Cellular mediators of inflammation: tregs and TH17 cells in gastrointestinal diseases

Clinically relevant cell culture model of inflammatory bowel diseases for identification of new therapeutic approaches

Inflammatory Bowel Diseases (IDB) are chronic disorders characterized by gut inflammation, mucosal damage, increased epithelial permeability and altered mucus layer. No accurate in vitro model exists to simulate these characteristics. In this context, drug development for IBD or intestinal inflammation requires in vivo evaluations to verify treatments efficacy. A new model with altered mucus layer composition; altered epithelial permeability and pro-inflammatory crosstalk between immune and epithelial cells will be developed to enhance in vitro models for studying IBD treatments. The effects of dextran sulfate sodium and/or lipopolysaccharides on intestinal permeability, cytokines synthesis (IL-6, IL-8, TNF-α and IL-1β), mucins (MUC2, MUC5AC) and tight junction proteins expression (Claudin-1, ZO-1 and Occludin) were investigated in a tri-coculture model combining differentiated Caco-2/HT29-MTX cells and THP-1 cells. Two anti-inflammatory agents were evaluated to assess the model's therapeutic strategy applicability (corticoids and pro-resolving factors). Two in vitro models have been developed. The first model, characterized by increased permeability of the epithelial layer and subsequent secretion of inflammatory cytokines, can reproduce the different phases of inflammation, and enables the evaluation of preventive treatments. The second model simulates the acute phase of inflammation and allows for the assessment of curative treatments. Both models demonstrated reversibility when treated with betamethasone and pro-resolving factors. These in vitro models are valuable for selecting therapeutic agents prior to their application in in vivo models. They enable the assessment of agents' anti-inflammatory effects and their ability to permeate the inflamed epithelial layer and interact with immune cells.

Gut Microbiota, Inflammatory Bowel Disease, and Cancer: The Role of Guardians of Innate Immunity

Inflammatory bowel diseases (IBDs) are characterized by a persistent low-grade inflammation that leads to an increased risk of colorectal cancer (CRC) development. Several factors are implicated in this pathogenetic pathway, such as innate and adaptive immunity, gut microbiota, environment, and xenobiotics. At the gut mucosa level, a complex interplay between the immune system and gut microbiota occurs; a disequilibrium between these two factors leads to an alteration in the gut permeability, called 'leaky gut'. Subsequently, an activation of several inflammatory pathways and an alteration of gut microbiota composition with a proliferation of pro-inflammatory bacteria, known as 'pathobionts', take place, leading to a further increase in inflammation. This narrative review provides an overview on the principal Pattern Recognition Receptors (PRRs), including Toll-like receptors (TLRs) and NOD-like receptors (NLRs), focusing on their recognition mechanisms, signaling pathways, and contributions to immune responses. We also report the genetic polymorphisms of TLRs and dysregulation of NLR signaling pathways that can influence immune regulation and contribute to the development and progression of inflammatory disease and cancer.

Transgenerational impacts of oral probiotic administration in pregnant mice on offspring gut immune cells and colitis susceptibility

BACKGROUND AND AIM

The study of the impact of environmental factors during pregnancy on fetal development has so far been focused primarily on those negatively affecting human health; however, little is known about the effects of probiotic treatment during pregnancy on inflammatory bowel diseases (IBD). In this study, we investigated whether oral administration of heat-killed probiotics isolated from fermented foods decreased the vulnerability of offspring to IBD.

METHODS

Probiotics were administered to the pregnant mice until the birth of pups, after which the parent mice were maintained with autoclaved water. Partial pups were evaluated for dextran sodium sulfate-induced colitis. The influence of CD11c⁺ CD103⁺ dendritic cells (DCs) and regulatory T cells (Tregs) in mesenteric lymph nodes of parent mice and their pups was analyzed.

RESULTS

Oral administration of heat-killed probiotics to pregnant dams significantly decreased inflammation induced by dextran sodium sulfate in pups. Probiotic treatment increased the number of CD103⁺ DCs, and the expression of β8-integrin in CD103⁺ DCs and Tregs in mesenteric lymph nodes, not only in dams themselves but also in their offspring.

