, including glomerulopathies and ischemia-reperfusion injury during kidney transplantation. Different studies have shown that activation of the complement system is an important component of tumorigenesis and its elements have been proved to be present in the TME of various human malignancies. The role of the complement system in renal cell carcinoma (RCC) has been recently explored. Clear cell and papillary RCC upregulate most of the complement genes relative to normal kidney tissue. The aim of this narrative review is to provide novel insights into the role of complement in kidney disorders.

Revealing the signaling of complement receptors C3aR and C5aR1 by anaphylatoxins

The complement receptors C3aR and C5aR1, whose signaling is selectively activated by anaphylatoxins C3a and C5a, are important regulators of both innate and adaptive immune responses. Dysregulations of C3aR and C5aR1 signaling lead to multiple inflammatory disorders, including sepsis, asthma and acute respiratory distress syndrome. The mechanism underlying endogenous anaphylatoxin recognition and activation of C3aR and C5aR1 remains elusive. Here we reported the structures of C3a-bound C3aR and C5a-bound C5aR1 as well as an apo-C3aR structure. These structures, combined with mutagenesis analysis, reveal a conserved recognition pattern of anaphylatoxins to the complement receptors that is different from chemokine receptors, unique pocket topologies of C3aR and C5aR1 that mediate ligand selectivity, and a common mechanism of receptor activation. These results provide crucial insights into the molecular understanding of C3aR and C5aR1 signaling and structural templates for rational drug design for treating inflammation disorders.

Association of Serum Complement C3 Levels with Severity and Mortality in COVID 19

The severe acute respiratory distress syndrome-associated coronavirus-2 infection can activate innate and adaptive immune responses which may lead to harmful tissue damage, both locally and systemically. C3, a member of complement system of serum proteins, is a major component of innate immune and inflammatory responses. This study is aimed to assess serum C3 as a marker of COVID-19 severity and a predictor of disease progression. A total of 150 COVID-19 patients, confirmed by RT-PCR, and 50 healthy controls were recruited. Serum C3 levels were determined by using direct colorimetric method. Median levels of serum C3 in total cases and controls were 157.8 and 165.7 mg/dL respectively. Serum C3 although not significantly decreased, they were lower in cases when compared to controls. Similarly, significant differences were found between the groups, with severe group (140.6 mg/dL) having low levels of serum C3 protein when compared to mild (161.0 mg/dL) and moderate group (167.1 mg/dL). Interestingly, during hospitalization, significant difference between baseline (admission) and follow-up (discharge) was observed only in patients with moderate disease. Based on our results, lower levels of C3, with an increase in IL-6 and d-dimer levels, are associated with higher odds of mortality. Therefore, we would like to emphasize that measuring serum C3 levels along with other inflammatory markers might give an added advantage in early identification of patients who are prone to having a severe disease course and can help in a more effective follow-up of disease progression.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12291-023-01148-x.

Deciphering the Role of the Anaphylatoxin C3a: A Key Function in Modulating the Tumor Microenvironment

The complement system plays a crucial role in cancer development. Our study investigated the role of C3a anaphylatoxin on the tumor microenvironment. Our models consisted of mesenchymal stem cells (MSC-like, 3T3-L1), macrophages (Raw 264.7 Blue, (RB)) and tumor cells (melanoma B16/F0). Recombinant mouse (Mo) C3a (rC3a) was produced in CHO cells transfected with a Mo-IL10-signal peptide-Mo C3a plasmid construct. The effects of rC3a, IFN-γ, TGF-β1, and LPS were tested on the expression of C3, C3aR, PI3K, cytokines, chemokines, transcription factors, antioxidant defense mechanisms, angiogenesis and macrophage polarization (M1/M2). 3T3-L1 expressed the highest levels of C3, while C3aR was expressed more by RB. Interestingly, expression of C3/3T3-L1 and C3aR/RB was markedly upregulated by IFN-γ. rC3a was found to upregulate the expression of anti-inflammatory cytokines (IL-10) on 3T3-L1 and TGF-β1 on RB. rC3a also upregulated the expression of pro-inflammatory cytokines in RB. The expression of CCL-5 increased in 3T3-L1 in response to rC3a. On RB, rC3a did not alter M1/M2 polarization but upregulated the expression of antioxidant defense genes, HO-1, and VEGF. C3/C3a produced mainly by MSC may play a critical role in TME remodeling by stimulating both anti-inflammatory and proangiogenic activities of tumor stromal cells.

C5a Serum Levels in Patients with Endometriosis: A Cross-Sectional Study

Endometriosis (EM) is a gynecological disorder that presents significant immune dysregulation in its pathophysiology. Recent studies indicate that the Complement System may play a significant role in the immune processes involved in peritoneal clearance and inflammation in EM patients. C5a is a potent anaphylatoxin molecule of complement associated with the development of inflammatory disorders, however its possible impact on EM development requires further investigation. The aim of this study was to determine the concentration of serum C5a in women with EM and to investigate its possible association with severity, symptoms, age and the timing of infertility. Ninety-four patients with EM (from stage I to IV) and 50 healthy controls were assessed for C5a serum levels. Clinical and demographic data were included in the analysis. C5a serum levels were higher in patients with EM than in controls (39.5 ng/mL vs. 26.0 ng/mL; p < .0001), but not different between the EM stages. No association was observed between C5a serum concentration and the presence of symptoms, age, symptom time or infertility time. The C5a serum levels were higher in patients with EM than in controls but not associated with the severity or clinical findings.

The anaphylatoxin C5a: Structure, function, signaling, physiology, disease, and therapeutics

The complement system is one of the oldest known tightly regulated host defense systems evolved for efficiently functioning cell-based immune systems and antibodies. Essentially, the complement system acts as a pivot between the innate and adaptive arms of the immune system. The complement system collectively represents a cocktail of ∼50 cell-bound/soluble glycoproteins directly involved in controlling infection and inflammation. Activation of the complement cascade generates complement fragments like C3a, C4a, and C5a as anaphylatoxins. C5a is the most potent proinflammatory anaphylatoxin, which is involved in inflammatory signaling in a myriad of tissues. This review provides a comprehensive overview of human C5a in the context of its structure and signaling under several pathophysiological conditions, including the current and future therapeutic applications targeting C5a.

MUC1 Expression Affects the Immunoflogosis in Renal Cell Carcinoma Microenvironment through Complement System Activation and Immune Infiltrate Modulation

Mucin1 (MUC1), a glycoprotein associated with an aggressive cancer phenotype and chemoresistance, is aberrantly overexpressed in a subset of clear cell renal cell carcinoma (ccRCC). Recent studies suggest that MUC1 plays a role in modulating cancer cell metabolism, but its role in regulating immunoflogosis in the tumor microenvironment remains poorly understood. In a previous study, we showed that pentraxin-3 (PTX3) can affect the immunoflogosis in the ccRCC microenvironment by activating the classical pathway of the complement system (C1q) and releasing proangiogenic factors (C3a, C5a). In this scenario, we evaluated the PTX3 expression and analyzed the potential role of complement system activation on tumor site and immune microenvironment modulation, stratifying samples in tumors with high (MUC1H) versus tumors with low MUC1 expression (MUC1L). We found that PTX3 tissue expression was significantly higher in MUC1H ccRCC. In addition, C1q deposition and the expressions of CD59, C3aR, and C5aR were extensively present in MUC1H ccRCC tissue samples and colocalized with PTX3. Finally, MUC1 expression was associated with an increased number of infiltrating mast cells, M2-macrophage, and IDO1+ cells, and a reduced number of CD8+ T cells. Taken together, our results suggest that expression of MUC1 can modulate the immunoflogosis in the ccRCC microenvironment by activating the classical pathway of the complement system and regulating the immune infiltrate, promoting an immune-silent microenvironment.

