Role of CCL25/CCR9 in immune homeostasis and disease

Early-Life Exposure to Lipopolysaccharide Induces Persistent Changes in Gene Expression Profiles in the Liver and Spleen of Female FVB/N Mice

The objective of this study was to investigate how subcutaneous (sc) lipopolysaccharide (LPS) administration affects the gene expression profiles of insulin signaling as well as innate and adaptive immunity genes in mouse livers and spleens. FVB/N female mice were randomly assigned to one of two treatment groups at 5 weeks of age: (1) a six-week subcutaneous injection of saline at 11 μL/h (control-CON), or (2) a six-week subcutaneous injection of LPS from Escherichia coli 0111:B4 at 0.1 μg/g body weight at 11 μL/h. At 106 weeks (i.e., 742 days) after the last treatment, mice were euthanized. Following euthanasia, liver and spleen samples were collected, snap frozen, and stored at -80 °C until gene expression profiling. LPS upregulated nine genes in the liver, according to the findings (Pparg, Frs3, Kras, Raf1, Gsk3b, Rras2, Hk2, Pik3r2, and Myd88). With a 4.18-fold increase over the CON group, Pparg was the most up-regulated gene in the liver. Based on the annotation cluster analysis, LPS treatment upregulated liver genes which are involved in pathways associated with hepatic steatosis, B- and T-cell receptor signaling, chemokine signaling, as well as other types of cancers such as endometrial cancer, prostate cancer, and colorectal cancer. LPS increased the spleen expression of Ccl11, Ccl25, Il6, Cxcl5, Pparg, Tlr4, Nos2, Cxcl11, Il1a, Ccl17, and Fcgr3, all of which are involved in innate and adaptive immune responses and the regulation of cytokine production. Furthermore, functional analysis revealed that cytokine-cytokine receptor interaction and chemokine signaling pathways were the most enriched in LPS-treated mice spleen tissue. Our findings support the notion that early-life LPS exposure can result in long-term changes in gene expression profiling in the liver and spleen tissues of FVB/N female mice.

Controlling in and out - the future of interfering with immune cell trafficking in inflammatory bowel disease

INTRODUCTION

Immune cell trafficking is a key requirement in the pathogenesis of inflammatory bowel diseases. Consistently, therapeutic strategies to target immune cell trafficking have been established and continue to be developed for the treatment of ulcerative colitis and Crohn's disease.

AREAS COVERED

In this review, we briefly summarize the most important checkpoints of intestinal immune cell trafficking and their importance during IBD. Moreover, we provide an overview of associated therapeutic targets and previous as well as current efforts on treatment strategies related to these targets.

EXPERT OPINION

Finally, we comment on potential future developments that might shape the field of immune cell trafficking in the context of IBD.

The intestine: A highly dynamic microenvironment for IgA plasma cells

To achieve longevity, IgA plasma cells require a sophisticated anatomical microenvironment that provides cytokines, cell-cell contacts, and nutrients as well as metabolites. The intestinal epithelium harbors cells with distinct functions and represents an important defense line. Anti-microbial peptide-producing paneth cells, mucus-secreting goblet cells and antigen-transporting microfold (M) cells cooperate to build a protective barrier against pathogens. In addition, intestinal epithelial cells are instrumental in the transcytosis of IgA to the gut lumen, and support plasma cell survival by producing the cytokines APRIL and BAFF. Moreover, nutrients are sensed through specialized receptors such as the aryl hydrocarbon receptor (AhR) by both, intestinal epithelial cells and immune cells. However, the intestinal epithelium is highly dynamic with a high cellular turn-over rate and exposure to changing microbiota and nutritional factors. In this review, we discuss the spatial interplay of the intestinal epithelium with plasma cells and its potential contribution to IgA plasma cell generation, homing, and longevity. Moreover, we describe the impact of nutritional AhR ligands on intestinal epithelial cell-IgA plasma cell interaction. Finally, we introduce spatial transcriptomics as a new technology to address open questions in intestinal IgA plasma cell biology.

Myo1f has an essential role in γδT intraepithelial lymphocyte adhesion and migration

γδT intraepithelial lymphocyte represents up to 60% of the small intestine intraepithelial compartment. They are highly migrating cells and constantly interact with the epithelial cell layer and lamina propria cells. This migratory phenotype is related to the homeostasis of the small intestine, the control of bacterial and parasitic infections, and the epithelial shedding induced by LPS. Here, we demonstrate that Myo1f participates in the adhesion and migration of intraepithelial lymphocytes. Using long-tailed class I myosins KO mice, we identified the requirement of Myo1f for their migration to the small intestine intraepithelial compartment. The absence of Myo1f affects intraepithelial lymphocytes' homing due to reduced CCR9 and α4β7 surface expression. In vitro, we confirm that adhesion to integrin ligands and CCL25-dependent and independent migration of intraepithelial lymphocytes are Myo1f-dependent. Mechanistically, Myo1f deficiency prevents correct chemokine receptor and integrin polarization, leading to reduced tyrosine phosphorylation which could impact in signal transduction. Overall, we demonstrate that Myo1f has an essential role in the adhesion and migration in γδT intraepithelial lymphocytes.

