The chemokine CCL5 regulates glucose uptake and AMP kinase signaling in activated T cells to facilitate chemotaxis

CCR5 and inflammatory storm

Chemokines and their corresponding receptors play crucial roles in orchestrating inflammatory and immune responses, particularly in the context of pathological conditions disrupting the internal environment. Among these receptors, CCR5 has garnered considerable attention due to its significant involvement in the inflammatory cascade, serving as a pivotal mediator of neuroinflammation and other inflammatory pathways associated with various diseases. However, a notable gap persists in comprehending the intricate mechanisms governing the interplay between CCR5 and its ligands across diverse and intricate inflammatory pathologies. Further exploration is warranted, especially concerning the inflammatory cascade instigated by immune cell infiltration and the precise binding sites within signaling pathways. This study aims to illuminate the regulatory axes modulating signaling pathways in inflammatory cells by providing a comprehensive overview of the pathogenic processes associated with CCR5 and its ligands across various disorders. The primary focus lies on investigating the pathomechanisms associated with CCR5 in disorders related to neuroinflammation, alongside the potential impact of aging on these processes and therapeutic interventions. The discourse culminates in addressing current challenges and envisaging potential future applications, advocating for innovative research endeavors to advance our comprehension of this realm.

A putative role for lactate in the crosstalk between chemokines and glycolysis in solid cancer

Chemokines are very important for carcinogenesis and the development of a malignant phenotype. Lactate is a small molecule produced during glycolysis; recently it has emerged as an immunomodulator that could impact tumor cell behavior. In this paper we explore the interplay between chemokines, glycolysis, and lactate in cancer progression, and propose the existence of a pro-tumoral lactate-chemokine-glycolysis loop driven by high glucose levels.

Mitochondrial metabolism sustains CD8+ T cell migration for an efficient infiltration into solid tumors

The ability of CD8+ T cells to infiltrate solid tumors and reach cancer cells is associated with improved patient survival and responses to immunotherapy. Thus, identifying the factors controlling T cell migration in tumors is critical, so that strategies to intervene on these targets can be developed. Although interstitial motility is a highly energy-demanding process, the metabolic requirements of CD8+ T cells migrating in a 3D environment remain unclear. Here, we demonstrate that the tricarboxylic acid (TCA) cycle is the main metabolic pathway sustaining human CD8+ T cell motility in 3D collagen gels and tumor slices while glycolysis plays a more minor role. Using pharmacological and genetic approaches, we report that CD8+ T cell migration depends on the mitochondrial oxidation of glucose and glutamine, but not fatty acids, and both ATP and ROS produced by mitochondria are required for T cells to migrate. Pharmacological interventions to increase mitochondrial activity improve CD8+ T cell intratumoral migration and CAR T cell recruitment into tumor islets leading to better control of tumor growth in human xenograft models. Our study highlights the rationale of targeting mitochondrial metabolism to enhance the migration and antitumor efficacy of CAR T cells in treating solid tumors.

Chemokine receptor CCR1 regulates macrophage activation through mTORC1 signaling in nonalcoholic steatohepatitis

BACKGROUND AND AIMS

Chemokine (CC motif) receptor 1 (CCR1) promotes liver fibrosis in mice. However, its effects on nonalcoholic steatohepatitis (NASH) remain unclear. Therefore, the present study aimed to investigate the role of CCR1 in the progression of NASH.

METHODS

Human serum and liver tissues were obtained from patients with NASH and controls. Systemic (Ccr1-/-) and liver macrophage-knockout Ccr1 (Ccr1LKD) mice were fed a high-cholesterol and high-fat (CL) diet for 12 weeks or a methionine/choline-deficient (MCD) diet for 4 weeks. BX471 was used to pharmacologically inhibit CCR1 in CL-fed mice.

RESULTS

CCR1 was significantly upregulated in liver samples from patients with NASH and in animal models of dietary-induced NASH. In the livers of mice fed a CL diet for 12 weeks, the CCR1 protein colocalized with F4/80+ macrophages rather than with hepatic stellate cells. Compared to their wild-type littermates, Ccr1-/- mice fed with the CL or MCD diet showed inhibition of NASH-associated hepatic steatosis, inflammation, and fibrosis. Mechanistically, Ccr1 deficiency suppressed macrophage infiltration and activation by attenuating the mechanistic target of rapamycin complex 1 (mTORC1) signaling. Similar results were observed in Ccr1LKD mice administered the CL diet. Moreover, CCR1 inhibition by BX471 effectively suppressed NASH progression in CL-fed mice.

CONCLUSIONS

Ccr1 deficiency mitigated macrophage activity by inhibiting mTORC1 signaling, thereby preventing the development of NASH. Notably, the CCR1 inhibitor BX471 protected against NASH. These findings would help in developing novel strategies for the treatment of NASH.

Cysteine-cysteine Chemokine Receptor Type 5 Plays a Critical Role in Exercise Performance by Regulating Mitochondrial Content in Skeletal Muscle

Cysteine-cysteine chemokine receptor type 5 (CCR5) is thought to play an important role in the trafficking of lymphoid cells but has recently also been associated with AMPK signaling pathways that are implicated in energy metabolism in skeletal muscle. We hypothesized that genetic deletions of CCR5 would alter mitochondria content and exercise performance in mice. CCR5-/- and wild-type mice with the same genetic background were subjected to endurance exercise and grip strength tests. The soleus muscle was stained with immunofluorescence for myosin heavy chain 7 (MYH7) and succinate dehydrogenase (SDH) analysis as well as the expression of genes associated with muscle atrophy and mitochondrial oxidative phosphorylation were measured using qPCR. Although there were no differences in the weight of the soleus muscle between the CCR5-/- group and the wild-type mice, the CCR5-/- mice showed the following muscular dysfunctions: (i) decreased MYH7 percentage and cross-section area, (ii) higher myostatin and atrogin-1 mRNA levels, (iii) dropped expression of mitochondrial DNA-encoded electron respiratory chain genes (cytochrome B, cytochrome c oxidase subunit III, and ATP synthase subunit 6) as well as mitochondrial generation genes (PPARγ and PGC-1α), and (iv) lower SDH activity and exercise performance when compared with wild-type mice. In addition, genes associated with mitochondrial biogenesis (PGC-1α, PPARγ, and MFN2) and mitochondrial complex (ND4 and Cytb) were upregulated when the skeletal muscle cell line C2C12 was exposed to cysteine-cysteine chemokine ligand 4 (a ligand of CCR5) in vitro. These findings suggested that attenuation of endurance exercise performance is related to the loss of mitochondrial content and lower SDH activity of soleus muscle in CCR5 knockout mice. The present study provides evidence indicating that the chemokine receptor CCR5 might modulate the skeletal muscle metabolic energy system during exercise.

FEN1 inhibitor SC13 promotes CAR-T cells infiltration into solid tumours through cGAS-STING signalling pathway

It is well known that chimeric antigen receptor T-cell immunotherapy (CAR-T-cell immunotherapy) has excellent therapeutic effect in haematological tumours, but it still faces great challenges in solid tumours, including inefficient T-cell tumour infiltration and poor functional persistence. Flap structure-specific endonuclease 1 (FEN1), highly expressed in a variety of cancer cells, plays an important role in both DNA replication and repair. Previous studies have reported that FEN1 inhibition is an effective strategy for cancer treatment. Therefore, we hypothesized whether FEN1 inhibitors combined with CAR-T-cell immunotherapy would have a stronger killing effect on solid tumours. The results showed that low dose of FEN1 inhibitors SC13 could induce an increase of double-stranded broken DNA (dsDNA) in the cytoplasm. Cytosolic dsDNA can activate the cyclic GMP-AMP synthase-stimulator of interferon gene signalling pathway and increase the secretion of chemokines. In vivo, under the action of FEN1 inhibitor SC13, more chemokines were produced at solid tumour sites, which promoted the infiltration of CAR-T cells and improved anti-tumour immunity. These findings suggest that FEN1 inhibitors could enable CAR-T cells to overcome poor T-cell infiltration and improve the treatment of solid tumours.

