NONO regulates multiple cytokine production in sepsis via the ERK1/2 signaling pathway.

The massive release of pro-inflammatory cytokines is a crucial step in triggering the inflammatory cascade in sepsis. Exploring the key molecules regulating the expression and release of multiple cytokines has important value for revealing the mechanism of the cytokine storm in sepsis. This study aimed to investigate the role of multifunctional nuclear protein non-POU domain containing octamer-binding protein (NONO) in the sepsis cytokine storm and to elucidate the underlying mechanism. We found that NONO expression in tissues and cells of sepsis mice was significantly upregulated. Downregulation of NONO expression inhibited the mRNA expression of multiple cytokines, including IL-6, IL-1ß, MCP-1, MIP-1α, and MIP-1ß in inflammatory cells from mice and human leukemic monocyte-THP1 cells challenged with lipopolysaccharide (LPS), and significantly decreased the level of these cytokines and TNF-α in the supernatant of THP1 cells challenged by LPS. Nono knockout also reduced the levels of TNF-α, IL-6, MIP-1α, and MIP-1ß in serum, alleviated hepatocyte edema, and improved the survival rate of sepsis mice. Reduced NONO expression decreased the phospho-ERK1/2 level in inflammatory cells from sepsis mice or THP1 cells challenged by LPS. Phospho-ERK1/2 inhibitor decreased the mRNA expression and concentration of cytokines in the culture supernatant of LPS-induced THP1 cells, similar to the effect of NONO knockdown. After LPS challenge, the levels of phospho-ERK1/2 and NONO were increased, with obvious colocalization in the nucleus and vesicular-like organelles in macrophages. NONO knockdown decreased nuclear translocation of phospho-ERK1/2 in LPS-challenged THP1 cells. These results suggest that NONO is a potentially critical molecule involved in multiple cytokine production in sepsis. Upregulated NONO in sepsis may promote the expression and release of multiple cytokines to participate in a sepsis cytokine storm by promoting ERK1/2 phosphorylation.

Modification of N-terminal α-amine of proteins via biomimetic ortho-quinone-mediated oxidation.

Naturally abundant quinones are important molecules, which play essential roles in various biological processes due to their reduction potential. In contrast to their universality, the investigation of reactions between quinones and proteins remains sparse. Herein, we report the development of a convenient strategy to protein modification via a biomimetic quinone-mediated oxidation at the N-terminus. By exploiting unique reactivity of an ortho-quinone reagent, the α-amine of protein N-terminus is oxidized to generate aldo or keto handle for orthogonal conjugation. The applications have been demonstrated using a range of proteins, including myoglobin, ubiquitin and small ubiquitin-related modifier 2 (SUMO2). The effect of this method is further highlighted via the preparation of a series of 17 macrophage inflammatory protein 1ß (MIP-1ß) analogs, followed by preliminary anti-HIV activity and cell viability assays, respectively. This method offers an efficient and complementary approach to existing strategies for N-terminal modification of proteins.

Recruitment of CD103+ dendritic cells via tumor-targeted chemokine delivery enhances efficacy of checkpoint inhibitor immunotherapy.

Although a clinical breakthrough for cancer treatment, it remains that a minority of patients respond to checkpoint inhibitor (CPI) immunotherapy. The composition of tumor-infiltrating immune cells has been identified as a key factor influencing CPI therapy success. Thus, enhancing tumor immune cell infiltration is a critical challenge. A lack of the chemokine CCL4 within the tumor microenvironment leads to the absence of CD103+ dendritic cells (DCs), a crucial cell population influencing CPI responsiveness. Here, we use a tumor stroma-targeting approach to deliver CCL4; by generating a fusion protein of CCL4 and the collagen-binding domain (CBD) of von Willebrand factor, we show that CBD fusion enhances CCL4 tumor localization. Intravenous CBD-CCL4 administration recruits CD103+ DCs and CD8+ T cells and improves the antitumor effect of CPI immunotherapy in multiple tumor models, including poor responders to CPI. Thus, CBD-CCL4 holds clinical translational potential by enhancing efficacy of CPI immunotherapy.

CCL4 enhances preosteoclast migration and its receptor CCR5 downregulation by RANKL promotes osteoclastogenesis.