Chemokine-mucinome interplay in shaping the heterogeneous tumor microenvironment of pancreatic cancer

Pancreatic cancer (PC) is exemplified by a complex immune-suppressive, fibrotic tumor microenvironment (TME), and aberrant expression of mucins. The constant crosstalk between cancer cells, cancer-associated fibroblasts (CAFs), and the immune cells mediated by the soluble factors and inflammatory mediators including cytokines, chemokines, reactive oxygen species (ROS) promote the dynamic temporal switch towards an immune-escape phenotype in the neoplastic cells and its microenvironment that bolsters disease progression. Chemokines have been studied in PC pathogenesis, albeit poorly in the context of mucins, tumor glycocalyx, and TME heterogeneity (CAFs and immune cells). With correlative analysis from PC patients' transcriptome data, support from available literature, and scientific arguments-based speculative extrapolations in terms of disease pathogenesis, we have summarized in this review a comprehensive understanding of chemokine-mucinome interplay during stromal modulation and immune-suppression in PC. Future studies should focus on deciphering the complexities of chemokine-mediated control of glycocalyx maturation, immune infiltration, and CAF-associated immune suppression. Knowledge extracted from such studies will be beneficial to mechanistically correlate the mucin-chemokine abundance in serum versus pancreatic tumors of patients, which may aid in prognostication and stratification of PC patients for immunotherapy.

Anti-CCR9 chimeric antigen receptor T cells for T-cell acute lymphoblastic leukemia

T cell acute lymphoblastic leukemia (T-ALL) is an aggressive malignancy of immature T lymphocytes, associated with higher rates of induction failure compared with those in B cell acute lymphoblastic leukemia. The potent immunotherapeutic approaches applied in B cell acute lymphoblastic leukemia, which have revolutionized the treatment paradigm, have proven more challenging in T-ALL, largely due to a lack of target antigens expressed on malignant but not healthy T cells. Unlike B cell depletion, T-cell aplasia is highly toxic. Here, we show that the chemokine receptor CCR9 is expressed in >70% of cases of T-ALL, including >85% of relapsed/refractory disease, and only on a small fraction (<5%) of normal T cells. Using cell line models and patient-derived xenografts, we found that chimeric antigen receptor (CAR) T-cells targeting CCR9 are resistant to fratricide and have potent antileukemic activity both in vitro and in vivo, even at low target antigen density. We propose that anti-CCR9 CAR-T cells could be a highly effective treatment strategy for T-ALL, avoiding T cell aplasia and the need for genome engineering that complicate other approaches.

An Update on the Chemokine System in the Development of NAFLD

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in the world. Sustained hepatic inflammation is a key driver of the transition from simple fatty liver to nonalcoholic steatohepatitis (NASH), the more aggressive form of NAFLD. Hepatic inflammation is orchestrated by chemokines, a family of chemoattractant cytokines that are produced by hepatocytes, Kupffer cells (liver resident macrophages), hepatic stellate cells, endothelial cells, and vascular smooth muscle cells. Over the last three decades, accumulating evidence from both clinical and experimental investigations demonstrated that chemokines and their receptors are increased in the livers of NAFLD patients and that CC chemokine ligand (CCL) 2 and CCL5 in particular play a pivotal role in inducing insulin resistance, steatosis, inflammation, and fibrosis in liver disease. Cenicriviroc (CVC), a dual antagonist of these chemokines’ receptors, CCR2 and CCR5, has been tested in clinical trials in patients with NASH-associated liver fibrosis. Additionally, recent studies revealed that other chemokines, such as CCL3, CCL25, CX3C chemokine ligand 1 (CX3CL1), CXC chemokine ligand 1 (CXCL1), and CXCL16, can also contribute to the pathogenesis of NAFLD. Here, we review recent updates on the roles of chemokines in the development of NAFLD and their blockade as a potential therapeutic approach.

CD10 and Das1: a biomarker study using immunohistochemistry to subtype gastric intestinal metaplasia

Background

Intestinal metaplasia (IM) is considered a key pivot point in the Correa model of gastric cancer (GC). It is histologically subtyped into the complete and incomplete subtypes, the latter being associated with a greater risk of progression. However, the clinical utility of IM subtyping remains unclear, partially due to the absence of reliable defining biomarkers.

Methods

Based on gene expression data and existing literature, we selected CD10 and Das1 as candidate biomarkers to distinguish complete and incomplete IM glands in tissues from patients without GC (IM-GC) and patients with GC (IM + GC). Immunohistochemical staining of individually subtyped IM glands was scored after blinding by two researchers using tissue belonging to both IM-GC and IM + GC patients. Whole tissue Das1 staining was further assessed using digital image quantification (cellSens Dimension, Olympus).