Fugetaxis of Cell-in-Catalytic-Coat Nanobiohybrids in Glucose Gradients

Manipulation and control of cell chemotaxis remain an underexplored territory despite vast potential in various fields, such as cytotherapeutics, sensors, and even cell robots. Herein is achieved the chemical control over chemotactic movement and direction of Jurkat T cells, as a representative model, by the construction of cell-in-catalytic-coat structures in single-cell nanoencapsulation. Armed with the catalytic power of glucose oxidase (GOx) in the artificial coat, the nanobiohybrid cytostructures, denoted as Jurkat[Lipo_GOx] , exhibit controllable, redirected chemotactic movement in response to d-glucose gradients, in the opposite direction to the positive-chemotaxis direction of naïve, uncoated Jurkat cells in the same gradients. The chemically endowed, reaction-based fugetaxis of Jurkat[Lipo_GOx] operates orthogonally and complementarily to the endogenous, binding/recognition-based chemotaxis that remains intact after the formation of a GOx coat. For instance, the chemotactic velocity of Jurkat[Lipo_GOx] can be adjusted by varying the combination of d-glucose and natural chemokines (CXCL12 and CCL19) in the gradient. This work offers an innovative chemical tool for bioaugmenting living cells at the single-cell level through the use of catalytic cell-in-coat structures.

S100A4-dependent glycolysis promotes lymphatic vessel sprouting in tumor

Tumor-induced lymphangiogenesis promotes the formation of new lymphatic vessels, contributing to lymph nodes (LNs) metastasis of tumor cells in both mice and humans. Vessel sprouting appears to be a critical step in this process. However, how lymphatic vessels sprout during tumor lymphangiogenesis is not well-established. Here, we report that S100A4 expressed in lymphatic endothelial cells (LECs) promotes lymphatic vessel sprouting in a growing tumor by regulating glycolysis. In mice, the loss of S100A4 in a whole body (S100A4^-/-), or specifically in LECs (S100A4^ΔLYVE1) leads to impaired tumor lymphangiogenesis and disrupted metastasis of tumor cells to sentinel LNs. Using a 3D spheroid sprouting assay, we found that S100A4 in LECs was required for the lymphatic vessel sprouting. Further investigations revealed that S100A4 was essential for the position and motility of tip cells, where it activated AMPK-dependent glycolysis during lymphatic sprouting. In addition, the expression of S100A4 in LECs was upregulated under hypoxic conditions. These results suggest that S100A4 is a novel regulator of tumor-induced lymphangiogenesis. Targeting S100A4 in LECs may be a potential therapeutic strategy for lymphatic tumor metastasis.

Single-nuclei analysis reveals depot-specific transcriptional heterogeneity and depot-specific cell types in adipose tissue of dairy cows

Adipose tissue (AT) is an endocrine organ with a central role on whole-body energy metabolism and development of metabolic diseases. Single-cell and single-nuclei RNA sequencing (scRNA-seq and snRNA-seq, respectively) analyses in mice and human AT have revealed vast cell heterogeneity and functionally distinct subtypes that are potential therapeutic targets to metabolic disease. In periparturient dairy cows, AT goes through intensive remodeling and its dysfunction is associated with metabolic disease pathogenesis and decreased productive performance. The contributions of depot-specific cells and subtypes to the development of diseases in dairy cows remain to be studied. Our objective was to elucidate differences in cellular diversity of visceral (VAT) and subcutaneous (SAT) AT in dairy cows at the single-nuclei level. We collected matched SAT and VAT samples from three dairy cows and performed snRNA-seq analysis. We identified distinct cell types including four major mature adipocytes (AD) and three stem and progenitor cells (ASPC) subtypes, along with endothelial cells (EC), mesothelial cells (ME), immune cells, and pericytes and smooth muscle cells. All major cell types were present in both SAT and VAT, although a strong VAT-specificity was observed for ME, which were basically absent in SAT. One ASPC subtype was defined as adipogenic (PPARG+) while the other two had a fibro-adipogenic profile (PDGFRA+). We identified vascular and lymphatic EC subtypes, and different immune cell types and subtypes in both SAT and VAT, i.e., macrophages, monocytes, T cells, and natural killer cells. Not only did VAT show a greater proportion of immune cells, but these visceral immune cells had greater activation of pathways related to immune and inflammatory response, and complement cascade in comparison with SAT. There was a substantial contrast between depots for gene expression of complement cascade, which were greatly expressed by VAT cell subtypes compared to SAT, indicating a pro-inflammatory profile in VAT. Unprecedently, our study demonstrated cell-type and depot-specific heterogeneity in VAT and SAT of dairy cows. A better understanding of depot-specific molecular and cellular features of SAT and VAT will aid in the development of AT-targeted strategies to prevent and treat metabolic disease in dairy cows, especially during the periparturient period.

Identifying platelet-derived factors as amplifiers of B. burgdorferi-induced cytokine production

Previous studies have shown that monocytes can be 'trained' or tolerized by certain stimuli to respond stronger or weaker to a secondary stimulation. Rewiring of glucose metabolism was found to be important in inducing this phenotype. As we previously found that Borrelia burgdorferi (B. burgdorferi), the causative agent of Lyme borreliosis (LB), alters glucose metabolism in monocytes, we hypothesized that this may also induce long-term changes in innate immune responses. We found that exposure to B. burgdorferi decreased cytokine production in response to the TLR4-ligand lipopolysaccharide (LPS). In addition, B. burgdorferi exposure decreased baseline levels of glycolysis, as assessed by lactate production. Using GWAS analysis, we identified a gene, microfibril-associated protein 3-like (MFAP3L) as a factor influencing lactate production after B. burgdorferi exposure. Validation experiments proved that MFAP3L affects lactate- and cytokine production following B. burgdorferi stimulation. This is mediated by functions of MFAP3L, which includes activating ERK2 and through activation of platelet degranulation. Moreover, we showed that platelets and platelet-derived factors play important roles in B. burgdorferi-induced cytokine production. Certain platelet-derived factors, such chemokine C-X-C motif ligand 7 (CXCL7) and (C-C motif) ligand 5 (CCL5), were elevated in the circulation of LB patients in comparison to healthy individuals.

Effects of Melatonin on the Transcriptome of Human Granulosa Cells, Fertilization and Blastocyst Formation

Melatonin is a promising reagent that can improve assisted reproductive technology (ART) outcomes in infertility patients. However, melatonin is not effective for all infertile patients, and it remains unclear for which patients melatonin would be effective. This study examined the effects of melatonin on ART outcomes and examined its mechanisms. Melatonin increased the fertilization rate in patients whose fertilization rates in the previous cycle were less than 50%, but not in patients whose fertilization rates were more than 50% in the previous cycle. Melatonin increased the blastocyst formation rate in patients whose embryo development rates in the previous cycle were less than 50%, but not in patients whose embryo development rates were more than 50% in the previous cycle. To clarify its mechanisms, transcriptome changes by melatonin treatment in granulosa cells (GCs) of the patients were examined by RNA-sequence. Melatonin treatment altered the transcriptomes of GCs of patients with poor ART outcomes so that they were similar to the transcriptomes of patients with good ART outcomes. The altered genes were associated with the inhibition of cell death and T-cell activity, and the activation of steroidogenesis and angiogenesis. Melatonin treatment was effective for patients with poor fertilization rates and poor embryo development rates in the previous ART cycle. Melatonin alters the GCs transcriptome and, thus, their functions, and this could improve the oocyte quality, leading to good ART outcomes.

Immune Checkpoint Proteins, Metabolism and Adhesion Molecules: Overlooked Determinants of CAR T-Cell Migration?

