CD11b+Ly6C++Ly6G- cells show distinct function in mice with chronic inflammation or tumor burden

Cannabinoid CB2 receptors enhance high-fat diet evoked peripheral neuroinflammation

It is known that the cannabinoid type 2 (CB2) receptor has an anti-inflammatory role. Therefore, animals without CB2 receptors show enhanced inflammation and pain in the model of chronic pain, e.g., neuropathic pain. We previously proposed the upregulated leptin signaling at the peripheral nerve as one of the underlying molecular mechanisms of pain exacerbation in nerve-injured CB2 knockouts, as they displayed robust upregulation of leptin receptors and leptin signaling in the peripheral nerve. Due to these past results, we hypothesized that CB2 receptor deficiency might also modify the peripheral neuroinflammation led by chronic exposure to a high-fat diet (HFD). Interestingly, CB2 knockout animals showed significant resistance to HFD-induced neuroinflammation. Namely, 5-week feeding of HFD induced substantial hypersensitivity in WT animals, while tactile sensitivity of HFD-fed CB2 knockouts remained intact. HFD-fed WT animals also displayed the robust upregulation of chemokine CXCR4 expression with increased macrophage infiltration, which was never observed in HFD-fed CB2 knockout mice. Moreover, 5-week HFD exposure led significant increase of CD11b+Ly6G-Ly6Chigh cells and a decrease of CD11b+Ly6G+Ly6Clow cells in the spleen of WT animals, which was also not found in either HFD-fed CB2 knockouts or standard diet-fed WT and CB2 animals. Together with past reports, these results suggest that CB2 receptors might have a double-sided regulatory role in the context of inflammation development or, more widely, immune system regulation. We propose that CB2 signaling is not always anti-inflammatory and could take a pro-inflammatory role depending on the cause of the inflammation.

Isolation and immunosuppressive functions of myeloid-derived suppressor cell-derived exosomes

Myeloid-derived suppressor cells (MDSCs) are an integral part of the tumor microenvironment (TME). MDSC's involvement in the TME starts as soon as the primary tumor starts to get its blood supply causing an immunosuppressive environment and tumor cell invasion, and then at the formation of premetastatic niche through full-blown metastasis in distal organs. All of these functions don't require physical interaction of MDSC as some of the MDSC's functions can be replicated by secreted exosomes (MDSC-derived exosomes), which can alter the microenvironment through cellular interaction by fusion with the plasma membrane and subsequent release of their cargo, consisting of proteins, soluble factors, lipids, DNAs, microRNAs (miRNAs), and RNAs. In this method paper, we explained how to isolate MDSC exosomes and how to use the exosome to observe immunosuppressive function. We also discussed how to measure the number of exosomes by nanoparticle tracking analysis. Additionally, we outlined how to measure the protein of exosomes as well as the types of protein by Bradford assay and membrane cytokine array respectively. We also provided instructions on how to utilize MDSC-derived exosomes to get knowledge about in vitro immune cell migration, scratch assay with the tumor cells, and in vivo effect of MDSC exosome along with T cell function and proliferation.

Anti-proliferative and immunomodulatory potencies of cinnamon oil on Ehrlich ascites carcinoma bearing mice

