Cellular Distribution of C-C Motif Chemokine Ligand 2 Like Immunoreactivities in Frontal Cortex and Corpus Callosum of Normal and Lipopolysaccharide Treated Animal

Background: C-C motif chemokine ligand 2 (CCL2) is reported to be involved in the pathogenesis of various neurological and/or psychiatric diseases. Tissue or cellular expression of CCL2, in normal or pathological condition, may play an essential role in recruiting of monocytes or macrophages into the targeted organs, and be involved in a certain pathogenic mechanism. However, only a few studies focused on tissue and cellular distribution of the CCL2 peptide in the brain’s grey and white matters (GM, WM), and the changes of the GM and WM cellular CCL2 level in septic or endotoxic encephalopathy was not explored. Hence, the CCL2 cellular distribution in the front brain cortex and the corpus callosum (CC) WM was investigated in the present work by using immunofluorescent staining. Results: 1) Normally, CCL2 like immunoreactivity (CCL2-ir) in the CC is significantly higher than the cortex, especially when the measurement includes ependymal layer attached to the CC. 2) Structures surrounding the vasculatures contribute major CCL2-ir positive profiles in both GM and WM, but significantly more in the CC WM, in which they are bilaterally distributed and predominantly located in the lateral CC between the cingulate cortex and the lateral ventricles. 3) Following systemic lipopolysaccharide (LPS), the number of neuron-like CCL2-ir positive cells are increased significantly in the cortex, but not in the CC. 4) More CCL2-ir positive elements are accumulated inside microvasculature like structures in the CC WM, compared to those found in the cortex following systemic LPS. 5) Few macrophage/microglia marker-Iba-1 labeled structures exhibit CCL2-ir in normal cortex and CC, but the co-localization is significantly increased following systemic LPS. 6) Following saline or LPS injection, CCL2-ir and GFAP or Iba-1 double labeled structures are observed within the ependymal layer between the lateral ventricles and the CC. No accumulation of neutrophils was detected.Conclusion: there exist differences in the cellular distribution of the CCL2 peptide in the front brain cortex GM and the subcortical WM - the CC, in both the physiological condition and experimental endotoxemia. Which might cause different pathological change in the GM and WM.

Distinct roles of KLF4 in mesenchymal cell subtypes during lung fibrogenesis

During lung fibrosis, the epithelium induces signaling to underlying mesenchyme to generate excess myofibroblasts and extracellular matrix; herein, we focus on signaling in the mesenchyme. Our studies indicate that platelet-derived growth factor receptor (PDGFR)-β+ cells are the predominant source of myofibroblasts and Kruppel-like factor (KLF) 4 is upregulated in PDGFR-β+ cells, inducing TGFβ pathway signaling and fibrosis. In fibrotic lung patches, KLF4 is down-regulated, suggesting KLF4 levels decrease as PDGFR-β+ cells transition into myofibroblasts. In contrast to PDGFR-β+ cells, KLF4 reduction in α-smooth muscle actin (SMA)+ cells non-cell autonomously exacerbates lung fibrosis by inducing macrophage accumulation and pro-fibrotic effects of PDGFR-β+ cells via a Forkhead box M1 to C-C chemokine ligand 2—receptor 2 pathway. Taken together, in the context of lung fibrosis, our results indicate that KLF4 plays opposing roles in PDGFR-β+ cells and SMA+ cells and highlight the importance of further studies of interactions between distinct mesenchymal cell types.

MicroRNA-206 promotes the recruitment of CD8+ T cells by driving M1 polarisation of Kupffer cells

ObjectiveKupffer cells (KCs) protect against hepatocellular carcinoma (HCC) by communicating with other immune cells. However, the underlying mechanism(s) of this process is incompletely understood.DesignFVB/NJ mice were hydrodynamically injected with AKT/Ras and Sleeping Beauty transposon to induce HCC. Mini-circle and Sleeping Beauty were used to overexpress microRNA-206 in KCs of mice. Flow cytometry and immunostaining were used to evaluate the change in the immune system.ResultsHydrodynamic injection of AKT/Ras into mice drove M2 polarisation of KCs and depletion of cytotoxic T cells (CTLs) and promoted HCC development. M1-to-M2 transition of KCs impaired microRNA-206 biogenesis. By targeting Klf4 (kruppel like factor 4) and, thereby, enhancing the production of M1 markers including C-C motif chemokine ligand 2 (CCL2), microRNA-206 promoted M1 polarisation of macrophages. Indeed, microRNA-206-mediated increase of CCL2 facilitated hepatic recruitment of CTLs via CCR2. Disrupting each component of the KLF4/CCL2/CCR2 axis impaired the ability of microRNA-206 to drive M1 polarisation of macrophages and recruit CTLs. In AKT/Ras mice, KC-specific expression of microRNA-206 drove M1 polarisation of KCs and hepatic recruitment of CTLs and fully prevented HCC, while 100% of control mice died from HCC. Disrupting the interaction between microRNA-206 and Klf4 in KCs and depletion of CD8+ T cells impaired the ability of miR-206 to prevent HCC.ConclusionsM2 polarisation of KCs is a major contributor of HCC in AKT/Ras mice. MicroRNA-206, by driving M1 polarisation of KCs, promoted the recruitment of CD8+ T cells and prevented HCC, suggesting its potential use as an immunotherapeutic approach.