Adoptive transfer of T cells genetically engineered to express chimeric antigen receptors (CAR) has demonstrated striking efficacy for the treatment of several hematological malignancies, including B-cell lymphoma, leukemia, and multiple myeloma. However, many patients still do not respond to this therapy or eventually relapse after an initial remission. In most solid tumors for which CAR T-cell therapy has been tested, efficacy has been very limited. In this context, it is of paramount importance to understand the mechanisms of tumor resistance to CAR T cells. Possible factors contributing to such resistance have been identified, including inherent CAR T-cell dysfunction, the presence of an immunosuppressive tumor microenvironment, and tumor-intrinsic factors. To control tumor growth, CAR T cells have to migrate actively enabling a productive conjugate with their targets. To date, many cells and factors contained within the tumor microenvironment have been reported to negatively control the migration of T cells and their ability to reach cancer cells. Recent evidence suggests that additional determinants, such as immune checkpoint proteins, cellular metabolism, and adhesion molecules, may modulate the motility of CAR T cells in tumors. Here, we review the potential impact of these determinants on CAR T-cell motility, and we discuss possible strategies to restore intratumoral T-cell migration with a special emphasis on approaches targeting these determinants.

IL-27 Induces CCL5 Production by T Lymphocytes, Which Contributes to Antitumor Activity

IL-27 is a pleiotropic cytokine that exhibits stimulatory/regulatory functions on multiple lineages of immune cells including T lymphocytes. In this study, we demonstrate that IL-27 directly induces CCL5 production by T lymphocytes, particularly CD8⁺ T cells in vitro and in vivo. IL-27-induced CCL5 production is IL-27R-dependent. In CD4⁺ T cells, IL-27-induced CCL5 production was primarily dependent on Stat1 activation, whereas in CD8⁺ T cells, Stat1 deficiency does not abrogate CCL5 induction. A chromatin immunoprecipitation assay revealed that in the CCL5 promoter region, both putative Stat3 binding sites exhibit significant binding to Stat3, whereas only one out of four Stat1 binding sites displays moderate binding to Stat1. In tumor-bearing mice, IL-27 induced dramatic production of CCL5 in tumor-infiltrating T cells. IL-27-induced CCL5 appears to contribute to an IL-27-mediated antitumor effect. This is signified by diminished tumor inhibition in anti-CCL5- and IL-27-treated mice. Additionally, intratumor delivery of CCL5 mRNA using lipid nanoparticles significantly inhibited tumor growth. Thus, IL-27 induces robust CCL5 production by T cells, which contributes to antitumor activity.

CCL5/CCR5 axis in human diseases and related treatments

To defense harmful stimuli or maintain the immune homeostasis, the body produces and recruits a superfamily of cytokines such as interleukins, interferons, chemokines etc. Among them, chemokines act as crucial regulators in defense systems. CCL5/CCR5 combination is known for facilitating inflammatory responses, as well as inducing the adhesion and migration of different T cell subsets in immune responses. In addition, recent studies have shown that the interaction between CCL5 and CCR5 is involved in various pathological processes including inflammation, chronic diseases, cancers as well as the infection of COVID-19. This review focuses on how CCL5/CCR5 axis participates in the pathological processes of different diseases and their relevant signaling pathways for the regulation of the axis. Moreover, we highlighted the gene therapy and chemotherapy studies for treating CCR5-related diseases, including the ongoing clinical trials. The barriers and perspectives for future application and translational research were also summarized.

The Chemokine Receptor CCR5 Links Memory CD4+ T Cell Metabolism to T Cell Antigen Receptor Nanoclustering

The inhibition of anabolic pathways, such as aerobic glycolysis, is a metabolic cornerstone of memory T cell differentiation and function. However, the signals that hamper these anabolic pathways are not completely known. Recent evidence pinpoints the chemokine receptor CCR5 as an important player in CD4⁺ T cell memory responses by regulating T cell antigen receptor (TCR) nanoclustering in an antigen-independent manner. This paper reports that CCR5 specifically restrains aerobic glycolysis in memory-like CD4⁺ T cells, but not in effector CD4⁺ T cells. CCR5-deficient memory CD4⁺ T cells thus show an abnormally high glycolytic/oxidative metabolism ratio. No CCR5-dependent change in glucose uptake nor in the expression of the main glucose transporters was detected in any of the examined cell types, although CCR5-deficient memory cells did show increased expression of the hexokinase 2 and pyruvate kinase M2 isoforms, plus the concomitant downregulation of Bcl-6, a transcriptional repressor of these key glycolytic enzymes. Further, the TCR nanoclustering defects observed in CCR5-deficient antigen-experienced CD4⁺ T cells were partially reversed by incubation with 2-deoxyglucose (2-DG), suggesting a link between inhibition of the glycolytic pathway and TCR nanoscopic organization. Indeed, the treatment of CCR5-deficient lymphoblasts with 2-DG enhanced IL-2 production after antigen re-stimulation. These results identify CCR5 as an important regulator of the metabolic fitness of memory CD4⁺ T cells, and reveal an unexpected link between T cell metabolism and TCR organization with potential influence on the response of memory T cells upon antigen re-encounter.

GSK3β Interacts With CRMP2 and Notch1 and Controls T-Cell Motility

The trafficking of T-cells through peripheral tissues and into afferent lymphatic vessels is essential for immune surveillance and an adaptive immune response. Glycogen synthase kinase 3β (GSK3β) is a serine/threonine kinase and regulates numerous cell/tissue-specific functions, including cell survival, metabolism, and differentiation. Here, we report a crucial involvement of GSK3β in T-cell motility. Inhibition of GSK3β by CHIR-99021 or siRNA-mediated knockdown augmented the migratory behavior of human T-lymphocytes stimulated via an engagement of the T-cell integrin LFA-1 with its ligand ICAM-1. Proteomics and protein network analysis revealed ongoing interactions among GSK3β, the surface receptor Notch1 and the cytoskeletal regulator CRMP2. LFA-1 stimulation in T-cells reduced Notch1-dependent GSK3β activity by inducing phosphorylation at Ser9 and its nuclear translocation accompanied by the cleaved Notch1 intracellular domain and decreased GSK3β-CRMP2 association. LFA-1-induced or pharmacologic inhibition of GSK3β in T-cells diminished CRMP2 phosphorylation at Thr514. Although substantial amounts of CRMP2 were localized to the microtubule-organizing center in resting T-cells, this colocalization of CRMP2 was lost following LFA-1 stimulation. Moreover, the migratory advantage conferred by GSK3β inhibition in T-cells by CHIR-99021 was lost when CRMP2 expression was knocked-down by siRNA-induced gene silencing. We therefore conclude that GSK3β controls T-cell motility through interactions with CRMP2 and Notch1, which has important implications in adaptive immunity, T-cell mediated diseases and LFA-1-targeted therapies.

The Chemokine Systems at the Crossroads of Inflammation and Energy Metabolism in the Development of Obesity

Obesity is characterized as a complex and multifactorial excess accretion of adipose tissue accompanied with alterations in the immune and metabolic responses. Although the chemokine systems have been documented to be involved in the control of tissue inflammation and metabolism, the dual role of chemokines and chemokine receptors in the pathogenesis of the inflammatory milieu and dysregulated energy metabolism in obesity remains elusive. The objective of this review is to present an update on the link between chemokines and obesity-related inflammation and metabolism dysregulation under the light of recent knowledge, which may present important therapeutic targets that could control obesity-associated immune and metabolic disorders and chronic complications in the near future. In addition, the cellular and molecular mechanisms of chemokines and chemokine receptors including the potential effect of post-translational modification of chemokines in the regulation of inflammation and energy metabolism will be discussed in this review.