Cinnamon is a well-known natural spice and flavoring substance used worldwide. The objective of the present work is to explore the possible antitumor and immunomodulatory potencies of cinnamon essential oil (Cinn) on Ehrlich ascites carcinoma (EAC). A total of fifty female Swiss albino mice were sub-grouped into five groups (n = 10), namely, normal (a non-tumorized and non-treated) group; EAC-tumorized and non-treated group; Cinn (non-tumorized mice received Cinn, 50 mg/kg per body weight daily) group; a group of EAC-tumorized mice treated with Cinn and the final positive control group of EAC-tumorized mice received cisplatin. Eight compounds were identified from Cinn using UPLC-MS-Qtof and NMR analysis. Compared to EAC untreated group, Cinn successfully (P < 0.05) inhibited tumor growth by reducing tumor cell count (45%), viability (53%) and, proliferation accompanied by the inhibition of tumor growth rate. Moreover, a significant (P < 0.05) arrest in the cell cycle at G0/G1 phase was noticed following Cinn treatments (~ 24.5%) compared to EAC group. Moreover, Cinn markedly evoked an antitumor immune response by elevating the percentage of splenic T helper (CD3+CD4+) and T cytotoxic (CD3+CD8+) cells. It is noteworthy that Cinn treatments significantly restored different hematological alterations as well as liver and kidney functions in EAC-tumorized mice. In conclusion, results suggest that Cinn has a good antitumor and immunostimulatory potencies against Ehrlich ascites carcinoma in vivo. The mechanism underlying its antitumor activity may be attributed to its immunostimulatory effects which increase its potential as a promising anticancer candidate.

Healthy myeloid-derived suppressor cells express the surface ectoenzyme Vanin-2 (VNN2)

Study of human monocytic Myeloid-Derived Suppressor cells Mo-MDSC (CD14⁺ HLA-DR^neg/low) has been hampered by the lack of positive cell-surface markers. In order to identify positive markers for Mo-MDSC, we performed microarray analysis comparing Mo-MDSC cells from healthy subjects versus CD14⁺ HLA-DR^high monocytes. We have identified the surface ectoenzyme Vanin-2(VNN2) protein as a novel biomarker highly-enriched in healthy subjects Mo-MDSC. Indeed, healthy subjects Mo-MDSC cells expressed 68 % VNN2, whereas only 9% VNN2 expression was observed on CD14⁺ HLA-DR^high cells (n = 4 p < 0.01). The top 10 percent positive VNN2 monocytes expressed CD33 and CD11b while being negative for HLA-DR, CD3, CD15, CD19 and CD56, consistent with a Mo-MDSC phenotype. CD14⁺VNN2^high monocytes were able to inhibit CD8 T cell proliferation comparably to traditional Mo-MDSC at 51 % and 48 % respectively. However, VNN2 expression on CD14⁺ monocytes from glioma patients was inversely correlated to their grade. CD14⁺VNN2^high monocytes thus appear to mark a monocytic population similar to Mo-MDSC only in healthy subjects, which may be useful for tumor diagnoses.

Immune cell targeting nanoparticles: a review

Immune cells are attractive targets for therapy as they are direct participants in a variety of diseases. Delivering a therapeutic agent only to cells that act on a disease by distinguishing them from other cells has the advantage of concentrating the therapeutic effect and lowering systemic side effects. Distinguishing each immune cell from other immune cells to deliver substances, including drugs and genes, can be achieved using nanotechnology. And also nanoparticles can ensure in vivo stability and sustained drug release. In addition, there is an ease of surface modification, which is an important characteristic that can be utilized in targeted drug delivery systems. This characteristic allows us to utilize various properties that are specifically expressed in each immune cell. A number of studies have delivered various substances specifically to immune cells through surface engineering with active target ligands that can target each immune cell and enzyme-responsive coating, and demonstrated high therapeutic effects compared to conventional treatments. Progress in research on target delivery has been suggested to be a breakthrough for the treatments of various diseases, including cancer treatment.