Identification and Analysis of Crucial Genes in H. pylori-Associated Gastric Cancer Using an Integrated Bioinformatics Approach

Background

The relationship between H. pylori infection and gastric cancer (GC) has been widely studied, and H. pylori is considered as the main factor. Utilizing bioinformatics analysis, this study examined gene signatures related to progressing H. pylori-associated GC.

Materials and Methods

The dataset GSE13195 was chosen to search for abnormally expressed genes in H. pylori-associated GC and normal tissues. The TCGA-STAD database was chosen to verify the expression of key genes in GC and normal tissues.

Results

In GSE13195, a total of 332 differential expression genes (DEGs) were screened. The results of weighted gene co-expression network analysis showed that the light cyan, plum2, black, and magenta4 modules were associated with stages (T3, T2, and T4), while the orangered4, salmon2, pink, and navajowhite2 modules were correlated with lymph node metastasis (N3, N2, and N0). Based on the results of DEGs and hub genes, a total of 7 key genes (ADAM28, FCER1G, MRPL14, SOSTDC1, TYROBP, C1QC, and C3) were screened out. These gene mRNA levels were able to distinguish between normal and H. pylori-associated GC tissue using receiver operating characteristic curves. After transcriptional level verification and survival analysis, ADAM28 and C1QC were excluded. An immune infiltration study revealed that key genes were involved in regulating the infiltration levels of cells associated with innate immune response, antigen presentation process, humoral immune response, or Tcell-mediated immune response. In addition, drugs targeting FCER1G and TYROBP have been approved and are under investigation.

Conclusion

Our study identified five key genes involved in H. pylori-associated GC tumorigenesis. Patients with higher levels of C3 expression had a poorer prognosis than those with lower levels. In addition, these key genes may serve as biomarkers and therapeutic targets for H. pylori-associated GC diagnosis, targeted therapy, and immunotherapy in the future.

Loss of alcohol dehydrogenase 1B in cancer-associated fibroblasts: contribution to the increase of tumor-promoting IL-6 in colon cancer

BACKGROUND

Increases in IL-6 by cancer-associated fibroblasts (CAFs) contribute to colon cancer progression, but the mechanisms involved in the increase of this tumor-promoting cytokine are unknown. The aim of this study was to identify novel targets involved in the dysregulation of IL-6 expression by CAFs in colon cancer.

METHODS

Colonic normal (N), hyperplastic, tubular adenoma, adenocarcinoma tissues, and tissue-derived myo-/fibroblasts (MFs) were used in these studies.

RESULTS

Transcriptomic analysis demonstrated a striking decrease in alcohol dehydrogenase 1B (ADH1B) expression, a gene potentially involved in IL-6 dysregulation in CAFs. ADH1B expression was downregulated in approximately 50% of studied tubular adenomas and all T1-4 colon tumors, but not in hyperplastic polyps. ADH1B metabolizes alcohols, including retinol (RO), and is involved in the generation of all-trans retinoic acid (atRA). LPS-induced IL-6 production was inhibited by either RO or its byproduct atRA in N-MFs, but only atRA was effective in CAFs. Silencing ADH1B in N-MFs significantly upregulated LPS-induced IL-6 similar to those observed in CAFs and lead to the loss of RO inhibitory effect on inducible IL-6 expression.

CONCLUSION

Our data identify ADH1B as a novel potential mesenchymal tumor suppressor, which plays a critical role in ADH1B/retinoid-mediated regulation of tumor-promoting IL-6.

A novel plasma proteomic-based model for predicting liver fibrosis in HIV/HBV co-infected adults

To establish a plasma model to predict the risk of liver fibrosis in HIV/HBV co-infected individuals. Quantitative liquid chromatography-tandem mass spectrometry(LC-MS/MS) was used to identify differentially expressed proteins (DEPs) in plasma collected from HIV/HBV co-infected individuals with and without liver fibrosis. In total, 97 DEPs were identified, among which 11 were further validated as potential biomarkers, with immunoglobulin and complement components being the most common proteins. These markedly altered proteins were found to mediate pathophysiological pathways, including humoral immune response, complement and coagulation cascades, and complement activation. A visual logistic model, in which immunoglobulin heavy variable 3-20 (IGHV3-20), immunoglobulin heavy variable 1-24 (IGHV1-24), and macrophage colony-stimulating factor 1 receptor (CSF1R) proteins were included, has been established to predict liver fibrosis in HIV/HBV co-infected individuals. The preliminary conclusion showed that the combination of IGHV3-20, IGFHV1-24, and CSF1R is expected to become a predictive model for liver fibrosis in the context of HIV/HBV co-infection and a further validation should be performed.

Identification of TREM2-positive tumor-associated macrophages in esophageal squamous cell carcinoma: implication for poor prognosis and immunotherapy modulation

Background

It is now understood that the effectiveness of checkpoint immunotherapy can be impaired by immunosuppressive tumor-associated macrophages (TAMs). Nonetheless, the impact of different TAM subpopulations on the antitumor immune response remains unclear, mainly due to their heterogeneity. Herein, we identified a novel TAM subpopulation in esophageal squamous cell carcinoma (ESCC) that might contribute to poor clinical outcomes and immunotherapy modulation.

Methods and results

We analyzed two single-cell RNA sequencing (scRNA-seq) datasets (GSE145370 and GSE160269) of esophageal squamous cell carcinoma to identify a novel TREM2-positive TAM subpopulation characterized by upregulation of TREM2, C1QC, C1QB, C1QA, SPP1, and APOE. Quantitative real-time PCR (qRT-PCR) and enzyme-linked immunosorbent assay (ELISA) demonstrated that these genes were significantly overexpressed in ESCC. Multiplex immunofluorescence validated the infiltration of TREM2⁺ TAMs in ESCC tissues, which correlated with poorer overall survival (OS). The scRNA-seq analysis in dataset GSE120575 indicated significant enrichment of TREM2⁺ TAMs in melanoma patients (n=48) with poor immunotherapy response, which had an identical gene signature with TREM2⁺ TAMs from ESCC. Analysis of 29 bulk-RNA melanoma samples from dataset GSE78220 revealed that a gene signature of 40 genes associated with TREM2⁺ TAMs was upregulated in the transcriptome of melanomas that did not respond to anti-PD1 therapy. Validation in the TCGA ESCC cohort (n=80) showed that a high enrichment score of the TREM2⁺ TAM was associated with poor prognosis. In addition, 10 ESCC patients treated with anti-PD1 therapy suggested that patients who are not sensitive to immunotherapy have higher density of TREM2+TAMs infiltration.

