M2A and M2C Macrophage Subsets Ameliorate Inflammation and Fibroproliferation in Acute Lung Injury Through Interleukin 10 Pathway. Shock. 2017;48:119-129. [PMID: 27941591 DOI: 10.1097/shk.0000000000000820]

Macrophages: versatile players in renal inflammation and fibrosis

Macrophages have important roles in immune surveillance and in the maintenance of kidney homeostasis; their response to renal injury varies enormously depending on the nature and duration of the insult. Macrophages can adopt a variety of phenotypes: at one extreme, M1 pro-inflammatory cells contribute to infection clearance but can also promote renal injury; at the other extreme, M2 anti-inflammatory cells have a reparative phenotype and can contribute to the resolution phase of the response to injury. In addition, bone marrow monocytes can differentiate into myeloid-derived suppressor cells that can regulate T cell immunity in the kidney. However, macrophages can also promote renal fibrosis, a major driver of progression to end-stage renal disease, and the CD206⁺ subset of M2 macrophages is strongly associated with renal fibrosis in both human and experimental diseases. Myofibroblasts are important contributors to renal fibrosis and recent studies provide evidence that macrophages recruited from the bone marrow can transition directly into myofibroblasts within the injured kidney. This process is termed macrophage-to-myofibroblast transition (MMT) and is driven by transforming growth factor-β1 (TGFβ1)-Smad3 signalling via a Src-centric regulatory network. MMT may serve as a key checkpoint for the progression of chronic inflammation into pathogenic fibrosis.

Bone marrow derived M2 macrophages protected against lipopolysaccharide-induced acute lung injury through inhibiting oxidative stress and inflammation by modulating neutrophils and T lymphocytes responses

Acute lung injury (ALI) is characterized by aggravated inflammatory responses and the subsequent alveolar-capillary injury for which there are no specific therapies available currently. The present study was designed to investigate the protective roles of bone marrow derived M₂ macrophages (M₂ BMDMs) in lipopolysaccharide (LPS) induced ALI. M₂ BMDMs were obtained from bone marrow cells stimulated with M-CSF and IL-4. Mice received M₂ BMDMs intratracheally 3 h after LPS administration. Histology and wet/dry (W/D) weight ratio, activated immune cells and total protein were detected. Cytokines production were measured in vivo and vitro study. The effects of PD-L1 blockade on M₂ BMDMs were calculated. The results showed that M₂ BMDMs administration reduced the infiltration of neutrophils, inhibited the oxidative stress, while increased the counts of CD3⁺T lymphocytes as well as CD4⁺CD25⁺ regulatory T lymphocytes. Further, M₂ BMDMs suppressed the TNF-α, IL-1β and IL-6 production, while increased the IL-10 production. Blockade of PD-L1/PD-1 pathway reversed cytokines production of M₂ BMDMs in the BALF. These findings indicated that M₂ BMDMs might be a promising therapeutic strategy for LPS-induced ALI through inhibiting oxidative stress and inflammation by modulating neutrophils and T lymphocytes responses.

Hypothermic Machine Perfusion's Protection on Porcine Kidney Graft Uncovers Greater Akt-Erk Phosphorylation

BACKGROUND

To investigate the potential mechanisms of hypothermic machine perfusion (HMP)'s beneficial effects on kidney graft over static cold storage (SCS) in vitro.

METHODS

Ten kidneys of 5 Bama miniature male pigs were paired into 2 groups: SCS group and HMP group. Preservation solutions were taken at 0, 1, 3, and 6 hours for the measurement of K⁺, Na⁺, Cl^-, blood urea nitrogen (BUN), creatinine (Cr), and lactate dehydrogenase (LDH) using the standard laboratory methods. Renal cortex were harvested at 6 hours for the following measurement: lactic acid (LD), adenosine triphosphate (ATP), malondialdehyde (MDA), neutrophil accumulation (MPO), interleukin-10 (IL-10), and transforming growth factor-β (TGF-β). Ischemia-induced apoptosis and the protein expression levels of total Akt, phospho-Akt, total Erk, and phospho-Erk were analyzed by Western blotting.

RESULTS

Almost all of the tested metabolites in preservation solutions were reduced with time in the HMP group. Levels of Na⁺, Cl^-, BUN, Cr, K⁺, and LDH were lower in the HMP group compared with the SCS group, with differences in the first 4 reaching statistical significance. HMP alleviated ATP degradation and LD accumulation, diminished the MDA (P < .05) and MPO (P = .227) levels, and greatly raised IL-10 and TGF-β (P < .05) expression. A marked decrease of proapoptotic and a large increase of antiapoptotic markers (P < .05) along with greatly raised Akt (P < .05) and Erk (P < .01) phosphorylation was observed in the kidney of the HMP group compared with the SCS group.