Results

Across both cohorts CD10 stained the IM brush border and was shown to have a high sensitivity (87.5% and 94.9% in IM-GC and IM + GC patients respectively) and specificity (100.0% and 96.7% respectively) with an overall AUROC of 0.944 for complete IM glands. By contrast Das1 stained mainly goblet cells and the apical membrane of epithelial cells, mostly of incomplete IM glands with a low sensitivity (28.6% and 29.3% in IM-GC and IM + GC patients respectively) but high specificity (98.3% and 85.1% respectively) and an overall AUROC of 0.603 for incomplete IM glands. A combined logistic regression model showed a significant increase in AUROC for detecting complete IM glands (0.955 vs 0.970). Whole tissue digital quantification of Das1 staining showed a significant association with incomplete IM compared to complete IM, both in IM-GC and in IM + GC patients (p = 0.016 and p = 0.009 respectively, Mann–Whitney test and unpaired t test used). Additionally, complete IM in IM + GC patients exhibited significantly more Das1 staining than in IM-GC patients (p = 0.019, Mann–Whitney test).

Conclusions

These findings suggest that CD10 is an outstanding biomarker for complete IM and Das1 may be useful as a secondary biomarker for IM glands at greater risk of progression irrespective of IM subtype. Overall, the clinical use of these biomarkers could lead to improved patient stratification and targeted surveillance.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12876-022-02268-z.

Gracilaria lemaneiformis polysaccharides alleviate colitis by modulating the gut microbiota and intestinal barrier in mice

Gracilaria lemaneiformis polysaccharide (GLP) has varieties of antioxidation, however, the therapeutic effects of GLP on ulcerative colitis (UC) and the potential mechanisms involved are still incomplete. In the study, the analysis of the ζ-potential, thermal, and morphology properties demonstrated that GLP was a negatively charged polymer, and had great thermostability and irregular network. Moreover, the GLP treatment has the effects of reducing the severity of colitis caused by dextran sulfate sodium by alleviating the colon damage of mice, and increasing the amount of short-chain fatty acids in the intestines, alleviating histopathological inflammation. The sequencing results and α-diversity analysis showed that GLP could improve biodiversity, restore the abundance of Bacteroidetes, and decrease the proportion of Firmicutes. The level of CCL-25 and CCR-9 were inhibited, CD40 and TGF-β1 were increased. In summary, GLP has potentiality to be utilized as a hopeful functional food to the UC patients.

Molecular characterization and chemotaxis assay of a CC motif chemokine ligand 25 from Japanese sea bass (Lateolabrax japonicus)

CC motif chemokine ligand 25 (CCL25) is a key chemokine that attracts various types of leukocytes, such as activated peritoneal macrophages. However, information on CCL25 in fish is limited. Here, a CCL25 gene (LjCCL25) was identified from Japanese sea bass (Lateolabrax japonicus), showing upregulation in multiple tissues against Vibrio harveyi infection. The recombinant LjCCL25 (rLjCCL25) only significantly induced the migration of monocytes/macrophages (MO/MΦ) both in vitro and in vivo, but didn't induce that of neutrophils or lymphocytes. Additionally, rLjCCL25 only induced migration of the lipopolysaccharide-stimulated MO/MΦ (M1 type). Knockdown of Japanese sea bass CC chemokine receptor 9 (LjCCR9) expression in MO/MФ by RNA interference inhibited the LjCCL25-induced chemotaxis of resting and M1 type MO/MФ. Moreover, administration of 300 ng/g rLjCCL25 effectively increased the survival of V. harveyi-infected fish and decreased bacterial load. Our study demonstrates that LjCCL25 functions as an MO/MФ chemoattractant via LjCCR9 in Japanese sea bass against V. harveyi.

Targeting Immune Cell Trafficking - Insights From Research Models and Implications for Future IBD Therapy

Inflammatory bowel diseases (IBDs), including Crohn's disease (CD) and ulcerative colitis (UC) are multifactorial diseases with still unknown aetiology and an increasing prevalence and incidence worldwide. Despite plentiful therapeutic options for IBDs, the lack or loss of response in certain patients demands the development of further treatments to tackle this unmet medical need. In recent years, the success of the anti-α4β7 antibody vedolizumab highlighted the potential of targeting the homing of immune cells, which is now an important pillar of IBD therapy. Due to its complexity, leukocyte trafficking and the involved molecules offer a largely untapped resource for a plethora of potential therapeutic interventions. In this review, we aim to summarise current and future directions of specifically interfering with immune cell trafficking. We will comment on concepts of homing, retention and recirculation and particularly focus on the role of tissue-derived chemokines. Moreover, we will give an overview of the mode of action of drugs currently in use or still in the pipeline, highlighting their mechanisms and potential to reduce disease burden.

Global prevalence of prolonged gastrointestinal symptoms in COVID-19 survivors and potential pathogenesis: A systematic review and meta-analysis