Blockade of Autocrine CCL5 Responses Inhibits Zika Virus Persistence and Spread in Human Brain Microvascular Endothelial Cells

Zika virus (ZIKV) is a neurovirulent flavivirus that uniquely causes fetal microcephaly, is sexually transmitted, and persists in patients for up to 6 months. ZIKV persistently infects human brain microvascular endothelial cells (hBMECs) that form the blood-brain barrier (BBB) and enables viral spread to neuronal compartments. We found that CCL5, a chemokine with prosurvival effects on immune cells, was highly secreted by ZIKV-infected hBMECs. Although roles for CCL5 in endothelial cell (EC) survival remain unknown, the presence of the CCL5 receptors CCR3 and CCR5 on ECs suggested that CCL5 could promote ZIKV persistence in hBMECs. We found that exogenous CCL5 induced extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation in hBMECs and that ERK1/2 cell survival signaling was similarly activated by ZIKV infection. Neutralizing antibodies to CCL5, CCR3, or CCR5 inhibited persistent ZIKV infection of hBMECs. While knockout (KO) of CCL5 failed to prevent ZIKV infection of hBMECs, at 3 days postinfection (dpi), we observed a >90% reduction in ZIKV-infected CCL5-KO hBMECs and a multilog reduction in ZIKV titers. In contrast, the addition of CCL5 to CCL5-KO hBMECs dose-dependently rescued ZIKV persistence in hBMECs. Inhibiting CCL5 responses using CCR3 (UCB35625) and CCR5 (maraviroc) receptor antagonists reduced the number of ZIKV-infected hBMECs and ZIKV titers (50% inhibitory concentrations [IC₅₀s] of 2.5 to 12 μM), without cytotoxicity (50% cytotoxic concentration [CC₅₀] of >80 μM). These findings demonstrate that ZIKV-induced CCL5 directs autocrine CCR3/CCR5 activation of ERK1/2 survival responses that are required for ZIKV to persistently infect hBMECs. Our results establish roles for CCL5 in ZIKV persistence and suggest the potential for CCL5 receptor antagonists to therapeutically inhibit ZIKV spread and neurovirulence.

DES-Tcell is a knowledgebase for exploring immunology-related literature

T-cells are a subtype of white blood cells circulating throughout the body, searching for infected and abnormal cells. They have multifaceted functions that include scanning for and directly killing cells infected with intracellular pathogens, eradicating abnormal cells, orchestrating immune response by activating and helping other immune cells, memorizing encountered pathogens, and providing long-lasting protection upon recurrent infections. However, T-cells are also involved in immune responses that result in organ transplant rejection, autoimmune diseases, and some allergic diseases. To support T-cell research, we developed the DES-Tcell knowledgebase (KB). This KB incorporates text- and data-mined information that can expedite retrieval and exploration of T-cell relevant information from the large volume of published T-cell-related research. This KB enables exploration of data through concepts from 15 topic-specific dictionaries, including immunology-related genes, mutations, pathogens, and pathways. We developed three case studies using DES-Tcell, one of which validates effective retrieval of known associations by DES-Tcell. The second and third case studies focuses on concepts that are common to Grave’s disease (GD) and Hashimoto’s thyroiditis (HT). Several reports have shown that up to 20% of GD patients treated with antithyroid medication develop HT, thus suggesting a possible conversion or shift from GD to HT disease. DES-Tcell found miR-4442 links to both GD and HT, and that miR-4442 possibly targets the autoimmune disease risk factor CD6, which provides potential new knowledge derived through the use of DES-Tcell. According to our understanding, DES-Tcell is the first KB dedicated to exploring T-cell-relevant information via literature-mining, data-mining, and topic-specific dictionaries.

Gene electrotransfer of proinflammatory chemokines CCL5 and CCL17 as a novel approach of modifying cytokine expression profile in the tumor microenvironment

The effectiveness of immunotherapy highly correlates with the degree and the type of infiltrated immune cells in the tumor tissue. Treatments based on modifying the immune cell infiltrate of the tumor microenvironment are thus gaining momentum. Therefore, the aim of our study was to investigate the effects of gene therapy with two proinflammatory chemokines CCL5 and CCL17 on inflammatory cytokine expression profile and immune cell infiltrate in two murine breast tumor models, 4T1 and E0771, and two murine colon tumor models, CT26 and MC38. In vitro, lipofection of plasmid DNA encoding CCL5 or CCL17 resulted in changes in the cytokine expression profile similar to control plasmid DNA, implying that the main driver of these changes was the entry of foreign DNA into the cell's cytosol. In vivo, gene electrotransfer resulted in high expression levels of both Ccl5 and Ccl17 transgenes in the 4T1 and CT26 tumor models. Besides a minor increase in the survival of the treated mice, the therapy also resulted in increased expression of Cxcl9 and Ifnγ, potent activators of the immune system, in CT26 tumors. However, this was not recapitulated in changes of TME, implying that a further refinement of the dosing schedule is needed.

Metabolic regulation of T lymphocyte motility and migration

In order to fulfill their effector and patrolling functions, lymphocytes traffic through the body and need to adapt to different tissue microenvironments. First, mature lymphocytes egress the bone marrow and the thymus into the vascular system. Circulating lymphocytes can exit the vasculature and penetrate into the tissues, either for patrolling in search for pathogens or to eliminate infection and activate the adaptive immune response. The cytoskeletal reorganization necessary to sustain migration require high levels of energy thus presenting a substantial bioenergetic challenge to migrating cells. The metabolic regulation of lymphocyte motility and trafficking has only recently begun to be investigated. In this review we will summarize current knowledge of the crosstalk between cell metabolism and the cytoskeleton in T lymphocytes, and discuss the concept that lymphocyte metabolism may reprogram in response to migratory stimuli and adapt to the different environmental cues received during recirculation in tissues.

Targeting inhibition of CCR5 on improving obesity-associated insulin resistance and impairment of pancreatic insulin secretion in high fat-fed rodent models

Obesity is closely linked with type 2 diabetes and the effective therapies on obesity-associated diabetes are under development. The aim of this study was undertaken to investigate whether the inhibition of the augmented CCR5-mediated signaling could be a common target for treatment of obesity-associated insulin resistance and impairment of pancreatic insulin secretion in high-fat diet (HFD) fed rats and CCR5 knockout mice and also in isolated islets and RIN-m5F cells. Conducted with SD rats, HFD-induced body weight gain was significantly decreased in those combined with Maraviroc treatment, but food intake remained similar compared to control. Maraviroc also significantly improved the impaired oral glucose tolerance test (OGTT). As compared with wild-type mice, CCR5 deletion significantly attenuated the HFD-induced increases in glucose area under curve of OGTT and the value of HOMA-IR as well as plasma lipid profile. It also reversed the HFD-suppressed gene expressions of GLUT4 and IRS-1 in adipose tissue. On the other hand, the HFD-associated islet macrophage and T-cell infiltration were significantly decreased in CCR5 KO mice. H2O2 significantly suppressed glucose-stimulated insulin secretion (GSIS) is isolated islets, which were significantly reversed in those cotreated with CCR5 mAb. H2O2 failed to change GSIS in those of CCR5 KO mice. The palmitate-induced reactive oxygen species production was significantly decreased in those cotreated with CCR5 antagonist in RIN-m5F cells. Collectively, it is suggested that targeting inhibition of the CCR5 mediated inflammatory pathway could not only improve obesity-associated insulin resistance but also directly alleviate pancreatic β-cell dysfunction.

Implications of cellular metabolism for immune cell migration

Cell migration is an essential, energetically demanding process in immunity. Immune cells navigate the body via chemokines and other immune mediators, which are altered under inflammatory conditions of injury or infection. Several factors determine the migratory abilities of different types of immune cells in diverse contexts, including the precise co-ordination of cytoskeletal remodelling, the expression of specific chemokine receptors and integrins, and environmental conditions. In this review, we present an overview of recent advances in our understanding of the relationship of each of these factors with cellular metabolism, with a focus on the spatial organization of glycolysis and mitochondria, reciprocal regulation of chemokine receptors and the influence of environmental changes.

