Development of Exhausted Memory Monocytes and Underlying Mechanisms.

Pathogenic inflammation and immuno-suppression are cardinal features of exhausted monocytes increasingly recognized in septic patients and murine models of sepsis. However, underlying mechanisms responsible for the generation of exhausted monocytes have not been addressed. In this report, we examined the generation of exhausted primary murine monocytes through prolonged and repetitive challenges with high dose bacterial endotoxin lipopolysaccharide (LPS). We demonstrated that repetitive LPS challenges skew monocytes into the classically exhausted Ly6Chi population, and deplete the homeostatic non-classical Ly6Clo population, reminiscent of monocyte exhaustion in septic patients. scRNAseq analyses confirmed the expansion of Ly6Chi monocyte cluster, with elevation of pathogenic inflammatory genes previously observed in human septic patients. Furthermore, we identified CD38 as an inflammatory mediator of exhausted monocytes, associated with a drastic depletion of cellular NAD+; elevation of ROS; and compromise of mitochondria respiration, representative of septic monocytes. Mechanistically, we revealed that STAT1 is robustly elevated and sustained in LPS-exhausted monocytes, dependent upon the TRAM adaptor of the TLR4 pathway. TRAM deficient monocytes are largely resistant to LPS-mediated exhaustion, and retain the non-classical homeostatic features. Together, our current study addresses an important yet less-examined area of monocyte exhaustion, by providing phenotypic and mechanistic insights regarding the generation of exhausted monocytes.

Antiinflammatory properties of antiLy6G antibody disappear during magnetic field exposure in rats with carrageenan induced acute paw inflammation.

Antiinflammatory properties of pulsed magnetic field (PMF) treatments or administration of antiLy6G antibody have been previously reported. In this study, we hypothesized that, the combination of PMF treatments and antiLy6G administration may synergistically potentiate their antiinflammatory actions. The effects of the combination of PMF treatments and antiLy6G administration were investigated by examining the inflammatory signs, histopathological properties of the inflamed site, and measuring the macrophage inflammatory protein-1 alpha (MIP-1α/CCL3) and myeloperoxidase (MPO) levels of inflamed paw tissues in rats with carrageenan-induced acute paw inflammation. In this present study, PMF treatments alone or administration of antiLy6G alone ameliorated the acute inflammation. However, their combination exacerbated the inflammatory signs, hyperalgesia, allodynia, edema and fever, and aggravated the inflammatory conditions by excessive infiltration of inflammatory cells to the inflamed site. These opposing effects of the combined treatments may correlate with enhanced levels of MIP-1α and MPO in inflamed paws. Present results indicated that the combination of the PMF treatments and antiLy6G administration may not provide additional benefits and may actually cause an aggravation of the acute inflammatory process. Findings may also suggest that during neutrophil or immune cell-targeted treatments for inflammatory states, magnetic field exposure may cause unexpected negative consequences.

Electroacupuncture preconditioning attenuates acute myocardial ischemia injury through inhibiting NLRP3 inflammasome activation in mice.

AIMS: Electro-acupuncture pretreatment (EAP) plays a protective role in myocardial ischemia (MI) injury. However, the underlying mechanism remains unclear. A growing body of evidence suggests postinfarction inflammatory response directly affects the remodeling of ventricular function. The purpose of this study was to investigate whether EAP alleviates MI through NLRP3 inflammasome inhibition. MATERIALS AND METHODS: We constructed an AMI model by ligating the left anterior descending (LAD) coronary artery after 3 days of EAP with C57BL/6 mice. Echocardiography and TTC staining were employed to evaluate cardiac function and infarct size after 24 h of ischemia. HE staining and immunohistochemistry were employed to determine inflammatory level. Then, inflammasome activation was detected by western blotting, and macrophage polarization and neutrophil infiltration were observed by flow cytometry. KEY FINDINGS: Our preliminary findings showed that EAP reduced the infarct area and increased fractional shortening (FS) and ejection fraction (EF) and decreased the degree of inflammation after AMI injury. Meanwhile, EAP inhibited the expression of NLRP3, cleaved caspase-1 and IL-1ß in ischemia myocardial tissue, companied by inhibiting the expression of F4/80+, CD11b+, CD206low macrophages and activated M2 macrophage, and decreasing Ly-6G+CD11b+ neutrophils in ischemia myocardial and spleen tissue. SIGNIFICANCE: EAP inhibits the activation of NLRP3 inflammasome, promotes M2 polarization of macrophages and reduces the recruitment of neutrophils in damaged myocardium, thereby decreases the infarct size and improves the cardiac function.