Complement factor H-deficient mice develop spontaneous hepatic tumors

Hepatocellular carcinoma (HCC) is difficult to detect, carries a poor prognosis, and is one of few cancers with an increasing yearly incidence. Molecular defects in complement factor H (CFH), a critical regulatory protein of the complement alternative pathway (AP), are typically associated with inflammatory diseases of the eye and kidney. Little is known regarding the role of CFH in controlling complement activation within the liver. While studying aging CFH-deficient (fH-/-) mice, we observed spontaneous hepatic tumor formation in more than 50% of aged fH-/- males. Examination of fH-/- livers (3-24 months) for evidence of complement-mediated inflammation revealed widespread deposition of complement-activation fragments throughout the sinusoids, elevated transaminase levels, increased hepatic CD8+ and F4/80+ cells, overexpression of hepatic mRNA associated with inflammatory signaling pathways, steatosis, and increased collagen deposition. Immunostaining of human HCC biopsies revealed extensive deposition of complement fragments within the tumors. Investigating the Cancer Genome Atlas also revealed that increased CFH mRNA expression is associated with improved survival in patients with HCC, whereas mutations are associated with worse survival. These results indicate that CFH is critical for controlling complement activation in the liver, and in its absence, AP activation leads to chronic inflammation and promotes hepatic carcinogenesis.

Anti-neoplastic and immunomodulatory potency of co-treatment based on bovine lactoferrin and/or muramyl dipeptide in tumor-bearing mice

The current study investigates anti-neoplastic and immunomodulatory activities of co-treatment based on bovine lactoferrin (bLF) and/or muramyl dipeptide (MDP) with or without cisplatin (Cis) in tumor-bearing mice. In the present study, bLF (100 mg/kg; orally) and MDP (0.5 mg/kg; subcutaneously) was administered alone or together. MDP or bLF was co-treated with Cis (1 mg/kg; intraperitoneally) in mice-bearing Ehrlich solid carcinoma. Tumor size, tumor mass proliferation, apoptosis using immunohistochemistry, the alteration in spleen cell proliferation, phenotype using flow cytometry and white blood cells total and differential counts were detected. Treatment with Cis or (bLF and MDP) significantly reduced tumor size, upregulated the pro-apoptotic p53 expression and downregulated the anti-apoptotic Bcl-2 and proliferative marker PCNA expression compared to non-treated tumor-bearing animals. Moreover, co-treatment of MDP and Cis significantly potentiated the reduction of the tumor size, downregulated the Bcl-2 and PCNA expression and upregulated the p53 expression compared to Cis-treated animals. While bLF and Cis co-treatment positively controlled PCNA and p53 expression compared to tumor-bearing animals, it significantly potentiated the reduction of the tumor size and downregulated the Bcl-2 expression compared to Cis-treated animals. Co-treatment of (bLF and MDP), (bLF and Cis) or (MDP and Cis) increased the spleen cell proliferation and altered the immunological profile of the CD3+CD4+, CD3+CD8+, CD3+CD4+CD69+, CD3+CD8+CD69+ and CD11b+Ly6G+ cells to achieve better immune response against tumor. In conclusion, co-treatments based on bLF and/or MDP are promising therapies against cancer, through their potency to control proliferation, enhance apoptosis and improve the immune status against tumor cells.

Distinct Role of CD11b+Ly6G-Ly6C- Myeloid-Derived Cells on the Progression of the Primary Tumor and Therapy-Associated Recurrent Brain Tumor

Myeloid-derived cells have been implicated as playing essential roles in cancer therapy, particularly in cancer immunotherapy. Most studies have focused on either CD11b⁺Ly6G⁺Ly6C⁺ granulocytic or polymorphonuclear myeloid-derived suppressor cells (G-MDSCs or PMN-MDSCs) or CD11b⁺Ly6G⁻Ly6C⁺ monocytic MDSCs (M-MDSCs), for which clear roles have been established. On the other hand, CD11b⁺Ly6G⁻Ly6C⁻ myeloid-derived cells (MDCs) have been less well studied. Here, the CD11b-diphtheria toxin receptor (CD11b-DTR) transgenic mouse model was used to evaluate the role of CD11b⁺ myeloid-derived cells in chemotherapy for an orthotopic murine astrocytoma, ALTS1C1. Using this transgenic mouse model, two injections of diphtheria toxin (DT) could effectively deplete CD11b⁺Ly6G⁻Ly6C⁻ MDCs while leaving CD11b⁺Ly6G⁺Ly6C⁺ PMN-MDSCs and CD11b⁺Ly6G⁻Ly6C⁺ M-MDSCs intact. Depletion of CD11b⁺Ly6G⁻Ly6C⁻ MDCs in mice bearing ALTS1C1-tk tumors and receiving ganciclovir (GCV) prolonged the mean survival time for mice from 30.7 to 37.8 days, but not the controls, while the effectiveness of temozolomide was enhanced. Mechanistically, depletion of CD11b⁺Ly6G⁻Ly6C⁻ MDCs blunted therapy-induced increases in tumor-associated macrophages (TAMs) and compromised therapy-elicited angiogenesis. Collectively, our findings suggest that CD11b⁺Ly6G⁻Ly6C⁻ MDCs could be manipulated to enhance the efficacy of chemotherapy for brain tumors. However, our study also cautions that the timing of any MDC manipulation may be critical to achieve the best therapeutic result.

