Monocyte Apoptosis Research Articles

Transient Effects of Anesthesia on Leukocyte Apoptosis and Monocyte Cytokine Stimulation: A Clinical Study

ABSTRACTThe effects of anesthetics on immune cell apoptosis and cytokine stimulation were studied in a prospective study. American Society of Anesthesiologists I/II patients underwent elective inguinal hernia repair or varicose veins stripping surgery and were randomized to either epidural anesthesia (n = 14) or general anesthesia with sevoflurane (n = 19) or propofol (n = 15). Blood was sampled before anesthesia induction (T0), at the end of surgery (T1), and 6 h later (T2). Apoptosis was determined by ANNEXIN-V staining of white blood cells; monocytes were isolated and stimulated for cytokine production. Results were compared with 10 healthy volunteers well-matched for age and gender. Apoptosis of lymphocytes and monocytes was increased in the epidural and sevoflurane groups at T2. Propofol group had increased production of interleukin-6 at T1 and sevoflurane and epidural groups had decreased production of tumor necrosis factor-alpha at T2. Results emphasize the modulation of immune function by epidural and sevoflurane but not propofol anesthesia in a clinical setting.

FC-99 ameliorates sepsis-induced liver dysfunction by modulating monocyte/macrophage differentiation via Let-7a related monocytes apoptosis.

BackgroundThe liver is a vital target for sepsis-related injury, leading to inflammatory pathogenesis, multiple organ dysfunction and high mortality rates. Monocyte-derived macrophage transformations are key events in hepatic inflammation. N1-[(4-methoxy)methyl]-4-methyl-1,2-benzenediamine (FC-99) previously displayed therapeutic potential on experimental sepsis. However, the underlying mechanism of this protective effect is still not clear.ResultsFC-99 treatment attenuated the liver dysfunction in septic mice that was accompanied with reduced numbers of pro-inflammatory Ly6Chi monocytes in the peripheral blood and CD11b+F4/80lo monocyte-derived macrophages in the liver. These effects were attributed to the FC-99-induced apoptosis of CD11b+ cells. In PMA-differentiated THP-1 cells, FC-99 repressed the expression of CD11b, CD14 and caspase3 and resulted in a high proportion of Annexin V+ cells. Moreover, let-7a-5p expression was abrogated upon CLP stimulation in vivo, whereas it was restored by FC-99 treatment. TargetScan analysis and luciferase assays indicated that the anti-apoptotic protein BCL-XL was targeted by let-7a-5p. BCL-XL was inhibited by FC-99 in order to induce monocyte apoptosis, leading to the impaired monocyte-to-macrophage differentiation.Materials and MethodsMurine acute liver failure was generated by caecal ligation puncture surgery after FC-99 administration; Blood samples and liver tissues were collected to determine the monocyte/macrophage subsets and the induction of apoptosis. Human acute monocytic leukemia cell line (THP-1) cells were pretreated with FC-99 followed by phorbol-12-myristate-13-acetate (PMA) stimulation, in order to induce monocyte-to-macrophage differentiation. The target of FC-99 and the mechanistic analyses were conducted by microarrays, qRT-PCR validation, TargetScan algorithms and a luciferase report assay.ConclusionsFC-99 exhibits potential therapeutic effects on CLP-induced liver dysfunction by restoring let-7a-5p levels.