AIM2 Co-immunization with VP1 Is Associated with Increased Memory CD8 T Cells and Mounts Long Lasting Protection against Coxsackievirus B3 Challenge.

The recurrent Coxsackievirus B3 (CVB3) infection is the most important cause of intractable myocarditis which often leads to chronic myocarditis and even dilated cardiomyopathy. Therefore, enhanced DNA vaccines capable of memory CD8 T cells are essential for long-lasting immunological protection against CVB3 infection. In this study, absent in melanoma 2 (AIM2) was used as an adjuvant to enhance the induction of memory CD8 T cells elicited by VP1 (viral capsid protein 1) vaccine. Mice were intramuscularly injected with 50 µg AIM2 plasmid and equal amount of VP1 plasmid (pAIM2/pVP1) vaccine 4 times at 2 week-intervals. We observed that the protection of pAIM2/pVP1 vaccine against CVB3 challenge was evidenced by significantly improved cardiac function, reduced myocardial injuries, and increased survival rate when compared with immunization with pVP1. Co-immunization with pAIM2/pVP1 robustly augmented T lymphocytes proliferation and CVB3-specific cytotoxic T lymphocyte responses. Importantly, 16 weeks after the last immunization, pAIM2/pVP1 co-immunization significantly enhanced the expression of Bcl-6, SOCS3, and Sca-1 which are critical for memory CD8 T cells as compared with pVP1 immunization. Notably, CD8 T cells that are likely vaccine-induced memory T cells were responsible for the protective efficacy of pAIM2/pVP1 vaccine by abolition of a CD8 T cell immune response following a lethal dose of CVB3 infection. Our results indicate that AIM2-adjuvanted vaccine could be a potential and promising approach to promote a long-lasting protection against CVB3-induced myocarditis.

Inactivation of the KSRP gene modifies collagen antibody induced arthritis.

The KH type splicing regulatory protein (KSRP) is a nucleic acid binding protein, which negatively regulates the stability and/or translatability of many mRNA species encoding immune-relevant proteins. As KSRP is expressed in immune cells including T and B cells, neutrophils, macrophages and dendritic cells, we wanted to analyze its importance for the development of autoimmune diseases. We chose collagen antibody-induced arthritis (CAIA) as an appropriate autoimmune disease mouse model in which neutrophils and macrophages constitute the main effector cell populations. We compared arthritis induction in wild type (WT) and KSRP-/- mice and paws were taken for histological sections and qPCR analysis. Furthermore, we determined the frequencies of spleen immune cells by flow cytometry. Cytokine levels in spleen cell supernatants were determined by cytometric bead array analyses (CBA). After CAIA induction we unexpectedly observed in WT animals much stronger swelling of the paws than in KSRP-/- mice. In accordance, histological staining of paw sections of KSRP-/- animals revealed much lower frequencies of infiltrating immune cells in the joints compared to WT animals. Furthermore, CAIA-treatment resulted in reduced expression of several inflammatory factors (like CXCL-1, iNOS, TNF-α and S100A8) as well as immune cell marker genes (e.g. LFA-1, CD68, Ly6G) in the joints of KSRP-/- mice. Spleen cells of KSRP-/- mice showed lower frequencies of myeloid cells. On cytokine level IFN-γ production was increased in spleen cells of KSRP-/- mice compared to WT samples. These data surprisingly suggest that the absence of KSRP protects against the induction of inflammatory arthritis.

Curcumin protects against liver fibrosis by attenuating infiltration of Gr1hi monocytes through inhibition of monocyte chemoattractant protein-1.