Conclusion

Overall, TREM2⁺ TAM infiltration in ESCC is associated with poor prognosis and may serve as a biomarker for predicting outcomes and immunotherapy modulation in this patient population. modulation; single-cell RNA sequencing.

RAGE Inhibitors for Targeted Therapy of Cancer: A Comprehensive Review

The receptor for advanced glycation end products (RAGE) is a member of the immunoglobulin family that is overexpressed in several cancers. RAGE is highly expressed in the lung, and its expression increases proportionally at the site of inflammation. This receptor can bind a variety of ligands, including advanced glycation end products, high mobility group box 1, S100 proteins, adhesion molecules, complement components, advanced lipoxidation end products, lipopolysaccharides, and other molecules that mediate cellular responses related to acute and chronic inflammation. RAGE serves as an important node for the initiation and stimulation of cell stress and growth signaling mechanisms that promote carcinogenesis, tumor propagation, and metastatic potential. In this review, we discuss different aspects of RAGE and its prominent ligands implicated in cancer pathogenesis and describe current findings that provide insights into the significant role played by RAGE in cancer. Cancer development can be hindered by inhibiting the interaction of RAGE with its ligands, and this could provide an effective strategy for cancer treatment.

Complement and Fungal Dysbiosis as Prognostic Markers and Potential Targets in PDAC Treatment

Pancreatic ductal adenocarcinoma (PDAC) is still hampered by a dismal prognosis. A better understanding of the tumor microenvironment within the pancreas and of the factors affecting its composition is of utmost importance for developing new diagnostic and treatment tools. In this context, the complement system plays a prominent role. Not only has it been shown to shape a T cell-mediated immune response, but it also directly affects proliferation and apoptosis of the tumor cells, influencing angiogenesis, metastatic spread and therapeutic resistance. This makes complement proteins appealing not only as early biomarkers of PDAC development, but also as therapeutic targets. Fungal dysbiosis is currently the new kid on the block in tumorigenesis with cancer-associated mycobiomes extracted from several cancer types. For PDAC, colonization with the yeast Malassezia seems to promote cancer progression, already in precursor lesions. One responsible mechanism appears to be complement activation via the lectin pathway. In the present article, we review the role of the complement system in tumorigenesis, presenting observations that propose it as the missing link between fungal dysbiosis and PDAC development. We also present the results of a small pilot study supporting the crucial interplay between the complement system and Malassezia colonization in PDAC pathogenesis.

Immune Checkpoint and Other Receptor-Ligand Pairs Modulating Macrophages in Cancer: Present and Prospects

Immunotherapy, especially immune checkpoint blocking, has become the primary anti-tumor treatment in recent years. However, the current immune checkpoint inhibitor (ICI) therapy is far from satisfactory. Macrophages are a key component of anti-tumor immunity as they are a common immune cell subset in tumor tissues and act as a link between innate and adaptive immunity. Hence, understanding the regulation of macrophage activation in tumor tissues by receptor-ligand interaction will provide promising macrophage-targeting strategies to complement current adaptive immunity-based immunotherapy and traditional anti-tumor treatment. This review aims to offer a systematic summary of the current advances in number, structure, expression, biological function, and interplay of immune checkpoint and other receptor-ligand between macrophages and tumor cells.

Identification of CFHR4 associated with poor prognosis of hepatocellular carcinoma

Background

Hepatocellular carcinoma (HCC) is one of the most leading causes of cancer death worldwide. The 5-year survival rate of HCC patients remains low due to the lack of early-stage symptoms. Human complement factor H-related protein 4 (CFHR4) is a critical gene that belongs to the factor H family of plasma glycoproteins, which has not been linked to HCC development. The correlations between CFHR4 and prognosis and tumor-infiltrating lymphocytes in HCC are yet unknown. The present study demonstrated the involvement of CFHR4 in HCC via data mining approaches.

Results

A total of 18 upregulated and 67 down-regulated differentially expressed genes (DEGs) were identified. Importantly, CFHR4, which was screened from DEGs, was shown to express at a lower level in HCC tumor tissue than normal tissues. Western blotting (WB), immunohistochemical (IHC) and quantitative reverse transcription PCR (qRT-PCR) experiments of clinical samples further validated CFHR4 was aberrantly expressed in HCC patients; Data from TCGA showed that CFHR4 was inversely correlated with a cancer family history, histological grade, tumor node metastasis (TNM) stage, and serum AFP level of HCC patients; Univariate and multivariate analyses revealed that low expression of CFHR4 was an independent predictive marker in patients with HCC; Kaplan-Meier analysis showed that the lower expression of CFHR4 was significantly associated with the progression of HCC and poor prognosis rates. Furthermore, TIMER analysis indicated that CFHR4 expression levels had correlations with infiltrating levels of immune cells in HCC.

Conclusion

CFHR4 expression was low in HCC and was significantly related to the poor prognosis of HCC and the level of immune infiltration. CFHR4 played important roles in regulating the initiation and progression of HCC and could be a potential biomarker for the diagnosis and prognosis of HCC.

Methods

The expression of CFHR4 was analyzed by GEO and TCGA-LIHC database and verified by WB and IHC assay. The biological function of CFHR4 was performed by GO and KEGG enrichment analysis, and the genomic alteration of CFHR4 was investigated by cBioPortal database.The correlation between CFHR4 expression and clinical relevance was evaluated through Cox proportional hazards model, and the correlation between CFHR4 expression and tumor immune infiltrates were studied by TIMER database.

Complement C5 is a novel biomarker for liver metastasis of colorectal cancer

BACKGROUND

Colorectal cancer (CRC) is one of the most prominent malignant diseases, with a high incidence and a dismal prognosis. Metastasis to the liver is the leading cause of death in CRC patients. This study aimed to identify accurate metastatic biomarkers of CRC and investigate the potential molecular mechanisms of liver metastasis of colorectal cancer (LMCRC).

METHODS

Three independent datasets were screened and downloaded from the Gene Expression Omnibus (GEO) database. The GEO2R tool was used to identify differentially expressed genes (DEGs) in CRC tissues and liver metastases. Next, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were conducted using the Database for Annotation, Visualization, and Integrated Discovery (DAVID). Furthermore, the protein-protein interactions (PPIs) of the DEGs were analyzed using the Search Tool for the Retrieval of Interacting Genes (STRING) database, Cytoscape, and Molecular Complex Detection (MCODE). Next, the expression levels and Kaplan-Meier survival analysis of the target gene between normal colon and CRC tissues were performed by UALCAN. The expression of the target gene in tissues and cell lines was verified by quantitative reverse transcription-polymerase chain reaction (qRT-PCR), western blot, and immunohistochemistry (IHC) assay. The impact of the target gene on the proliferation, invasion, and migration ability of COAD cells was explored in vitro.

RESULTS

A total of 92 common DEGs were found in the three independent datasets. GO/KEGG enrichment analysis showed that the DEGs were mainly involved in 14 different pathways. The protein-protein interaction (PPI) network revealed that complement 5 (C5), the upstream gene of C8A in the complement system, was associated with C8 and other key hub genes. Meanwhile, the online UALCAN resource showed that C5 was up-regulated and facilitated malignant progression in COAD samples. Next, we confirmed that C5 remarkably increased and promoted cell proliferation, migration, and invasion in CRC cell lines, SW620 and SW480. The IHC assay showed C5 was also highly expressed in a majority of LMCRC tissues compared with paired CRC tissues.