Determinants of Monocyte Apoptosis in Cardiorenal Syndrome Type 1

Background: Cardiorenal syndrome type 1 (CRS type 1) is characterized by a rapid worsening of cardiac function leading to acute kidney injury (AKI). Its pathophysiology is complex and not completely understood. In this study, we examined the role of apoptosis and the caspase pathways involved. Material and Methods: We enrolled 40 acute heart failure (AHF) patients, 11 of whom developed AKI characterizing CRS type 1. We exposed the human cell line U937 to plasma from the CRS type 1 and AHF groups and then we evaluated apoptotic activity by annexin-V evaluation, determination of caspase-3, -8 and -9 levels, and BAX, BAD, and FAS gene expression. Results: We observed significant upregulation of apoptosis in monocytes exposed to CRS type 1 plasma compared to AHF, with increased levels of caspase-3 (p < 0.01), caspase-9 (p < 0.01), and caspase-8 (p < 0.03) showing activation of both intrinsic and extrinsic pathways. Furthermore, monocytes exposed to CRS type 1 plasma had increased gene expression of BAX and BAD (intrinsic pathways) (p = 0.010 for both). Furthermore, strong significant correlations between the caspase-9 levels and BAD and BAX gene expression were observed (Spearman ρ = – 0.76, p = 0.011, and ρ = – 0.72, p = 0.011). Conclusion: CRS type 1 induces dual apoptotic pathway activation in monocytes; the two pathways converged on caspase-3. Many factors may induce activation of both intrinsic and extrinsic apoptotic pathways in CRS type 1 patients, such as upregulation of proinflammatory cytokines and hypoxia/ischemia. Further investigations are necessary to corroborate the present findings, and to better understand the pathophysiological mechanism and consequent therapeutic and prognostic implications for CRS type 1.

Effects of Birch Polypore Mushroom, Piptoporus betulinus (Agaricomycetes), the "Iceman's Fungus", on Human Immune Cells.

Piptoporus betulinus, the mushroom that has been carried by Ötzi the "Iceman", has a long tradition of use in medicinal practice for its antiseptic, anticancer, and immune-enhancing properties. With this study, we aimed to investigate the immunomodulatory effects of P. betulinus on primary human immunocompetent cells. The influence of P. betulinus water and methanol extract on apoptosis and necrosis induction of T cells and monocytes was analyzed using annexin V/propidium iodide staining and proliferation of T cells by carboxyfluorescein diacetate succinimidyl ester staining using flow cytometry. The effects on T-cell activation (CD69/CD25) and dendritic cell maturation (CD83, CD86, and CD14) were assessed using flow cytometric analysis of distinct marker expression. Alterations of the secretion of effector mediators interferon (IFN)-γ by T cells and interleukin (IL)-8 by monocytes and dendritic cells were detected by enzyme-linked immunosorbent assay. None of the P. betulinus extracts had a significant influence on apoptosis and necrosis induction, T-cell proliferation, or T-cell activation status, but P. betulinus water extract caused a strong increase in IFN-γ release. The same extract was slightly protective against apoptosis of monocytes and further triggered IL-8 secretion by monocytes and dendritic cells. Moreover, P. betulinus water extract induced dendritic cell maturation. Our results demonstrate the immune-enhancing properties of P. betulinus.

Effects of CTLA4-Ig on human monocytes

BackgroundAbatacept, a CTLA4-Ig fusion protein attenuates T cell activation by inhibiting the CD80/86-CD28 costimulatory pathway that is required for the proper T cell activation and thus displays beneficial effects in the treatment of rheumatoid arthritis (RA). Although some studies have disclosed the in vitro effects of this biological agent on the immune-competent cells, the precise mechanisms of action in RA still remain unclear. The current studies were therefore undertaken to explore the effects of abatacept on monocytes in detail.MethodsMonocytes from healthy donors were cultured in the presence of staphylococcal enterotoxin B (SEB) with pharmacologically attainable concentrations of abatacept or control IgG-Fc. The expression of CD80 and CD86 and the induction of apoptosis of monocytes were measured by flow cytometry. The expression of CD80 and CD86 messenger RNA (mRNA) was determined by quantitative RT-PCR.ResultsAbatacept promoted apoptosis of SEB-stimulated monocytes. The induction of apoptosis of monocytes by these biological agents was reversed by the addition of IgG, but not IgG-F(ab′)2 fragments. Furthermore, abatacept significantly suppressed the expression of CD80, but not that of CD86 at protein levels. Finally, abatacept significantly suppressed the expression of mRNA for CD80 of monocytes stimulated with SEB, but not that of CD86.ConclusionsThese results demonstrate that one of the mechanisms of action of abatacept involves the induction of apoptosis of monocytes, which involves interaction with Fc receptor on monocytes. Moreover, the data also demonstrate that abatacept selectively suppresses the expression of CD80 at mRNA levels.

