Effect of β-Alanine Supplementation on Monocyte Recruitment and Cognition During a 24-Hour Simulated Military Operation

Wells, AJ, Varanoske, AN, Coker, NA, Kozlowski, GJ, Frosti, CL, Boffey, D, Harat, I, Jahani, S, Gepner, Y, and Hoffman, JR. Effect of β-alanine supplementation on monocyte recruitment and cognition during a 24-hour simulated military operation. J Strength Cond Res 34(11): 3042-3054, 2020-Sustained military operations (SUSOPs) result in psychological stress and cognitive dysfunction, which may be related to the recruitment of classical monocytes into the brain. This study examined the effect of beta-alanine (BA) on cognition and monocyte recruitment during a simulated 24-hour SUSOP. Nineteen healthy men ingested 12-g/d BA or placebo for 14 days before an SUSOP. Monocyte chemoattractant protein-1 (MCP-1), C-C chemokine receptor-2 (CCR2), and macrophage-1-antigen (CD11b) expression were assessed through multiplex assay and flow cytometry. Psychological stress and cognition were assessed through Automated Neuropsychological Assessment Metrics (ANAM). A composite measure of cognition (COGcomp) was generated from throughput scores extracted from 7 ANAM cognitive tests. Assessments occurred at baseline (0H), 12 hours (12H), 18 hours (18H), and 24 hours (24H). Significance was accepted at p ≤ 0.05. No significant effect of BA was noted for any variable (p's > 0.05). The frequency and severity of symptoms of psychological stress increased significantly at 18 and 24H compared with 0 and 12H (p's < 0.05). COGcomp decreased significantly at 18 and 24H compared with 0 and 12H (p's ≤ 0.001). MCP-1 peaked at 18H was significantly lower at 24H compared with 18H but remained elevated at 24H compared with 0H (p's < 0.001). CCR2 expression was significantly lower at 12 (p = 0.031), 18, and 24H (p's < 0.001). CD11b expression was significantly higher at 12H (p = 0.039) and 24H (p's = 0.003). MCP-1 was negatively associated with COGcomp (β = -0.395, p = 0.002, r2 = 0.174). Neither CCR2 or CD11b was related to COGcomp (p's > 0.05). Cognitive dysfunction during SUSOPs is related to serum concentrations of MCP-1 but is not influenced by BA supplementation.

Transcriptional down-regulation of ccr5 in a subset of HIV+ controllers and their family members

HIV +Elite and Viremic controllers (EC/VCs) are able to control virus infection, perhaps because of host genetic determinants. We identified 16% (21 of 131) EC/VCs with CD4 +T cells with resistance specific to R5-tropic HIV, reversed after introduction of ccr5. R5 resistance was not observed in macrophages and depended upon the method of T cell activation. CD4 +T cells of these EC/VCs had lower ccr2 and ccr5 RNA levels, reduced CCR2 and CCR5 cell-surface expression, and decreased levels of secreted chemokines. T cells had no changes in chemokine receptor mRNA half-life but instead had lower levels of active transcription of ccr2 and ccr5, despite having more accessible chromatin by ATAC-seq. Other nearby genes were also down-regulated, over a region of ~500 kb on chromosome 3p21. This same R5 resistance phenotype was observed in family members of an index VC, also associated with ccr2/ccr5 down-regulation, suggesting that the phenotype is heritable.