Chemokine CCL4 (MIP-1ß) is released from osteoblast cells to restore the homeostasis of hematopoietic stem cells during the activation of bone marrow. In this study, we investigated the function of CCL4 and its receptor CCR5 during osteoclastogenesis. CCL4 promoted the migration and viability of preosteoclast cells. However, CCL4 had no direct effect on the receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast differentiation in mouse preosteoclast cells. In addition, CCR5 expression was rapidly reduced by RANKL treatment, which was recovered by IFN-γ during osteoclastogenesis. CCR5 downregulation by RANKL was mediated by MEK and JNK in preosteoclast cells and promoted osteoclastogenesis. These results suggest that CCL4 can enhance the recruitment of preosteoclasts to bone in the early stage, and the reduction of CCR5 promotes osteoclastogenesis when RANKL is prevalent.

Chemokines (CCL3, CCL4, and CCL5) Inhibit ATP-Induced Release of IL-1ß by Monocytic Cells.

Chemokines and ATP are among the mediators of inflammatory sites that can enter the circulation via damaged blood vessels. The main function of chemokines is leukocyte mobilization, and ATP typically triggers inflammasome assembly. IL-1ß, a potent inflammasome-dependent cytokine of innate immunity, is essential for pathogen defense. However, excessive IL-1ß may cause life-threatening systemic inflammation. Here, we hypothesize that chemokines control ATP-dependent secretion of monocytic IL-1ß. Lipopolysaccharide-primed human monocytic U937 cells were stimulated with the P2X7 agonist BzATP for 30 min to induce IL-1ß release. CCL3, CCL4, and CCL5 dose dependently inhibited BzATP-stimulated release of IL-1ß, whereas CXCL16 was ineffective. The effect of CCL3 was confirmed for primary mononuclear leukocytes. It was blunted after silencing CCR1 or calcium-independent phospholipase A2 (iPLA2) by siRNA and was sensitive to antagonists of nicotinic acetylcholine receptors containing subunits α7 and α9. U937 cells secreted small factors in response to CCL3 that mediated the inhibition of IL-1ß release. We suggest that CCL chemokines inhibit ATP-induced release of IL-1ß from U937 cells by a triple-membrane-passing mechanism involving CCR, iPLA2, release of small mediators, and nicotinic acetylcholine receptor subunits α7 and α9. We speculate that whenever chemokines and ATP enter the circulation concomitantly, systemic release of IL-1ß is minimized.

Deregulated neddylation in liver fibrosis.

Hepatic fibrosis is a global health problem currently without effective therapeutic approaches. Even though the ubiquitin-like posttranslational modification of neddylation, that conjugates Nedd8 (neural precursor cell expressed developmentally downregulated) to specific targets, is aberrant in many pathologies, its relevance in liver fibrosis (LF) remained unexplored. Our results show deregulated neddylation in clinical fibrosis and both in mouse bileductligation- and CCl4 -induced fibrosis. Importantly, neddylation inhibition, by using the pharmacological inhibitor, MLN4924, reduced liver injury, apoptosis, inflammation, and fibrosis by targeting different hepatic cell types. On one hand, increased neddylation was associated with augmented caspase 3 activity in bile-acid-induced apoptosis in mouse hepatocytes whereas neddylation inhibition ameliorated apoptosis through reduction of expression of the Cxcl1 and Ccl2 chemokines. On the other hand, chemokine receptors and cytokines, usually induced in activated macrophages, were reduced after neddylation inhibition in mouse Kupffer cells. Under these circumstances, decreased hepatocyte cell death and inflammation after neddylation inhibition could partly account for reduction of hepatic stellate cell (HSC) activation. We provide evidence that augmented neddylation characterizes activated HSCs, suggesting that neddylation inhibition could be important for resolving LF by directly targeting these fibrogenic cells. Indeed, neddylation inhibition in activated HSCs induces apoptosis in a process partly mediated by accumulation of c-Jun, whose cullin-mediated degradation is impaired under these circumstances. CONCLUSION: Neddylation inhibition reduces fibrosis, suggesting neddylation as a potential and attractive therapeutic target in liver fibrosis. (Hepatology 2017;65:694-709).

CC-chemokine ligand 4/macrophage inflammatory protein-1ß participates in the induction of neuropathic pain after peripheral nerve injury.