BACKGROUND AND AIMS: Liver fibrosis is concomitant with monocyte infiltration, which has been highlighted as novel therapeutic targets for chronic liver diseases. We aimed to investigate whether curcumin might protect the liver from carbon tetrachloride (CCl4)-induced fibrosis by attenuating the recruitment of Gr1hi monocytes through inhibition of monocyte chemoattractant protein-1 (MCP-1). METHODS: Mice were intraperitoneally injected with CCl4 to induce liver fibrosis. Curcumin was orally administrated to mice. Hepatic inflammation and fibrosis were evaluated by analysis of liver function and hepatic histopathology. Infiltration of the Gr1hi monocytes was assessed by flow cytometry and immunohistochemistry. Moreover, mRNA expression levels of tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-1ß, and transforming growth factor (TGF)-ß1 were determined by real time PCR. Hepatic expression of MCP-1 was determined by real time PCR and immunohistochemistry. RESULTS: Curcumin significantly attenuated inflammation and fibrosis, as revealed by histological and biochemical analysis. The intrahepatic infiltration of Gr1hi monocytes was attenuated by curcumin administration. T cells, NK cells, NKT cells, and dendritic cells were not affected by curcumin. Curcumin significantly reduced the expression of TNF-α and TGF-ß1, which is in line with the decreased numbers of intrahepatic Gr1hi monocytes. Intrahepatic MCP-1 expression of CCl4-challenged mice was inhibited by curcumin. CONCLUSIONS: The anti-inflammatory and antifibrotic effects of curcumin could be contributed to its prevention of Gr1hi monocyte infiltration into the injured livers through inhibition of MCP-1. These new findings extend our understanding on the mechanisms of the anti-inflammatory and antifibrotic effects of curcumin.

Therapeutic targeting of myeloid-derived suppressor cells involves a novel mechanism mediated by clusterin.

Myeloid-derived suppressor cells (MDSCs) constitute a key checkpoint that impedes tumor immunity against cancer. Chemotherapeutic intervention of MDSCs has gained ground as a strategy for cancer therapy but its mechanism remains obscure.We report here a unique mechanism by which monocytic (M)-MDSCs are spared, allowing them to polarize towards M1 macrophages for reactivation of immunity against breast cancer. We first demonstrated that curcumin, like docetaxel (DTX), can selectively target CD11b(+)Ly6G(+)Ly6C(low) granulocytic (G)-MDSCs, sparing CD11b(+)Ly6G(-)Ly6C(high) M-MDSCs, with reduced tumor burden in 4T1-Neu tumor-bearing mice. Curcumin treatment polarized surviving M-MDSCs toward CCR7(+) Dectin-1(-)M1 cells, accompanied by IFN-γ production and cytolytic function in T cells. Selective M-MDSC chemoresistence to curcumin and DTX was mediated by secretory/cytoplasmic clusterin (sCLU). sCLU functions by trapping Bax from mitochondrial translocation, preventing the apoptotic cascade. Importantly, sCLU was only found in M-MDSCs but not in G-MDSCs. Knockdown of sCLU in M-MDSCs and RAW264.7 macrophages was found to reverse their natural chemoresistance. Clinically, breast cancer patients possess sCLU expression only in mature CD68(+) macrophages but not in immature CD33(+) immunosuppressive myeloid cells infiltrating the tumors. We thus made the seminal discovery that sCLU expression in M-MDSCs accounts for positive immunomodulation by chemotherapeutic agents.

The anti-tumor effect of the quinoline-3-carboxamide tasquinimod: blockade of recruitment of CD11b(+) Ly6C(hi) cells to tumor tissue reduces tumor growth.

BACKGROUND: Previous work has demonstrated immunomodulatory, anti-tumor, anti-metastatic and anti-angiogenic effects of the small molecule quinoline-3-carboxamide tasquinimod in pre-clinical cancer models. To better understand the anti-tumor effects of tasquinimod in transplantable tumor models, we have evaluated the impact of the compound both on recruitment of myeloid cells to tumor tissue and on tumor-induced myeloid cell expansion as these cells are known to promote tumor development. METHODS: Mice bearing subcutaneous 4 T1 mammary carcinoma tumors were treated with tasquinimod in the drinking water. A BrdU-based flow cytometry assay was utilized to assess the impact of short-term tasquinimod treatment on myeloid cell recruitment to tumors. Additionally, long-term treatment was performed to study the anti-tumor effect of tasquinimod as well as its effects on splenic myeloid cells and their progenitors. Myeloid cell populations were also immune-depleted by in vivo antibody treatment. RESULTS: Short-term tasquinimod treatment did not influence the proliferation of splenic Ly6C(hi) and Ly6G(hi) cells, but instead reduced the influx of Ly6C(hi) cells to the tumor. Treatment with tasquinimod for various periods of time after tumor inoculation revealed that the anti-tumor effect of this compound mainly operated during the first few days of tumor growth. Similar to tasquinimod treatment, antibody-mediated depletion of Ly6C(hi) cells within that same time frame, caused reduced tumor growth, thereby confirming a significant role for these cells in tumor development. Additionally, long-term tasquinimod treatment reduced the splenomegaly and expansion of splenic myeloid cells during a later phase of tumor development. In this phase, tasquinimod normalized the tumor-induced alterations in myeloerythroid progenitor cells in the spleen but had only limited impact on the same populations in the bone marrow. CONCLUSIONS: Our results indicate that tasquinimod treatment reduces tumor growth by operating early after tumor inoculation and that this effect is at least partially caused by reduced recruitment of Ly6C(hi) cells to tumor tissue. Long-term treatment also reduces the number of splenic myeloid cells and myeloerythroid progenitors, but these effects did not influence established rapidly growing tumors.