CONCLUSIONS

Oral administration of probiotics during gestation induced transgenerational immunomodulatory effects on the gut-associated immune system and resilience to experimental colitis in the offspring. Our results suggest that consumption of fermented foods during pregnancy can be effective in preventing inflammatory diseases such as IBD beyond generation.

The Role of Gut Microbiota in Heart Failure: When Friends Become Enemies

Heart failure is a complex health issue, with important consequences on the overall wellbeing of patients. It can occur both in acute and chronic forms and, in the latter, the immune system appears to play an important role in the pathogenesis of the disease. In particular, in the forms with preserved ejection fraction or with only mildly reduced ejection fraction, some specific associations with chronic inflammatory diseases have been observed. Another interesting aspect that is worth considering is the role of microbiota modulation, in this context: given the importance of microbiota in the modulation of immune responses, it is possible that changes in its composition may somewhat influence the progression and even the pathogenesis of heart failure. In this narrative review, we aim to examine the relationship between immunity and heart failure, with a special focus on the role of microbiota in this pathological condition.

Bacteroides thetaiotaomicron relieves colon inflammation by activating aryl hydrocarbon receptor and modulating CD4+T cell homeostasis

Inflammatory bowel disease (IBD) is a form of nonspecific chronic intestinal inflammation associated with gut microbiome dysbiosis. Modulating the composition of the intestinal flora may be a viable means of alleviating such inflammatory pathology. Bacteroides thetaiotaomicron (B. thetaiotaomicron) is a symbiotic intestinal microbe that has been associated with IBD, although the mechanistic basis for this association remains to be clarified. In this present study, we determined that B. thetaiotaomicron can alleviate colonic inflammation through mechanisms associated with the modulation of tryptophan metabolism and T cell subsets within inflamed intestinal tissues. Specifically, we found that B. thetaiotaomicron promotes the preferential differentiation of anti-inflammatory Treg/Th2 cells while suppressing the relative differentiation of pro-inflammatory Th1/Th17 cells, thereby decreasing inflammation within the colon. At a molecular level, B. thetaiotaomicron treatment was linked to altered CpG methylation within the Foxp3 promoter that was associated with enhanced Treg cell functionality. In a murine dextran sulfate sodium (DSS) colitis model system, B. thetaiotaomicron increased the levels of the aryl hydrocarbon receptor (AHR) ligands indole metabolites-indole acetic acid (IAA) and indole propionic acid (IPA), thereby increasing AHR activation that is related to changes of transcription factor expression profiles within T cells. In summary, our data suggest that B. thetaiotaomicron can activate AHR and modulate CD4⁺ T cell differentiation profiles in a murine DSS colitis model system, suggesting that this bacterium may be of therapeutic relevance for the treatment of IBD.

Carbamylated erythropoietin regulates immune responses and promotes long-term kidney allograft survival through activation of PI3K/AKT signaling

Modulation of alloimmune responses is critical to improving transplant outcome and promoting long-term graft survival. To determine mechanisms by which a nonhematopoietic erythropoietin (EPO) derivative, carbamylated EPO (CEPO), regulates innate and adaptive immune cells and affects renal allograft survival, we utilized a rat model of fully MHC-mismatched kidney transplantation. CEPO administration markedly extended the survival time of kidney allografts compared with the transplant alone control group. This therapeutic effect was inhibited when the recipients were given LY294002, a selective inhibitor of the phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) signaling pathway or anti-EPO receptor (EPOR) antibody, in addition to CEPO. In vitro, CEPO inhibited the differentiation and function of dendritic cells and modulated their production of pro-inflammatory and anti-inflammatory cytokines, along with activating the PI3K/AKT signaling pathway and increasing EPOR mRNA and protein expression by these innate immune cells. Moreover, after CD4⁺ T cells were exposed to CEPO the Th1/Th2 ratio decreased and the regulatory T cell (Treg)/Th17 ratio increased. These effects were abolished by LY294002 or anti-EPOR antibody, suggesting that CEPO regulates immune responses and promotes kidney allograft survival by activating the PI3K/AKT signaling pathway in an EPOR-dependent manner. The immunomodulatory and specific signaling pathway effects of CEPO identified in this study suggest a potential therapeutic approach to promoting kidney transplant survival.