Background: This study aimed to determine the cumulative prevalence of prolonged gastrointestinal (GI) symptoms, including nausea, vomiting, diarrhea, lack of appetite, abdominal pain, and dysgeusia, in survivors of both mild and severe COVID-19 worldwide and to discuss the potential pathogenesis.   Methods: Three databases (PubMed, Scopus, and Web of Science) were searched for relevant articles up to January 30, 2021. Data on study characteristics, clinical characteristics during follow-up, the number of patients with prolonged GI symptoms, and total number of COVID-19 survivors were retrieved according to PRISMA guidelines. The quality of eligible studies was assessed using the Newcastle-Ottawa scale. The pooled prevalence of specific prolonged GI symptoms was calculated and the association between COVID-19 severity and the occurrence of prolonged GI symptoms was assessed if appropriate.   Results: The global prevalence of prolonged nausea was 3.23% (95% CI: 0.54%-16.53%) among 527 COVID-19 survivors. Vomiting persisted in 93 of 2,238 COVID-19 survivors (3.19%, 95% CI: 1.62%-6.17%) and prolonged diarrhea was found in 34 of 1,073 survivors (4.12%, 95% CI: 1.07%-14.64%). A total of 156 patients among 2,238 COVID-19 survivors (4.41%, 95% CI: 1.91%-9.94%) complained of persistent decreased or loss of appetite. The cumulative prevalence of prolonged abdominal pain was 1.68% (95% CI: 0.84%-3.32%), whereas persistent dysgeusia was identified in 130 cases among 1,887 COVID-19 survivors (7.04%, 95% CI: 5.96%-8.30%). Data was insufficient to assess the relationship between COVID-19 severity and the occurrence of all prolonged GI symptoms.   Conclusion: Persistent GI symptoms among COVID-19 survivors after discharge or recovery raises a concern regarding the long-term impact of the COVID-19 infection on the quality of life of the survivors. Despite several potential explanations proposed, studies that aim to follow patients after recovery from COVID-19 and determine the pathogenesis of the prolonged symptoms of COVID-19 survivors are warranted.   PROSPERO registration: CRD42021239187.

Elevated markers of gut leakage and inflammasome activation in COVID-19 patients with cardiac involvement

BACKGROUND

A high proportion of COVID-19 patients have cardiac involvement, even those without known cardiac disease. Downregulation of angiotensin converting enzyme 2 (ACE2), a receptor for SARS-CoV-2 and the renin-angiotensin system, as well as inflammatory mechanisms have been suggested to play a role. ACE2 is abundant in the gut and associated with gut microbiota composition. We hypothesized that gut leakage of microbial products, and subsequent inflammasome activation could contribute to cardiac involvement in COVID-19 patients.

METHODS

Plasma levels of a gut leakage marker (LPS-binding protein, LBP), a marker of enterocyte damage (intestinal fatty acid binding protein, IFABP), a gut homing marker (CCL25, ligand for chemokine receptor CCR9) and markers of inflammasome activation (IL-1β, IL-18 and their regulatory proteins) were measured at three time points (day 1, 3-5 and 7-10) in 39 hospitalized COVID-19 patients and related to cardiac involvement.

RESULTS

Compared to controls, COVID-19 patients had elevated plasma levels of LBP and CCL25 but not IFABP, suggesting impaired gut barrier function and accentuated gut homing of T cells without excessive enterocyte damage. Levels of LBP were twice as high at baseline in patients with elevated cardiac markers compared with those without and remained elevated during hospitalization. Also, markers of inflammasome activation were moderately elevated in patients with cardiac involvement. LBP was associated with higher NT-pro-BNP levels, whereas IL-18, IL-18BP and IL-1Ra were associated with higher troponin levels.

CONCLUSION

Patients with cardiac involvement had elevated markers of gut leakage and inflammasome activation, suggestive of a potential gut-heart axis in COVID-19.

Chemokines as the critical factors during bladder cancer progression: an overview

Bladder cancer (BCa) is one of the most frequent urogenital malignancies which is mainly observed among men. There are various genetic and environmental risk factors associated with BCa progression. Transurethral endoscopic resection and open ablative surgery are the main treatment options for muscle invasive BCa. BCG therapy is also employed following the endoscopic resection to prevent tumor relapse. The tumor microenvironment is the main interaction site of tumor cells and immune system in which the immune cells are recruited via chemokines and chemokine receptors. In present review we summarized the main chemokines and chemokine receptors which have been associated with histopathological features of BCa patients in the world. This review highlights the chemokines and chemokine receptors as critical markers in early detection and therapeutic purposes among BCa patients and clarifies their molecular functions during BCa progression and metastasis.

Vedolizumab and Extraintestinal Manifestations in Inflammatory Bowel Disease

In Crohn's disease and ulcerative colitis, inflammation is not limited to the digestive tract. Extraintestinal manifestations (EIMs), which affect up to 50% of patients, can substantially impair quality of life. EIMs may parallel luminal disease activity or have an independent course. They most commonly involve the musculoskeletal system (e.g., peripheral or axial arthritis) and skin (e.g., erythema nodosum and pyoderma gangrenosum). Less commonly, the hepatobiliary tract (e.g., primary sclerosing cholangitis [PSC]) and the eye (e.g., episcleritis, scleritis, and uveitis) are involved. Although the pathophysiology of EIMs is poorly understood, they are likely either manifestations of a primary systemic immune disease with variable expression amongst organs, or secondary phenomena to bowel inflammation. Additional pathophysiologic mechanisms may include aberrant lymphocyte homing mediated by ectopic expression of gut-specific chemokines and adhesion molecules, cross-reactivity between microbial and self-antigens, autoantibodies against epitopes shared by the intestine and extraintestinal tissues, elevated serum concentrations of cytokines, and alterations in innate immunity. Many EIMs independent of intestinal disease activity can be successfully treated with tumor necrosis factor (TNF) antagonists. The efficacy of vedolizumab-a monoclonal antibody targeting the α4β7 integrin-for the treatment of EIMs is uncertain, but data are emerging from post hoc analyses of randomized controlled trials, prospective and retrospective cohort studies, and case series. Vedolizumab may be effective in treating EIMs related to luminal disease activity (e.g., type 1 peripheral arthritis and erythema nodosum) but has not shown biochemical improvement in PSC. Its postulated role in the development of de novo EIMs is heavily confounded by the high proportion of patients previously exposed to TNF antagonists; new EIMs could result from TNF antagonist treatment cessation rather than being caused by vedolizumab. A common limitation of clinical studies is the lack of multidisciplinary involvement in the diagnosis and monitoring of EIMs, which may lead to misdiagnosis and overreporting. Future studies should rigorously measure EIMs in parallel with objective measures of luminal disease activity to provide more robust data on the relative efficacy of new drugs, especially as increasing numbers of gut-selective compounds enter clinical development.