CONCLUSIONS

The findings of our integrated bioinformatics study suggest that complement C5 might serve as a potential therapeutic target in patients with CRC.

The Complement System: A Potential Therapeutic Target in Liver Cancer

Liver cancer is the sixth most common cancer and the fourth most fatal cancer in the world. Immunotherapy has already achieved modest results in the treatment of liver cancer. Meanwhile, the novel and optimal combinatorial strategies need further research. The complement system, which consists of mediators, receptors, cofactors and regulators, acts as the connection between innate and adaptive immunity. Recent studies demonstrate that complement system can influence tumor progression by regulating the tumor microenvironment, tumor cells, and cancer stem cells in liver cancer. Our review concentrates on the potential role of the complement system in cancer treatment, which is a promising strategy for killing tumor cells by the activation of complement components. Conclusions: Our review demonstrates that complement components and regulators might function as biomarkers and therapeutic targets for liver cancer diagnosis and treatment.

Neutrophils: Musketeers against immunotherapy

Neutrophils, the most copious leukocytes in human blood, play a critical role in tumorigenesis, cancer progression, and immune suppression. Recently, neutrophils have attracted the attention of researchers, immunologists, and oncologists because of their potential role in orchestrating immune evasion in human diseases including cancer, which has led to a hot debate redefining the contribution of neutrophils in tumor progression and immunity. To make this debate fruitful, this review seeks to provide a recent update about the contribution of neutrophils in immune suppression and tumor progression. Here, we first described the molecular pathways through which neutrophils aid in cancer progression and orchestrate immune suppression/evasion. Later, we summarized the underlying molecular mechanisms of neutrophil-mediated therapy resistance and highlighted various approaches through which neutrophil antagonism may heighten the efficacy of the immune checkpoint blockade therapy. Finally, we have highlighted several unsolved questions and hope that answering these questions will provide a new avenue toward immunotherapy revolution.

The role of C5a-C5aR1 axis in bone pathophysiology: A mini-review

Bone remodeling is a physiological, dynamic process that mainly depends on the functions of 2 cell types: osteoblasts and osteoclasts. Emerging evidence suggests that complement system is crucially involved in the regulation of functions of these cells, especially during inflammatory states. In this context, complement component 5a (C5a), a powerful pro-inflammatory anaphylatoxin that binds the receptor C5aR1, is known to regulate osteoclast formation and osteoblast inflammatory responses, and has thus been proposed as potential therapeutic target for the treatment of inflammatory bone diseases. In this review, we will analyze the role of C5a-C5aR1 axis in bone physiology and pathophysiology, describing its involvement in the pathogenesis of some of the most frequent inflammatory bone diseases such as rheumatoid arthritis, and also in osteoporosis and bone cancer and metastasis. Moreover, we will examine C5aR1-based pharmacological approaches that are available and have been tested so far for the treatment of these conditions. Given the growing interest of the scientific community on osteoimmunology, and the scarcity of data regarding the role of C5a-C5aR1 axis in bone pathophysiology, we will highlight the importance of this axis in mediating the interactions between skeletal and immune systems and its potential use as a therapeutic target.

Inside-Out of Complement in Cancer

The role of complement in cancer has received increasing attention over the last decade. Recent studies provide compelling evidence that complement accelerates cancer progression. Despite the pivotal role of complement in fighting microbes, complement seems to suppress antitumor immunity via regulation of host cell in the tumor microenvironment. Although most studies link complement in cancer to complement activation in the extracellular space, the discovery of intracellular activation of complement, raises the question: what is the relevance of this process for malignancy? Intracellular activation is pivotal for the survival of immune cells. Therefore, complement can be important for tumor cell survival and growth regardless of the role in immunosuppression. On the other hand, because intracellular complement (the complosome) is indispensable for activation of T cells, these functions will be essential for priming antitumor T cell responses. Here, we review functions of complement in cancer with the consideration of extra and intracellular pathways of complement activation and spatial distribution of complement proteins in tumors and periphery and provide our take on potential significance of complement as biomarker and target for cancer therapy.

Plasma proteomic analysis reveals altered protein abundances in HIV-infected patients with or without Non-Hodgkin Lymphoma

The identification of circulating proteins associated with acquired immunodeficiency syndrome-related non-Hodgkin lymphoma (AIDS-NHL) may help in the development of promising biomarkers for screening, diagnosis, treatment and prognosis. Here, we used quantitative liquid chromatography-tandem mass spectrometry (LC-MS/MS) to identify differentially expressed proteins (DEPs) in plasma collected from patients with AIDS-NHL and human immunodeficiency virus (HIV)-infected patients without NHL (HIV⁺ ). Proteins with a log₂ (fold change) in abundance >0.26 and p value less than 0.05 (p < 0.05) were considered differentially abundant. In total, 84 DEPs were identified, among which 20 were further validated as potential biomarkers, with immunoglobulin and complement components being the most common proteins. Some of the proteins were further verified in a retrospective analysis of the medical records of patients in a larger cohort. These markedly altered proteins were found to mediate pathophysiological pathways that likely contribute to AIDS-NHL pathogenesis, such as the humoral immune response, complement activation, and complement and coagulation cascades. Our findings provide a new molecular understanding of AIDS-NHL pathogenesis and provide new evidence supporting the identification of these proteins as possible biomarkers in AIDS-NHL. This article is protected by copyright. All rights reserved.

Local Release of TGF-β Inhibitor Modulates Tumor-Associated Neutrophils and Enhances Pancreatic Cancer Response to Combined Irreversible Electroporation and Immunotherapy

Pancreatic cancer is a deadly disease with little response to standard therapies. Irreversible electroporation (IRE) has emerged as a novel ablative technique for the clinical treatment of pancreatic cancer. Combinations of IRE and immunotherapies, including anti-programmed death 1 (αPD1) immune checkpoint blockade, have shown promising efficacy in both preclinical and clinical studies. However, tumor recurrence remains an obstacle that needs to be overcome. It herein is shown that IRE induces a substantial infiltration of neutrophils into pancreatic tumors. These neutrophils are then polarized into a protumor phenotype by immunosuppressive cues, in particular transforming growth factor β (TGF-β). Using glutathione-responsive degradable mesoporous silica nanoparticles loaded with SB525334, an inhibitor of TGF-β1 receptor, it is demonstrated that local inhibition of TGF-β within the tumor microenvironment promotes neutrophil polarization into an antitumor phenotype, enhances pancreatic cancer response to combined IRE and αPD1 therapy, and induces long-term antitumor memory. The therapeutic efficacy is also attributed to tumor infiltration by CD8⁺ cytotoxic T cells, depletion of regulatory T cells, and maturation of antigen-presenting dendritic cells. Thus, modulating neutrophil polarization with nanomedicine is a promising strategy for treating pancreatic cancer.

Recruitment of IL-1β-producing intermediate monocytes enhanced by C5a contributes to the development of malignant pleural effusion

Background

Monocytes are involved in tumor growth and metastasis, but the distribution of monocyte phenotypes and their role in the development of malignant pleural effusion (MPE) remains unknown.