BACKGROUND: Neuropathic pain is caused by neural damage or dysfunction and neuropathic pain-related symptoms are resistant to conventional analgesics. Neuroinflammation due to the cytokine-chemokine network may play a pivotal role in neuropathic pain. We demonstrate that macrophage inflammatory protein-1ß (MIP-1ß) participates in neuropathic pain. METHODS: Mice received partial sciatic nerve ligation (PSL), and tactile allodynia and thermal hyperalgesia were assessed by von Frey test and Hargreaves test, respectively. Agents were administered into the region surrounding the sciatic nerve (SCN). RESULTS: Using reverse transcription polymerase chain reaction, the mRNA expressions of MIP-1ß and its receptor (CC-chemokine receptor 5; CCR5) in the injured SCN were up-regulated after PSL. MIP-1ß immunoreactivity was localized in macrophages and Schwann cells and increased in the injured SCN on day 1. PSL-induced tactile allodynia on days 4 to 7 was prevented by the administration of MIP-1ß neutralizing antibody (anti-MIP-1ß; on days 0, 3 and 6). PSL-induced up-regulations of inflammatory cytokine-chemokine mRNAs in the injured SCN were suppressed with anti-MIP-1ß treatment on day 7. Administration of CCR5 antagonist, D-ala-peptide T-amide (on days 0, 3 and 6) prevented tactile allodynia and thermal hyperalgesia on days 4 to 14. Single administration of recombinant mouse MIP-1ß (rmMIP-1ß) elicited tactile allodynia. Moreover, rmMIP-1ß increased the mRNA expression of inflammatory mediators in the SCN on day 1 after administration. CONCLUSIONS: These results suggest that MIP-1ß is a novel key mediator, and the peripheral MIP-1ß-CCR5 axis contributes to neuropathic pain. Therefore, investigation of this cascade might be a validated approach for the elucidation of neuropathic pain mechanisms.

Virus stimulation of human mast cells results in the recruitment of CD56⁺ T cells by a mechanism dependent on CCR5 ligands.

The trafficking of effector cells to sites of infection is crucial for antiviral responses. However, the mechanisms of recruitment of the interferon-γ-producing and cytotoxic CD56(+) T cells are poorly understood. Human mast cells are sentinel cells found in the skin and airway and produce selected proinflammatory mediators in response to multiple pathogen-associated signals. The role of human mast cell-derived chemokines in T-cell recruitment to virus infection was examined. Supernatants from primary human cord blood-derived mast cells (CBMCs) infected with mammalian reovirus were examined for chemokine production and utilized in chemotaxis assays. Virus-infected CBMCs produced several chemokines, including CCL3, CCL4, and CCL5. Supernatants from reovirus-infected CBMCs selectively induced the chemotaxis of CD8(+) T cells (10±1%) and CD3(+)CD56(+) T cells (19±5%). CD56(+) T-cell migration was inhibited by pertussis toxin (65±9%) and met-RANTES (56±7%), a CCR1/CCR5 antagonist. CD56(+) T cells expressed CCR5, but little CCR1. The depletion of CCL3, CCL4, and CCL5 from reovirus-infected CBMC supernatants significantly (41±10%) inhibited CD56(+) T-cell chemotaxis. This study demonstrates a novel role for mast cells and CCR5 in CD56(+) T-cell trafficking and suggests that human mast cells enhance immunity to viruses through the selective recruitment of cytotoxic effector cells to virus infection sites. These findings could be exploited to enhance local T-cell responses in chronic viral infection and malignancies at mast cell-rich sites.

FROUNT is a common regulator of CCR2 and CCR5 signaling to control directional migration.

FROUNT is a known CCR2-binding protein that facilitates monocyte/macrophage infiltration. Here we report that FROUNT also binds to the C-terminal region of CCR5 and enhances CCR5-mediated cellular chemotaxis. We show that FROUNT overexpression enhances the directionality of chemotaxis, while FROUNT suppression results in impaired responsiveness. Furthermore, we found an increase in consolidated pseudopodium formation in FROUNT-overexpressing cells (FNT cells) on uniform stimulation with CCL4 (MIP1-beta), a specific ligand of CCR5. In most FNT cells, one to two pseudopodia directed toward higher chemokine concentration were found, whereas most FNT-suppressed cells had multiple pseudopodia. The data indicate that FROUNT is involved in sensing and amplifying a shallow extracellular chemokine gradient that leads to a limited number of accurate pseudopodia directed toward the chemokine concentration. In addition to its separate roles in CCR2- and CCR5-mediated chemotaxis, FROUNT, as a common regulator of these receptors, possibly plays a crucial role in the recruitment of immune cells expressing these receptors.

An arrestin-dependent multi-kinase signaling complex mediates MIP-1beta/CCL4 signaling and chemotaxis of primary human macrophages.