The nonreceptor protein tyrosine kinase Pyk2 promotes the turnover of monocytes at steady state.

Monocytes are short-lived myeloid cells that perform functions essential for tissue homeostasis and disease resolution. However, the cellular mechanisms controlling the maintenance and turnover of monocyte populations are largely undefined. Proline-rich tyrosine kinase 2 (Pyk2) is a nonreceptor tyrosine kinase that regulates numerous immune cell functions, but its role in monocytes is currently unknown. In this study, we sought to characterize the expression and function of Pyk2 in lineage-committed monocyte populations. Here, we report that Pyk2 protein expression is increased in the Ly6C- monocyte population. Using a Pyk2 knockout mouse model (Pyk2-/-), we show that Pyk2 regulates the relative proportion of monocyte subsets normally represented in the bone marrow (BM) at steady state. In support of this conclusion, a similar phenotype was observed in the peripheral blood and spleen. Data from reciprocal BM chimera experiments indicate that the alterations in monocyte populations exhibited by Pyk2-/- mice are due to factors intrinsic to the monocytes. Lineage-tracing of monocyte populations suggests that Pyk2 promotes apoptosis in BM monocytes, thereby acting as an important homeostatic regulator of turnover in these short-lived, innate immune cells.

The Role of Monocyte Percentage in Osteoporosis in Male Rheumatic Diseases.

Osteoporosis is easily overlooked in male patients, especially in the field of rheumatic diseases mostly prevalent with female patients, and its link to pathogenesis is still lacking. Attenuated monocyte apoptosis from a transcriptome-wide expression study illustrates the role of monocytes in osteoporosis. This study tested the hypothesis that the monocyte percentage among leukocytes could be a biomarker of osteoporosis in rheumatic diseases. Eighty-seven males with rheumatic diseases were evaluated in rheumatology outpatient clinics for bone mineral density (BMD) and surrogate markers, such as routine peripheral blood parameters and autoantibodies. From the total number of 87 patients included in this study, only 15 met the criteria for diagnosis of osteoporosis. Both age and monocyte percentage remained independently associated with the presence of osteoporosis. Steroid dose (equivalent prednisolone dose) was negatively associated with BMD of the hip area and platelet counts were negatively associated with BMD and T score of the spine area. Besides age, monocyte percentage meets the major requirements for osteoporosis in male rheumatic diseases. A higher monocyte percentage in male rheumatic disease patients, aged over 50 years in this study, and BMD study should be considered in order to reduce the risk of osteoporosis-related fractures.

Effects of Schiff base aromatic amino acid derivatives on antioxidant and immune system disturbances in a rat model of aflatoxin B1 induced experimental mycotoxicosis