Protective effects of ginsenoside Rg1 on aging Sca-1⁺ hematopoietic cells.

In adults, bone hematopoietic cells are responsible for the lifelong production of all blood cells. It is affected in aging, with progressive loss of physiological integrity leading to impaired function by cellular intrinsic and extrinsic factors. However, intervention measures, which directly inhibit the aging of hematopoietic cells, remain to be investigated. In the present study, 10 µmol/l ginsenoside Rg1 (Rg1) markedly alleviated the aging phenotypes of Sca­1+ hematopoietic cells following in vitro exposure. In addition, the protective effects of ginsenoside Rg1 on the aging of Sca­1+ hematopoietic cells was confirmed using a serial transplantation assay in C57BL/6 mice. The mechanistic investigations revealed that Rg1­mediated Sca­1+ hematopoietic cell aging alleviation was linked to a series of characteristic events, including telomere end attrition compensation, telomerase activity reconstitution and the activation of genes involved in p16­Rb signaling pathways. Based on the above results, it was concluded that ginsenoside Rg1 is a potent agent, which acts on hematopoietic cells to protect them from aging, which has implications for therapeutic approaches in hemopoietic diseases.

[Effect of SIRT6/NF-κB signal axis in delaying hematopoietic stem/progenitor cell senescence with ginsenoside Rg1].

OBJECTIVE: To investigate the effect of SIRT6/NF-κB signal axis in delaying hematopoietic stem/progenitor cell senescence with ginsenoside Rg1, in order to provide theatrical and experimental basis for looking for methods for delaying HSC senescence. METHOD: Sca-1 + HSC/HPC was isolated by magnetic cell sorting (MACS) and divided into five groups: the normal control group, the aging group, the positive control group, the Rg1 anti-senescence group, and the Rg1-treated group. Senescence-associated ß-galactosidase (SA-ß-Gal) staining, cell cycle analysis and hemopoietic progenitor cell mix (CFU-Mix) were adopted to determine the effect Rg1 in delaying or treating Sca-1 + HSC/HPC senescence biology. The mRNA and protein of senescence regulation molecules SIRT6 and NF-KB were examined by realtime fluorescence quantitative PCR (FQ-PCR) and western blotting. RESULT: Compared with the senescence group, the Rg1 anti-senescence group and the Rg1-treated group showed lower percentage in SA-ß-Gal-stained positive cells, decreased cell proportion in G1 phase, increased number of CFU-Mix, up-regulated in SIRT6 mRNA and protein expression, down-regulation in NF-KB mRNA and protein expression. The Rg1 anti-senescence group showed more evident changes in indexes than the Rg1-treated group. CONCLUSION: Rg, may inhibit Sca-1 + HSC/HPC senescence induced by t-BHP by regulating SIRT6/NF-KB signal path.

Cardiac stem cells with electrical stimulation improve ischaemic heart function through regulation of connective tissue growth factor and miR-378.

AIMS: In this study, we investigated whether pre-conditioning (PC) by electrical stimulation (EleS) induces cytoprotective effect on cardiac stem cells (CSCs) and determined its underlying molecular mechanisms. METHODS AND RESULTS: Sca-1(+) CSCs were isolated from male C57BL6 mice (12 weeks) hearts. PC of CSCs with EleS ((EleS)CSCs) was carried out for 3 h at 1.5 V followed by exposure to 300 µM H2O2 for 5 h. Cytoprotective effects and cell adhesion ability were significantly increased by EleS as evaluated by transferase-mediated dUTP nick-end labelling (TUNEL), lactate dehydrogenase (LDH) release assay, and adhesion assay. EleS increased phosphorylation of AKT, focal adhesion kinase (FAK), and glycogen synthase kinase (GSK3ß), as well as decreased caspase-3 cleavage. Interestingly, inhibition of AKT or FAK abolished the pro-survival effects of EleS. We found that connective tissue growth factor (Ctgf) was responsible for EleS-induced CSC survival and adhesion.The survival rate of (EleS)CSCs after transplantation in the infarcted myocardium was significantly increased together with improvement in cardiac function. Importantly, knockdown of Ctgf abolished EleS-induced cytoprotective effects and recovery of cardiac function. Furthermore, we identified miR-378 as a potential Ctgf regulator in (EleS)CSCs. CONCLUSION: EleS enhanced CSC survival in vitro and in vivo as well as functional recovery of the ischaemic heart through an AKT/FAK/CTGF signalling pathway. It is suggested that Ctgf and miR-378 are novel therapeutic targets for stem cell-based therapy.