Microtopography of Immune Cells in Osteoporosis and Bone Lesions by Endocrine Disruptors

Osteoporosis stems from an unbalance between bone mineral resorption and deposition. Among the numerous cellular players responsible for this unbalance bone marrow (BM) monocytes/macrophages, mast cells, T and B lymphocytes, and dendritic cells play a key role in regulating osteoclasts, osteoblasts, and their progenitor cells through interactions occurring in the context of the different bone compartments (cancellous and cortical). Therefore, the microtopography of immune cells inside trabecular and compact bone is expected to play a relevant role in setting initial sites of osteoporotic lesion. Indeed, in physiological conditions, each immune cell type preferentially occupies either endosteal, subendosteal, central, and/or perisinusoidal regions of the BM. However, in the presence of an activation, immune cells recirculate throughout these different microanatomical areas giving rise to a specific distribution. As a result, the trabeculae of the cancellous bone and endosteal free edge of the diaphyseal case emerge as the primary anatomical targets of their osteoporotic action. Immune cells may also transit from the BM to the depth of the compact bone, thanks to the efferent venous capillaries coursing in the Haversian and Volkmann canals. Consistently, the innermost parts of the osteons and the periosteum are later involved by their immunomodulatory action, becoming another site of mineral reabsorption in the course of an osteoporotic insult. The novelty of our updating is to highlight the microtopography of bone immune cells in the cancellous and cortical compartments in relation to the most consistent data on their action in bone remodeling, to offer a mechanist perspective useful to dissect their role in the osteoporotic process, including bone damage derived from the immunomodulatory effects of endocrine disrupting chemicals.

Influence of microbiota on immunity and immunotherapy for gastric and esophageal cancers

Gastric and esophageal cancers are multifactorial and multistage-involved malignancy. While the impact of gut microbiota on overall human health and diseases has been well documented, the influence of gastric and esophageal microbiota on gastric and esophageal cancers remains unclear. This review will discuss the reported alteration in the composition of gastric and esophageal microbiota in normal and disease conditions, and the potential role of dysbiosis in carcinogenesis and tumorigenesis. This review will also discuss how dysbiosis stimulates local and systemic immunity, which may impact on the immunotherapy for cancer.

Th17 immune response to adipose tissue-derived mesenchymal stromal cells

Adipose tissue-derived mesenchymal stromal cells (ASCs) hold the promise of achieving successful immunotherapeutic results due to their ability to regulate different T-cell fate. ASCs also show significant adaptability to environmental stresses by modulating their immunologic profile. Cell-based therapy for inflammatory diseases requires a detailed understanding of the molecular relation between ASCs and Th17 lymphocytes taking into account the influence of inflammation and cell ratio on such interaction. Accordingly, a dose-dependent increase in Th17 generation was only observed in high MSC:T-cell ratio with no significant impact of inflammatory priming. IL-23 receptor (IL-23R) expression by T cells was not modulated by ASCs when compared to levels in activated T cells, while ROR-γt expression was significantly increased reaching a maximum in high (1:5) unprimed ASC:T-cell ratio. Finally, multiplex immunoassay showed substantial changes in the secretory profile of 15 cytokines involved in the Th17 immune response (IL-1β, IL-4, IL-6, IL-10, IL-17A, IL-17F, IL-22, IL-21, IL-23, IL-25, IL-31, IL-33, IFN-γ, sCD40, and TNF-α), which was modulated by both cell ratio and inflammatory priming. These findings suggest that Th17 lymphocyte pathway is significantly modulated by ASCs that may lead to immunological changes. Therefore, future ASC-based immunotherapy should take into account the complex and detailed molecular interactions that depend on several factors including inflammatory priming and cell ratio.