Methods

A total of 94 MPE patients (76 diagnosed with adenocarcinoma lung cancer and 18 with squamous cell lung cancer) and 102 volunteers for health examination in Xiangya Hospital from December 2016 to December 2019 were included in the study.

Results

The distribution of monocyte subtypes identified by the expression of CD14 and CD16 were analyzed by flow cytometry. The proportion of CD14⁺⁺CD16⁺ intermediate monocytes were significantly increased in pleural effusion of MPE patients. The complement system components were assayed by immunohistochemistry and ELISA, and higher expression of the classical and alternative pathways were detected in malignant pleural tissue. Transwell assay further revealed that C5a enhanced the infiltration of intermediate monocytes into the pleural cavity by promoting CCL2 production in pleural mesothelial cells (PMCs). In addition, C5a promoted the secretion of IL‐1β by intermediate monocytes. Furthermore, C5a activated in intermediate monocytes and IL‐1β released after C5a stimulation by monocytes promoted the proliferation, migration, adhesion, and epithelial‐to‐mesenchymal transition (EMT) of tumor cells, and attenuated tumor cell apoptosis.

Conclusions

C5a, activated by the classical and alternative pathways of the complement system, not only mediated the infiltration of intermediate monocytes by enhancing CCL2 production in PMCs but also induced IL‐1β release from the recruited monocytes in MPE. The consequence of C5a activation and the subsequent IL‐1β overexpression in intermediate monocytes contributed to MPE progression.

Binding of raloxifene to human complement fragment 5a (hC5a): a perspective on cytokine storm and COVID19

Human C5a (hC5a), one of the pro-inflammatory glycoproteins of the complement system is known to undergo production hyperdrive in response to stress and infection. hC5a has been associated with the pathogenesis of many chronic and acute diseases, due to its proven ability in triggering the 'cytokine storm', by binding to its cognate receptor C5aR, expressed in myriad of tissues. Given the pleiotropic downstream function of hC5a, it is logical to consider the hC5a or its precursors as potential drug targets, and thus, we have been rationally pursuing the idea of neutralizing the harmful effect of excessive hC5a, by implementing the repurposing strategies for FDA-approved drugs. Indeed, the proof of principle biophysical studies published recently is encouraging, which strongly supports the potential of this strategy. Considering BSA-carprofen as a reference model system, the current study further explores the inherent conformational plasticity of hC5a and its effect in accommodating more than one drug molecule cooperatively at multiple sites. The data generated by recruiting a battery of experimental and computational biology techniques strongly suggest that hC5a can sequentially accommodate more than one raloxifene molecule with an estimated Ki ∼ 0.5 µM and Ki ∼ 3.58 µM on its surface at non-analogous sites. The study hints at exploration of polypharmacology approach, as a new avenue for discovering synergistic drug molecule pairs, or drug molecules with 'broad-range' binding affinity for targeting the different 'hot spots' on hC5a, as an alternative combination therapy for possible management of the 'cytokine storm'-related inflammatory diseases, like COVID19.Communicated by Ramaswamy H. Sarma.

Complement System: An Immunotherapy Target in Colorectal Cancer

Colorectal cancer (CRC) is the third most common malignant tumor and the second most fatal cancer worldwide. Several parts of the immune system contribute to fighting cancer including the innate complement system. The complement system is composed of several players, namely component molecules, regulators and receptors. In this review, we discuss the complement system activation in cancer specifically CRC and highlight the possible interactions between the complement system and the various TME components. Additionally, the role of the complement system in tumor immunity of CRC is reviewed. Hence, such work could provide a framework for researchers to further understand the role of the complement system in CRC and explore the potential therapies targeting complement activation in solid tumors such as CRC.

Patients with MPNs and retinal drusen show signs of complement system dysregulation and a high degree of chronic low-grade inflammation

BACKGROUND

The hematopoietic stem cell disorders, myeloproliferative neoplasms (MPNs), are characterised by chronic low-grade inflammation (CLI). Recently, we showed that patients with MPNs have an increased prevalence of drusen and age-related macular degeneration (AMD), and drusen prevalence seemed associated with higher CLI. Studying MPNs may reveal more about drusen pathophysiology. This study investigated CLI further by measuring cytokine levels and complement system markers, comparing these between patients with MPNs and AMD.

METHODS

This cross-sectional study, between July 2018 and November 2020 conducted at Zealand University Hospital (ZUH) - Roskilde, Denmark, included 29 patients with neovascular AMD (nAMD), 28 with intermediate-stage AMD (iAMD), 62 with MPNs (35 with drusen - MPNd and 27 with healthy retinas - MPNn). With flow cytometry, we measured complement-regulatory-proteins (Cregs). With immunoassays, we investigated cytokine levels combined into a summary-inflammation-score (SIS).

FINDINGS

The MPNd and nAMD groups had similar SIS, significantly higher than the MPNn and iAMD groups. Additionally, we found SIS to increase over the MPN biological continuum from early cancer stage, essential thrombocytaemia (ET), over polycythaemia vera (PV) to the late-stage primary myelofibrosis (PMF). MPNs showed signs of complement dysregulation, with Cregs expression lower in PV than ET and PMF and even lower in PV patients with drusen.

INTERPRETATION

This study suggests that MPNd have a higher CLI than MPNn and may indicate systemic CLI to play a greater part in, and even initiate drusen formation. We suggest using MPNs as a "Human Inflammation Model" of drusen development. The CLI in MPNs elicits drusen formation, triggering more CLI creating a vicious cycle, increasing the risk of developing AMD.

FUNDING

Fight for Sight, Denmark, and Region Zealand's research promotion fund.

Complement C5a induces the formation of neutrophil extracellular traps by myeloid-derived suppressor cells to promote metastasis

Myeloid-derived suppressor cells (MDSCs) play a major role in cancer progression. In this study, we investigated the mechanisms by which complement C5a increases the capacity of polymorphonuclear MDSCs (PMN-MDSCs) to promote tumor growth and metastatic spread. Stimulation of PMN-MDSCs with C5a favored the invasion of cancer cells via a process dependent on the formation of neutrophil extracellular traps (NETs). NETosis was dependent on the production of high mobility group box 1 (HMGB1) by cancer cells. Moreover, C5a induced the surface expression of the HMGB1 receptors TLR4 and RAGE in PMN-MDSCs. In a mouse lung metastasis model, inhibition of C5a, C5a receptor-1 (C5aR1) or NETosis reduced the number of circulating-tumor cells (CTCs) and the metastatic burden. In support of the translational relevance of these findings, C5a was able to stimulate migration and NETosis in PMN-MDSCs obtained from lung cancer patients. Furthermore, myeloperoxidase (MPO)-DNA complexes, as markers of NETosis, were elevated in lung cancer patients and significantly correlated with C5a levels. In conclusion, C5a induces the formation of NETs from PMN-MDSCs in the presence of cancer cells, which may facilitate cancer cell dissemination and metastasis.

Nomogram based on clinical characteristics and serological inflammation markers to predict overall survival of oral tongue squamous cell carcinoma patient after surgery

BACKGROUND

Oral tongue squamous cell carcinoma (OTSCC) is a prevalent malignant disease that is characterized by high rates of metastasis and postoperative recurrence. The aim of this study was to establish a nomogram to predict the outcome of OTSCC patients after surgery.