RNA Sequencing Keloid Transcriptome Associates Keloids With Th2, Th1, Th17/Th22, and JAK3-Skewing

Keloids are disfiguring, fibroproliferative growths and their pathogenesis remains unclear, inhibiting therapeutic development. Available treatment options have limited efficacy and harbor safety concerns. Thus, there is a great need to clarify keloid pathomechanisms that may lead to novel treatments. In this study, we aimed to elucidate the profile of lesional and non-lesional keloid skin compared to normal skin. We performed gene (RNAseq, qRT-PCR) and protein (immunohistochemistry) expression analyses on biopsy specimens obtained from lesional and non-lesional skin of African American (AA) keloid patients compared to healthy skin from AA controls. Fold-change≥2 and false-discovery rate (FDR)<0.05 was used to define significance. We found that lesional versus normal skin showed significant up-regulation of markers of T-cell activation/migration (ICOS, CCR7), Th2- (IL-4R, CCL11, TNFSF4/OX40L), Th1- (CXCL9/CXCL10/CXCL11), Th17/Th22- (CCL20, S100As) pathways, and JAK/STAT-signaling (JAK3) (false-discovery rate [FDR]<0.05). Non-lesional skin also exhibited similar trends. We observed increased cellular infiltrates in keloid tissues, including T-cells, dendritic cells, mast cells, as well as greater IL-4rα⁺, CCR9⁺, and periostin⁺ immunostaining. In sum, comprehensive molecular profiling demonstrated that both lesional and non-lesional skin show significant immune alternations, and particularly Th2 and JAK3 expression. This advocates for the investigation of novel treatments targeting the Th2 axis and/or JAK/STAT-signaling in keloid patients.

Thymus‑expressed chemokine secreted by breast cancer cells promotes metastasis and inhibits apoptosis

The aim of the present study was to investigate the underlying mechanisms of thymus-expressed chemokine (TECK) autocrine signaling, and its effect on carcinogenesis and the development of breast cancer. The present study also assessed epithelial-mensenchymal transition (EMT) and cell migration, invasion, proliferation and apoptosis. Breast cancer cell lines MCF-7 and MDA-MB-231 were used in the present study, and TECK basic expression in cancer cells was investigated using western blotting (WB). EMT markers, Akt pathway molecules and apoptosis indicators were detected by reverse transcription-quantitative PCR or WB. In order to assess migration and invasion, wound healing and Matrigel invasion assays were performed. Moreover, flow cytometry was used to assess the rate of proliferation and apoptosis. In vivo experiments were conducted in nude mice to assess cancer growth. It was revealed that breast cancer cells could secrete TECK in an autocrine manner. Furthermore, TECK could increase cell migration and invasion by promoting EMT and inhibit apoptosis via the Akt signaling pathway.

Intratumoral delivery of CCL25 enhances immunotherapy against triple-negative breast cancer by recruiting CCR9+ T cells

CCR9⁺ T cells have an increased potential to be activated and therefore may mediate strong antitumor responses. Here, we found, however, that CCL25, the only chemokine for CCR9⁺ cells, is not expressed in human or murine triple-negative breast cancers (TNBCs), raising a hypothesis that intratumoral delivery of CCL25 may enhance antitumor immunotherapy in TNBCs. We first determined whether this approach can enhance CD47-targeted immunotherapy using a tumor acidity-responsive nanoparticle delivery system (NP-siCD47/CCL25) to sequentially release CCL25 protein and CD47 small interfering RNA in tumor. NP-siCD47/CCL25 significantly increased infiltration of CCR9⁺CD8⁺ T cells and down-regulated CD47 expression in tumor, resulting in inhibition of tumor growth and metastasis through a T cell-dependent immunity. Furthermore, the antitumor effect of NP-siCD47/CCL25 was synergistically enhanced when used in combination with programmed cell death protein-1/programmed death ligand-1 blockades. This study offers a strategy to enhance immunotherapy by promoting CCR9⁺CD8⁺ T cell tumor infiltration.