The Interplay between Immunity and Microbiota at Intestinal Immunological Niche: The Case of Cancer

The gut microbiota is central to the pathogenesis of several inflammatory and autoimmune diseases. While multiple mechanisms are involved, the immune system clearly plays a special role. Indeed, the breakdown of the physiological balance in gut microbial composition leads to dysbiosis, which is then able to enhance inflammation and to influence gene expression. At the same time, there is an intense cross-talk between the microbiota and the immunological niche in the intestinal mucosa. These interactions may pave the way to the development, growth and spreading of cancer, especially in the gastro-intestinal system. Here, we review the changes in microbiota composition, how they relate to the immunological imbalance, influencing the onset of different types of cancer and the impact of these mechanisms on the efficacy of traditional and upcoming cancer treatments.

The Intricate Link among Gut "Immunological Niche," Microbiota, and Xenobiotics in Intestinal Pathology

Inflammatory bowel diseases (IBDs) are diseases characterized by various degrees of inflammation involving the gastrointestinal tract. Ulcerative colitis and Crohn's disease are characterized by a dysregulated immune response leading to structural gut alterations in genetically predisposed individuals. Diverticular disease is characterized by abnormal immune response to normal gut microbiota. IBDs are linked to a lack of physiological tolerance of the mucosal immune system to resident gut microbiota and pathogens. The disruption of immune tolerance involves inflammatory pathways characterized by an unbalance between the anti-inflammatory regulatory T cells and the proinflammatory Th1/Th17 cells. The interaction among T cell subpopulations and their related cytokines, mediators of inflammation, gut microbiota, and the intestinal mucosa constitute the gut “immunological niche.” Several evidences have shown that xenobiotics, such as rifaximin, can positively modulate the inflammatory pathways at the site of gut immunological niche, acting as anti-inflammatory agents. Xenobiotics may interfere with components of the immunological niche, leading to activation of anti-inflammatory pathways and inhibition of several mediators of inflammation. In summary, xenobiotics may reduce disease-related gut mucosal alterations and clinical symptoms. Studying the complex interplay between gut immunological niche and xenobiotics will certainly open new horizons in the knowledge and therapy of intestinal pathologies.

Therapeutic Potential to Modify the Mucus Barrier in Inflammatory Bowel Disease

Recently, numerous studies have shown that disruption of the mucus barrier plays an important role in the exacerbation of inflammatory bowel disease, particularly in ulcerative colitis. Alterations in the mucus barrier are well supported by published data and are widely accepted. The use of fluorescence in situ hybridization and Carnoy's fixation has revealed the importance of the mucus barrier in maintaining a mutualistic relationship between host and bacteria. Studies have raised the possibility that modulation of the mucus barrier may provide therapies for the disease, using agents such as short-chain fatty acids, prebiotics and probiotics. This review describes changes in the mucus barrier of patients with inflammatory bowel disease and in animal models of the disease. We also review the involvement of the mucus barrier in the exacerbation of the disease and explore the therapeutic potential of modifying the mucus barrier with short-chain fatty acids, prebiotics, probiotics, fatty acid synthase, H₂S, neutrophil elastase inhibitor and phophatidyl choline.

The role of "bone immunological niche" for a new pathogenetic paradigm of osteoporosis

Osteoporosis is characterized by low bone mass and microarchitectural deterioration of bone tissue. The etiology and pathogenetic mechanisms of osteoporosis have not been clearly elucidated. Osteoporosis is linked to bone resorption by the activation of the osteoclastogenic process. The breakdown of homeostasis among pro- and antiosteoclastogenic cells causes unbalanced bone remodeling. The complex interactions among these cells in the bone microenvironment involve several mediators and proinflammatory pathways. Thus, we may consider the bone microenvironment as a complex system in which local and systemic immunity are regulated and we propose to consider it as an "immunological niche." The study of the "bone immunological niche" will permit a better understanding of the complex cell trafficking which regulates bone resorption and disease. The goal of a perfect therapy for osteoporosis would be to potentiate good cells and block the bad ones. In this scenario, additional factors may take part in helping or hindering the proosteoblastogenic factors. Several proosteoblastogenic and antiosteoclastogenic agents have already been identified and some have been developed and commercialized as biological therapies for osteoporosis. Targeting the cellular network of the "bone immunological niche" may represent a successful strategy to better understand and treat osteoporosis and its complications.