[Study on anti-aging effect of ginsenoside Rg1 in serial transplantation of hematopoietic stem cells and progenitor cells].

OBJECTIVE: To investigate the anti-aging effect of ginsenoside R1 in serial transplantation of hematopoietic stem cells and progenitor cells. METHOD: HSC/HPC aging model in vivo was established through the Sca-1 (+) HSC/HPC serial transplantation of male donor mice that had been separated and purified by the magnetic-activated cell sorting method. The female recipient mice that had been radiated with lethal dose of 60Co gamma ray were divided into four groups: the control group, the aging group, the Rg1-treated aging group and the Rg1 anti-aging group. The expression of Sry genes in bone marrow cells of recipient mice was analyzed by fluorescence quantitative PCR, in order to determine the source of hematopoietic reconstruction cells, observe the survival time and the recovery of the hematology of peripheral blood, and study the reconstruction of the hematopoietic function of recipient mice, the hematopoietic recovery promoted by Rg1, the culture of CFU-Mix of hemopoietic progenitor cells, the cell cycle analysis and aging-related SA-beta-Gal staining analysis on biological characteristics of Sca-1 (+) HSC/HPC aging, and the effect of Rg1 in vivo regulation on Sca-1 + HSC/HPC aging. RESULT: The hematopoietic reconstruction cells of female recipient mice were derived from male donor mice. With the serial transplantation, the 30-day survival rate and the hematology in peripheral blood of recipient mice decreased. Sca-1 (+) HSC/HPC showed aging characteristics: the ratio of cells in G0/G1 phase and the positive rate of SA-beta-gal staining increased, whereas the number of CFU-Mix decreased. Compared with the aging group of the same generation, Rg1 -treated aging group and Rg1 anti-aging group showed higher 30-day survival rate and WBC, HCT, PLT and CFU-Mix, and lower cell ratio in Sca-1 (+) HSC/HPC G0/G1 stage and positive rate of SA-beta-gal staining. The Rg1 anti-aging group showed more significant changes than the Rg1 -treated aging group. CONCLUSION: Ginsenoside Rg1 has the effect of delaying and treating Sca-1 (+) HSC/HPC aging during the serial transplantation. Rg1 's anti-aging effect is superior to its effect of treating aging.

Boosting the pentose phosphate pathway restores cardiac progenitor cell availability in diabetes.

AIMS: Diabetes impinges upon mechanisms of cardiovascular repair. However, the biochemical adaptation of cardiac stem cells to sustained hyperglycaemia remains largely unknown. Here, we investigate the molecular targets of high glucose-induced damage in cardiac progenitor cells (CPCs) from murine and human hearts and attempt safeguarding CPC viability and function through reactivation of the pentose phosphate pathway. METHODS AND RESULTS: Type-1 diabetes was induced by streptozotocin. CPC abundance was determined by flow cytometry. Proliferating CPCs were identified in situ by immunostaining for the proliferation marker Ki67. Diabetic hearts showed marked reduction in CPC abundance and proliferation when compared with controls. Moreover, Sca-1(pos) CPCs isolated from hearts of diabetic mice displayed reduced activity of key enzymes of the pentose phosphate pathway, glucose-6-phosphate dehydrogenase (G6PD), and transketolase, increased levels of superoxide and advanced glucose end-products (AGE), and inhibition of the Akt/Pim-1/Bcl-2 signalling pathway. Similarly, culture of murine CPCs or human CD105(pos) progenitor cells in high glucose inhibits the pentose phosphate and pro-survival signalling pathways, leading to the activation of apoptosis. In vivo and in vitro supplementation with benfotiamine reactivates the pentose phosphate pathway and rescues CPC availability and function. This benefit is abrogated by either G6PD silencing by small interfering RNA (siRNA) or Akt inhibition by dominant-negative Akt. CONCLUSION: We provide new evidence of the negative impact of diabetes and high glucose on mechanisms controlling CPC redox state and survival. Boosting the pentose phosphate pathway might represent a novel mechanistic target for protection of CPC integrity.