METHODS

We retrospectively analyzed 169 OTSCC patients who underwent treatments in the Cancer Hospital of Shantou University Medical College from 2008 to 2019. The Cox regression analysis was performed to determine the independent prognostic factors associated with patient's overall survival (OS). A nomogram based on these prognostic factors was established and internally validated using a bootstrap resampling method.

RESULTS

Multivariate Cox regression analysis revealed the independent prognostic factors for OS were TNM stage, age, lymphocyte-to-monocyte ratio and immunoglobulin G, all of which were identified to create the nomogram. The Akaike Information Criterion and Bayesian Information Criterion of the nomogram were lower than those of TNM stage (292.222 vs. 305.480; 298.444 vs. 307.036, respectively), indicating a better goodness-of-fit of the nomogram for predicting OS. The bootstrap-corrected of concordance index (C-index) of nomogram was 0.784 (95% CI 0.708-0.860), which was higher than that of TNM stage (0.685, 95% CI 0.603-0.767, P = 0.017). The results of time-dependent C-index for OS also showed that the nomogram had a better discriminative ability than that of TNM stage. The calibration curves of the nomogram showed good consistency between the probabilities and observed values. The decision curve analysis also revealed the potential clinical usefulness of the nomogram. Based on the cutoff value obtained from the nomogram, the proposed high-risk group had poorer OS than low-risk group (P < 0.0001).

CONCLUSIONS

The nomogram based on clinical characteristics and serological inflammation markers might be useful for outcome prediction of OTSCC patient.

Association between peripheral blood WBCs C3aR mRNA level and plasma C3a, C3aR, IL-1β concentrations and acute exacerbation of chronic obstructive pulmonary disease

BACKGROUND

The relationship between C3a-C3aR, IL-1β, and the acute exacerbation of chronic obstructive pulmonary disease is still unclear. This study aims to explore the expression levels of C3aR in peripheral blood WBCs and the concentrations of C3a, C3aR, and IL-1β in plasma in healthy controls and patients with chronic obstructive pulmonary disease (COPD).

METHODS

WBCs C3aR level in the peripheral blood, the concentrations of C3a, C3aR, and IL-1β in plasma were measured in 60 patients with acute exacerbation of COPD (AECOPD), 30 patients with stable COPD (SCOPD), and 30 healthy controls. The baseline characteristics and clinical data collected from enrolled patients, including age, gender, laboratory indicators, and lung function. We analyzed the correlation between C3a, C3aR, IL-1β, and lung function indicators (forced expiratory volume in the first second as a percentage of predicted value, FEV₁%pred) in the AECOPD group.

RESULTS

The white blood cell count (WBC), neutrophil/lymphocyte ratio (NLR), and C-reactive protein (CRP) of patients in COPD were higher than in healthy controls (P < 0.05). The peripheral blood WBCs C3aR mRNA and plasma C3a, C3aR, and IL-1β in AECOPD were higher than in SCOPD and healthy controls (P < 0.05). The peripheral blood WBCs C3aR mRNA and plasma C3aR, and IL-1β in AECOPD combined with respiratory failure were higher than in the non-respiratory failure group (P < 0.05). The peripheral blood WBCs C3aR mRNA and plasma C3a, C3aR, and IL-1β in AECOPD with high-risk were higher than in the low-risk group (P < 0.05). The peripheral blood WBCs C3aR mRNA and plasma C3a, C3aR, and IL-1β in AECOPD were negatively correlated with FEV₁pred%. The peripheral blood WBCs C3aR mRNA, the plasma C3a and C3aR in AECOPD were positively correlated with IL-1β.

CONCLUSION

The peripheral blood WBCs C3aR mRNA and plasma C3a, C3aR, and IL-1β in COPD patients were significantly related to the risk of disease deterioration. The C3a-C3aR axis may be involved in airway inflammation in patients with COPD.

By Increasing the Expression and Activation of STAT3, Sustained C5a Stimulation Increases the Proliferation, Migration, and Invasion of RCC Cells and Promotes the Growth of Transgrafted Tumors

Background

Contradictive results about the direct role of C5a/C5aR1 axis in different cancer cells have been reported. The direct effect of C5a on human renal cell carcinoma (RCC) cells and the underlying mechanism are not clear. The aim of this study is to investigate the role of C5a/C5aR1 axis in RCC cells and its working mechanism.

Methods

RCC cells were infected with lentivirus Lenti-C5a, which was designed to over-express secretory C5a in the cells, or directly treated with recombinant C5a, the influence of these treatments in the cells and the underlying mechanism were explored.

Results

Transfection of RCC cells with Lenti-C5a markedly increased the production of C5a and significantly increased the proliferation, migration, and invasion of RCC cells, but direct addition of C5a to the cell culture medium had no such effects though it indeed induced a transient intracellular calcium rise. RCC cells were found to express carboxypeptidase D and M, which reportedly to inactivate C5a. Also, the RCC cells stably transfected with Lenti-C5a produced larger transgrafted tumors in nude mice compared with the non-transfected or control virus transfected cells. In addition, over-expression of C5a significantly increased the expression and phosphorylation of STAT3 as well as the phosphorylated JNK level. Furthermore, the effect of C5a over-expression on RCC cells' proliferation, migration, and invasion could be blocked by Stattic, a STAT3-specific inhibitor.

Conclusion

Chronic over-activation of C5a/C5aR1 axis could directly increase RCC cells' proliferation, migration, and invasion and thus contribute directly to the progression of the disease. Over-activation of STAT3 pathway is among the underlying mechanism.

Exploration of the Proteomic Landscape of Small Extracellular Vesicles in Serum as Biomarkers for Early Detection of Colorectal Neoplasia

Background

Patient participation in colorectal cancer (CRC) screening via a stool test and colonoscopy is suboptimal, but participation can be improved by the development of a blood test. However, the suboptimal detection abilities of blood tests for advanced neoplasia, including advanced adenoma (AA) and CRC, limit their application. We aimed to investigate the proteomic landscape of small extracellular vesicles (sEVs) from the serum of patients with colorectal neoplasia and identify specific sEV proteins that could serve as biomarkers for early diagnosis.

Materials and Methods

We enrolled 100 patients including 13 healthy subjects, 12 non-AAs, 13 AAs, and 16 stage-I, 15 stage-II, 16 stage-III, and 15 stage-IV CRCs. These patients were classified as normal control, early neoplasia, and advanced neoplasia. The sEV proteome was explored by liquid chromatography-tandem mass spectrometry. Generalized association plots were used to integrate the clustering methods, visualize the data matrix, and analyze the relationship. The specific sEV biomarkers were identified by a decision tree via Orange3 software. Functional enrichment analysis was conducted by using the Ingenuity Pathway Analysis platform.

Results

The sEV protein matrix was identified from the serum of 100 patients and contained 3353 proteins, of which 1921 proteins from 98 patients were finally analyzed. Compared with the normal control, subjects with early and advanced neoplasia exhibited a distinct proteomic distribution in the data matrix plot. Six sEV proteins were identified, namely, GCLM, KEL, APOF, CFB, PDE5A, and ATIC, which properly distinguished normal control, early neoplasia, and advanced neoplasia patients from each other. Functional enrichment analysis revealed that APOF⁺ and CFB⁺ sEV associated with clathrin-mediated endocytosis signaling and the complement system, which have critical implications for CRC carcinogenesis.