Discovery, synthesis and anti-atherosclerotic activities of a novel selective sphingomyelin synthase 2 inhibitor

The sphingomyelin synthase 2 (SMS2) is a potential target for pharmacological intervention in atherosclerosis. However, so far, few selective SMS2 inhibitors and their pharmacological activities were reported. In this study, a class of 2-benzyloxybenzamides were discovered as novel SMS2 inhibitors through scaffold hopping and structural optimization. Among them, Ly93 as one of the most potent inhibitors exhibited IC₅₀ values of 91 nM and 133.9 μM against purified SMS2 and SMS1 respectively. The selectivity ratio of Ly93 was more than 1400-fold for purified SMS2 over SMS1. The in vitro studies indicated that Ly93 not only dose-dependently diminished apoB secretion from Huh7 cells, but also significantly reduced the SMS activity and increased cholesterol efflux from macrophages. Meanwhile, Ly93 inhibited the secretion of LPS-mediated pro-inflammatory cytokine and chemokine in macrophages. The pharmacokinetic profiles of Ly93 performed on C57BL/6J mice demonstrated that Ly93 was orally efficacious. As a potent selective SMS2 inhibitor, Ly93 significantly decreased the plasma SM levels of C57BL/6J mice. Furthermore, Ly93 was capable of dose-dependently attenuating the atherosclerotic lesions in the root and the entire aorta as well as macrophage content in lesions, in apolipoprotein E gene knockout mice treated with Ly93. In conclusion, we discovered a novel selective SMS2 inhibitor Ly93 and demonstrated its anti-atherosclerotic activities in vivo. The preliminary molecular mechanism-of-action studies revealed its function in lipid homeostasis and inflammation process, which indicated that the selective inhibition of SMS2 would be a promising treatment for atherosclerosis.

Fecal calprotectin Level in patients with IBD and noninflammatory disease of colon: a study in Babol, Northern, Iran

BACKGROUND

Inflammatory bowel disease (IBD) is a chronic disease with a relapsing course of inflammation in the digestive system. Endoscopy and histopathology are the golden standard methods for detection and assessment of IBD. A distinct increase of fecal calprotectin level can be a useful marker for the diagnosis of IBD. The aim of this study was to evaluate the fecal calprotectin level in patients with IBD and without inflammatory diseases of the colon.

METHODS

Calprotectin levels of patients referred to the Ayatollah Rouhani Hospital of Babol, northern Iran with clinical symptoms of colon disease were evaluated. After a week, colonoscopy and biopsy were performed on all patients and they were divided into two groups. The first group included patients with confirmed IBD and the second group included patients with diseases other than IBD, patients with IBS and healthy persons. Then the measured fecal calprotectin level was compared between the two groups before colonoscopy.

RESULTS

We observed correlation between calprotection in these two groups (p<0.0001). 38 (86.8%) patients in the case group and 5 (13.2%) patients in the control group had positive fecal calprotectin test and 12 (23.1%) patients in the case group and 40 (76.9%) patients in the control group had negative results. Basad on ROC curve, the cutoff point of calprotectin was 127.65 with 73% sensitivity and 89% specificity. The area under the curve was 0.83 with 95% confidence interval, 0.74-0.91 (p<0.0001).