The Interaction among Microbiota, Immunity, and Genetic and Dietary Factors Is the Condicio Sine Qua Non Celiac Disease Can Develop

Celiac disease (CD) is an immune-mediated enteropathy, triggered by dietary wheat gluten and similar proteins of barley and rye in genetically susceptible individuals. This is a complex disorder involving both environmental and immune-genetic factors. The major genetic risk factor for CD is determined by HLA-DQ genes. Dysfunction of the innate and adaptive immune systems can conceivably cause impairment of mucosal barrier function and development of localized or systemic inflammatory and autoimmune processes. Exposure to gluten is the main environmental trigger responsible for the signs and symptoms of the disease, but exposure to gluten does not fully explain the manifestation of CD. Thus, both genetic determination and environmental exposure to gluten are necessary for the full manifestation of CD; neither of them is sufficient alone. Epidemiological and clinical data suggest that other environmental factors, including infections, alterations in the intestinal microbiota composition, and early feeding practices, might also play a role in disease development. Thus, this interaction is the condicio sine qua non celiac disease can develop. The breakdown of the interaction among microbiota, innate immunity, and genetic and dietary factors leads to disruption of homeostasis and inflammation; and tissue damage occurs. Focusing attention on this interaction and its breakdown may allow a better understanding of the CD pathogenesis and lead to novel translational avenues for preventing and treating this widespread disease.

How the Intricate Interaction among Toll-Like Receptors, Microbiota, and Intestinal Immunity Can Influence Gastrointestinal Pathology

The gut is able to maintain tolerance to microbial and food antigens. The intestine minimizes the number of harmful bacteria by shaping the microbiota through a symbiotic relationship. In healthy human intestine, a constant homeostasis is maintained by the perfect regulation of microbial load and the immune response generated against it. Failure of this balance may result in various pathological conditions. Innate immune sensors, such as Toll-like receptors (TLRs), may be considered an interface among intestinal epithelial barrier, microbiota, and immune system. TLRs pathway, activated by pathogens, is involved in the pathogenesis of several infectious and inflammatory diseases. The alteration of the homeostasis between physiologic and pathogenic bacteria of intestinal flora causes a condition called dysbiosis. The breakdown of homeostasis by dysbiosis may increase susceptibility to inflammatory bowel diseases. It is evident that environment, genetics, and host immunity form a highly interactive regulatory triad that controls TLR function. Imbalanced relationships within this triad may promote aberrant TLR signaling, critically contributing to acute and chronic intestinal inflammatory processes, such as in IBD, colitis, and colorectal cancer. The study of interactions between different components of the immune systems and intestinal microbiota will open new horizons in the knowledge of gut inflammation.

Effect of Th17 and Treg axis disorder on outcomes of pulmonary arterial hypertension in connective tissue diseases

This prospective cohort study is to verify the hypothesis that the balance of Th17 and Treg cells frequencies in the peripheral circulation is disturbed in patients with varying degrees of connective tissue diseases-associated pulmonary arterial hypertension (CTD-aPAH) and to prove the influence of Th17/Treg imbalance on prognosis. We detected the frequencies and absolute counts of Th17 and Treg cells and related serum cytokines secretion and expressions of key transcription factors in 117 patients with connective tissue diseases (CTD), 53 patients with CTD-aPAH, and 48 healthy volunteers. Moreover, the median value according to levels of Th17/Treg ratios in patients with CTD-aPAH was chosen as basis of group division for survival analysis. CTD-aPAH patients revealed significant increase in peripheral Th17 cells, Th17-related cytokines, and ROR γt mRNA levels. They also presented a significant decrease in Treg cells, Treg-related cytokines, and Foxp3 mRNA levels as compared with CTD patients and healthy controls. More importantly, the Th17/Treg ratio was significantly related to the severity and prognosis of CTD-aPAH. This study indicated that the Th17/Treg axis disorder plays a critical role in CTD-aPAH. Furthermore, the dynamic balance between Th17 and Treg cells was likely to influence prognosis of patients with CTD-aPAH.