Background:Alflatoxin B1 (AFB1) is the most hepatotoxic and hepatocarcinogenic of the aflatoxins and occurs as a contaminant in a variety of foods. The toxicity of AFB1 has been shown to be associated with a wide range of pathological events, such as enhanced apoptosis and oxidative events. Currently there is no treatment for mycotoxin exposure. The aim of this study was to evaluate the potential ability of picolinyl-L-phenylalaninate (PLP), picolinyl-L-tryptophanate (PLT), and nicotinyl-L-tryptophanate (NLT) Schiff base amino acid derivatives to act against damaging effects of AFB1 using a rat model of mycotoxicosis. For this purpose, a range of markers of immune and antioxidant systems in liver and blood plasma samples, as well as the apoptotic rate in neutrophils and monocytes was assessed.Methods:Mongrel white pubescent rats (with 180-200g b/w) were used in all experiments. Concentration of the markers of immune and antioxidant systems was measured in plasma by ELISA, using commercially available kits according to manufacturers’ instructions. The rate of apoptosis in neutrophils and monocytes was analyzed by flow cytometry.Results:AFB1 induced mycotoxicosis caused significant elevation of malonic dialdehyde contents (plasma and liver: p = 0.0001 compared with untreated rats), the levels of superoxide dismutase (p=0.005), total non-enzymatic water-soluble antioxidants (p = 0.0001), and terminal complement complex (p = 0.021). Moreover, the increased rates of early and late apoptosis in neutrophils and monocytes were observed as well. Treatment with PLP, PLT and NLT were shown to mitigate these effects, though to a different extent.Conclusions:The results obtained in this study clearly demonstrated that chronic AFB1 exposure induced oxidative cell damage, immunosuppression and apoptosis of circulating immune cells. The oral administration of Schiff base cyclic amino acid derivatives was capable of minimizing the detrimental effects of mycotoxicosis by possessing multi-mechanistic effects that target AFB1-induced pathological events.

Transcriptome profiling of monocytes from XLA patients revealed the innate immune function dysregulation due to the BTK gene expression deficiency

X-linked agammaglobulinemia (XLA) is a rare genetic disorder, caused by mutations in BTK (Bruton’s Tyrosine Kinase) gene. Deep high-throughput RNA sequencing (RNA-Seq) approach was utilized to explore the possible differences in transcriptome profiles of primary monocytes in XLA patients compared with healthy subjects. Our analysis revealed the differences in expression of 1,827 protein-coding genes, 95 annotated long non-coding RNAs (lncRNAs) and 20 novel lincRNAs between XLA patients and healthy subjects. GO and KEGG pathway analysis of differentially expressed (DE) protein-coding genes showed downregulation of several innate immune-related genes and upregulation of oxidative phosphorylation and apoptosis-related genes in XLA patients compared to the healthy subjects. Moreover, the functional prediction analysis of DE lncRNAs revealed their potential role in regulating the monocytes cell cycle and apoptosis in XLA patients. Our results suggested that BTK mutations may contribute to the dysregulation of innate immune system and increase susceptibility to apoptosis in monocytes of XLA patients. This study provides significant finding on the regulation of BTK gene in monocytes and the potential for development of innovative biomarkers and therapeutic monitoring strategies to increase the quality of life in XLA patients.

The non-receptor protein tyrosine kinase Pyk2 promotes the turnover of mouse monocyte populations at steady-state

Abstract Peripheral monocytes, consisting of distinct Ly6C+ and Ly6Cneg subsets in mice, are innate immune effector cells that exhibit a relatively short half-life of 1–3 days. While the differentiation and function of these monocyte subpopulations have been explored extensively, the cellular mechanisms regulating the maintenance and turnover of these populations are not completely understood. The focus of our current study is to investigate the role of proline-rich tyrosine kinase 2 (Pyk2) in the establishment and/or maintenance of monocyte populations at steady-state. Using a Pyk2 knock-out mouse model (Pyk2−/−), we show for the first time that Pyk2−/− mice exhibit reduced bone marrow (BM) cellularity, resulting in a reduction of total BM monocytes in these mice. Accordingly, Pyk2−/− mice display reduced numbers of BM monocyte progenitors and Ly6C+ monocytes; however, there is no reduction in the representation of Ly6Cneg monocytes in the absence of Pyk2, suggesting that Pyk2 regulates the relative proportion of monocyte subsets normally represented in the BM at steady state. In support of this conclusion, a similar phenotype was observed in the peripheral blood and spleen. Data from reciprocal and mixed BM chimera experiments indicate that the alterations in monocyte populations exhibited by Pyk2−/− mice are due to factors intrinsic to the monocytes. Pyk2 does not appear to regulate the proliferation, differentiation, or egress of monocyte subsets. Instead, experiments using annexin V and cleaved caspase as markers for apoptosis indicate that Pyk2 may promote apoptosis in BM monocytes, thereby acting as an important regulator of turnover in these short-lived effector cells.