Conclusion

Patients with colorectal neoplasia had a distinct sEV proteome expression pattern in serum compared with those patients who were healthy and did not have neoplasms. Moreover, the six identified specific sEV proteins had the potential to discriminate colorectal neoplasia between early-stage and advanced neoplasia. Collectively, our study provided a six-sEV protein biomarker panel for CRC diagnosis at early or advanced stages. Furthermore, the implication of the sEV proteome in CRC carcinogenesis via specific signaling pathways was explored.

Role of C5a and C5aR in doxorubicin-induced cardiomyocyte senescence

Doxorubicin (DOX) is an efficacious antineoplastic drug; however, its use is limited due to its cardiotoxicity. Cardiomyocyte senescence is considered to be a key factor in the development of DOX-related cardiomyopathy. Complement component 5a (C5a) and the C5a receptor (C5aR) have been reported to play a key role in the process of cellular senescence. However, to the best of our knowledge, the exact role of C5a and C5aR in cellular senescence in the heart remains largely unknown. Reverse transcription-quantitative (RT-q)PCR and western blot assays were used to analyze the expression levels of C5a and C5aR in H9c2 embryonic rat cardiomyocytes and AC16 human cardiomyocyte-like cells. The cells were treated with DOX and a C5aR antagonist (C5aRA). The expression of TNF-α and IFN-γ was determined using ELISA and western blotting. The levels of reactive oxygen species (ROS) were also measured using ELISA. Cellular senescence was determined using senescence-associated β-galactosidase (SA-β-gal) staining and by analyzing the protein expression levels of p53, p16, p21 and insulin-like growth factor-binding protein 3 (IGFBP3). The expression levels of C5a and C5aR were found to be upregulated during the DOX-induced senescence of H9c2 and AC16 cardiomyocytes. Treatment with C5aRA downregulated TNF-α and IFN-γ expression, in addition to ROS levels. Furthermore, C5aRA prevented DOX-induced cellular senescence and decreased the levels of positive SA-β-gal staining in H9c2 and AC16 cardiomyocytes, in addition to downregulating the expression levels of p53, p16, p21 and IGFBP3. C5aRA also increased the telomere length and telomerase activity in H9c2 and AC16 cardiomyocytes following DOX stimulation. In conclusion, the findings of the present study indicated that C5a and C5aR may play a key role in cardiomyocyte senescence, and treatment with C5aRA may be an effective method for preventing DOX-induced cardiomyocyte aging.

Complement Component C3: A Novel Biomarker Participating in the Pathogenesis of Non-alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is currently the most common cause of chronic liver disorder worldwide. The pathological spectrum of NAFLD ranges from simple steatosis to non-alcoholic steatohepatitis (NASH) that induces progressive liver cirrhosis and eventually hepatocellular carcinoma (HCC). However, the molecular mechanisms driving the transformation of NASH are obscure. There is a compelling need for understanding the pathogenic mechanisms of NASH, and thereby providing new insight into mechanism-based therapy. Currently, several studies reported that complement system, an innate immune system, played an important role in the pathogenesis of NAFLD, which was also proved by our recent study. Complement component 3 (C3), a protein of the innate immune system, plays a hub role in the complement system. Herein, we present a review on the role and molecular mechanism of C3 in NASH as well as its implication in NASH diagnosis and treatment.

The Complement System in Ovarian Cancer: An Underexplored Old Path

Ovarian cancer is one of the most lethal gynecological cancers. Current therapeutic strategies allow temporary control of the disease, but most patients develop resistance to treatment. Moreover, although successful in a range of solid tumors, immunotherapy has yielded only modest results in ovarian cancer. Emerging evidence underscores the relevance of the components of innate and adaptive immunity in ovarian cancer progression and response to treatment. Particularly, over the last decade, the complement system, a pillar of innate immunity, has emerged as a major regulator of the tumor microenvironment in cancer immunity. Tumor-associated complement activation may support chronic inflammation, promote an immunosuppressive microenvironment, induce angiogenesis, and activate cancer-related signaling pathways. Recent insights suggest an important role of complement effectors, such as C1q or anaphylatoxins C3a and C5a, and their receptors C3aR and C5aR1 in ovarian cancer progression. Nevertheless, the implication of these factors in different clinical contexts is still poorly understood. Detailed knowledge of the interplay between ovarian cancer cells and complement is required to develop new immunotherapy combinations and biomarkers. In this context, we discuss the possibility of targeting complement to overcome some of the hurdles encountered in the treatment of ovarian cancer.

Phototherapy Facilitates Tumor Recruitment and Activation of Natural Killer T cells for Potent Cancer Immunotherapy

Adoptively transferred natural killer T (NKT) cells confer distinct cancer surveillance without causing obvious side effects, making them a promising candidate for cancer immunotherapy. However, their therapeutic efficacy is limited by inefficient tumor infiltration and inadequate activation in an immunosuppressive tumor microenvironment. To overcome these obstacles, we develop a strategy of using photothermal therapy (PTT) to promote the antitumor ability of adoptively transferred NKT cells. The transferred NKT cells are efficiently recruited to PTT-treated tumors in response to PTT-created inflammation. Moreover, PTT treatment promotes the activation of NKT cells and enhances the NKT cell-initiated immune cascade. As a consequence, the combined therapy of PTT plus NKT cell transfer exhibits excellent growth inhibition of local tumors. Moreover, it efficiently rejects distant tumors and elicits long-term immunological memory to prevent tumor recurrence. Overall, the current study opens new paths to the clinical translation of NKT cells for cancer immunotherapy.

Targeting the Complement Pathway in Malignant Glioma Microenvironments

Malignant glioma is a highly fatal type of brain tumor, and its reoccurrence is largely due to the ordered interactions among the components present in the complex microenvironment. Besides its role in immune surveillance and clearance under physiological conditions, the complement system is expressed in a variety of tumor types and mediates the interactions within the tumor microenvironments. Recent studies have uncovered the broad expression spectrum of complement signaling molecules in the tumor microenvironment and various tumor cells, in particular, malignant glioma cells. Involvement of the complement system in tumor growth, immunosuppression and phenotype transition have also been elucidated. In this review, we enumerate the expression and function of complement molecules in multiple tumor types reported. Moreover, we elaborate the complement pathways in glioma cells and various components of malignant glioma microenvironments. Finally, we summarize the possibility of the complement molecules as prognostic factors and therapeutic targets in the treatment of malignant glioma. Specific targeting of the complement system maybe of great significance and value in the future treatment of multi-type tumors including malignant glioma.

Type III TGF-β Receptor Down-Regulation Promoted Tumor Progression via Complement Component C5a Induction in Hepatocellular Carcinoma

Simple Summary

The clinical implications of TGFβR3 downregulation are currently unknown in hepatocellular carcinoma (HCC). Clinically, we identified that HCC patients with low expression levels of tumoral TGFβR3 exhibited significantly late tumor stages and shortened survival outcomes. Moreover, HCC patients developed lower plasma levels of TGFβR3 (sTGFβR3) (8.9 ng/mL) compared to healthy individuals (15.9 ng/mL), which represented a potential diagnostic marker. Similar to tumoral TGFβR3, low levels of plasma sTGFβR3 are also associated with poor clinical outcomes in HCC. To determine its tumor-suppressing capacities, continuous injection of sTGFβR3 in an orthotopic liver tumor model was performed, resulting in 2-fold tumor volume reduction compared to control. Decreased expression of TGFβR3 induced the upregulation of tumoral complement component C5a in HCC, which was found to contribute to poor clinical outcomes and promote tumor progression via a novel function in activating the tumor-promoting macrophages.