AMPK-Activated Protein Kinase Suppresses Ccr2 Expression by Inhibiting the NF-κB Pathway in RAW264.7 Macrophages

C-C chemokine receptor 2 (Ccr2) is a key pro-inflammatory marker of classic (M1) macrophage activation. Although Ccr2 is known to be expressed both constitutively and inductively, the full regulatory mechanism of its expression remains unclear. AMP-activated protein kinase (AMPK) is not only a master regulator of energy homeostasis but also a central regulator of inflammation. In this study, we sought to assess AMPK’s role in regulating RAW264.7 macrophage Ccr2 protein levels in resting (M0) or LPS-induced M1 states. In both M0 and M1 RAW264.7 macrophages, knockdown of the AMPKα1 subunit by siRNA led to increased Ccr2 levels whereas pharmacologic (A769662) activation of AMPK, attenuated LPS-induced increases in Ccr2 expression in an AMPK dependent fashion. The increases in Ccr2 levels by AMPK downregulation were partially reversed by NF-κB inhibition whereas TNF-a inhibition had minimal effects. Our results indicate that AMPK is a negative regulator of Ccr2 expression in RAW264.7 macrophages, and that the mechanism of action of AMPK inhibition of Ccr2 is mediated, in part, through the NF-κB pathway.

Lycopene protects against LPS-induced proinflammatory cytokine cascade in HUVECs

The aim of the study was to explore whether lycopene protects against the activation of human umbilical vein endothelial cells (HUVECs) induced by a proinflammatory stimulus. HUVECs were pretreated with different concentrations of lycopene (1 microm or 10 microm), then incubated with 1 microg/ml LPS for 24 h. After an incubation, the mRNA and protein levels of proinflammatory cytokines (MCP-1, IL-6, VCAM-1), the expression KLF2, TLR4, ERK1/2 and NF-kappaB were assayed. The result showed that lycopene treatment significantly suppressed the response of HUVECs to LPS and reduced the levels of proinflammatory cytokines. Also, lycopene increased KLF2 expression, while it inhibited the activation TLR4 and its downstream ERK and the NF-kappaB signaling pathway in HUVECs.

Loss of Pdk1-Foxo1 signaling in myeloid cells predisposes to adipose tissue inflammation and insulin resistance

Chronic inflammation in adipose tissue contributes to obesity-related insulin resistance. The 3-phosphoinositide-dependent protein kinase 1 (Pdk1)/forkhead transcription factor (Foxo1) pathway is important in regulating glucose and energy homeostasis, but little is known about this pathway in adipose tissue macrophages (ATMs). To investigate this, we generated transgenic mice that carried macrophage/granulocyte-specific mutations, including a Pdk1 knockout (LysMPdk1(-/-)), a Pdk1 knockout with transactivation-defective Foxo1 (Δ256LysMPdk1(-/-)), a constitutively active nuclear (CN) Foxo1 (CNFoxo1(LysM)), or a transactivation-defective Foxo1 (Δ256Foxo1(LysM)). We analyzed glucose metabolism and gene expression in ATM populations isolated with fluorescence-activated cell sorting. The LysMPdk1(-/-) mice exhibited elevated M1 macrophages in adipose tissue and insulin resistance. Overexpression of transactivation-defective Foxo1 rescued these phenotypes. CNFoxo1(LysM) promoted transcription of the C-C motif chemokine receptor 2 (Ccr2) in ATMs and increased M1 macrophages in adipose tissue. On a high-fat diet, CNFoxo1(LysM) mice exhibited insulin resistance. Pdk1 deletion or Foxo1 activation in bone marrow-derived macrophages abolished insulin and interleukin-4 induction of genes involved in alternative macrophage activation. Thus, Pdk1 regulated macrophage infiltration by inhibiting Foxo1-induced Ccr2 expression. This shows that the macrophage Pdk1/Foxo1 pathway is important in regulating insulin sensitivity in vivo.