Bacterial β-(1,3)-glucan prevents DSS-induced IBD by restoring the reduced population of regulatory T cells

Bacterial β-(1,3)-glucan has more advantages in terms of cost, yield and efficiency than that derived from mushrooms, plants, yeasts and fungi. We have previously developed a novel and high-yield β-(1,3)-glucan produced by Agrobacterium sp. R259. This study aimed to elucidate the functional mechanism and therapeutic efficacy of bacterial β-(1,3)-glucan in dextran sulfate sodium (DSS)-induced inflammatory bowel disease (IBD).Mice were orally pretreated with bacterial β-(1,3)-glucan at daily doses of 2.5 or 5mg/kg for 2 weeks. After 6 days of DSS treatment, clinical assessment of IBD severity and expression of pro-inflammatory cytokines were evaluated. In vivo cell proliferation was examined by immunohistochemistry using Ki-67 and ER-TR7 antibodies. The frequency of regulatory T cells (Tregs) was analyzed by flow cytometry. Natural killer (NK) activity and IgA level were evaluated using NK cytotoxicity assay and ELISA.The deterioration of body weight gain, colonic architecture, disease score and histological score was recovered in DSS-induced IBD mice when pretreated with bacterial β-(1,3)-glucan. The recruitment of macrophages and the gene expression of proinflammatory cytokines, such as IL-1β, IL-6 and IL-17A/F, were markedly decreased in the colon of β-(1,3)-glucan-pretreated mice. β-(1,3)-Glucan induced the recovery of Tregs in terms of their frequency in DSS-induced IBD mice. Intriguingly, β-(1,3)-glucan reversed the functional defects of NK cells and excessive IgA production in DSS-induced IBD mice.We conclude that bacterial β-(1,3)-glucan prevented the progression of DSS-induced IBD by recovering the reduction of Tregs, functional defect of NK cells and excessive IgA production.

Uncomplicated diverticular disease: innate and adaptive immunity in human gut mucosa before and after rifaximin

Background/Aim. Uncomplicated diverticular disease (UDD) is a frequent condition in adults. The pathogenesis of symptoms remains unknown. Bacteria are able to interact with Toll-like receptors (TLRs) and to induce inflammation through both innate immunity and T-cell recruitment. We investigated the pattern of TLRs 2 and 4 and the intestinal homing in patients with UDD before and after a course of Rifaximin. Methods. Forty consecutive patients with UDD and 20 healthy asymptomatic subjects were enrolled. Among UDD patients, 20 were assigned to a 2-month course of treatment with Rifaximin 1.2 g/day for 15 days/month and 20 received placebo. Blood sample and colonic biopsies were obtained from patients and controls. The samples were collected and analyzed at baseline and at the end of treatment. Flow cytometry was performed using monoclonal antibodies (CD3, CD4, CD8, CD103, TCR-gamma/delta, CD14, TLR2, and TLR4). Results. In UDD, TLR2 and TLR4 expression on immune cell subpopulations from blood and mucosa of the affected colon are altered as compared with controls. Rifaximin treatment induced significant modifications of altered conditions. Conclusions. Our data show the role of TLRs in the development of inflammation in UDD. TLRs distribution is altered in UDD and these alterations are reversed after antibiotic treatment. This trial is registered with ClinicalTrials.gov: NCT02068482.

Th17 cells and IL-17 a--focus on immunopathogenesis and immunotherapeutics

IMPORTANCE

Accumulating evidence suggests that IL-17 A has broad pathogenic roles in multiple autoimmune and immune-mediated inflammatory diseases, including psoriasis and rheumatoid arthritis (RA). The development of new therapies that inhibit IL-17 pathway signaling is of clinical significance.

OBJECTIVES

This review aims to summarize the current preclinical evidence on the role of Th17 cells and IL-17 and related cytokines in immune-mediated disease pathophysiology, with a focus on psoriasis and rheumatoid arthritis, as well as to summarize recent clinical trials in these indications with newly developed IL-17 pathway inhibitors.