Triphenyl phosphate modulated saturation of phospholipids: Induction of endoplasmic reticulum stress and inflammation

Although triphenyl phosphate (TPHP) has been reported to disrupt lipid metabolism, the effect of TPHP on lipid saturation remains unexplored. In this study, a lipidomic analysis demonstrated decreases in the levels of poly-unsaturated phosphatidylcholine (PC), phosphatidylethanolamine (PE), and phosphatidylserine (PS) in RAW264.7 murine macrophage cells exposed to 10 μM TPHP. The expression of the gene encoding lysophosphatidylcholine acyltransferase 3 (Lpcat3) was significantly downregulated by 0.76 ± 0.03 and 0.70 ± 0.08-fold in 10 and 20 μM TPHP exposure groups, relative to the control group. This finding explains the observed decrease in lipid saturation. Correspondingly, exposure to 10 and 20 μM TPHP induced endoplasmic reticulum (ER) stress and inflammatory responses, which have been linked to metabolic dysfunction such as insulin resistance and hypertriglyceridemia. Therefore, TPHP may pose a risk to human health by promoting metabolic diseases.

β-hydroxybutyrate and hydroxycarboxylic acid receptor 2 agonists activate the AKT, ERK and AMPK pathways, which are involved in bovine neutrophil chemotaxis

Elevated plasma concentrations of the ketone body β-hydroxybutyrate (BHB), an endogenous agonist of the hydroxycarboxylic acid receptor 2 (HCA2), is associated with an increased incidence of inflammatory diseases during lactation in dairy cows. In the early stages of this pathology, an increase in neutrophil recruitment is observed; however, the role of BHB remains elusive. This study characterized the effect of BHB and synthetic agonists of the HCA2 receptor on bovine neutrophil chemotaxis and the signaling pathways involved in this process. We demonstrated that treatment with BHB concentrations between 1.2 and 10 mM and two full selective agonists of the HCA2 receptor, MK-1903 and nicotinic acid, increased bovine neutrophil chemotaxis. We also observed that BHB and HCA2 agonists induced calcium release and phosphorylation of AKT, ERK 1/2 and AMPKα. To evaluate the role of these pathways in bovine neutrophil chemotaxis, we used the pharmacological inhibitors BAPTA-AM, pertussis toxin, U73122, LY294002, U0126 and compound C. Our results suggest that these pathways are required for HCA2 agonist-induced bovine neutrophil chemotaxis in non-physiological condition. Concentrations around 1.4 mM of BHB after calving may exert a chemoattractant effect that is key during the onset of the inflammatory process associated with metabolic disorders in dairy cows.

Emerging role of mTOR in tumor immune contexture: Impact on chemokine-related immune cells migration

During the last few decades, cell-based anti-tumor immunotherapy emerged and it has provided us with a large amount of knowledge. Upon chemokines recognition, immune cells undergo rapid trafficking and activation in disease milieu, with immune cells chemotaxis being accompanied by activation of diverse intercellular signal transduction pathways. The outcome of chemokines-mediated immune cells chemotaxis interacts with the cue of mammalian target of rapamycin (mTOR) in the tumor microenvironment (TME). Indeed, the mTOR cascade in immune cells involves migration and infiltration. In this review, we summarize the available mTOR-related chemokines, as well as the characterized upstream regulators and downstream targets in immune cells chemotaxis and assign potential underlying mechanisms in each evaluated chemokine. Specifically, we focus on the involvement of mTOR in chemokine-mediated immune related cells in the balance between tumor immunity and malignancy.

Metabolomics as an Approach to Characterise the Contrasting Roles of CCR5 in the Presence and Absence of Disease

Chemokine receptors such as C-C chemokine receptor 5 (CCR5) are activated through interaction with their ligands and are well known for their role in chemotaxis and signal transduction. While serving these roles, cellular responses are effected, hence the immune function of these molecules is established. Given the role of CCR5 in immune function and that the immune and metabolic systems are interlinked, subsequent immune-directed changes should be measurable at a metabolic level. Numerous investigations have reported on metabolic changes associated with CCR5 status in the presence of disease, so as to understand whether specific CCR5 genotypes, frequency and/or levels offer protection to the host or not. However, these metabolic changes were recorded using older conventional techniques. Depending on certain factors such as the disease model, the geography of the samples and/or the ethnic group under study, the role of CCR5 in disease differs. In addition, little is known about CCR5’s role in the absence of an enhanced inflammatory state, such as when infection persists. Metabolomics is defined as the study of metabolites and informs on metabolic changes within living organisms as induced by various stimuli, such as the interaction of CCR5 with its ligand. Since metabolomics reflects the underlying biochemical activity and state of cells/tissues, this review proposes it as a tool to clarify the contrasting roles of CCR5.

Chemokines in breast cancer: Regulating metabolism

Accumulating evidence indicates that chemokine-chemokine receptor interactions invoke biological responses beyond their originally described function of orchestrating leukocyte trafficking. In this review we will extend the findings that chemokines participate actively in the neoplastic process, and consider the contribution of CCL5 activation of CCR5 on breast cancer cells to upregulation of anabolic metabolic events that would support the energy demands of cell replication and proliferation.

Cellular Metabolism Is a Major Determinant of HIV-1 Reservoir Seeding in CD4+ T Cells and Offers an Opportunity to Tackle Infection

HIV persists in long-lived infected cells that are not affected by antiretroviral treatment. These HIV reservoirs are mainly located in CD4⁺ T cells, but their distribution is variable in the different subsets. Susceptibility to HIV-1 increases with CD4⁺ T cell differentiation. We evaluated whether the metabolic programming that supports the differentiation and function of CD4⁺ T cells affected their susceptibility to HIV-1. We found that differences in HIV-1 susceptibility between naive and more differentiated subsets were associated with the metabolic activity of the cells. Indeed, HIV-1 selectively infected CD4⁺ T cells with high oxidative phosphorylation and glycolysis, independent of their activation phenotype. Moreover, partial inhibition of glycolysis (1) impaired HIV-1 infection in vitro in all CD4⁺ T cell subsets, (2) decreased the viability of preinfected cells, and (3) precluded HIV-1 amplification in cells from HIV-infected individuals. Our results elucidate the link between cell metabolism and HIV-1 infection and identify a vulnerability in tackling HIV reservoirs.

Fructose 2,6-Bisphosphate in Cancer Cell Metabolism

For a long time, pioneers in the field of cancer cell metabolism, such as Otto Warburg, have focused on the idea that tumor cells maintain high glycolytic rates even with adequate oxygen supply, in what is known as aerobic glycolysis or the Warburg effect. Recent studies have reported a more complex situation, where the tumor ecosystem plays a more critical role in cancer progression. Cancer cells display extraordinary plasticity in adapting to changes in their tumor microenvironment, developing strategies to survive and proliferate. The proliferation of cancer cells needs a high rate of energy and metabolic substrates for biosynthesis of biomolecules. These requirements are met by the metabolic reprogramming of cancer cells and others present in the tumor microenvironment, which is essential for tumor survival and spread. Metabolic reprogramming involves a complex interplay between oncogenes, tumor suppressors, growth factors and local factors in the tumor microenvironment. These factors can induce overexpression and increased activity of glycolytic isoenzymes and proteins in stromal and cancer cells which are different from those expressed in normal cells. The fructose-6-phosphate/fructose-1,6-bisphosphate cycle, catalyzed by 6-phosphofructo-1-kinase/fructose 1,6-bisphosphatase (PFK1/FBPase1) isoenzymes, plays a key role in controlling glycolytic rates. PFK1/FBpase1 activities are allosterically regulated by fructose-2,6-bisphosphate, the product of the enzymatic activity of the dual kinase/phosphatase family of enzymes: 6-phosphofructo-2-kinase/fructose 2,6-bisphosphatase (PFKFB1-4) and TP53-induced glycolysis and apoptosis regulator (TIGAR), which show increased expression in a significant number of tumor types. In this review, the function of these isoenzymes in the regulation of metabolism, as well as the regulatory factors modulating their expression and activity in the tumor ecosystem are discussed. Targeting these isoenzymes, either directly or by inhibiting their activating factors, could be a promising approach for treating cancers.