CONCLUSIONS

The results pointed to this fact that fecal calprotectin can be a noninvasive marker in differentiating IBD from IBS.

Depletion of Neutrophils Promotes the Resolution of Pulmonary Inflammation and Fibrosis in Mice Infected with Paracoccidioides brasiliensis

Chronic stages of paracoccidioidomycosis (PCM) are characterized by granulomatous lesions which promote the development of pulmonary fibrosis leading to the loss of respiratory function in 50% of patients; in addition, it has been observed that neutrophils predominate during these chronic stages of P. brasiliensis infection. The goal of this study was to evaluate the role of the neutrophil during the chronic stages of experimental pulmonary PCM and during the fibrosis development and tissue repair using a monoclonal specific to this phagocytic cell. Male BALB/c mice were inoculated intranasally with 1.5x106 P. brasiliensis yeast cells. A monoclonal antibody specific to neutrophils was administered at 4 weeks post-inoculation followed by doses every 48h during two weeks. Mice were sacrificed at 8 and 12 weeks post-inoculation to assess cellularity, fungal load, cytokine/chemokine levels, histopathological analysis, collagen and expression of genes related to fibrosis development. Depletion of neutrophils was associated with a significant decrease in the number of eosinophils, dendritic cells, B cells, CD4-T cells, MDSCs and Treg cells, fungal load and levels of most of the pro-inflammatory cytokines/chemokines evaluated, including IL-17, TNF-α and TGF-β1. Recovery of lung architecture was also associated with reduced levels of collagen, high expression of TGF-β3, matrix metalloproteinase (MMP)-12 and -14, and decreased expression of tissue inhibitor metalloproteinase (TIMP)-2, and MMP-8. Depletion of neutrophils might attenuate lung fibrosis and inflammation through down-regulating TGF-β1, TNF-α, IL-17, MMP-8 and TIMP-2. These results suggest that neutrophil could be considered as a therapeutic target in pulmonary fibrosis induced by P. brasiliensis.

Acute inflammation induces immunomodulatory effects on myeloid cells associated with anti-tumor responses in a tumor mouse model

Given the self nature of cancer, anti-tumor immune response is weak. As such, acute inflammation induced by microbial products can induce signals that result in initiation of an inflammatory cascade that helps activation of immune cells. We aimed to compare the nature and magnitude of acute inflammation induced by toll-like receptor ligands (TLRLs) on the tumor growth and the associated inflammatory immune responses. To induce acute inflammation in tumor-bearing host, CD1 mice were inoculated with intraperitoneal (i.p.) injection of Ehrlich ascites carcinoma (EAC) (5 × 10(5) cells/mouse), and then treated with i.p. injection on day 1, day 7 or days 1 + 7 with: (1) polyinosinic:polycytidylic (poly(I:C)) (TLR3L); (2) Poly-ICLC (clinical grade of TLR3L); (3) Bacillus Calmette Guerin (BCG) (coding for TLR9L); (4) Complete Freund's adjuvant (CFA) (coding for TLR9L); and (5) Incomplete Freund's Adjuvant (IFA). Treatment with poly(I:C), Poly-ICLC, BCG, CFA, or IFA induced anti-tumor activities as measured by 79.1%, 75.94%, 73.94%, 71.88% and 47.75% decreases, respectively in the total number of tumor cells collected 7 days after tumor challenge. Among the tested TLRLs, both poly(I:C) (TLR3L) and BCG (contain TLR9L) showed the highest anti-tumor effects as reflected by the decrease in the number of EAc cells. These effects were associated with a 2-fold increase in the numbers of inflammatory cells expressing the myeloid markers CD11b(+)Ly6G(+), CD11b(+)Ly6G(-), and CD11b(+)Ly6G(-). We concluded that Provision of the proper inflammatory signal with optimally defined magnitude and duration during tumor growth can induce inflammatory immune cells with potent anti-tumor responses without vaccination.