Avian influenza virus A H7N9 infects multiple mononuclear cell types in peripheral blood and induces dysregulated cytokine responses and apoptosis in infected monocytes.

Most patients with avian influenza A H7N9 virus (H7N9) infection suffer from severe illness, accompanied by dysregulated cytokine/chemokine response, delayed viral clearance and impaired neutralizing antibody response. Here, we evaluated the role of peripheral blood mononuclear cells (PBMCs) in the pathogenesis of H7N9 infection using an ex vivo infection model. H7N9 infected a significantly higher percentage of PBMCs (23.9 %) than those of avian influenza A H5N1 virus (H5N1) (12.3 %) and pandemic H1N1 virus (pH1N1) (5.5 %) (P<0.01). H7N9 infected significantly more B and T lymphocytes than H5N1. When compared with pH1N1, H7N9-infected PBMCs had significantly higher mRNA levels of proinflammatory cytokines and type I interferons (IFNs) at 6 h post-infection (p.i.), but significantly lower levels of IFN-γ and IP-10 at 12 h p.i. Among the PBMCs, CD14+ monocytes were most permissive to H7N9 infection. The percentage of infected CD14+ monocytes was significantly higher for H7N9 than that of pH1N1, but not significantly different from that of H5N1. H7N9-infected monocytes showed higher expression of MIP-1α, MIP-1β and RANTES than that of pH1N1 at 6 h p.i. H7N9- but not pH1N1-infected monocytes died rapidly via apoptosis. Furthermore, pH1N1- but not H7N9-infected monocytes showed increased expression of the monocyte activation and differentiation markers. Unlike pH1N1, H7N9 showed similar PBMC/monocyte cytokine/chemokine expression profile, monocyte cell death and expression of activation/differentiation markers to H5N1. Besides proinflammatory cytokine activation leading to a cytokine storm, impaired IFN-γ production, rapid monocytic death and lack of monocyte differentiation may affect the ability of H7N9-infected innate immune cells to recruit protective adaptive immunity.

Abstract 179: Computational Modelling Of Early Atherosclerotic Plaque Structure Reveals The Role Of The Rate Of Lipid Deposition On Plaque Structure And Growth Rate

Much current research on inflammation in atherosclerosis focuses on specific cellular and biochemical processes as isolated phenomena. There is scope, therefore, for an integrated approach that examines the interactions between the various mechanisms involved in early plaque growth. An in silico modelling approach is promising in this regard as multiple biological processes can easily be incorporated into the model and used to simulate early plaque growth under a variety of conditions. We present a computational model to simulate early plaque growth and test the hypothesis that higher rates of lipid deposition in the artery wall will cause accelerated plaque growth and influence the plaque’s morphology and composition. We formulate a mathematical model based on the observed interactions between macrophages, pro-atherogenic extracellular lipid, lipid accumulated by macrophages, and apoptotic cells/cellular debris. This basic model incorporates several key processes including monocyte recruitment, phagocytosis, proliferation, apoptosis, lipid cytotoxicity, and cell migration. The model is used to computationally simulate how the early development of the plaque is influenced by its physiological environment, focusing in particular on the rate of lipid influx into the artery wall. Individual simulations yield a profile of how cells and lipids are spatially distributed over the plaque, and how this distribution and the total plaque size evolve in time. The model qualitatively suggests that the rate of lipid deposition has a key influence on early plaque morphology and behaviour. Specifically, increasing the rate of lipid deposition (simulating higher fat diets) accelerates the rate of plaque growth. The ratio of apoptotic cells to active macrophages also increases with distance from the endothelium, with the ratio becoming more pronounced in older plaques. The computational model provides a novel methodology with which to capture the dynamics and structure of early atherosclerotic plaques, and provides a foundation on which to build models that can account for further aspects of the relevant biology, including plaque regression and necrotic core formation.