METHODS

A systematic literature search was conducted of PubMed using relevant keywords. Studies were assessed according to recent relevance to IL-17-mediated pathophysiology and clinical IL-17 inhibition. Experimental animal models of autoimmune disease and clinical studies that focused on IL-17 pathway inhibitors were included.

RESULTS

Preclinical studies suggest that IL-17A is an attractive therapeutic target. Several IL-17A inhibitors have advanced into clinical trials, including the anti-IL-17A monoclonal antibodies, secukinumab and ixekizumab, and the anti-17RA monoclonal antibody brodalumab. Each has shown variable and sometimes favorable results in proof-of-concept and phase II clinical trials and is currently undergoing further clinical evaluation in a range of immune-mediated diseases.

CONCLUSION

Targeting the IL-17 pathway shows promise as strategy to treat immune-mediated diseases ranging from skin to joints.

Chemotherapy ± cetuximab modulates peripheral immune responses in metastatic colorectal cancer

OBJECTIVE

To identify changes in peripheral immune responses in patients with metastatic colorectal cancer (mCRC) treated with irinotecan/5-fluorouracil/leucovorin (IFL) alone or in combination with cetuximab (C-IFL).

METHODS

Peripheral blood mononuclear cells (PBMCs) collected from healthy donors (n = 20) and patients with mCRC receiving treatment with either IFL (n = 30) or C-IFL (n = 30) were tested for cytokine production upon polyclonal stimulation with anti-CD3 monoclonal antibody, T cell proliferation in the autologous mixed lymphocyte reaction (auto-MLR) and T regulatory cell (Treg) frequency. The respective results were evaluated over two treatment cycles and further assessed in relation to response to treatment.

RESULTS

PBMCs prior to treatment exhibited significantly lower production of IL-2, IFN-γ, IL-12 and IL-18 cytokines and lower auto-MLR responses, whereas Treg frequency, IL-4, IL-10 cytokines were increased compared to healthy donors. During treatment, IL-2, IFN-γ, IL-12, IL-18 and auto-MLR responses increased, while Treg frequency and IL-10 secretion decreased significantly compared to the baseline. Responders to treatment exhibited a significantly higher increase in IL-2, IFN-γ, IL-12 and IL-18 production and auto-MLR responses, and higher decrease in IL-4, IL-10 secretion and Treg frequency. Among all patient subgroups analysed, responders to C-IFL demonstrated significantly higher increase in auto-MLR responses, IL-12 and IL-18 secretion and higher decrease in Treg frequency.

CONCLUSION

The disturbed immune parameters observed in patients with mCRC at presentation can be significantly improved during treatment with IFL and this effect can be potentiated by the addition of cetuximab. Monitoring of the peripheral immune system function could be used as surrogate marker in predicting treatment-related outcome.

Tissue-infiltrating lymphocytes analysis reveals large modifications of the duodenal "immunological niche" in coeliac disease after gluten-free diet

OBJECTIVES

The role of T lymphocytes in the pathogenesis of Celiac disease (CD) is well established. However, the mechanisms of T-cell involvement remain elusive. Little is known on the distribution of T subpopulations: T-regulatory (Treg), Th17, CD103, and CD62L cells at disease onset and after gluten-free diet (GFD). We investigated the involvement of several T subpopulations in the pathogenesis of CD.

METHODS

We studied T cells both in the peripheral blood (PB) and the tissue-infiltrating lymphocytes (TILs) from the mucosa of 14 CD patients at presentation and after a GFD, vs. 12 controls.

RESULTS

Our results extend the involvement of Treg, Th1, and Th17 cells in active CD inflammation both in the PB and at the TILs. At baseline, Tregs, Th1, and Th17 cells are significantly higher in active CD patients in TILs and PB. They decreased after diet. Moreover, CD62L+ TILs were increased at diagnosis as compared with GFD patients.