MIP-1beta/CCL4 is a principal regulator of macrophage migration and signals through CCR5. Several protein kinases are linked to CCR5 in macrophages including the src kinase Lyn, PI3K, focal adhesion related kinase Pyk2, and members of the MAPK family, but whether and how these kinases regulate macrophage chemotaxis are not known. To define the role of these signaling molecules, we examined the functions and interactions of endogenous proteins in primary human macrophages. Using siRNA gene silencing and pharmacologic inhibition, we show that chemotaxis in response to CCR5 stimulation by MIP-1beta requires activation of Pyk2, PI3K p85, and Lyn, as well as MAPK ERK. MIP-1beta activation of CCR5 triggered translocation of Pyk2 and PI3K p85 from the cytoplasm to colocalize with Lyn at the plasma membrane with formation of a multimolecular complex. We show further that arrestins were recruited into the complex, and arrestin down-regulation impaired complex formation and macrophage chemotaxis toward MIP-1beta. Together, these results identify a novel mechanism of chemokine receptor regulation of chemotaxis and suggest that arrestins may serve as scaffolding proteins linking CCR5 to multiple downstream signaling molecules in a biologically important primary human cell type.

Macrophage inflammatory protein-1beta induced cell adhesion with increased intracellular reactive oxygen species.

UNLABELLED: To investigate the role of macrophage inflammatory protein-1 beta (MIP-1beta) in the development of atherosclerosis, we designed an in vitro study to elucidate the mechanisms of monocyte-endothelium adhesion via intracellular reactive oxygen species (ROS). Angiotensin II (AngII) was used as a positive control. Furthermore, we examined the efficacy of MIP-1beta as a predictor of stroke and cardiovascular events in hypertensive patients. MIP-1beta or AngII stimulation significantly increased ROS production and adhesion of THP-1 cells to inflamed human umbilical vein endothelial cells. Cell adhesion and ROS production were inhibited in stimulated THP-1 cells by: inhibition of ROS signaling with N-acetylcysteine, diphenyleneiodonium, or PEG-Catalase; inhibition of PI3Kgamma with siRNA or LY294002; and by Rac1 siRNA. The MIP-1 beta or AngII stimulation did not increase surface expression of integrins, very late antigen 4 (VLA-4) and lymphocyte function-associated antigen 1 (LFA-1), but cell adhesion was reduced by using an antiVLA-4 or an antiLFA-1 antibody. Moreover, cell adhesion and ROS production stimulated with MIP-1beta or AngII were completely inhibited by fluvastatin. In our clinical study, patients with the highest quartile of MIP-1beta showed a higher risk of stroke and cardiovascular events by a Cox proportional-hazards model. In conclusion, MIP-1beta directly induced cell adhesion to endothelial cells through oxidative stress via PI3k-Rac1 cascades. Serum MIP-1beta level might be a useful predictor for cerebro-cardiovascular events in hypertensive patients. CONDENSED ABSTRACT: We designed an in vitro investigation to examine the role of MIP-1beta on the development of atherosclerosis, including cell adhesion involving CAMs and ROS production, compared with angiotensin II. Furthermore, we investigated the prognostic impact of MIP-1beta on stroke and cardiovascular events in hypertensive patients in a small cohort study.

Role of the cytokine environment and cytokine receptor expression on the generation of functionally distinct dendritic cells from human monocytes.

Myeloid dendritic cells (DC) and macrophages evolve from a common precursor. However, factors controlling monocyte differentiation toward DC or macrophages are poorly defined. We report that the surface density of the GM-CSF receptor (GM-CSFR) alpha subunit in human peripheral blood monocytes varies among donors. Although no correlation was found between the extent of GM-CSFR and monocyte differentiation into DC driven by GM-CSF and IL-4, GM-CSFR expression strongly influenced the generation of CD1a(+) dendritic-like cells in the absence of IL-4. CD1a(+) cells generated in the presence of GM-CSF express CD40, CD80, MHC class I and II, DC-SIGN, MR, CCR5, and partially retain CD14 expression. Interestingly, they spontaneously induce the expansion of CD4(+) and CD8(+) allogeneic T lymphocytes producing IFN-gamma, and migrate toward CCL4 and CCL19. Upon stimulation with TLR ligands, they acquire the phenotypic features of mature DC. In contrast, the allostimulatory capacity is not further increased upon LPS activation. However, by blocking LPS-induced IL-10, a higher T cell proliferative response and IL-12 production were observed. Interestingly, IL-23 secretion was not affected by endogenous IL-10. These results highlight the importance of GM-CSFR expression in monocytes for cytokine-induced DC generation and point to GM-CSF as a direct player in the generation of functionally distinct DC.