Pyroptosis and Apoptosis Pathways Engage in Bidirectional Crosstalk in Monocytes and Macrophages

Pyroptosis is a lytic form of programmed cell death mediated by the inflammatory caspase-1, -4, and -5. We recently discovered that small-molecule inhibitors of the serine peptidases DPP8 and DPP9(DPP8/9) induce pro-caspase-1-dependent pyroptosis in monocytes and macrophages. Notably, DPP8/9 inhibitors, unlike microbial agents, absolutely require caspase-1 to induce cell death. Therefore, DPP8/9 inhibitors are useful probes to study caspase-1 in cells. Here, we show that, in the absence of the pyroptosis-mediating substrate gasdermin D (GSDMD), caspase-1 activates caspase-3 and -7 and induces apoptosis, demonstrating that GSDMD is the only caspase-1 substrate that inducespyroptosis. Conversely, we found that, during apoptosis, caspase-3/-7 specifically block pyroptosis by cleaving GSDMD at a distinct site from the inflammatory caspases that inactivates the protein. Overall, this work reveals bidirectional crosstalk between apoptosis and pyroptosis in monocytes and macrophages, further illuminating the complex interplay between cell death pathways in the innate immune system.

Immunological implications of bovine leukemia virus infection

This study examined neutrophil and monocyte functions and the blood lymphocyte profile of naturally BLV-infected cows with or without persistent lymphocytosis (PL). The percentage of neutrophils and monocytes that phagocytosed Staphylococcus aureus was lower in BLV-infected dairy cows, particularly those with PL. The relative percentage of CD44+ monocytes and neutrophils and CD11b expression by neutrophils was also lower in BLV-infected dairy cows with PL. A correlation between the percentage of CD11b+ neutrophils and that produced reactive oxygen species (ROS) was found. Furthermore, the percentage of CD44+ monocytes was positively correlated with the percentage of monocytes that phagocytosed S. aureus and the same phenomenon was observed for neutrophils. In BLV-infected dairy cows, particularly those with PL, inhibition of monocyte and neutrophil apoptosis was observed. Additionally, the percentage of neutrophils producing ROS was lower in BLV-infected cows with PL, in contrast to higher intensity of intracellular production of ROS by monocytes. The result from the lymphocyte immunophenotyping of BLV-infected cows with PL was an increase in B cells, mainly B CD5+ CD11b+, due to the apoptosis inhibition. In conclusion, this study provides novel insight into the implications of BLV infection for cattle, which can include the dysfunction of blood monocytes and neutrophils.

Early apoptosis of monocytes induced by Helicobacter pylori infection through multiple pathways

Only a small percentage of people infected with Helicobacter pylori (H. pylori) will develop overt chronic gastric diseases. To understand the pathological mechanism, the action of H. pylori on monocyte apoptosis was detected. H. pylori co-culturing with peripheral blood monocytes, THP-1 or U937 cells result in early apoptosis at 6, 12, and 24 h after infection. The phosphorylated Bad and JNK were increased, and Bcl-2 was declined at 6, 12, and 24 h in peripheral blood monocytes after H. pylori infection. The phosphorylated Akt was augmented at 6 and 12 h post-infection. A slow apoptotic response was induced by H. pylori via Bad and Bcl-2 regulators, activated caspase-8 and caspase-9, and JNK at 24 h in THP-1 cells. Meanwhile, only Bad and JNK were involved in regulating U937 cells apoptosis at 24 h after infection. These results supported a novel mechanism of H. pylori escaping from monocytes by upregulation of early apoptosis and inhibition of late apoptosis. The differences among the three cells may reveal why H. pylori-derived disease occurs in relatively few people and provide a pathological mechanism whereby a treatment for H. pylori-derived disease may be developed.