Correlation between myeloid-derived suppressor cells and S100A8/A9 in tumor and autoimmune diseases

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of cells that constitute an important component of immune regulatory system. Two calcium-binding proteins S100A8 and S100A9 act as important mediators in acute and chronic inflammation. In recent years, many researchers have found that MDSCs and S100A8/A9 operated with one another through a positive feedback loop to promote tumor development and metastasis. However, the correlation between MDSCs and S100A8/A9 in autoimmune diseases (AIDs) remains unknown. In this review, we discussed the co-operation of MDSCs and S100A8/A9 in tumor environment, and also, the role of these two components in AIDs.

Immunosuppressive and Prometastatic Functions of Myeloid-Derived Suppressive Cells Rely upon Education from Tumor-Associated B Cells

Myeloid-derived suppressive cells (MDSC) have been reported to promote metastasis, but the loss of cancer-induced B cells/B regulatory cells (tBreg) can block metastasis despite MDSC expansion in cancer. Here, using multiple murine tumor models and human MDSC, we show that MDSC populations that expand in cancer have only partially primed regulatory function and limited prometastatic activity unless they are fully educated by tBregs. Cancer-induced tBregs directly activate the regulatory function of both the monocyte and granulocyte subpopulations of MDSC, relying, in part, on TgfβR1/TgfβR2 signaling. MDSC fully educated in this manner exhibit an increased production of reactive oxygen species and NO and more efficiently suppress CD4(+) and CD8(+) T cells, thereby promoting tumor growth and metastasis. Thus, loss of tBregs or TgfβR deficiency in MDSC is sufficient to disable their suppressive function and to block metastasis. Overall, our data indicate that cancer-induced B cells/B regulatory cells are important regulators of the immunosuppressive and prometastatic functions of MDSC.

Immature myeloid cells directly contribute to skin tumor development by recruiting IL-17-producing CD4+ T cells

Ortiz et al. report the accumulation of immature myeloid cells in skin tissue of patients with inflammatory conditions, which predisposes to the development of cancer.

Evidence links chronic inflammation with cancer, but cellular mechanisms involved in this process remain unclear. We have demonstrated that in humans, inflammatory conditions that predispose to development of skin and colon tumors are associated with accumulation in tissues of CD33⁺S100A9⁺ cells, the phenotype typical for myeloid-derived suppressor cells in cancer or immature myeloid cells (IMCs) in tumor-free hosts. To identify the direct role of these cells in tumor development, we used S100A9 transgenic mice to create the conditions for topical accumulation of these cells in the skin in the absence of infection or tissue damage. These mice demonstrated accumulation of granulocytic IMCs in the skin upon topical application of 12-O-tetradecanoylphorbol-13-acetate (TPA), resulting in a dramatic increase in the formation of papillomas during epidermal carcinogenesis. The effect of IMCs on tumorigenesis was not associated with immune suppression, but with CCL4 (chemokine [C-C motif] ligand 4)-mediated recruitment of IL-17–producing CD4⁺ T cells. This chemokine was released by activated IMCs. Elimination of CD4⁺ T cells or blockade of CCL4 or IL-17 abrogated the increase in tumor formation caused by myeloid cells. Thus, this study implicates accumulation of IMCs as an initial step in facilitation of tumor formation, followed by the recruitment of CD4⁺ T cells.