Epigallocatechin-3-gallate inhibits apoptosis and protects testicular seminiferous tubules from ischemia/reperfusion-induced inflammation

Testicular torsion (TT) is a urologic emergency that may result in future infertility problems. The pathologic process of TT is similar to an ischemia reperfusion injury (IRI). The purpose of this study was to evaluate the effect of epigallocatechin-3-gallate (EGCG) on reversing the damaging consequences of TT-induced IRI by examining its inhibitory effects on the expression of inflammatory and apoptosis mediators in a unilateral TT rat model. Eighteen male Sprague-Dawley rats were divided into 3 groups. Group 1 underwent a sham operation of the left testis under general anesthesia. Group 2 underwent ischemia for 1h followed by 4h reperfusion in the presence of saline. The third group was similar to group 2, however, EGCG (50 mg/kg) was injected i.p. 30 min after ischemia induction. The in vivo protective effect of EGCG was tested by measuring testicular levels of TNF-α, IL-6 and IL-1β by ELISA and mRNA expression of iNOS, MCP-1, p53, Bax, Bcl-2 and survivin by real-time PCR. Also, testicular morphological changes and damage to spermatogenesis were evaluated using H&E staining and Johnsen's scoring system, respectively. EGCG treatment improved testicular structures in the ipsilateral testis, markedly inhibited germ cell apoptosis (GCA) and significantly decreased testicular cytokine levels. In addition, EGCG was able to down regulate the mRNA expression of iNOS, MCP-1 and pro-apoptosis genes in favor of cell survival. For the first time we show that in vivo EGCG treatment rescued the torsed testes from IRI-induced inflammation, GCA and damage to spermatogenesis thus suggesting a new preventive approach to inhibiting the inflammatory and apoptotic consequences of TT-induced IRI.

Accumulation of CD11b+ lung dendritic cells in response to fungal infection results from the CCR2-mediated recruitment and differentiation of Ly-6Chigh monocytes

Pulmonary clearance of the encapsulated yeast Cryptococcus neoformans is associated with the CCR2-mediated accumulation of lung dendritic cells (DC) and the development of a T1 adaptive immune response. The objective of this study was to identify the circulating DC precursor(s) responsible for this large increase in lung DC numbers. An established murine model was used to evaluate putative DC precursors in the blood, bone marrow, and lungs of CCR2(+/+) mice and CCR2(-/-) mice throughout a time course following infection with C. neoformans. Results demonstrate that numbers of Ly-6C(high) monocytes increased in parallel in the peripheral blood and lungs of CCR(+/+) mice, whereas CD11c(+) MHC class II(+) pre-DC were 10-fold less prevalent in the peripheral blood and did not differ between the two strains. Accumulation of Ly-6C(high) monocytes correlated with a substantial increase in the numbers of CD11b(+) DC in the lungs of infected CCR2(+/+) mice. Comparative phenotypic analysis of lung cells recovered in vivo suggests that Ly-6C(high) monocytes differentiate into CD11b(+) DC in the lung; differentiation is associated with up-regulation of costimulatory molecules and decreased Ly-6C expression. Furthermore, in vitro experiments confirmed that Ly-6C(high) monocytes differentiate into CD11b(+) DC. Accumulation of Ly-6C(high) monocytes and CD11b(+) DC was not attributable to their proliferation in situ. We conclude that the CCR2-mediated accumulation of CD11b(+) DC in the lungs of Cryptococcus-infected mice is primarily attributable to the continuous recruitment and differentiation of Ly-6C(high) monocytes.

n-Nonanoyl-CCL14 (NNY-CCL14), a novel inhibitor of allergic airway inflammation is a partial agonist of human CCR2

BACKGROUND

Modulation of leukocyte recruitment through blocking of chemokine receptors has been proposed as an attractive therapeutic strategy. We have previously demonstrated that n-Nonanoyl-CC chemokine ligand 14 (NNY-CCL14), a modified analog of the naturally occurring chemokine CCL14(9-74) internalizes and desensitizes human CCR3 resulting in the inactivation of eosinophils. However, inhibitory effects of NNY-CCL14 in murine models of allergic airway inflammation are assigned to its interaction with CCR1 and CCR5.

AIM OF THE STUDY

As CCL2 and its receptor CCR2 have been shown to play important roles in the development of Th2 inflammation, we further evaluated the effects of NNY-CCL14 treatment on CCL2-mediated activation of CCR2.