CONCLUSION

HMP's kidney graft protection involves inhibition of accumulation of toxic metabolites, oxidative damage, and apoptosis along with upregulation of the Akt and Erk signaling pathway.

Effects of Educated Monocytes with Xenogeneic Mesenchymal Stem Cell-Derived Conditioned Medium in a Mouse Model of Chronic Asthma

BACKGROUND

This study was conducted to determine the potential of the monocytes educated with rat bone marrow mesenchymal stem cell-derived conditioned medium (MCM) in ameliorating animal model of asthma.

METHODS

Chronic asthma was induced in the BALB/c mice using ovalbumin (OVA) sensitization. The monocytes were isolated from blood of mice and supplemented with 50% MCM or negative control media. After 24 h, the cells were designated as "non-educated or educated". Fourteen weeks after the onset of the study, animals were treated with educated or non-educated monocytes twice with a 1-week interval.

RESULTS

The educated monocytes showed a reduction in the potential production of the respiratory burst and nitric oxide and the secretion of IL-12 and IL-4 compared to non-educated monocytes. Conversely, these monocytes exhibited a significant increase in the production of IL-10 and TGF-?. Also, the levels of CD68+/CD206+ cells significantly increased in the population of educated monocytes. More importantly, the severity of histopathological lesions, NF-?B p65 mRNA level in lung tissues, total serum IgE and the total cell count, as well as the eosinophil count in the bronchoalveolar lavage fluid, were significantly decreased in OVA-inhaled mice treated with educated monocytes compared to OVA-sensitized group receiving non-educated monocytes. With no advantage in up-regulation of Foxp3 Treg cells, the treatment with educated monocytes reduced the secretion of IL-5 and IL-13 by splenocytes of asthma mice more than splenocytes of the asthma mice treated with non-educated monocytes.

CONCLUSION

The educated monocytes with MCM may be as a promising strategy for cell-based therapies of asthma.

Glucocorticoid attenuates acute lung injury through induction of type 2 macrophage

BACKGROUND

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are severe inflammatory lung diseases. Methylprednisolone (MP) is a common drug against inflammation in clinic. In this study, we aim to investigate the protective effect of MP on ALI and potential mechanisms.

METHODS

Male BABL/c mice were injected through tail vein using lipopolysaccharide (LPS, 5 mg/kg) with or without 5 mg/kg MP. Lung mechanics, tissue injury and inflammation were examined. Macrophage subsets in the lung were identified by flow cytometry. Macrophages were cultured from bone marrow of mice with or without MP. Then, we analyzed and isolated the subsets of macrophages. These isolated macrophages were then co-cultured with CD4⁺ T cells, and the percentage of regulatory T cells (Tregs) was examined. The expression of IL-10 and TGF-β in the supernatant was measured. The Tregs immunosuppression function was examined by T cell proliferation assay. To disclose the mechanism of the induction of Tregs by M2c, we blocked IL-10 or/and TGF-β using neutralizing antibody.

RESULTS

Respiratory physiologic function was significantly improved by MP treatment. Tissue injury and inflammation were ameliorated in the MP-treated group. After MP treatment, the number of M1 decreased and M2 increased in the lung. In in vitro experiment, MP promoted M2 polarization rather than M1. We then induced M1, M2a and M2c from bone marrow cells. M1 induced more Th17 while M2 induced more CD4⁺CD25⁺Fxop3⁺ Tregs. Compared with M2a, M2c induced more Tregs, and this effect could be blocked by anti-IL-10 and anti-TGF-β antibodies. However, M2a and M2c have no impact on Tregs immunosuppression function.

CONCLUSION

In conclusion, MP ameliorated ALI by promoting M2 polarization. M2, especially M2c, induced Tregs without any influence on Tregs immunosuppression function.

SOCS molecules: the growing players in macrophage polarization and function

The concept of macrophage polarization is defined in terms of macrophage phenotypic heterogeneity and functional diversity. Cytokines signals are thought to be required for the polarization of macrophage populations toward different phenotypes at different stages in development, homeostasis and disease. The suppressors of cytokine signaling family of proteins contribute to the magnitude and duration of cytokines signaling, which ultimately control the subtle adjustment of the balance between divergent macrophage phenotypes. This review highlights the specific roles and mechanisms of various cytokines family and their negative regulators link to the macrophage polarization programs. Eventually, breakthrough in the identification of these molecules will provide the novel therapeutic approaches for a host of diseases by targeting macrophage phenotypic shift.