Effect of the Miaoyao Fanggan sachet-derived isorhamnetin on TLR2/4 and NKp46 expression in mice.

ETHNOPHARMACOLOGICAL RELEVANCE: Miaoyao Fanggan Sachets (MFS) has long been used as a folk medicine for the prevention of influenza in Southeast of Guizhou Province, China. However, the precise immunological mechanisms by which MFS confers protection have not been defined. STUDY AIM: To explore the effects of MFS on innate immune system responses using a cold stress-induced immune impairment model as a means of examining MFS-mediated influenza prevention. We investigated the effects of MFS on toll-like receptor 2 and 4 (TLR2/4) gene and protein expression levels and on the percentage of NKp46(+) cells present in serum. No overt toxicity was observed following continuous administration of MFS at high doses. METHODS: Kunming male mice (n=40) were randomly divided into 4 groups consisting of the continuous inhalation Sachet group, Yu-Ping-Feng powder (YPF-P) gavage positive control group, discontinuous inhalation MFS group and untreated controls. After 4 weeks, mice were sacrificed and lungs harvested. The expression of toll-like receptors 2 and 4 (TLR2/4) gene and protein levels was assessed using real-time polymerase chain reaction (RT-PCR) and Western blot analyses, respectively. An additional 60 Kunming mice were randomly divided into 6 groups comprised of a blank control group, continuous MFS inhalation group, an immune-compromised continuous MFS inhalation group, an immuno-compromised group, an immune-compromised MFS discontinuous inhalation group and an immune-compromised positive control group. Immune suppression was induced by cold stress (4 °C/4 h daily for 3 days) and mice were treated with MFS or YPF-P before cold stress treatments. Immuno-compromised mice were treated with MFS continuously or intermittently, or treated with YPF-P. Blood samples were collected and examined for natural killer cells based on positive NKp46 staining. The isorhamnetin associated with MFS-induced immune modulation was obtained from 'wo ga le' which is considered to be a major component of MFS, and analyzed by HPLC. RESULTS: Mice continuously inhaling MFS showed a moderate increase in TLR2/4 mRNA and protein levels compared to mice in the control and discontinuous inhalation groups. MFS significantly increased the TLR2/4 expression in a dose-dependent manner. Furthermore, there was also a slightly significant increase in the number of NKp46(+) cells in the continuous inhalation group compared to controls and discontinuous inhalation group. Pretreatment with MFS partially prevented cold stress-induced inhibition of NKp46(+) cells. HPLC analysis of the 'wo ga le' associated with immune function identified the major component to be isorhamnetin. CONCLUSIONS: Taken together, these data suggested that MFS significantly enhanced TLR2/4 expression levels and the number of NKp46(+) cells in mice and moderately affected innate immune responses associated with protection against influenza, suggesting that isorhamnetin in the MFS enhanced innate immune potency. The use of MFS for the prevention of various respiratory tract infections can be attributed to its antimicrobial properties. In a pilot study, a large quantity (40 g) was administered over a prolonged period did not produce apparent toxicity.

Omega-3 fatty acids ameliorate atherosclerosis by favorably altering monocyte subsets and limiting monocyte recruitment to aortic lesions.

OBJECTIVE: Fish oil, containing omega-3 fatty acids, attenuates atherosclerosis. We hypothesized that omega-3 fatty acid-enriched oils are atheroprotective through alteration of monocyte subsets and their trafficking into atherosclerotic lesions. METHODS AND RESULTS: Low-density lipoprotein receptor knockout and apolipoprotein E(-/-) mice were fed diets containing 10% (calories) palm oil and 0.2% cholesterol, supplemented with an additional 10% palm oil, echium oil (containing 18:4 n-3), or fish oil. Compared with palm oil-fed low-density lipoprotein receptor knockout mice, echium oil and fish oil significantly reduced plasma cholesterol, splenic Ly6C(hi) monocytosis by ≈50%, atherosclerosis by 40% to 70%, monocyte trafficking into the aortic root by ≈50%, and atherosclerotic lesion macrophage content by 30% to 44%. In contrast, atherosclerosis and monocyte trafficking into the artery wall was not altered by omega-3 fatty acids in apolipoprotein E(-/-) mice; however, Ly6C(hi) splenic monocytes positively correlated with aortic root intimal area across all diet groups. In apolipoprotein E(-/-) mice, fish oil reduced the percentage of blood Ly6C(hi) monocytes, despite an average 2-fold higher plasma cholesterol relative to palm oil. CONCLUSIONS: The presence of splenic Ly6C(hi) monocytes parallels the appearance of atherosclerotic disease in both low-density lipoprotein receptor knockout and apolipoprotein E(-/-) mice. Furthermore, omega-3 fatty acids favorably alter monocyte subsets independently from effects on plasma cholesterol and reduce monocyte recruitment into atherosclerotic lesions.