METHODS

Effects of NNY-CCL14 treatment were studied on cell lines transfected with human CCR2 and primary leukocytes. Functional effects were assessed by calcium efflux assays, flow cytometry and chemotaxis.

RESULTS

Prestimulation with NNY-CCL14 desensitized CCR2-mediated responses to further stimulation with its selective ligand CCL2. No significant internalization of CCR2 was observed when the cells were stimulated with NNY-CCL14, even at concentrations eliciting maximal [Ca(2+)]i mobilization. Above all, NNY-CCL14 pretreatment blocked CCL2-induced chemotaxis of monocytes.

CONCLUSIONS

This study demonstrates that NNY-CCL14 is a partial agonist of CCR2, inhibiting responses of monocytes to the CCR2-selective ligand CCL2. NNY-CCL14 attenuates CCR2-mediated responses by rapidly desensitizing the receptor and preventing chemotaxis, although it is able to induce calcium mobilization but does not lead to CCR2 internalization. Hence this study provides further insights into the possible mechanisms of action of NNY-CCL14, which interacts with multiple chemokine receptors inhibiting the migration and activation of different cell populations involved, thus acting as a potential therapeutic compound to alleviate allergic inflammation.

[Chronic HCV-infection and expression of mRNA of CC-chemokines and their receptors]

The aim of this study was to evaluate some patterns in expression of CC-chemokines (MIP-1alpha, MIP-1beta, MCP-1, RANTES) and their receptors (CCR1, CCR2, CCR3, CCR5) in peripheral blood leukocytes and liver biopsy samples from 21 patients with chronic hepatitis C. 10 healthy subjects were included in the control group. In patients with chronic HCV-infection significant increase of MCP-1 mRNA in liver tissue was observed as the disease progressed. Moreover, content of MCP-1 mRNA was significantly higher in liver as compared with blood. Level of MCP-1 mRNA in liver was directly related with histological changes. Levels of mRNA of CCR1, CCR2, CCR3, and CCR5 in blood of patients with minimal histological manifestations of chronic HCV-infection were significantly lower than in patients with more marked lesions. Expression of CCR1 and CCR5 mRNA in blood was directly correlated with histological activity index and degree of fibrosis. Conducted study demonstrates that progression of chronic hepatitis C is realized through local activation of MCP-1 mRNA synthesis leading to systemic response which manifested by increase of expression of CCR1, CCR2, CCR3, and CCR5 in peripheral blood leukocytes.

CCR5 is involved in controlling the early stage of Cryptosporidium parvum infection in neonates but is dispensable for parasite elimination

Chemokines play a critical role in immune cell trafficking and the transition from an innate to an acquired immune response. We analyzed host response in neonatal mice deficient in chemokine receptor CCR5 following infection with the intracellular protozoan parasite Cryptosporidium parvum. CCR5 neonatal mice had a higher parasite burden at the early stage of infection but eliminated the parasite as efficiently as their wild-type counterparts. The higher sensitivity of neonates at the beginning of infection was not due to an altered IFNgamma response. An increased CCR2-attracting chemokine response associated with the recruitment of CCR2-positive cells in the infected mucosa may have compensated for the absence of CCR5. A lack of CCR5 thus has an impact in the early stage of C. parvum infection in neonates, but this receptor is dispensable for subsequent parasite elimination.

Preferential migration of regulatory T cells mediated by glioma-secreted chemokines can be blocked with chemotherapy