HIV-1 Envelope Protein gp120 Promotes Proliferation and the Activation of Glycolysis in Glioma Cell

Patients infected with human immunodeficiency virus (HIV) are more prone to developing cancers, including glioblastomas (GBMs). The median survival for HIV positive GBM patients is significantly shorter than for those who are uninfected, despite the fact that they receive the same treatments. The nature of the GBM–HIV association remains poorly understood. In this study, we analyzed the effect of the HIV envelope glycoprotein gp120 on GBM cell proliferation. Specifically, we performed cell cycle, western blot, protein synthesis and metabolomics analysis as well as ATP production and oxygen consumption assays to evaluate proliferation and metabolic pathways in primary human glioma cell line, U87, A172 cells and in the HIVgp120tg/GL261 mouse model. Glioma cells treated with gp120 (100 ng/mL for 7–10 days) showed higher proliferation rates and upregulation in the expression of enolase 2, hexokinase and glyceraldehyde-3-phosphate dehydrogenase when compared to untreated cells. Furthermore, we detected an increase in the activity of pyruvate kinase and a higher glycolytic index in gp120 treated cells. Gp120 treated GBM cells also showed heightened lipid and protein synthesis. Overall, we demonstrate that in glioma cells, the HIV envelope glycoprotein promotes proliferation and activation of glycolysis resulting in increased protein and lipid synthesis.

Metabolic regulation of leukocyte motility and migration

Dynamic reorganization of the cytoskeleton is essential for numerous cellular processes including leukocyte migration. This process presents a substantial bioenergetic challenge to migrating cells as actin polymerization is dependent on ATP hydrolysis. Hence, migrating cells must increase ATP production to meet the increased metabolic demands of cytoskeletal reorganization. Despite this long-standing evidence, the metabolic regulation of leukocyte motility and trafficking has only recently begun to be investigated. In this review, we will summarize current knowledge of the crosstalk between cell metabolism and the cytoskeleton in leukocytes, and discuss the concept that leukocyte metabolism may reprogram in response to migratory stimuli and the different environmental cues received during recirculation ultimately regulating leukocyte motility and migration.

Human Plasmablast Migration Toward CXCL12 Requires Glucose Oxidation by Enhanced Pyruvate Dehydrogenase Activity via AKT

Migration of human plasmablast to the bone marrow is essential for the final differentiation of plasma cells and maintenance of effective humoral immunity. This migration is controlled by CXCL12/CXCR4-mediated activation of the protein kinase AKT. Herein, we show that the CXCL12-induced migration of human plasmablasts is dependent on glucose oxidation. Glucose depletion markedly inhibited plasmablast migration by 67%, and the glucose analog 2-deoxyglucose (2-DG) reduced the migration by 53%; conversely, glutamine depletion did not reduce the migration. CXCL12 boosted the oxygen consumption rate (OCR), and 2-DG treatment significantly reduced the levels of all measured tricarboxylic acid (TCA) cycle intermediates. AKT inhibitors blocked the CXCL12-mediated increase of OCR. CXCL12 enhanced the pyruvate dehydrogenase (PDH) activity by 13.5-fold in an AKT-dependent manner to promote mitochondrial oxidative phosphorylation. The knockdown and inhibition of PDH confirmed its indispensable role in CXCL12-induced migration. Cellular ATP levels fell by 91% upon exposure to 2-DG, and the mitochondrial ATP synthase inhibitor oligomycin inhibited CXCL12-induced migration by 85%. Low ATP levels inhibited the CXCL12-induced activation of AKT and phosphorylation of myosin light chains by 42%, which are required for cell migration. Thus, we have identified a mechanism that controls glucose oxidation via AKT signaling and PDH activation, which supports the migration of plasmablasts. This mechanism can provide insights into the proper development of long-lived plasma cells and is, therefore, essential for optimal humoral immunity. To our knowledge, this study is the first to investigate metabolic mechanisms underlying human plasmablast migration toward CXCL12.

Live Images of GLUT4 Protein Trafficking in Mouse Primary Hypothalamic Neurons Using Deconvolution Microscopy

Type 2 diabetes mellitus (T2DM) is a global health crisis which is characterized by insulin signaling impairment and chronic inflammation in peripheral tissues. The hypothalamus in the central nervous system (CNS) is the control center for energy and insulin signal response regulation. Chronic inflammation in peripheral tissues and imbalances of certain chemokines (such as CCL5, TNFα, and IL-6) contribute to diabetes and obesity. However, the functional mechanism(s) connecting chemokines and hypothalamic insulin signal regulation still remain unclear.

In vitro primary neuron culture models are convenient and simple models which can be used to investigate insulin signal regulation in hypothalamic neurons. In this study, we introduced exogeneous GLUT4 protein conjugated with GFP (GFP-GLUT4) into primary hypothalamic neurons to track GLUT4 membrane translocation upon insulin stimulation. Time-lapse images of GFP-GLUT4 protein trafficking were recorded by deconvolution microscopy, which allowed users to generate high-speed, high-resolution images without damaging the neurons significantly while conducting the experiment. The contribution of CCR5 in insulin regulated GLUT4 translocation was observed in CCR5 deficient hypothalamic neurons, which were isolated and cultured from CCR5 knockout mice. Our results demonstrated that the GLUT4 membrane translocation efficiency was reduced in CCR5 deficient hypothalamic neurons after insulin stimulation.

CCL5 activation of CCR5 regulates cell metabolism to enhance proliferation of breast cancer cells

In earlier studies, we showed that CCL5 enhances proliferation and survival of MCF-7 breast cancer cells in an mTOR-dependent manner and we provided evidence that, for T cells, CCL5 activation of CCR5 results in increased glycolysis and enhanced ATP production. Increases in metabolic activity of cancer cells, specifically increased glycolytic activity and increased expression of glucose transporters, are associated with tumour progression. In this report, we provide evidence that CCL5 enhances the proliferation of human breast cancer cell lines (MDA-MB-231, MCF-7) and mouse mammary tumour cells (MMTV-PyMT), mediated by CCR5 activation. Concomitant with enhanced proliferation we show that CCL5 increases cell surface expression of the glucose transporter GLUT1, and increases glucose uptake and ATP production by these cells. Blocking CCL5-inducible glucose uptake abrogates the enhanced proliferation induced by CCL5. We provide evidence that increased glucose uptake is associated with enhanced glycolysis, as measured by extracellular acidification. Moreover, CCL5 enhances the invasive capacity of these breast cancer cells. Using metabolomics, we demonstrate that the metabolic signature of CCL5-treated primary mouse mammary tumour cells reflects increased anabolic metabolism. The implications are that CCL5–CCR5 interactions in the tumour microenvironment regulate metabolic events, specifically glycolysis, to promote tumour proliferation and invasion.