Tyrosine kinase inhibitor tyrphostin AG490 reduces liver injury in LPS-induced shock

Sepsis remains a serious clinical problem despite continuous efforts to increase survival. Experimental animal models of sepsis are pointed to a great extent on blocking the activity of cytokines. A number of signal-transducing molecules are associated with the occurrence of excessive tissue inflammation. Through inhibition of tyrosine phosphorilation and thereby changing cell signaling, tyrosine kinase inhibitors can influence multiple inflammatory pathways. The purpose of the present investigation was to evaluate the effect of tyrosine kinase inhibitor tyrphostin AG490 in a mouse LPS-induced shock. Cytokine and chemokine blood levels were determined by ELISA assays. CD11b(+) Ly6C(+), CD3(+)CD69(+) and C5aR positive cell populations in the peritoneal exudate were detected by flow cytometry. The expression of iNOS and Signal Transducer and Activator of Transcription (STAT) in the liver were observed by immunohistochemistry. We found that tyrphostin AG490 inhibited Regulated upon activation normal T cell expressed and secreted (RANTES), IL-6 and IL-12 serum levels, decreased the number of CD11b(+)Ly6C(+) and CD3(+)CD69(+) subpopulations in the peritoneal exudate and prevented the decrease of cells expressing C5a receptor and TNF-alpha receptor. Tyrphostin ameliorated liver injury associated with suppressed iNOS, STAT3 and pSTAT3 expression. Our data suggest that tyrphostin AG490 diminished the degree of inflammation starting in peritoneal cavity and minimized liver dysfunction thus representing one approach for better outcome of sepsis conditions.

Functional characterization of myeloid-derived suppressor cell subpopulations during the development of experimental arthritis

Recent evidence indicates the existence of subpopulations of myeloid-derived suppressor cells (MDSCs) with distinct phenotypes and functions. Here, we characterized the role of MDSC subpopulations in the pathogenesis of autoimmune arthritis in a collagen-induced arthritis (CIA) mouse model. The splenic CD11b(+) Gr-1(+) MDSC population expanded in CIA mice, and these cells could be subdivided into polymorphonuclear (PMN) and mononuclear (MO) MDSC subpopulations based on Ly6C and Ly6G expression. During CIA, the proportion of splenic MO-MDSCs was increased in association with the severity of joint inflammation, while PMN-MDSCs were decreased. MO-MDSCs expressed higher levels of surface CD40 and CD86 protein, but lower levels of Il10, Tgfb1, Ccr5, and Cxcr2 mRNA. PMN-MDSCs exhibited a more potent capacity to suppress polyclonal T-cell proliferation in vitro, compared with MO-MDSCs. Moreover, the adoptive transfer of PMN-MDSCs, but not MO-MDSCs, decreased joint inflammation, accompanied by reduced levels of serum cytokine secretion and the frequencies of Th1 and Th17 cells in draining lymph nodes. These results suggest that there could be a shift from potently suppressive PMN-MDSCs to poorly suppressive MO-MDSCs during the development of experimental arthritis, which might reflect the failure of expanded MDSCs to suppress autoimmune arthritis.

Mechanisms of intimate and long-distance cross-talk between glioma and myeloid cells: how to break a vicious cycle

Glioma-associated microglia and macrophages (GAMs) and myeloid-derived suppressor cells (MDSCs) condition the glioma microenvironment to generate an immunosuppressed niche for tumour expansion. This immunosuppressive microenvironment is considered to be shaped through a complex multi-step interactive process between glioma cells, GAMs and MDSCs. Glioma cells recruit GAMs and MDSCs to the tumour site and block their maturation. Glioma cell-derived factors subsequently skew these cells towards an immunosuppressive, tumour-promoting phenotype. Finally, GAMs and MDSCs enhance immune suppression in the glioma microenvironment and promote glioma growth, invasiveness, and neovascularization. The local and distant cross-talk between glioma cells and GAMs and MDSCs is regulated by a plethora of soluble proteins and cell surface-bound factors, and possibly via extracellular vesicles and platelets. Importantly, GAMs and MDSCs have been reported to impair the efficacy of glioma therapy, in particular immunotherapeutic approaches. Therefore, advancing our understanding of the function of GAMs and MDSCs in brain tumours and targeted intervention of their immunosuppressive function may benefit the treatment of glioma.