Despite the immunogenicity of glioblastoma multiforme (GBM), immune-mediated eradication of these tumors remains deficient. Regulatory T cells (Tregs) in the blood and within the tumor microenvironment of GBM patients are known to contribute to their dismal immune responses. Here, we determined which chemokine secreted by gliomas can preferentially induce Treg recruitment and migration. In the malignant human glioma cell lines D-54, U-87, U-251, and LN-229, the chemokines CCL22 and CCL2 were detected by intracellular cytokine analysis. Furthermore, tumor cells from eight patients with GBM had a similar chemokine expression profile. However, only CCL2 was detected by enzyme-linked immunosorbent assay, indicating that CCL2 may be the principal chemokine for Treg migration in GBM patients. Interestingly, the Tregs from GBM patients had significantly higher expression levels of the CCL2 receptor CCR4 than did Tregs from healthy controls. Glioma supernatants and the recombinant human chemokines CCL2 and CCL22 induced Treg migration and were blocked by antibodies to the chemokine receptors. Production of CCL2 by glioma cells could also be mitigated by the chemotherapeutic agents temozolomide and carmustine [3-bis (2-chloroethyl)-1-nitrosourea]. Our results indicate that gliomas augment immunosuppression by selective chemokine-mediated recruitment of Tregs into the tumor microenvironment and that modulating this interaction with chemotherapy could facilitate the development of novel immunotherapeutics to malignant gliomas.

Changes in CCR2 chemokine receptor expression and plasma MCP-1 concentration after the implantation of bare metal stents versus sirolimus-eluting stents in patients with stable angina

BACKGROUND

Although restenosis after successful coronary stenting is associated with changes in adhesion molecules and chemokines, it is unclear whether the differential effects of these molecules between a bare metal stent (BMS) and sirolimus-eluting stent (SES) may help to prevent coronary restenosis. The aim of this clinical study was to compare the expression levels of those molecules after elective placement of either a BMS or SES.

METHODS AND RESULTS

The subjects included 32 consecutive patients with stable angina who had undergone successful coronary stenting and who randomly received either a BMS (n=16) or SES (n=16). Quantitative angiographic analysis 6 months after stenting showed that the minimal lumen diameter was significantly greater in the SES as compared to the BMS group, while the percent diameter stenosis and in-stent lumen loss were significantly lower. Plasma monocyte chemotactic protein-1 (MCP-1) increased significantly after 14 days and 6 months and monocyte CCR2 expression increased 24 hr and 48 hr after stenting in the BMS but not the SES group. Changes in plasma MCP-1 (DeltaMCP-1) within 6 months after stenting correlated significantly with in-stent lumen loss. The DeltaMCP-1 (between 6 months and baseline) was significantly related only to the lumen loss (r=0.443, p=0.023), which suggests that the reduction of MCP-1 is the best contributor to decreased lumen loss.

CONCLUSIONS

These data suggest that reduction in MCP-1 production by SES may be one mechanism to prevent restenosis after coronary stenting.

Targeting of Gr-1+,CCR2+ monocytes in collagen-induced arthritis

OBJECTIVE

The chemokine receptor CCR2 is highly expressed on monocytes and considered a promising target for treatment of rheumatoid arthritis. However, blockade of CCR2 with a monoclonal antibody (mAb) during progression of collagen-induced arthritis results in a massive aggravation of the disease. In this study we investigated why CCR2 antibodies have proinflammatory effects, how these effects can be avoided, and whether CCR2+ monocytes are useful targets in the treatment of arthritis.

METHODS

Arthritis was induced in DBA/1 mice by immunization with type II collagen. Mice were treated with mAb against CCR2 (MC-21), IgE, or isotype control antibodies at various time points. Activation of basophils and depletion of monocyte subsets were determined by fluorescence-activated cell sorter analysis and enzyme-linked immunosorbent assay.

RESULTS

Crosslinkage of CCR2 activated basophils to release interleukin-6 (IL-6) and IL-4. In vivo, IL-6 release occurred only after exposure to high doses of MC-21, whereas application of low doses of the mAb circumvented the release of IL-6. Regardless of the dose level used, the antibody MC-21 efficiently depleted Gr-1+,CCR2+ monocytes from the synovial tissue, peripheral blood, and spleen of DBA/1 mice. Activation of basophils with high doses of MC-21 or with antibodies against IgE resulted in a marked aggravation of collagen-induced arthritis and an increased release of IL-6. In contrast, low-dose treatment with MC-21 in this therapeutic setting had no effect on IL-6 and led to marked improvement of arthritis.