CONCLUSIONS

Our data show significant modifications of the above-mentioned subpopulations both in the PB and TILs. The increase of suppressive Tregs in active CD both in the PB and TILs is intriguing. T lymphocytes are known to have a crucial role in the pathogenesis of CD. We have shown that gluten trigger results in systemic recruitment of T lymphocytes, the unbalance between pro-inflammatory and anti-inflammatory populations and the increase of CD62L+ T cells in TILs. Our results delineate a more complete picture of T-cell subsets in active vs. GFD disease. Our data of T-cell subpopulations, combined with known data on cytokine production, support the concept that duodenal micro-environment acts as an immunological niche and this recognition may have an important role in the diagnosis, prognosis and therapeutical approach of CD.

Increased systemic exposure to rhizoma coptidis alkaloids in lipopolysaccharide-pretreated rats attributable to enhanced intestinal absorption

Rhizoma coptidis is a rhizome commonly used in traditional Chinese medicine. After oral administration of rhizoma coptidis extract, the plasma concentrations of its effective alkaloid constituents are so low that their systemic therapeutic actions cannot be explained. This study aimed to investigate the influence of lipopolysaccharide (LPS) on the pharmacokinetics of the rhizoma coptidis alkaloids. Pharmacokinetic experiments were performed with rats; both in vitro absorption and efflux experiments were carried out with everted rat gut sacs, whereas in vitro metabolism experiments were conducted with rat liver microsomes and intestinal S9 fractions. Mucosal changes were evaluated with light microscopy and transmission electron microscopy. The results showed that, in rat plasma, LPS pretreatment increased systemic alkaloid exposure. LPS pretreatment increased the in vitro absorption of the alkaloids and decreased their efflux. The efflux of vinblastine and rhodamine 123, P-glycoprotein substrates, also was decreased. The absorption of fluorescein isothiocyanate-labeled dextran (average molecular mass, 4 kDa), a gut paracellular permeability probe, was not influenced. Obvious damage was observed in the mucosa, but the tight junctions between epithelial cells remained intact. Intestinal, rather than hepatic, alkaloid metabolism was decreased. These findings indicated that LPS pretreatment increased systemic exposure to the alkaloids through enhancement of their absorption, which was related to decreased intestinal efflux and metabolism. The results add to the understanding of why rhizoma coptidis is active despite the low plasma concentrations of the rhizoma coptidis alkaloids measured in normal subjects and experimental animals.

The immune response to tumors as a tool toward immunotherapy

Until recently cancer medical therapy was limited to chemotherapy that could not differentiate cancer cells from normal cells. More recently with the remarkable mushroom of immunology, newer tools became available, resulting in the novel possibility to attack cancer with the specificity of the immune system. Herein we will review some of the recent achievement of immunotherapy in such aggressive cancers as melanoma, prostatic cancer, colorectal carcinoma, and hematologic malignancies. Immunotherapy of tumors has developed several techniques: immune cell transfer, vaccines, immunobiological molecules such as monoclonal antibodies that improve the immune responses to tumors. This can be achieved by blocking pathways limiting the immune response, such as CTLA-4 or Tregs. Immunotherapy may also use cytokines especially proinflammatory cytokines to enhance the activity of cytotoxic T cells (CTLs) derived from tumor infiltrating lymphocytes (TILs). The role of newly discovered cytokines remains to be investigated. Alternatively, an other mechanism consists in enhancing the expression of TAAs on tumor cells. Finally, monoclonal antibodies may be used to target oncogenes.

Gut microbiota and inflammation

Systemic and local inflammation in relation to the resident microbiota of the human gastro-intestinal (GI) tract and administration of probiotics are the main themes of the present review. The dominating taxa of the human GI tract and their potential for aggravating or suppressing inflammation are described. The review focuses on human trials with probiotics and does not include in vitro studies and animal experimental models. The applications of probiotics considered are systemic immune-modulation, the metabolic syndrome, liver injury, inflammatory bowel disease, colorectal cancer and radiation-induced enteritis. When the major genomic differences between different types of probiotics are taken into account, it is to be expected that the human body can respond differently to the different species and strains of probiotics. This fact is often neglected in discussions of the outcome of clinical trials with probiotics.