Axl acts as a tumor suppressor by regulating LIGHT expression in T lymphoma

Axl is an oncogenic receptor tyrosine kinase that plays a role in many cancers. LIGHT (Lymphotoxin-related inducible ligand that competes for glycoprotein D binding to herpesvirus entry mediator on T cells) is a ligand that induces robust anti-tumor immunity by enhancing the recruitment and activation of effector immune cells at tumor sites. We observed that mouse EL4 and human Jurkat T lymphoma cells that stably overexpressed Axl also showed high expression of LIGHT. When Jurkat-Axl cells were treated with Gas6, a ligand for Axl, LIGHT expression was upregulated through activation of the PI3K/AKT signaling pathway and transcriptional induction by Sp1. The lytic activity of cytotoxic T lymphocytes and natural killer cells was enhanced by EL4-Axl cells. In addition, tumor volume and growth were markedly reduced due to enhanced apoptotic cell death in EL4-Axl tumor-bearing mice as compared to control mice. We also observed upregulated expression of CCL5 and its receptor, CCR5, and enhanced intratumoral infiltration of cytotoxic T lymphocytes and natural killer cells in EL4-Axl-bearing mice as compared to mock controls. These data strongly suggested that Axl exerts novel tumor suppressor effects by inducing upregulation of LIGHT in the tumor microenvironment of T lymphoma.

Zika Virus Persistently Infects and Is Basolaterally Released from Primary Human Brain Microvascular Endothelial Cells

Zika virus (ZIKV) is a mosquito-borne Flavivirus that has emerged as the cause of encephalitis and fetal microencephaly in the Americas. ZIKV uniquely persists in human bodily fluids for up to 6 months, is sexually transmitted, and traverses the placenta and the blood-brain barrier (BBB) to damage neurons. Cells that support persistent ZIKV replication and mechanisms by which ZIKV establishes persistence remain enigmatic but central to ZIKV entry into protected neuronal compartments. The endothelial cell (EC) lining of capillaries normally constrains transplacental transmission and forms the BBB, which selectively restricts access of blood constituents to neurons. We found that ZIKV (strain PRVABC59) persistently infects and continuously replicates in primary human brain microvascular ECs (hBMECs), without cytopathology, for >9 days and following hBMEC passage. ZIKV did not permeabilize hBMECs but was released basolaterally from polarized hBMECs, suggesting a direct mechanism for ZIKV to cross the BBB. ZIKV-infected hBMECs were rapidly resistant to alpha interferon (IFN-α) and transiently induced, but failed to secrete, IFN-β and IFN-λ. Global transcriptome analysis determined that ZIKV constitutively induced IFN regulatory factor 7 (IRF7), IRF9, and IFN-stimulated genes (ISGs) 1 to 9 days postinfection, despite persistently replicating in hBMECs. ZIKV constitutively induced ISG15, HERC5, and USP18, which are linked to hepatitis C virus (HCV) persistence and IFN regulation, chemokine CCL5, which is associated with immunopathogenesis, as well as cell survival factors. Our results reveal that hBMECs act as a reservoir of persistent ZIKV replication, suggest routes for ZIKV to cross hBMECs into neuronal compartments, and define novel mechanisms of ZIKV persistence that can be targeted to restrict ZIKV spread.IMPORTANCE ZIKV persists in patients, crossing placental and neuronal barriers, damaging neurons, and causing fetal microencephaly. We found that ZIKV persistently infects brain endothelial cells that normally protect neurons from viral exposure. hBMECs are not damaged by ZIKV infection and, analogous to persistent HCV infection, ZIKV constitutively induces and evades antiviral ISG and IFN responses to continuously replicate in hBMECs. As a result, hBMECs provide a protective niche for systemic ZIKV spread and a viral reservoir localized in the normally protective blood-brain barrier. Consistent with the spread of ZIKV into neuronal compartments, ZIKV was released basolaterally from hBMECs. Our findings define hBMEC responses that contribute to persistent ZIKV infection and potential targets for clearing ZIKV infections from hBMECs. These results further suggest roles for additional ZIKV-infected ECs to facilitate viral spread and persistence in the protected placental, retinal, and testicular compartments.

CCL5/RANTES contributes to hypothalamic insulin signaling for systemic insulin responsiveness through CCR5

Many neurodegenerative diseases are accompanied by metabolic disorders. CCL5/RANTES, and its receptor CCR5 are known to contribute to neuronal function as well as to metabolic disorders such as type 2 diabetes mellitus, obesity, atherosclerosis and metabolic changes after HIV infection. Herein, we found that the lack of CCR5 or CCL5 in mice impaired regulation of energy metabolism in hypothalamus. Immunostaining and co-immunoprecipitation revealed the specific expression of CCR5, associated with insulin receptors, in the hypothalamic arcuate nucleus (ARC). Both ex vivo stimulation and in vitro tissue culture studies demonstrated that the activation of insulin, and PI3K-Akt pathways were impaired in CCR5 and CCL5 deficient hypothalamus. The inhibitory phosphorylation of insulin response substrate-1 at Ser302 (IRS-1^S302) but not IRS-2, by insulin was markedly increased in CCR5 and CCL5 deficient animals. Elevating CCR5/CCL5 activity induced GLUT4 membrane translocation and reduced phospho-IRS-1^S302 through AMPKα-S6 Kinase. Blocking CCR5 using the antagonist, ^MetCCL5, abolished the de-phosphorylation of IRS-1^S302 and insulin signal activation. In addition, intracerebroventricular delivery of ^MetCCL5 interrupted hypothalamic insulin signaling and elicited peripheral insulin responsiveness and glucose intolerance. Taken together, our data suggest that CCR5 regulates insulin signaling in hypothalamus which contributes to systemic insulin sensitivity and glucose metabolism.

ORM Promotes Skeletal Muscle Glycogen Accumulation via CCR5-Activated AMPK Pathway in Mice

We found previously that acute phase protein orosomucoid reacts to fatigue and activates C-C chemokine receptor type 5 to increase muscle glycogen storage and enhance muscle endurance (Lei et al., 2016). To explore the underlying molecular mechanisms, we investigated the role of AMP-activated protein kinase, a critical fuel sensor in skeletal muscle, in C-C chemokine receptor type 5-mediated orosomucoid action. It was found orosomucoid increased skeletal muscle AMP-activated protein kinase activation in a time- and dose- dependent manner, which was largely prevented by pharmacological blocking or knockout of C-C chemokine receptor type 5. Administration of orosomucoid also significantly increased the de-phosphorylation and activity of muscle glycogen synthase, the rate-limiting enzyme for glycogen synthesis. The effect was largely absent in mice deficient in C-C chemokine receptor type 5^−/− or AMP-activated protein kinase α2^−/−, the predominant isoform in skeletal muscle. Moreover, deletion of AMP-activated protein kinase α2 abolished the effect of orosomucoid on fatigue and muscle glycogen. These findings indicate that orosomucoid may promote glycogen storage and enhance muscle function through C-C chemokine receptor type 5-mdiated activation of AMP-activated protein kinase, which in turn activates glycogen synthase and increases muscle glycogen.

A Novel mTORC1-Dependent, Akt-Independent Pathway Differentiates the Gut Tropism of Regulatory and Conventional CD4 T Cells

The vitamin A metabolite all-trans retinoic acid (ATRA) induces a gut-homing phenotype in activated CD4(+) conventional T cells (Tconv) by upregulating the integrin α4β7 and the chemokine receptor CCR9. We report that, in contrast to mouse Tconv, only ∼50% of regulatory T cells (Treg) upregulate CCR9 when stimulated by physiological levels of ATRA, even though Tconv and Treg express similar levels of the retinoic acid receptor (RAR). The resulting bimodal CCR9 expression is not associated with differences in the extent of their proliferation, level of Foxp3 expression, or affiliation with naturally occurring Treg or induced Treg in the circulating Treg pool. Furthermore, we find that exposure of Treg to the mechanistic target of rapamycin (mTOR) inhibitor rapamycin suppresses upregulation of both CCR9 and α4β7, an effect that is not evident with Tconv. This suggests that in Treg, ATRA-induced upregulation of CCR9 and α4β7 is dependent on activation of a mTOR signaling pathway. The involvement of mTOR is independent of Akt activity, because specific inhibition of Akt, pyruvate dehydrogenase kinase-1, or its downstream target glycogen synthase kinase-3 did not prevent CCR9 expression. Additionally, Rictor (mTOR complex [mTORC]2)-deficient Treg showed unaltered ability to express CCR9, whereas Raptor (mTORC1)-deficient Treg were unable to upregulate CCR9, suggesting the selective participation of mTORC1. These findings reveal a novel difference between ATRA signaling and chemokine receptor induction in Treg versus Tconv and provide a framework via which the migratory behavior of Treg versus Tconv might be regulated differentially for therapeutic purposes.