CONCLUSION

These results show that depletion of CCR2+ monocytes may prove to be a therapeutic option in inflammatory arthritis, as long as the dose-dependent proinflammatory effects of CCR2 mAb are taken into account.

Regulation of C-C motif chemokine ligand 2 and its receptor in human decidual stromal cells by pregnancy-associated hormones in early gestation

BACKGROUND

Decidua is in close contact with the fetal trophoblasts, and involved in immune relationship of mother to fetus. However, the roles of decidua and decidual stromal cells (DSC) in materno-fetal immune regulation remain to be elucidated. In the present study, the expression and regulation of chemokines and their receptors in decidua and DSCs were investigated.

METHODS AND RESULTS

The transcription of 18 chemokine receptors in human first-trimester decidual tissue and DSC were first analysed by RT-PCR. Among these receptors, C-C motif chemokine receptor-2 (CCR2) was highly transcribed. It was demonstrated by RT-PCR and immunostaining that both CCR2 and its major ligand, C-C motif chemokine ligand 2 (CCL2, monocyte chemoattractant protein-1), were expressed in decidua and DSC. We then detected CCL2 in the supernatant of primary cultures of DSC by enzyme-linked immunosorbent assay. It was shown that DSC secreted CCL2 spontaneously and continuously over 72 h (21.72 +/- 2.34 ng/ml), and the CCR2 antagonist RS102895 and an inhibitor of the map kinase kinase/mitogen-activated protein kinase (ERK/MAPK) signal pathway decreased significantly the CCL2 secretion of DSC (both P < 0.05). We further studied effects of the pregnancy-associated hormones, estrogen, progesterone or HCG on CCL2 secretion by DSC. CCL2 secretion by DSC was up-regulated by estrogen, progesterone or HCG.

CONCLUSIONS

CCR2 and CCL2 are co-expressed by human first-trimester DSC and decidual tissue. CCL2 is secreted in an autocrine manner through the ERK/MAPK pathway, and is up-regulated by the pregnancy-associated hormones, estrogen, progesterone and HCG, which suggests that CCL2 may play an important role at materno-fetal interface.

Resveratrol inhibits expression and binding activity of the monocyte chemotactic protein-1 receptor, CCR2, on THP-1 monocytes

Monocyte chemotactic protein-1 and its receptor, CCR2, play a key role in atherosclerosis. We determined the effect of the polyphenol, resveratrol, on CCR2 and the mechanisms involved. Resveratrol treatment inhibited 125I-MCP-1 binding to THP-1 cells; 31, 56, 84% decrease for 10, 50 and 100 microM resveratrol, in the absence of any effect on receptor affinity. The inhibitory effect of resveratrol on 125I-MCP-1 binding to THP-1 cells and on CCR2 protein expression determined by FACS analysis was attenuated by treatment with L-NAME (NOS inhibitor), PD98059 (MAPK inhibitor) and LY294002 (PI3K inhibitor), whereas neither X/XO (reactive oxygen species generator) nor ICI182780 (estrogen receptor antagonist) had any effect. Concomitant with a decrease in CCR2 protein expression, resveratrol inhibited THP-1 CCR2 mRNA levels, in the absence of any effect on its stability; 26 and 45% inhibition at 10 and 50 microM resveratrol, respectively. This effect was not altered by co-treatment with L-NAME, PD98059 or ICI182780, but was potentiated by LY294002 and X/XO.

CONCLUSIONS

Resveratrol inhibits monocyte CCR2 binding activity in an NO-, MAPK- and PI3K-dependent manner, whereas it inhibits CCR2 mRNA in an NO- and MAPK-independent, PI3K-dependent manner. These inhibitory effects of resveratrol on chemokine receptor binding and expression may contribute, in part, to its cardiovascular protective activity in vivo.