A hypomorphic mutation in the Gfi1 transcriptional repressor results in a novel form of neutropenia.

Using N-ethyl-N-nitrosourea-induced mutagenesis, we established a mouse model with a novel form of neutropenia resulting from a point mutation in the transcriptional repressor Growth Factor Independence 1 (Gfi1). These mice, called Genista, had normal viability and no weight loss, in contrast to mice expressing null alleles of the Gfi1 gene. Furthermore, the Genista mutation had a very limited impact on lymphopoiesis or on T- and B-cell function. Within the bone marrow (BM), the Genista mutation resulted in a slight increase of monopoiesis and in a block of terminal granulopoiesis. This block occurred just after the metamyelocytic stage and resulted in the generation of small numbers of atypical CD11b(+) Ly-6G(int) neutrophils, the nuclear morphology of which resembled that of mature WT neutrophils. Unexpectedly, once released from the BM, these atypical neutrophils contributed to induce mild forms of autoantibody-induced arthritis and of immune complex-mediated lung alveolitis. They additionally failed to provide resistance to acute bacterial infection. Our study demonstrates that a hypomorphic mutation in the Gfi1 transcriptional repressor results in a novel form of neutropenia characterized by a split pattern of functional responses, reflecting the distinct thresholds required for eliciting neutrophil-mediated inflammatory and anti-infectious responses.

Neutrophil depletion reduces edema formation and tissue loss following traumatic brain injury in mice.

BACKGROUND: Brain edema as a result of secondary injury following traumatic brain injury (TBI) is a major clinical concern. Neutrophils are known to cause increased vascular permeability leading to edema formation in peripheral tissue, but their role in the pathology following TBI remains unclear. METHODS: In this study we used controlled cortical impact (CCI) as a model for TBI and investigated the role of neutrophils in the response to injury. The outcome of mice that were depleted of neutrophils using an anti-Gr-1 antibody was compared to that in mice with intact neutrophil count. The effect of neutrophil depletion on blood-brain barrier function was assessed by Evan's blue dye extravasation, and analysis of brain water content was used as a measurement of brain edema formation (24 and 48 hours after CCI). Lesion volume was measured 7 and 14 days after CCI. Immunohistochemistry was used to assess cell death, using a marker for cleaved caspase-3 at 24 hours after injury, and microglial/macrophage activation 7 days after CCI. Data were analyzed using Mann-Whitney test for non-parametric data. RESULTS: Neutrophil depletion did not significantly affect Evan's blue extravasation at any time-point after CCI. However, neutrophil-depleted mice exhibited a decreased water content both at 24 and 48 hours after CCI indicating reduced edema formation. Furthermore, brain tissue loss was attenuated in neutropenic mice at 7 and 14 days after injury. Additionally, these mice had a significantly reduced number of activated microglia/macrophages 7 days after CCI, and of cleaved caspase-3 positive cells 24 h after injury. CONCLUSION: Our results suggest that neutrophils are involved in the edema formation, but not the extravasation of large proteins, as well as contributing to cell death and tissue loss following TBI in mice.

Stem Cells are mobilized from the bone marrow into the peripheral circulation in response to retinal pigment epithelium damage--a pathophysiological attempt to induce endogenous regeneration.