Gr-1⁺CD11b⁺ immature myeloid cells (IMC) promote resistance of pro-inflammatory T cells to suppression by regulatory T cells in atherosclerotic Apo E- deficient mice

Accumulating evidence indicates that both defects in Treg numbers and/or function as well as resistance of effector T cells to suppression may contribute to the development of human chronic inflammatory diseases. However, which mechanism involved in the progression of atherosclerosis remains unclear. In this study, we evaluated the production and function of CD4⁺ inflammatory and regulatory T cells in atherosclerosis-prone mice. We found that the hyperactivity and unresponsiveness to Treg-mediated suppression of inflammatory CD4⁺ T cells occurred in the progression of atherosclerosis, though Treg cells were present in very large numbers and fully functional. We further found that Gr-1⁺CD11b⁺ immature myeloid cells were significantly accumulated in atherosclerotic Apo E^−/− mice, and they promoted resistance of inflammatory CD4⁺ T cells to Treg-mediated suppression in vitro and in vivo. we further confirmed that Gr-1⁺CD11b⁺ immature myeloid cells produced high level of interleukin 6 which was at least partially responsible for inducing unresponsiveness of inflammatory CD4⁺ T cells to suppression via activation of Jak/Stat signaling pathway. Taken together, these findings might provide new insights to explore potential targets for immune therapeutic intervention in atherosclerosis.

Human papillomavirus e7 oncoprotein transgenic skin develops an enhanced inflammatory response to 2,4-dinitrochlorobenzene by an arginase-1-dependent mechanism

We have shown that the expression of human papillomavirus type 16 E7 (HPV16.E7) protein within epithelial cells results in local immune suppression and a weak and ineffective immune response to E7 similar to that occuring in HPV-associated premalignancy and cancers. However, a robust acute inflammatory stimulus can overcome this to enable immune elimination of HPV16.E7-transformed epithelial cells. 2,4-Dinitrochlorobenzene (DNCB) can elicit acute inflammation and it has been shown to initiate the regression of HPV-associated genital warts. Although the clinical use of DNCB is discouraged owing to its mutagenic potential, understanding how DNCB-induced acute inflammation alters local HPV16.E7-mediated immune suppression might lead to better treatments. Here, we show that topical DNCB application to skin expressing HPV16.E7 as a transgene induces a hyperinflammatory response, which is not seen in nontransgenic control animals. The E7-associated inflammatory response is characterized by enhanced expression of Th2 cytokines and increased infiltration of CD11b(+)Gr1(int)F4/80(+)Ly6C(hi)Ly6G(low) myeloid cells, producing arginase-1. Inhibition of arginase with an arginase-specific inhibitor, N(omega)-hydroxy-nor-L-arginine, ameliorates the DNCB-induced inflammatory response. Our results demonstrate that HPV16.E7 protein enhances DNCB-associated production of arginase-1 by myeloid cells and consequent inflammatory cellular infiltration of skin.

Faecal calprotectin concentrations in gastrointestinal diseases

OBJECTIVE

To quantify faecal calprotectin concentrations in a variety of gastrointestinal disorders in order to determine its diagnostic value.

METHODS

Patients with gastrointestinal symptoms undergoing upper or lower endoscopy and healthy control subjects provided stool samples. Calprotectin was quantified by enzyme-linked immunosorbent assay.

RESULTS

The study recruited 210 patients with definitively diagnosed gastrointestinal diseases and 50 control subjects. Calprotectin concentrations were significantly higher in patients with ulcerative colitis or Crohn's disease compared with controls, or patients with colorectal polyps or irritable bowel syndrome. The faecal calprotectin concentration significantly differentiated between inflammatory bowel diseases (IBD) and non-IBD (area under ROC curve 0.949). Calprotectin concentrations were significantly higher in patients with oesophageal polyps or gastric neoplasms than in those with chronic gastritis, stomach ulcers, duodenal ulcers or acute pancreatitis.

CONCLUSION

Calprotectin may be a useful noninvasive marker for the diagnosis of IBD.