Participation of the spleen in the IgA immune response in the gut

The role of the spleen in the induction of an immune response to orally administered antigens is still under discussion. Although it is well known that after oral antigen administration specific germinal centres are not only formed in the Peyers patches (PP) and the mesenteric lymph nodes (mLN) but also in the spleen, there is still a lack of functional data showing a direct involvement of splenic B cells in an IgA immune response in the gut. In addition, after removal of mLN a high level of IgA+ B cells was observed in the gut. Therefore, in this study we analysed the role of the spleen in the induction of IgA+ B cells in the gut after mice were orally challenged with antigens. Here we have shown that antigen specific splenic IgM+ B cells after in vitro antigen stimulation as well as oral immunisation of donor mice were able to migrate into the gut of recipient mice, where they predominantly switch to IgA+ plasma cells. Furthermore, stimulation of recipient mice by orally administered antigens enhanced the migration of the splenic B cells into the gut as well as their switch to IgA+ plasma cells. Removal of the mLN led to a higher activation level of the splenic B cells. Altogether, our results imply that splenic IgM+ B cells migrate in the intestinal lamina propria, where they differentiate into IgA+ plasma cells and subsequently proliferate. In conclusion, we demonstrated that the spleen plays a major role in the gut immune response serving as a reservoir of immune cells that migrate to the site of antigen entrance.

Chemokines and Chemokine Receptors as Therapeutic Targets in Inflammatory Bowel Disease; Pitfalls and Promise

The principal targets for anti-chemokine therapy in inflammatory bowel disease (IBD) have been the receptors CCR9 and CXCR3 and their respective ligands CCL25 and CXCL10. More recently CCR6 and its ligand CCL20 have also received attention, the expression of the latter in enterocytes being manipulated through Smad7 signalling. These pathways, selected based on their fundamental role in regulating mucosal immunity, have led to the development of several therapeutic candidates that have been tested in early phase clinical trials with variable clinical efficacy. In this article, we appraise the status of chemokine-directed therapy in IBD, review recent developments, and nominate future areas for therapeutic focus.

Chemokines in homeostasis and diseases

For the past twenty years, chemokines have emerged as a family of critical mediators of cell migration during immune surveillance, development, inflammation and cancer progression. Chemokines bind to seven transmembrane G protein-coupled receptors (GPCRs) that are expressed by a wide variety of cell types and cause conformational changes in trimeric G proteins that trigger the intracellular signaling pathways necessary for cell movement and activation. Although chemokines have evolved to benefit the host, inappropriate regulation or utilization of these small proteins may contribute to or even cause diseases. Therefore, understanding the role of chemokines and their GPCRs in the complex physiological and diseased microenvironment is important for the identification of novel therapeutic targets. This review introduces the functional array and signals of multiple chemokine GPCRs in guiding leukocyte trafficking as well as their roles in homeostasis, inflammation, immune responses and cancer.

Reducing insulin via conditional partial gene ablation in adults reverses diet-induced weight gain

Excess circulating insulin is associated with obesity in humans and in animal models. However, the physiologic causality of hyperinsulinemia in adult obesity has rightfully been questioned because of the absence of clear evidence that weight loss can be induced by acutely reversing diet-induced hyperinsulinemia. Herein, we describe the consequences of inducible, partial insulin gene deletion in a mouse model in which animals have already been made obese by consuming a high-fat diet. A modest reduction in insulin production/secretion was sufficient to cause significant weight loss within 5 wk, with a specific effect on visceral adipose tissue. This result was associated with a reduction in the protein abundance of the lipodystrophy gene polymerase I and transcript release factor ( Ptrf; Cavin) in gonadal adipose tissue. RNAseq analysis showed that reduced insulin and weight loss also associated with a signature of reduced innate immunity. This study demonstrates that changes in circulating insulin that are too fine to adversely affect glucose homeostasis nonetheless exert control over adiposity.-Page, M. M., Skovsø, S., Cen, H., Chiu, A. P., Dionne, D. A., Hutchinson, D. F., Lim, G. E., Szabat, M., Flibotte, S., Sinha, S., Nislow, C., Rodrigues, B., Johnson, J. D. Reducing insulin via conditional partial gene ablation in adults reverses diet-induced weight gain.

In vivo inhibition of tryptophan catabolism reorganizes the tuberculoma and augments immune-mediated control of Mycobacterium tuberculosis

Mycobacterium tuberculosis continues to cause devastating levels of mortality due to tuberculosis (TB). The failure to control TB stems from an incomplete understanding of the highly specialized strategies that M. tuberculosis utilizes to modulate host immunity and thereby persist in host lungs. Here, we show that M. tuberculosis induced the expression of indoleamine 2,3-dioxygenase (IDO), an enzyme involved in tryptophan catabolism, in macrophages and in the lungs of animals (mice and macaque) with active disease. In a macaque model of inhalation TB, suppression of IDO activity reduced bacterial burden, pathology, and clinical signs of TB disease, leading to increased host survival. This increased protection was accompanied by increased lung T cell proliferation, induction of inducible bronchus-associated lymphoid tissue and correlates of bacterial killing, reduced checkpoint signaling, and the relocation of effector T cells to the center of the granulomata. The enhanced killing of M. tuberculosis in macrophages in vivo by CD4⁺ T cells was also replicated in vitro, in cocultures of macaque macrophages and CD4⁺ T cells. Collectively, these results suggest that there exists a potential for using IDO inhibition as an effective and clinically relevant host-directed therapy for TB.

