Multifaceted Roles of Chemokine C-X-C Motif Ligand 7 in Inflammatory Diseases and Cancer

A narrative review of chemokine receptors CXCR1 and CXCR2 and their role in acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a severe form of acute respiratory failure characterised by extensive inflammatory injury to the alveolocapillary barrier leading to alveolar oedema, impaired gas exchange and, ultimately, hypoxaemia necessitating the use of supplemental oxygen combined with some degree of positive airway pressure. Although much heterogeneity exists regarding the aetiology, localisation and endotypic characterisation of ARDS, what remains largely undisputed is the role of the innate immune system, and in particular of neutrophils, in precipitating and propagating lung injury. Activated neutrophils, recruited to the lung through chemokine gradients, promote injury by releasing oxidants, proteases and neutrophil extracellular traps, which ultimately cause platelet aggregation, microvascular thrombosis and cellular death. Among various neutrophilic chemoattractants, interleukin-8/C-X-C motif ligand 8 and related chemokines, collectively called ELR+ chemokines, acting on neutrophils through the G protein-coupled receptors CXCR1 and CXCR2, are pivotal in orchestrating the neutrophil activation status and chemotaxis in the inflamed lung. This allows efficient elimination of infectious agents while at the same time minimising collateral damage to host tissue. Therefore, understanding how CXCR1 and CXCR2 receptors are regulated is important if we hope to effectively target them for therapeutic use in ARDS. In the following narrative review, we provide an overview of the role of ELR+ chemokines in acute lung injury (ALI) and ARDS, we summarise the relevant regulatory pathways of their cognisant receptors CXCR1/2 and highlight current preclinical and clinical evidence on the therapeutic role of CXCR1 and CXCR2 inhibition in animal models of ALI, as well as in ARDS patients.

Chemokine receptor 7 contributes to T- and B-cell filtering in ageing bladder, cystitis and bladder cancer

BACKGROUND

Research has suggested significant correlations among ageing, immune microenvironment, inflammation and tumours. However, the relationships among ageing, immune microenvironment, cystitis and bladder urothelial carcinoma (BLCA) in the bladder have rarely been reported.

METHODS

Bladder single-cell and transcriptomic data from young and old mice were used for immune landscape analysis. Transcriptome, single-cell and The Cancer Genome Atlas Program datasets of BLCA and interstitial cystitis/bladder pain syndrome (IC/BPS) were used to analyse immune cell infiltration and molecular expression. Bladder tissues from mice, IC/BPS and BLCA were collected to validate the results.

RESULTS

Eight types of immune cells (macrophages, B-cells, dendritic cells, T-cells, monocytes, natural killer cells, γδ T-cells and ILC2) were identified in the bladder of mice. Aged mice bladder tissues had a significantly higher number of T-cells, γδ T-cells, ILC2 and B-cells than those in the young group (P < 0.05). Three types of T-cells (NK T-cells, γδ T-cells and naïve T-cells) and three types of B-cells (follicular B-cells, plasma and memory B-cells) were identified in aged mice bladder. Chemokine receptor 7 (CCR7) is highly expressed in aged bladder, IC/BPS and BLCA (P < 0.05). CCR7 is likely to be involved in T- and B-cell infiltration in aged bladder, IC/BPS and BLCA. Interestingly, the high CCR7 expression on BLCA cell membranes was a prognostic protective factor.

CONCLUSIONS

In this study, we characterised the expression profiles of immune cells in bladder tissues of aged and young mice and demonstrated that CCR7-mediated T- and B-cell filtration contributes to the development of bladder ageing, IC/BPS and BLCA.

Personalized identification and characterization of genome-wide gene expression differences between patient-matched intracranial and extracranial melanoma metastasis pairs

Melanoma is the most serious type of skin cancer that frequently spreads to other organs of the human body. Especially melanoma metastases to the brain (intracranial metastases) are hard to treat and a major cause of death of melanoma patients. Little is known about molecular alterations and altered mechanisms that distinguish intra- from extracranial melanoma metastases. So far, almost all existing studies compared intracranial metastases from one set of patients to extracranial metastases of an another set of melanoma patients. This neglects the important facts that each melanoma is highly individual and that intra- and extracranial melanoma metastases from the same patient are more similar to each other than to melanoma metastases from other patients in the same organ. To overcome this, we compared the gene expression profiles of 16 intracranial metastases to their corresponding 21 patient-matched extracranial metastases in a personalized way using a three-state Hidden Markov Model (HMM) to identify altered genes for each individual metastasis pair. This enabled three major findings by considering the predicted gene expression alterations across all patients: (i) most frequently altered pathways include cytokine-receptor interaction, calcium signaling, ECM-receptor interaction, cAMP signaling, Jak-STAT and PI3K/Akt signaling, (ii) immune-relevant signaling pathway genes were downregulated in intracranial metastases, and (iii) intracranial metastases were associated with a brain-like phenotype gene expression program. Further, the integration of all differentially expressed genes across the patient-matched melanoma metastasis pairs led to a set of 103 genes that were consistently down- or up-regulated in at least 11 of the 16 of the patients. This set of genes contained many genes involved in the regulation of immune responses, cell growth, cellular signaling and transport processes. An analysis of these genes in the TCGA melanoma cohort showed that the expression behavior of 11 genes was significantly associated with survival. Moreover, a comparison of the 103 genes to three closely related melanoma metastasis studies revealed a core set of eight genes that were consistently down- or upregulated in intra- compared to extracranial metastases in at least two of the three related studies (down: CILP, DPT, FGF7, LAMP3, MEOX2, TMEM119; up: GLDN, PMP2) including FGF7 that was also significantly associated with survival. Our findings contribute to a better characterization of genes and pathways that distinguish intra- from extracranial melanoma metastasis and provide important hints for future experimental studies to identify potential targets for new therapeutic approaches.