CCL2 (C-C Motif Chemokine Ligand 2) Biomarker Responses in Central Versus Peripheral Compartments After Focal Cerebral Ischemia

Background and Purpose: Inflammatory mediators in blood have been proposed as potential biomarkers in stroke. However, a direct relationship between these circulating factors and brain-specific ischemic injury remains to be fully defined. Methods: An unbiased screen in a nonhuman primate model of stroke was used to find out the most responsive circulating biomarker flowing ischemic stroke. Then this phenomenon was checked in human beings and mice. Finally, we observed the temporospatial responsive characteristics of this biomarker after ischemic brain injury in mice to evaluate the direct relationship between this circulating factor and central nervous system–specific ischemic injury. Results: In a nonhuman primate model, an unbiased screen revealed CCL2 (C-C motif chemokine ligand 2) as a major response factor in plasma after stroke. In mouse models of focal cerebral ischemia, plasma levels of CCL2 showed a transient response, that is, rapidly elevated by 2 to 3 hours postischemia but then renormalized back to baseline levels by 24 hours. However, a different CCL2 temporal profile was observed in whole brain homogenate, cerebrospinal fluid, and isolated brain microvessels, with a progressive increase over 24 hours, demonstrating a mismatch between brain versus plasma responses. In contrast to the lack of correlation with central nervous system responses, 2 peripheral compartments showed transient profiles that matched circulating plasma signatures. CCL2 protein in lymph nodes and adipose tissue was significantly increased at 2 hours and renormalized by 24 hours. Conclusions: These findings may provide a cautionary tale for biomarker pursuits in plasma. Besides a direct central nervous system response, peripheral organs may also contribute to blood signatures in complex and indirect ways.

The CCL2-CCR2 astrocyte-cancer cell axis in tumor extravasation at the brain

Although brain metastases are common in cancer patients, little is known about the mechanisms of cancer extravasation across the blood-brain barrier (BBB), a key step in the metastatic cascade that regulates the entry of cancer cells into the brain parenchyma. Here, we show, in a three-dimensional in vitro BBB microvascular model, that astrocytes promote cancer cell transmigration via their secretion of C-C motif chemokine ligand 2 (CCL2). We found that this chemokine, produced primarily by astrocytes, promoted the chemotaxis and chemokinesis of cancer cells via their C-C chemokine receptor type 2 (CCR2), with no notable changes in vascular permeability. These findings were validated in vivo, where CCR2-deficient cancer cells exhibited significantly reduced rates of arrest and transmigration in mouse brain capillaries. Our results reveal that the CCL2-CCR2 astrocyte-cancer cell axis plays a fundamental role in extravasation and, consequently, metastasis to the brain.

m6A demethylase ALKBH5 controls CD4+ T cell pathogenicity and promotes autoimmunity

N6-methyladenosine (m6A) modification is dynamically regulated by “writer” and “eraser” enzymes. m6A “writers” have been shown to ensure the homeostasis of CD4+ T cells, but the “erasers” functioning in T cells is poorly understood. Here, we reported that m6A eraser AlkB homolog 5 (ALKBH5), but not FTO, maintains the ability of naïve CD4+ T cells to induce adoptive transfer colitis. In addition, T cell–specific ablation of ALKBH5 confers protection against experimental autoimmune encephalomyelitis. During the induced neuroinflammation, ALKBH5 deficiency increased m6A modification on interferon-γ and C-X-C motif chemokine ligand 2 messenger RNA (mRNA), thus decreasing their mRNA stability and protein expression in CD4+ T cells. These modifications resulted in attenuated CD4+ T cell responses and diminished recruitment of neutrophils into the central nervous system. Our findings reveal an unexpected specific role of ALKBH5 as an m6A eraser in controlling the pathogenicity of CD4+ T cells during autoimmunity.

Predictive Role of CC-Chemokine Ligand 2 in Digestive System Cancers: A Meta-Analysis

Background: CC-chemokine ligand 2 (CCL2) expression as a prognostic factor in digestive system cancers (DSCs) is inconclusive. Methods:Thus, our aim was to summarize the prognostic role of CCL2 in DSCs. Electronic database was carefully searched. Studies focusing on CCL2 expression as a prognostic marker in DSCs were included for analysis. Pooled data for survival outcomes and clinical features were recorded in terms of the hazard ratio (HR) or odds ratio (OR) and the 95% confidence interval (CI).Results: In all,1,458 patients with DSCs from 11 studies were included for analysis.The pooled data revealed that high CCL2 expression group was more easy to occur the presence of distal metastases (OR = 3.83, 95% CI: 1.98–7.38, P < 0.001), severer tumor invasion (OR = 2.38, 95% CI: 1.31–4.34, P = 0.005), and advanced Tumor Nodal Metastasis stages (OR = 2.47, 95% CI: 1.12–5.45, P = 0.02). Moreover, poorer overall survival (HR = 2.09, P < 0.001) were observed in the group with high CCL2 expression. High levels of CCL2 also indicated dismay disease-free survival (HR = 1.87, P = 0.005) .Conclusions: Our findings indicate that CCL2 can serve as a prognostic indicator in DSCs.