Distribution of M1 and M2 macrophages in cerebral granulomas caused by Encephalitozoon cuniculi

Encephalitozoon cuniculi spores cause severe granulomatous inflammation in the brain where mononuclear cells and macrophages infiltrate. Here, we orally infected New Zealand white rabbits with 1 × 10⁶E. cuniculi viable spores to study the recruitment and localization of macrophages in brain granulomas. At day 30 post-infection, the positive phenotype markers iNOS (M1) and Arg-1 (M2) were located in the periphery and center of granulomas, respectively. Live intracytoplasmic spores were found only in positive Arg-1 cells. This is the first work to describe the recruitment and distribution of M1 and M2 macrophages in the brain granulomas of rabbits infected with E. cuniculi.

Early-Released Interleukin-10 Significantly Inhibits Lipopolysaccharide-Elicited Neuroinflammation In Vitro

Anti-inflammatory cytokine interleukin (IL)-10 is pivotal for limiting excessive inflammation in the central nervous system. Reports show that lipopolysaccharide (LPS)-induced microglial IL-10 emerges in a delayed manner in vitro and in vivo, lagging behind proinflammatory cytokines to facilitate the resolution of neuroinflammation. We hypothesized that IL-10 releases quite quickly based on our pilot investigation. Here, we uncovered a bimodal expression of microglial IL-10 gene transcription induced by LPS in mouse primary mixed glial cultures. This pattern consisted of a short brief early-phase and a long-lived late-phase, enabling the production of IL-10 protein in a rapid manner. The removal and addition of IL-10 protein assays indicated that early-released IL-10 exerted potent modulatory effects on neuroinflammation at picomolar levels, and IL-10 released at the onset of neuroinflammation is tightly controlled. We further showed that the early-released, but not the late-released, IL-10 was crucial for mediating and potentiating the anti-inflammatory function of a β2-adrenergic receptor agonist salmeterol. This study in vitro highlights the essential role of early-released IL-10 in regulating the appropriate degree of neuroinflammation, overturning the previous notion that microglial IL-10 produces and functions in a delayed manner and providing new insights into anti-inflammatory mechanisms-mediated neuroimmune homeostasis.

M-CSF and prostratin induced Mregs promote immune tolerance in transplanted mice through Arg-1 pathway

OBJECTIVE

Regulatory macrophages (Mregs) are a group of heterogeneous macrophages. These cells could induce immunosuppressive effects through the expression of immune regulatory molecules and cytokines.

METHODS

The differentiation of Mregs was induced by treating bone marrow cells with M-CSF and prostratin in vitro. The cell-phenotypes and immunosuppressive function were determined by flow cytometry. Rt-PCR was employed to assess the mechanisms of Mregs. Skin grafted mouse model was used for in vivo validation.

RESULTS

Mregs induced by M-CSF + prostratin had a strong inhibitory effect on T cell proliferation and cytokines production. The phenotype of induced bone marrow cells changed towards Mregs. These Mregs could induce the differentiation of Tregs in vivo. Arg-1 expression in these cells were significantly upregulated. Inhibition of arginase (Arg) or arginine supplement significantly reversed the immunosuppressive function. In mice skin-grafted models, adoptive transfer of these Mregs significantly prolonged allograft survival. In mice models, Arg-1 expression significantly elevated on skin grafts cells and Tregs increased in graft tissues.

CONCLUSIONS

We successfully developed a Mregs-inducing protocol with the combination of M-CSF and prostratin in vitro. M-CSF + prostratin induced Mregs prevented mice skin graft rejection through upregulating the expression Arg-1.

Hepatocyte paraffin 1 and arginase-1 are effective panel of markers in HBV-related HCC diagnosis in fine-needle aspiration specimens

Objective

In order to make successful treatment for HBV-related hepatocellular carcinoma, an early diagnosis is necessary. In this research we aimed to evaluate the IHC staining pattern of Hepatocyte paraffin 1 and arginase-1 and their performance in early diagnosis of HCC. The incidence of HepPar-1 and Arg-1 were evaluated by IHC in 121 patients (HBV, HCC, HBV + HCC) and 30 healthy subjects.

Results

Arg-1 had significantly increased sensitivity in identification of HBV + HCC patients compared to HepPar-1 (P < 0.001). The sensitivity of arginase-1 is 96.3% whereas, the sensitivity of HepPar-1 is 72.7%. Arg-1 had higher specificity in identification of HBV + HCC patients compared to HepPar-1 (P < 0.05). With one positive marker, the sensitivity, the specificity and the positive predictive values and negative predictive value were 84.3%, 82.4%, 88.6% and 85.4% respectively. Also with one positive marker, the sensitivity and negative predictive value were significantly higher compared to the both 2 positive combinations. It was concluded that Arg-1 can improves the ability to detect HBV + HCC patients when compared with HepPar-1. When, both markers being positive, the specificity and PPVs of this combination were fairly higher. Concurrent use of these two proteins may be one of the best HCC detection patterns in needle specimens.

M2 macrophage immunotherapy abolishes glucose intolerance by increasing IL-10 expression and AKT activation

Aim: Glucose intolerance associates with M1/M2 macrophage unbalance. We thus wanted to examine the effect of M2 macrophage administration on mouse model of glucose intolerance. Materials & methods: C57BL/6 mice fed a high-fat diet (HFD) for 12 weeks and then received thrice 20 mg/kg streptozotocin (HFD-GI). Bone marrow-derived stem cells were collected from donor mice and differentiated/activated into M2 macrophages for intraperitoneal administration into HFD-GI mice. Results: M2 macrophage treatment abolished glucose intolerance independently of obesity. M2 macrophage administration increased IL-10 in visceral adipose tissue and serum, but showed no effect on serum insulin. While nitric oxide synthase-2 and arginase-1 remained unaltered, M2 macrophage treatment restored AKT phosphorylation in visceral adipose tissue. Conclusion: M2 macrophage treatment abolishes glucose intolerance by increasing IL-10 and phosphorylated AKT.