Beyond Chemoattraction: Multifunctionality of Chemokine Receptors in Leukocytes

The word chemokine is a combination of the words chemotactic and cytokine, in other words cytokines that promote chemotaxis. Hence, the term chemokine receptor refers largely to the ability to regulate chemoattraction. However, these receptors can modulate additional leukocyte functions, as exemplified by the case of CCR7 which, apart from chemotaxis, regulates survival, migratory speed, endocytosis, differentiation and cytoarchitecture. We present evidence highlighting that multifunctionality is a common feature of chemokine receptors. Based on the activities that they regulate, we suggest that chemokine receptors can be classified into inflammatory (which control both inflammatory and homeostatic functions) and homeostatic families. The information accrued also suggests that the non-chemotactic functions controlled by chemokine receptors may contribute to optimizing leukocyte functioning under normal physiological conditions and during inflammation.

Chemokines and their receptors in lung cancer progression and metastasis

Lung cancer is the leading cause of cancer-related mortality around the world. Despite advancements in diagnosis, surgical techniques, and neoadjuvant chemoradiotherapy over the last decade, the mortality rate is still high and the 5-year survival is a dismal 15%. Fortunately, early detection by low-dose computed tomography (LDCT) scans has reduced mortality by 20%; yet, overall, 5-year-survival remains low at less than 20%. Therefore, in order to ameliorate this situation, a thorough understanding of the underlying molecular mechanisms is urgently needed. Chemokines and their receptors, crucial microenvironmental factors, play important roles in lung tumor genesis, progression, and metastasis, and exploring the mechanisms of this might bring new insights into early diagnosis and precisely targeted treatment. Consequently, this review will mainly focus on recent advancements on the axes of chemokines and their receptors of lung cancer.

Intestinal CCL25 expression is increased in colitis and correlates with inflammatory activity

CCL25-mediated activation of CCR9 is critical for mucosal lymphocyte recruitment to the intestine. In immune-mediated liver injury complicating inflammatory bowel disease, intrahepatic activation of this pathway allows mucosal lymphocytes to be recruited to the liver, driving hepatobiliary destruction in primary sclerosing cholangitis (PSC). However, in mice and healthy humans CCL25 expression is restricted to the small bowel, whereas few data exist on activation of this pathway in the inflamed colon despite the vast majority of PSC patients having ulcerative colitis. Herein, we show that colonic CCL25 expression is not only upregulated in patients with active colitis, but strongly correlates with endoscopic Mayo score and mucosal TNFα expression. Moreover, approximately 90% (CD4(+)) and 30% (CD8(+)) of tissue-infiltrating T-cells in colitis were identified as CCR9(+) effector lymphocytes, compared to <10% of T-cells being CCR9(+) in normal colon. Sorted CCR9(+) lymphocytes also demonstrated enhanced cellular adhesion to stimulated hepatic sinusoidal endothelium compared with their CCR9(-) counterparts when under flow. Collectively, these results suggest that CCR9/CCL25 interactions are not only involved in colitis pathogenesis but also correlate with colonic inflammatory burden; further supporting the existence of overlapping mucosal lymphocyte recruitment pathways between the inflamed colon and liver.

CCR9/CCL25 expression in non-small cell lung cancer correlates with aggressive disease and mediates key steps of metastasis

Poor clinical outcome of lung cancer (LuCa) is primarily due to lack of knowledge about specific molecules involved in its progression and metastasis. In this study, we for the first time show the clinical and biological significance of CC chemokine receptor-9 (CCR9) in non-small cell lung cancer (NSCLC). Expression of CCR9 and CCL25, the only natural ligand of CCR9, was significantly higher (p < 0.0001) in NSCLC tissues and serum respectively, compared to their respective controls. Interestingly, expression of both CCR9 and CCL25 was significantly higher in adenocarcinomas (ACs) compared to squamous cell carcinomas (SCCs) (p = 0.04, and p < 0.0001). Similar to tissues, AC and SCC cell lines were positive for CCR9 expression. Despite of marginal difference in CCR9 expression, AC cells showed higher migratory and invasive potential in response to CCL25, compared to SCC cells. This differential biological response of AC cells was primarily due to differential expression of matrix metalloproteinases and tissue inhibitor of metalloproteinases under the influence of CCL25. Our results suggest CCR9 as a potential target for developing new treatment modality for NSCLC. Additionally, differential serum CCL25 level in ACs and SCCs, two NSCLC subtypes, suggest its potential as a non-invasive diagnostic/prognostic biomarker.

Expression of CC chemokine receptor 9 predicts poor prognosis in patients with lung adenocarcinoma

Background

The CC chemokine receptor 9 (CCR9) plays an important role in tumorigenesis and metastasis in various cancers. Our previous studies have shown the aberrant expression of CCR9 in non-small cell lung cancer (NSCLC) cell lines, revealing that the CCR9-CCL25 axis modulates cell migration and invasion, and supports cancer cell survival by inhibiting apoptosis in vitro and in vivo. In the present study, we aimed to evaluate the expression and possible prognostic role of CCR9 in lung adenocarcinoma.