The Acute-Phase Protein Orosomucoid Regulates Food Intake and Energy Homeostasis via Leptin Receptor Signaling Pathway

The acute-phase protein orosomucoid (ORM) exhibits a variety of activities in vitro and in vivo, notably modulation of immunity and transportation of drugs. We found in this study that mice lacking ORM1 displayed aberrant energy homeostasis characterized by increased body weight and fat mass. Further investigation found that ORM, predominantly ORM1, is significantly elevated in sera, liver, and adipose tissues from the mice with high-fat diet (HFD)-induced obesity and db/db mice that develop obesity spontaneously due to mutation in the leptin receptor (LepR). Intravenous or intraperitoneal administration of exogenous ORM decreased food intake in C57BL/6, HFD, and leptin-deficient ob/ob mice, which was absent in db/db mice and was significantly reduced in mice with arcuate nucleus (ARC) LepR knockdown, whereas enforced expression of ORM1 in ARC significantly decreased food intake, body weight, and serum insulin level. Furthermore, we found that ORM is able to bind directly to LepR and activate the receptor-mediated JAK2-STAT3 signaling in hypothalamus tissue and GT1-7 cells, which was derived from hypothalamic tumor. These data indicated that ORM could function through LepR to regulate food intake and energy homeostasis in response to nutrition status. Modulating the expression of ORM is a novel strategy for the management of obesity and related metabolic disorders.

Metabolic reprogramming of alloantigen-activated T cells after hematopoietic cell transplantation

Alloreactive donor T cells are the driving force in the induction of graft-versus-host disease (GVHD), yet little is known about T cell metabolism in response to alloantigens after hematopoietic cell transplantation (HCT). Here, we have demonstrated that donor T cells undergo metabolic reprograming after allogeneic HCT. Specifically, we employed a murine allogeneic BM transplant model and determined that T cells switch from fatty acid β-oxidation (FAO) and pyruvate oxidation via the tricarboxylic (TCA) cycle to aerobic glycolysis, thereby increasing dependence upon glutaminolysis and the pentose phosphate pathway. Glycolysis was required for optimal function of alloantigen-activated T cells and induction of GVHD, as inhibition of glycolysis by targeting mTORC1 or 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3) ameliorated GVHD mortality and morbidity. Together, our results indicate that donor T cells use glycolysis as the predominant metabolic process after allogeneic HCT and suggest that glycolysis has potential as a therapeutic target for the control of GVHD.

Fatigue-induced Orosomucoid 1 Acts on C-C Chemokine Receptor Type 5 to Enhance Muscle Endurance

Understanding and managing fatigue is a significant challenge in clinic and society. In attempting to explore how the body responds to and regulates fatigue, we found in rodent fatigue models that orosomucoid 1 (ORM1) was significantly increased in multiple tissues, including blood and muscle. Interestingly, administration of exogenous ORM1 increased muscle glycogen and enhanced muscle endurance, whereas ORM1 deficiency resulted in a significant decrease of muscle endurance both in vivo and in vitro, which could largely be restored by exogenous ORM1. Further studies demonstrated that ORM1 can bind to C-C chemokine receptor type 5 (CCR5) on muscle cells and deletion of the receptor abolished the effect of ORM1. Thus, fatigue upregulates the level of ORM1, which in turn functions as an anti-fatigue protein to enhance muscle endurance via the CCR5 pathway. Modulation of the level of ORM1 and CCR5 signaling could be a novel strategy for the management of fatigue.

Epigenome-modifying tools in asthma

Asthma is a chronic disease which causes recurrent breathlessness affecting 300 million people worldwide of whom 250,000 die annually. The epigenome is a set of heritable modifications and tags that affect the genome without changing the intrinsic DNA sequence. These marks include DNA methylation, modifications to histone proteins around which DNA is wrapped and expression of noncoding RNA. Alterations in all of these processes have been reported in patients with asthma. In some cases these differences are linked to disease severity and susceptibility and may account for the limited value of genetic studies in asthma. Animal models of asthma suggest that epigenetic modifications and processes are linked to asthma and may be tractable targets for therapeutic intervention.

Neutrophil-Derived MMP-8 Drives AMPK-Dependent Matrix Destruction in Human Pulmonary Tuberculosis

Pulmonary cavities, the hallmark of tuberculosis (TB), are characterized by high mycobacterial load and perpetuate the spread of M. tuberculosis. The mechanism of matrix destruction resulting in cavitation is not well defined. Neutrophils are emerging as key mediators of TB immunopathology and their influx are associated with poor outcomes. We investigated neutrophil-dependent mechanisms involved in TB-associated matrix destruction using a cellular model, a cohort of 108 patients, and in separate patient lung biopsies. Neutrophil-derived NF-kB-dependent matrix metalloproteinase-8 (MMP-8) secretion was up-regulated in TB and caused matrix destruction both in vitro and in respiratory samples of TB patients. Collagen destruction induced by TB infection was abolished by doxycycline, a licensed MMP inhibitor. Neutrophil extracellular traps (NETs) contain MMP-8 and are increased in samples from TB patients. Neutrophils lined the circumference of human pulmonary TB cavities and sputum MMP-8 concentrations reflected TB radiological and clinical disease severity. AMPK, a central regulator of catabolism, drove neutrophil MMP-8 secretion and neutrophils from AMPK-deficient patients secrete lower MMP-8 concentrations. AMPK-expressing neutrophils are present in human TB lung biopsies with phospho-AMPK detected in nuclei. These data demonstrate that neutrophil-derived MMP-8 has a key role in the immunopathology of TB and is a potential target for host-directed therapy in this infectious disease.

PFKFB4 controls embryonic patterning via Akt signalling independently of glycolysis

How metabolism regulators play roles during early development remains elusive. Here we show that PFKFB4 (6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 4), a glycolysis regulator, is critical for controlling dorsal ectoderm global patterning in gastrulating frog embryos via a non-glycolytic function. PFKFB4 is required for dorsal ectoderm progenitors to proceed towards more specified fates including neural and non-neural ectoderm, neural crest or placodes. This function is mediated by Akt signalling, a major pathway that integrates cell homeostasis and survival parameters. Restoring Akt signalling rescues the loss of PFKFB4 in vivo. In contrast, glycolysis is not essential for frog development at this stage. Our study reveals the existence of a PFKFB4-Akt checkpoint that links cell homeostasis to the ability of progenitor cells to undergo differentiation, and uncovers glycolysis-independent functions of PFKFB4.

AMPK in lymphocyte metabolism and function

Adenosine monophosphate-activated protein kinase (AMPK) is a serine/threonine kinase that is crucial for cellular energy metabolism homeostasis. AMPK monitors cellular energy status in response to nutritional variations and, once activated by low energy status, switches on ATP-producing catabolic pathways and switches off ATP-consuming anabolic pathways to restore cellular energy homeostasis. When T lymphocytes encounter foreign antigens, they initiate a program of differentiation leading to the rapid generation of effector and memory cells that clear the pathogen and prevent future infection, respectively. Differentiation of naïve T cells in effector or long term memory cells is tightly associated with changes in their energy metabolic activity and recent data have revealed that fine-tuning of metabolism could modulate T cell functions. Here, we will review recent data about the regulation of T cell metabolism by AMPK and discuss its influence on T cell function.