AMPK activation reduces the number of atheromata macrophages in ApoE deficient mice

Background and aimsCC chemokine receptor 2 (Ccr2) governs migration of inflammatory Ly6Chi monocytes from the bone marrow (BM) to the circulating blood, which is a key step for macrophage accumulation during progression of atherosclerosis. Hyperlipidemia is often accompanied by low AMP-activated kinase (AMPK) activity and increased expression of Ccr2. The aim of this study was to examine whether there is a link between AMPK and chemokine networks. MethodsApoE−/− mice were fed a western diet and treated daily with AMPK activators (AICAR, A769662, or Metformin) or vehicle for 10 weeks. The effect of AMPK activators on pro-inflammatory myeloid cell numbers within the BM, blood, spleen, and aorta of ApoE−/− mice was then examined. ResultsWe found that AMPK activation significantly reduced the number of Ly6Chi monocytes in the blood and atherosclerotic plaques. This reduction was caused by down-regulation of Ccr2 protein expression, which inhibited Ccr2-mediated migration of Ly6Chi monocytes from the BM to the circulation. There was no effect on proliferation or apoptosis of BM-derived Ly6Chi monocytes. AMPK activation caused Ly6Chi monocytes to accumulate in the BM, with a concomitant reduction in numbers in the blood and spleen. ConclusionsAMPK activation reduces the formation of atheromata-inducing macrophages in ApoE−/−-deficient mice by inhibiting expression of Ccr2, thereby preventing the Ccr2-mediated migration of Ly6Chi monocytes from the BM. Therefore, AMPK may be a promising target for the treatment of atherosclerosis.

MicroRNA-155 contributes to enhanced resistance to apoptosis in monocytes from patients with rheumatoid arthritis

Monocytes and macrophages are key mediators of inflammation in rheumatoid arthritis (RA). Their persistence at the inflammatory site is likely to contribute to immunopathology. We sought to characterise one mechanism by which persistence may be achieved: resistance to apoptosis and the role of mir-155 in this process. CD14+ monocytes from peripheral blood (PBM) and synovial fluid (SFM) of RA patients were found to be resistant to spontaneous apoptosis relative to PBM from healthy control (HC) individuals. RA SFM were also resistant to anti-Fas-mediated apoptosis and displayed a gene expression profile distinct from HC and RA PBM populations. Gene expression profiling analysis revealed that the differentially expressed genes in RA SFM vs. PBM were enriched for apoptosis-related genes and showed increased expression of the mir-155 precursor BIC. Following identification of potential mir-155 target transcripts by bioinformatic methods, we show increased levels of mature mir-155 expression in RA PBM and SFM vs. HC PBM and a corresponding decrease in SFM of two predicted mir-155-target mRNAs, apoptosis mediators CASP10 and APAF1. Using miR mimics, we demonstrate that mir-155 over-expression in healthy CD14+ cells conferred resistance to spontaneous apoptosis, but not Fas-induced death in these cells, and resulted in increased production of cytokines and chemokines. Collectively our data indicate that CD14+ cells from patients with RA show enhanced resistance to apoptosis, and suggest that an increase in mir-155 may partially contribute to this phenotype.

TRIM22-Mediated Apoptosis is Associated with Bak Oligomerization in Monocytes

Monocyte apoptosis is a key mechanism that orchestrates host immune responses during sepsis. TRIM22 is constitutively expressed at high levels in monocytes and plays important roles in the antiviral response and inflammation. Overexpression of TRIM22 interferes with the clonogenic growth of monocytic cells, suggesting that TRIM22 may regulate monocyte survival. However, the effect of TRIM22 on monocyte apoptosis remains unknown. In the present report, lipopolysaccharides (LPS)-primed human peripheral blood monocytes expressing higher levels of TRIM22 were more sensitive to apoptosis. This phenomenon was also observed in TRIM22-overexpressing THP-1 monocytes and was associated with the activation of caspase-9 and caspase-3, as well as the increased expression and oligomerization of the pro-apoptotic protein Bak. Similar expression patterns of TRIM22 and Bak were also observed in LPS-primed, apoptotic human peripheral blood monocytes. In addition, the deletion of either the RING domain or the SPRY domain of TRIM22 significantly attenuated TRIM22-mediated monocyte apoptosis and decreased Bak expression and oligomerization. Furthermore, in monocytes from septic patients, TRIM22 levels were down-regulated and positively correlated with Bak levels. Taken together, these results indicate that TRIM22 plays a critical role in monocyte apoptosis by regulating Bak oligomerization and may have a potential function in the pathogenesis of sepsis.