PURPOSE: Stem cell regeneration of damaged tissue has recently been reported in many different organs. Here, we investigated the mobilization of different stem/progenitor cell (SPC) populations into the peripheral blood (PB), their subsequent homing to the injured retina (IR) and contribution to its regeneration in a retinal pigment epithelium (RPE) damage model induced by sodium iodate (NaIO(3)). METHODS: Mobilization of SPCs was evaluated by flow cytometry. SPCs distribution in IR was assessed using bone marrow (BM)-derived GFP(+)Lin(-) cells transplanted intravenously into NaIO(3)-treated C57Bl/6 mice. The quantity of the chemokine SDF-1 in PB and IR was measured by ELISA and qRT-PCR, respectively. Apoptosis (TUNEL assay), cell proliferation (PCNA analysis) as well as functional retinal activity (electroretinogram) were examined at several time points after NaIO(3) administration. RESULTS: Mobilization of SPCs along with the highest cell proliferation and massive apoptosis within IR were observed on the third day after NaIO(3) administration. Similarly, donor GFP(+)Lin(-) cells were detected in the retina as soon as day 4 after NaIO(3) injection. Plasma levels of SDF-1 did not differ significantly in mice exposed to NaIO(3) compared to healthy controls, however mRNA for SDF-1 was overexpressed locally in IR. Functional retinal recovery was not achieved. CONCLUSION: Our study provides evidence that BM SPCs egress into PB and home to the injured retina, but are not capable of restoring its function. These results indicate that if the range of retinal destruction is profound, endogenous regeneration is ineffective and may ultimately require adjuvant therapeutic transplantation of specific SPCs subpopulations.

Upregulation of nuclear factor-kappaB expression by SLURP-1 is mediated by alpha7-nicotinic acetylcholine receptor and involves both ionic events and activation of protein kinases.

SLURP-1 (secreted mammalian Ly-6/urokinase plasminogen activator receptor-related protein-1) is a novel auto/paracrine cholinergic peptide that can bind to α(7)-nicotinic acetylcholine receptor (nAChR), a high Ca(2+)-permeable ion channel coupled to regulation of nuclear factor-κB (NF-κB) expression. Elucidation of intracellular signaling events elicited by SLURP-1 is crucial for understanding the molecular mechanism of functioning of this novel hormone-like peptide that alters vital cell functions and can protect from tumorigenic transformation. In this study, we sought to dissect out the role of α(7)-nAChR in mediating the biologic effects of recombinant SLURP-1 on the immortalized line of human oral keratinocytes Het-1A. A multifold upregulation of the NF-κB expression at the mRNA and protein levels by SLURP-1 was only slightly diminished due to elimination of Na(+), whereas in Ca(2+)-free medium the effect of SLURP-1 was inhibited by >50%. Both in the absence of extracellular Ca(2+) and in the presence of Cd(2+) or Zn(2+), the SLURP-1-dependent elevation of NF-κB was almost completely blocked by inhibiting MEK1 activity. Downstream of α(7)-nAChR, the SLURP-1 signaling coupled to upregulation of NF-κB also involved Jak2 as well as Ca(2+)/calmodulin-dependent kinase II (CaMKII) and protein kinase C (PKC), whose inhibition significantly (P < 0.05) reduced the SLURP-1-induced upregulation of NF-κB. The obtained results indicated that activation of α(7)-nAChR by SLURP-1 leads to upregulation of the NF-κB gene expression due to activation of the Raf-1/MEK1/ERK1/2 cascade that proceeds via two complementary signaling pathways. One is mediated by the Ca(2+)-entry dependent CaMKII/PKC activation and another one by Ca(2+)-independent involvement of Jak2. Thus, there exists a previously not appreciated network of noncanonical auto/paracrine ligands of nAChR of the Ly-6 protein family, which merits further investigations.

Effects of inorganic arsenic on bone marrow hematopoietic cells: an emphasis on apoptosis and Sca-1/c-Kit positive population.

Apoptosis, proliferation and differentiation are balanced molecular processes which may alter their pattern during environmental insults. Arsenic is an environmental pollutant, ranks 20(th) in abundance in the earth crust, 14(th) in sea water and 12(th) in the human body. Millions of people worldwide are chronically exposed to arsenic often due to naturally occurring arsenic in ground water. Hematopoietic stem cells within the bone marrow are the source of all haematopoietic cell lineages and are essential for tissue development throughout the life. In this experimental study, we have evaluated the impact of arsenic, on blood and blood forming cells by the changes in their cellular morphology, immune functional capacity, alteration of bone marrow CD34 positive stem/progenitors and changes in the phenotype of Sca-1, c-Kit dual positive primitive stem cell population. The study revealed that arsenic has a significant effect on bone marrow and hematopoietic stem cells, their immune capacity and upregulation of death process, all indicative of impairment in differentiation suggesting presence of deregulation in their precursors by arsenic toxicity.