The plasma proteome differentiates the multisystem inflammatory syndrome in children (MIS-C) from children with SARS-CoV-2 negative sepsis

BACKGROUND

The Multi-System Inflammatory Syndrome in Children (MIS-C) can develop several weeks after SARS-CoV-2 infection and requires a distinct treatment protocol. Distinguishing MIS-C from SARS-CoV-2 negative sepsis (SCNS) patients is important to quickly institute the correct therapies. We performed targeted proteomics and machine learning analysis to identify novel plasma proteins of MIS-C for early disease recognition.

METHODS

A case-control study comparing the expression of 2,870 unique blood proteins in MIS-C versus SCNS patients, measured using proximity extension assays. The 2,870 proteins were reduced in number with either feature selection alone or with a prior COMBAT-Seq batch effect adjustment. The leading proteins were correlated with demographic and clinical variables. Organ system and cell type expression patterns were analyzed with Natural Language Processing (NLP).

RESULTS

The cohorts were well-balanced for age and sex. Of the 2,870 unique blood proteins, 58 proteins were identified with feature selection (FDR-adjusted P < 0.005, P < 0.0001; accuracy = 0.96, AUC = 1.00, F1 = 0.95), and 15 proteins were identified with a COMBAT-Seq batch effect adjusted feature selection (FDR-adjusted P < 0.05, P < 0.0001; accuracy = 0.92, AUC = 1.00, F1 = 0.89). All of the latter 15 proteins were present in the former 58-protein model. Several proteins were correlated with illness severity scores, length of stay, and interventions (LTA4H, PTN, PPBP, and EGF; P < 0.001). NLP analysis highlighted the multi-system nature of MIS-C, with the 58-protein set expressed in all organ systems; the highest levels of expression were found in the digestive system. The cell types most involved included leukocytes not yet determined, lymphocytes, macrophages, and platelets.

CONCLUSIONS

The plasma proteome of MIS-C patients was distinct from that of SCNS. The key proteins demonstrated expression in all organ systems and most cell types. The unique proteomic signature identified in MIS-C patients could aid future diagnostic and therapeutic advancements, as well as predict hospital length of stays, interventions, and mortality risks.

Storage of Transfusion Platelet Concentrates Is Associated with Complement Activation and Reduced Ability of Platelets to Respond to Protease-Activated Receptor-1 and Thromboxane A2 Receptor

Platelet activation and the complement system are mutually dependent. Here, we investigated the effects of storage time on complement activation and platelet function in routinely produced platelet concentrates. The platelet concentrates (n = 10) were stored at 22 °C for seven days and assessed daily for complement and platelet activation markers. Additionally, platelet function was analyzed in terms of their responsiveness to protease-activated receptor-1 (PAR-1) and thromboxane A2 receptor (TXA2R) activation and their capacity to adhere to collagen. Complement activation increased over the storage period for all analyzed markers, including the C1rs/C1-INH complex (fold change (FC) = 1.9; p < 0.001), MASP-1/C1-INH complex (FC = 2.0; p < 0.001), C4c (FC = 1.8, p < 0.001), C3bc (FC = 4.0; p < 0.01), and soluble C5b-9 (FC = 1.7, p < 0.001). Furthermore, the levels of soluble platelet activation markers increased in the concentrates over the seven-day period, including neutrophil-activating peptide-2 (FC = 2.5; p < 0.0001), transforming growth factor beta 1 (FC = 1.9; p < 0.001) and platelet factor 4 (FC = 2.1; p < 0.0001). The ability of platelets to respond to activation, as measured by surface expression of CD62P and CD63, decreased by 19% and 24% (p < 0.05) for PAR-1 and 69-72% (p < 0.05) for TXA2R activation, respectively, on Day 7 compared to Day 1. The extent of platelet binding to collagen was not significantly impaired during storage. In conclusion, we demonstrated that complement activation increased during the storage of platelets, and this correlated with increased platelet activation and a reduced ability of the platelets to respond to, primarily, TXA2R activation.