Methods

Immunohistochemical analysis of CCR9 expression was performed on 144 lung adenocarcinoma tissues and 30 adjacent normal lung parenchymal tissues. We assessed the correlation of CCR9 expression with clinicopathological characteristics and the prognosis of lung adenocarcinoma.

Results

The expression of CCR9 was increased in lung adenocarcinoma tissue compared with normal lung tissue. Moreover, such an expression was positively correlated with tumor size (p = 0.032), lymph node metastasis (p = 0.002) and advanced TNM stage (p = 0.012). In addition, the patients with negative CCR9 expression exhibited a higher overall survival (OS) compared with those with positive CCR9 expression. Multivariate analysis showed that the CCR9 expression was an independent prognostic factor for the OS of patients with lung adenocarcinoma.

Conclusions

We, for the first time, reported that CCR9 could be beneficial in predicting lymph node metastasis, and it might act as a novel prognostic biomarker for lung adenocarcinoma.

The role of chemoattractant receptors in shaping the tumor microenvironment

Chemoattractant receptors are a family of seven transmembrane G protein coupled receptors (GPCRs) initially found to mediate the chemotaxis and activation of immune cells. During the past decades, the functions of these GPCRs have been discovered to not only regulate leukocyte trafficking and promote immune responses, but also play important roles in homeostasis, development, angiogenesis, and tumor progression. Accumulating evidence indicates that chemoattractant GPCRs and their ligands promote the progression of malignant tumors based on their capacity to orchestrate the infiltration of the tumor microenvironment by immune cells, endothelial cells, fibroblasts, and mesenchymal cells. This facilitates the interaction of tumor cells with host cells, tumor cells with tumor cells, and host cells with host cells to provide a basis for the expansion of established tumors and development of distant metastasis. In addition, many malignant tumors of the nonhematopoietic origin express multiple chemoattractant GPCRs that increase the invasiveness and metastasis of tumor cells. Therefore, GPCRs and their ligands constitute targets for the development of novel antitumor therapeutics.

CCR9 as a prognostic marker and therapeutic target in hepatocellular carcinoma

The chemokine receptor CCR9 was recently implicated in tumor biology. In the present study, our objective was to evaluate the clinical significance and potential role of CCR9 in hepatocellular carcinoma (HCC). CCR9 expression was detected by immunohistochemistry, quantitative PCR (qPCR) and western blotting in HCC patients. The prognostic significance of CCR9 expression was assessed. The functional roles of CCR9 in HCC were investigated using MTT, BrdU, colony formation assay and flow cytometry. CCR9 was significantly elevated in HCC tissue samples. High CCR9 expression was correlated with multiple tumor nodes, high Edmondson-Steiner grade and vascular invasion. Multivariate analysis showed that CCR9 expression was an independent prognostic factor for the overall survival (OS) of HCC patients. Further investigations revealed that ectopic expression of CCR9 enhanced cell proliferation and tumorigenicity in HCC cells, whereas CCR9 silencing impaired cell proliferation and tumorigenicity, which was mediated through downregulation of the cell cycle regulators p21, p27 as well as upregulation of cyclin D1. These results suggest that CCR9 can act as a novel prognostic marker and therapeutic target for HCC.

Paracrine Activation of Chemokine Receptor CCR9 Enhances The Invasiveness of Pancreatic Cancer Cells

Chemokine receptors mediate cancer progression and metastasis. We have previously examined chemokine receptor CCR9 expression in pancreatic cancer. Here, our objective was to evaluate pancreatic stellate cells (PSCs) as a source of CCL25, the CCR9 ligand, and as an activator of CCL25-CCR9 signaling in pancreatic cancer cells. CCL25 and CCR9 expression levels in human pancreatic cancer tissues and normal human pancreas were assessed by immunohistochemsitry. In vitro secretion of CCL25 in PSCs and PANC-1 cells was verified by enzyme-linked immunosorbent assay. Pancreatic cancer cell invasion was measured using a modified Boyden chamber assay with CCL25, PSC secreted proteins, and PANC-1 secreted proteins as the chemoattractant. There was immunostaining for CCR9 expression in human pancreatic tumor tissues, but not in normal pancreatic tissue. CCL25 expression was absent in the normal pancreatic tissue sample, but was observed in cancer cells and in the stromal cells surrounding the tumor. In vitro, both PANC-1 cells and PSCs secreted CCL25. In an invasion assay, exposure to CCL25, PSC- and PANC-1-conditioned media significantly increased the invasiveness of PANC-1 cells. Inclusion of a CCR9-neutralizing antibody in the invasion assay blocked the increase in invading cells elicited by the chemoattractants. Our studies show that pancreatic cancer invasiveness is enhanced by autocrine and paracrine stimulation of CCR9. PSCs in the tumor microenvironment appear to contribute to paracrine activation of CCR9. Investigations into CCR9 as a potential therapeutic target in pancreatic cancer must consider cancer cell autocrine signaling and also paracrine signaling from interactions in the tumor microenvironment.