NecroX-5 ameliorates inflammation by skewing macrophages to the M2 phenotype

This study aimed to evaluate the role of NecroX-5, a powerful anti-inflammatory agent, on the functional plasticity of macrophages and the possible underlying mechanism using RAW264.7 cells, thioglycollate-elicited peritoneal macrophages from C57BL/6 mice, and a murine model of dextran sodium sulfate (DSS)-induced colitis. The change in cell morphology was examined by scanning electron microscopy. The expression of CD206, arginase (Arg)-1, and inducible nitric oxide synthase (iNOS) were examined by western blotting. The production of inflammatory cytokines was detected by enzyme-linked immunosorbent assays and statistical comparisons were made. The results showed that treatment of RAW264.7 cells with NecroX-5 caused an elongated shape in comparison to non-treated cells. The expression levels of macrophage mannose receptor CD206 and Arg-1, specific markers of M2 cells, were significantly upregulated by NecroX-5 treatment, while those of iNOS (M1 macrophages) was decreased. In addition, NecroX-5 significantly reduced the secretion of inflammatory cytokines, while interleukin (IL)-4 and IL-13 secretion in the supernatant was significantly enhanced. Treatment with NecroX-5 considerably ameliorated the progression of DSS-induced colitis and significantly inhibited the mRNA expression of pro-inflammatory cytokines, including tumor necrosis factor-α and IL-1β. Taken together, our findings demonstrated that NecroX-5 might dampen inflammation by switching the M1 phenotype to the M2 phenotype due to IL-4 and IL-13 induction.

Rapamycin Nano-Micelle Ophthalmic Solution Reduces Corneal Allograft Rejection by Potentiating Myeloid-Derived Suppressor Cells' Function

Allograft rejection is the major cause of corneal allograft failure. Rapamycin (RAPA) has been reported as an effective and novel immunosuppressive agent for patients undergoing corneal transplantation. However, its high water insolubility and low bioavailability have strongly constrained its clinical application. In this study, we successfully developed a RAPA nano-micelle ophthalmic solution and found that corneal allograft survival in recipients treated with RAPA nano-micelle ophthalmic solution was significantly prolonged for more than 2 months, with less inflammatory infiltration, decreased production of pro-inflammatory factors, and elevated recruitment of myeloid-derived suppressor cells (MDSCs). MDSCs from mice treated with RAPA nano-micelle ophthalmic solution could significantly inhibit the proliferation of CD4⁺T cells through increased expressions of inducible nitric oxidase (iNOS) and arginase-1 (Arg-1). The activity blockade of Arg-1 and iNOS pharmacologically reversed their immunosuppressive ability. Moreover, the effects of RAPA were antagonized by the administration of anti-Gr-1 antibody or by inhibiting the activity of iNOS pharmacologically. In addition, RAPA nano-micelle also effectively alleviated allograft rejection in high-risk rabbit penetrating keratoplasty (PKP) models with corneal vascularization. Collectively, our results demonstrate that RAPA nano-micelle ophthalmic solution could improve the immunosuppressive activity of MDSCs through elevated expression of Arg-1 and iNOS, which highlights the possible therapeutic applications of RAPA against corneal allograft rejection.

High salt induces anti-inflammatory MΦ2-like phenotype in peripheral macrophages

Macrophages play a critical role in inflammation and antigen-presentation. Abnormal macrophage function has been attributed in autoimmune diseases and cancer progression. Recent evidence suggests that high salt tissue micro-environment causes changes in macrophage activation. In our current report, we studied the role of extracellular sodium chloride on phenotype changes in peripheral circulating monocyte/macrophages collected from healthy donors. High salt (0.2 M NaCl vs basal 0.1 M NaCl) treatment resulted in a decrease in MΦ1 macrophage phenotype (CD11b⁺CD14^highCD16^low) from 77.4±6.2% (0.1 M) to 29.3±5.7% (0.2 M, p<0.05), while there was an increase in MΦ2 macrophage phenotype (CD11b⁺ CD14^lowCD16^high) from 17.2±5.9% (0.1 M) to 67.4±9.4% (0.2 M, p<0.05). ELISA-based cytokine analysis demonstrated that high salt treatment induced decreased expression of in the MΦ1 phenotype specific pro-inflammatory cytokine, TNFα (3.3 fold), IL-12 (2.3 fold), CCL-10 (2 fold) and CCL-5 (3.8 fold), but conversely induced an enhanced expression MΦ2-like phenotype specific anti-inflammatory cytokine, IL-10, TGFβ, CCL-17 (3.7 fold) and CCR-2 (4.3 fold). Further high salt treatment significantly decreased phagocytic efficiency of macrophages and inducible nitric oxide synthetase expression. Taken together, these data suggest that high salt extracellular environment induces an anti-inflammatory MΦ2-like macrophage phenotype with poor phagocytic and potentially reduced antigen presentation capacity commonly found in tumor microenvironment.

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High salt induced macrophage switch from MΦ1 to MΦ2-like phenotype.

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High salt induced anti-inflammatory MΦ2-specific cytokine profile.

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Reduced phagocytic efficiency upon high salt treatment.

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Inhibition of iNOS activity following high salt stimulation.