Evaluation of Stress Response and Apoptosis on Leucocytes in TIVA versus Balanced Anesthesia

Background: The aim of this study was to assess the stress response and apoptosis on leucocytes, in patients under two different anesthetics techniques. Methods: Thirty patients ASA I-II were prospectively randomized into two groups to receive either total intravenous anesthesia with propofol-remifentanil (TIVA Group, n = 15) or balanced inhalation anesthesia with sevoflurane-remifentanil (BAL Group, n = 15). The hemodynamic response: systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate (HR) at different time points: baseline, after intubation, after skin incision and at the end of surgery, was measured along with plasma levels of lactate, glucose, cortisol and leucocytes count. The biomarkers of apoptosis (Annexin V and Propidium Iodide) in neutrophils, monocytes and lymphocytes were evaluated at baseline, intraoperatively and two hours after surgery. Results: The study groups were comparable with respect to anthropometric data. No significant intergroup differences in SBP and DBP were revealed. The HR in the BAL group was lower after intubation (p = 0.007). In both groups, lactate, plasma glucose, cortisol and leucocytes count remained stable during surgery and two hours post-operatively. In the BAL group there were significant differences in Annexin V in neutrophils, baseline moment (p = 0.010). No significant differences were found in apoptosis markers (Annexin V and Propidium Iodide) in neutrophils, monocytes and lymphocytes, at different time points. Conclusion: Both TIVA and BAL were effective in suppressing the surgical stress, without inducing apoptosis in immune cells, in patients undergoing VCL.

Infliximab Selectively Modulates the Circulating Blood Monocyte Repertoire in Crohn's Disease.

Infliximab (IFX), an anti-tumour necrosis factor alpha (TNFα) monoclonal antibody, provides clinical benefits in treating Crohn's disease (CD) but its mechanisms of action are not fully elucidated. This study investigated blood monocyte repertoires and the acute effects of IFX infusion on monocyte subset phenotype and function in IFX-treated patients with CD. Monocytes and monocyte subsets were enumerated and phenotypically characterized by multicolor flow cytometry in freshly isolated blood from healthy controls (n = 21) and patients with CD treated with (IFX, n = 24) and without (non-IFX, n = 20) IFX. For the IFX-CD group, blood was sampled immediately before (tough-IFX) and after (peak-IFX) infusion. Monocyte responses to lipopolysaccharide were analyzed by whole-blood intracellular cytokine staining. Non-IFX and IFX-CD patients had increased numbers of intermediate (CD14CD16) monocytes compared with healthy controls, whereas classical (CD14CD16) and nonclassical (CD14CD16) monocytes were numerically reduced in the IFX-CD group alone. In all groups, monocyte subsets expressed high surface levels of transmembrane (tm)TNFα. After IFX infusion, a significant reduction in monocyte numbers occurred. Post-IFX monocytopenia was proportionately greatest for classical and intermediate subsets, correlated with postinfusion IFX levels and was not associated with monocyte apoptosis. In contrast, lipopolysaccharide-induced production of TNFα and IL-12 by monocytes was significantly reduced in peak-IFX compared with trough-IFX blood samples. Actively managed CD is associated with monocyte repertoire skewing suggestive of chronic inflammatory stimulation. Infused IFX acutely targets monocytes, likely by binding to tmTNFα, resulting in a non-apoptosis-related decline in circulating monocyte numbers and blunting of the inflammatory response of monocytes remaining in the blood.