Abstract

Background and Aims—Transforming growth factor-beta (TGF-β) signaling orchestrates tumorigenesis and one of the family members, TGF-β receptor type III (TGFβR3), are distinctively under-expressed in numerous malignancies. Currently, the clinical impact of TGFβR3 down-regulation and the underlying mechanism remains unclear in hepatocellular carcinoma (HCC). Here, we aimed to identify the tumor-promoting roles of decreased TGFβR3 expression in HCC progression. Materials and Methods—For clinical analysis, plasma and liver specimens were collected from 100 HCC patients who underwent curative resection for the quantification of TGFβR3 by q-PCR and ELISA. To study the tumor-promoting mechanism of TGFβR3 downregulation, HCC mouse models and TGFβR3 knockout cell lines were applied. Results—Significant downregulation of TGFβR3 and its soluble form (sTGFβR3) were found in HCC tissues and plasma compared to healthy individuals (p < 0.01). Patients with <9.4 ng/mL sTGFβR3 exhibited advanced tumor stage, higher recurrence rate and shorter disease-free survival (p < 0.05). The tumor-suppressive function of sTGFβR3 was further revealed in an orthotopic mouse HCC model, resulting in 2-fold tumor volume reduction. In TGFβR3 knockout hepatocyte and HCC cells, increased complement component C5a was observed and strongly correlated with shorter survival and advanced tumor stage (p < 0.01). Interestingly, C5a activated the tumor-promoting Th-17 response in tumor associated macrophages. Conclusion—TGFβR3 suppressed tumor progression, and decreased expression resulted in poor prognosis in HCC patients through upregulation of tumor-promoting complement C5a.

The relationship among Girdin DNA methylation, its high expression, and immune infiltration in hepatocellular carcinoma: Clues from in silico analysis

Objective: The aim of the present study was to explore the relationship among Girdin DNA methylation, its high expression, and immune infiltration in human hepatocellular carcinoma (HCC).

Materials and methods: The Cancer Genome Atlas (TCGA), Gene Expression Omnibus (GEO), and International Cancer Genome Consortium (ICGC) databases were used to compare Girdin mRNA expression between HCC tissues and normal tissues, and determine the relationship between Girdin expression and HCC prognosis. TCGA database was also used to analyze the expression of Girdin and its methylation status, as well as the relationship between Girdin DNA methylation and HCC prognosis. The Tumor IMmune Estimation Resource (TIMER) database was used to explore the correlation between Girdin expression and HCC immune infiltration.

Results: Girdin expression was elevated in HCC tissues compared with that in normal tissues. The degree of methylation at cg03188526, a CpG site in the Girdin gene body, was positively correlated with Girdin mRNA expression, while high Girdin expression and cg03188526 hypermethylation were both correlated with poor HCC prognosis. Additionally, HCC tissue with high Girdin expression exhibited abundant immune infiltration, and the high Girdin expression was associated with a worse prognosis in macrophage-enriched HCC specimens.

Conclusion: Our findings indicated that Girdin likely functions as an oncogene in HCC and that hypermethylation at cg03188526 in the Girdin gene body may explain the high Girdin expression levels in HCC tissue. Furthermore, we report for the first time that the adverse effects of high Girdin expression in HCC patients may be partially mediated by tumor macrophage infiltration.

"Complimenting the Complement": Mechanistic Insights and Opportunities for Therapeutics in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the most common primary malignancy of the liver and a leading cause of death in the US and worldwide. HCC remains a global health problem and is highly aggressive with unfavorable prognosis. Even with surgical interventions and newer medical treatment regimens, patients with HCC have poor survival rates. These limited therapeutic strategies and mechanistic understandings of HCC immunopathogenesis urgently warrant non-palliative treatment measures. Irrespective of the multitude etiologies, the liver microenvironment in HCC is intricately associated with chronic necroinflammation, progressive fibrosis, and cirrhosis as precedent events along with dysregulated innate and adaptive immune responses. Central to these immunological networks is the complement cascade (CC), a fundamental defense system inherent to the liver which tightly regulates humoral and cellular responses to noxious stimuli. Importantly, the liver is the primary source for biosynthesis of >80% of complement components and expresses a variety of complement receptors. Recent studies implicate the complement system in liver inflammation, abnormal regenerative responses, fibrosis, carcinogenesis, and development of HCC. Although complement activation differentially promotes immunosuppressive, stimulant, and angiogenic microenvironments conducive to HCC development, it remains under-investigated. Here, we review derangement of specific complement proteins in HCC in the context of altered complement regulatory factors, immune-activating components, and their implications in disease pathogenesis. We also summarize how complement molecules regulate cancer stem cells (CSCs), interact with complement-coagulation cascades, and provide therapeutic opportunities for targeted intervention in HCC.

High Expression of the Component 3a Receptor 1 (C3AR1) Gene in Stomach Adenocarcinomas Infers a Poor Prognosis and High Immune-Infiltration Levels

Background

This study was designed to explore the incompletely investigated role of the complement component 3a receptor 1 (C3AR1) in the prognosis of stomach adenocarcinomas (STAD).

Material/Methods

Using bioinformatic methods, we systematically determined the expression and prognosis value of C3AR1 in various cancers by using the TIMER (Tumor Immune Estimation Resource) database, UALCAN platform, GEPIA (Gene Expression Profiling Interactive Analysis) server, and the OncoLnc tool. The biological processes influenced by C3AR1 were determined using the GSEA (Gene Set Enrichment Analysis) software (Copyright 2004–2020 Broad Institute, Inc., Massachusetts Institute of Technology, and Regents of the University of California). The correlation between C3AR1 expression and the immune-infiltrating cells as well as the correlation analysis between C3AR1 expression and the corresponding immune-marker sets were conducted using the TIMER and GEPIA databases.

Results

The expression of C3AR1 was significantly (P<0.001) differentially expressed on several tumor types, while its prognosis value could only be determined on STAD, with a high expression of C3AR1 closely correlated with a poor prognosis. The GSEA analysis revealed that the differential expression of C3AR1 profoundly affected the immune-related biological processes. The expression of C3AR1 was strongly and positively correlated with the infiltration of monocytes, tumor-associated macrophages, M2 macrophages, dendritic cells, and exhausted T cells.

Conclusions

Our results have revealed that a high expression of C3AR1 is positively correlated with a poor prognosis and increased tumor-immune infiltration. C3AR1 can promote the polarization of M2 macrophages and T cell exhaustion, leading to the immune escape of STAD. These findings suggest that C3AR1 could be used as a prognostic and immune-infiltration marker in the pathogenesis of STAD.

Complement activation promoted by the lectin pathway mediates C3aR-dependent sarcoma progression and immunosuppression

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.