Systemic Immune Modulation Induced by Ephedrine in Obese-Diabetes (db/db) Mice

Immune-modulatory effects in obese-diabetes (db/db) mice were observed to understand the possible mechanism(s) of ephedrine-induced unfavorable responses. The ephedrine doses were selected based on the FDA report (NTP Tech Rep Ser NO 307; CAS# 134-72-5), which showed the non-toxic dose for B6C3F1 mice. In db/db mice, higher doses (6 and 12 mg/mouse) of ephedrine significantly harmed the liver and lung morphology, including fatty liver with multiple blood vessel engorgement, alveolar wall thickening, and inflammatory response in the lung. The immune micro-environment of db/db mice was an inflammatory state with suppressed adaptive cellular immunity. After the administration of ephedrine, significant deterioration of NK activity was observed with lowered gene transcription of klrk1 encoding NKG2D, and of ccl8, a NK cell targeting chemokine. Suppressed cellular immunity in db/db mice was lowered ever further by single ephedrine treatment, as was evidenced by mitogen-induced T or B cell proliferations. These observations demonstrate that at the non-toxic doses in normal B6C3F1 mice, ephedrine clearly suppressed systemic immunity of db/db mice. The data suggest that the immune micro-environment of obese individuals is fragile and susceptible to ephedrine-related pathologic response, and this may be a prelude to the induction of obesity-related secondary immunological disorders.

The role of CXCL family members in different diseases

Chemokines are a large family mediating a lot of biological behaviors including chemotaxis, tumor growth, angiogenesis and so on. As one member of this family, CXC subfamily possesses the same ability. CXC chemokines can recruit and migrate different categories of immune cells, regulate tumor's pathological behaviors like proliferation, invasion and metastasis, activate angiogenesis, etc. Due to these characteristics, CXCL subfamily is extensively and closely associated with tumors and inflammatory diseases. As studies are becoming more and more intensive, CXCLs' concrete roles are better described, and CXCLs' therapeutic applications including biomarkers and targets are also deeply explained. In this review, the role of CXCL family members in various diseases is summarized.

Immune-Hot tumor features associated with recurrence in early-stage ovarian clear cell carcinoma

Ovarian clear cell carcinoma (OCCC) is a distinct histotype of ovarian cancer, which usually presages a worse prognosis upon recurrence. Identifying patients at risk for relapse is an unmet need to improve outcomes. A retrospective cohort analysis of 195 early-stage OCCC patients diagnosed between January 2011 and December 2019 at National Taiwan University Hospital was conducted to identify prognostic factors for recurrence, progression-free survival (PFS) and overall survival (OS). Molecular profiling of tumors was performed in a case-controlled cohort matched for adjuvant therapy for biomarker discovery. Multivariate Cox proportional hazard model revealed that paclitaxel-based chemotherapy was associated with better PFS than nonpaclitaxel chemotherapy (HR = 0.19, P = .006). The addition of bevacizumab was associated with better PFS, compared to no bevacizumab (HR = 0.09, P = .02). Neither showed significant improvement in OS. Recurrence is associated with an Immune-Hot tumor feature (P = .03), the CTLA-4-high subtype (P = .01) and increased infiltration of immune cells in general. The Immune-Hot feature (HR = 3.39, P = .005) and the CTLA-4-high subtype (HR = 2.13, P = .059) were associated with worse PFS. Immune-Hot tumor features could prognosticate recurrence in early-stage OCCC.

Identification and validation of chemokine system-related genes in idiopathic pulmonary fibrosis

Background

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive interstitial lung disease with limited therapeutic options. Recent studies have demonstrated that chemokines play a vital role in IPF pathogenesis. In the present study, we explored whether the gene signature associated with chemokines could be used as a reliable biological marker for patients with IPF.

Methods

Chemokine-related differentially expressed genes (CR-DEGs) in IPF and control lung tissue samples were identified using data from the Gene Expression Omnibus database. A chemokine-related signature of the diagnostic model was established using the LASSO-Cox regression. In addition, unsupervised cluster analysis was conducted using consensus-clustering algorithms. The CIBERSORT algorithm was used to calculate immune cell infiltration across patient subgroups. Finally, we established a mouse model of bleomycin-induced pulmonary fibrosis and a model of fibroblasts treated with TGFβ1. Expression levels of chemokine-related signature genes were determined using real-time quantitative polymerase chain reaction (RT-qPCR).

Results

We established a chemokine-related eleven-gene signature of a diagnostic model consisting of CXCL2, CCRL2, ARRB1, XCL1, GRK5, PPBP, CCL19, CCL13, CCL11, CXCL6, and CXCL13, which could easily distinguish between IPF patients and controls. Additionally, we identified two subtypes of IPF samples based on chemokine-related gene expression. Pulmonary function parameters and stromal scores were significantly higher in subtype 1 than in subtype 2. Several immune cell types, especially plasma cells and macrophages, differ significantly between the two subtypes. RT-qPCR results showed that the expression levels of Cxcl2 and Ccl2 increased considerably in bleomycin-induced mice. Meanwhile, Arrb1, Ccrl2, Grk5, and Ppbp expression was significantly reduced. Furthermore, multiple chemokine-related genes were altered in TGFβ1 or TNFα-induced fibroblast cells.

Conclusions

A novel chemokine-related eleven-signature of diagnostic model was developed. These genes are potential biomarkers of IPF and may play essential roles in its pathogenesis.