The aim of the present study was to investigate the levels of YKL-40 during and after coronary artery bypass grafting surgery (CABG) and to establish possible connections between YKL-40 and markers of oxidative stress, inflammation, and myocardial injury. Patients undergoing elective CABG utilizing cardiopulmonary bypass (CPB) were recruited into the study. Blood samples were collected at the onset of anesthesia, during surgery and post-operatively. Levels of YKL-40, 8-isoprostane, interleukin-8 (IL-8), monocyte chemotactic protein-1 (MCP-1) and troponin T (TnT) were measured by immunoassay. YKL-40 levels increased significantly 24 h after CPB. Positive correlation was seen between post-operative TnT and YKL-40 levels (r = 0.457, p = 0.016) and, interestingly, baseline YKL-40 predicted post-operative TnT increase (r = 0.374, p = 0.050). There was also a clear association between YKL-40 and the chemotactic factors MCP-1 (r = 0.440, p = 0.028) and IL-8 (r = 0.484, p = 0.011) linking YKL-40 to cardiac inflammation and fibrosis following CABG. The present results show, for the first time, that YKL-40 is associated with myocardial injury and leukocyte-activating factors following coronary artery bypass surgery. YKL-40 may be a factor and/or biomarker of myocardial inflammation and injury and subsequent fibrosis following heart surgery.

During infection, neutrophils are the most abundantly recruited innate immune cells at sites of infection, playing critical roles in the elimination of local infection and healing of the injury. Neutrophils are considered to be short-lived effector cells that undergo cell death at infection sites and in damaged tissues. However, recent in vitro and in vivo evidence suggests that neutrophil behavior is more complex and that they can migrate away from the inflammatory site back into the vasculature following the resolution of inflammation. Microfluidic devices have contributed to an improved understanding of the interaction and behavior of neutrophils ex vivo in 2D and 3D microenvironments. The role of reverse migration and its contribution to the resolution of inflammation remains unclear. In this review, we will provide a summary of the current applications of microfluidic devices to investigate neutrophil behavior and interactions with other immune cells with a focus on forward and reverse migration in neutrophils.

Diabetes mellitus is a main risk factor for delayed fracture healing and fracture non-unions. Successful fracture healing requires stimuli from different immune cells, known to be affected in diabetics. Especially, application of mononuclear cells has been proposed to promote wound and fracture healing. Thus, aim was to investigate the effect of pre-/diabetic conditions on mononuclear cell functions essential to promote osteoprogenitor cell function. We here show that pre-/diabetic conditions suppress the expression of chemokines, e.g., CCL2 and CCL8 in osteoprogenitor cells. The associated MCP-1 and MCP-2 were significantly reduced in serum of diabetics. Both MCPs chemoattract mononuclear THP-1 cells. Migration of these cells is suppressed under hyperglycemic conditions, proposing that less mononuclear cells invade the site of fracture in diabetics. Further, we show that the composition of cytokines secreted by mononuclear cells strongly differ between diabetics and controls. Similar is seen in THP-1 cells cultured under hyperinsulinemia or hyperglycemia. The altered secretome reduces the positive effect of the THP-1 cell conditioned medium on migration of osteoprogenitor cells. In summary, our data support that factors secreted by mononuclear cells may support fracture healing by promoting migration of osteoprogenitor cells but suggest that this effect might be reduced in diabetics.

The adaptive immune response is initiated in lymph nodes by contact between antigen-bearing dendritic cells (DCs) and antigen-specific T cells. A selected number of naïve T cells that recognize a specific antigen may proliferate into expanded clones, differentiate, and acquire an effector phenotype. Despite growing experimental knowledge, certain mechanistic aspects of T cell behavior in lymph nodes remain poorly understood. Computational modeling approaches may help in addressing such gaps. Here we introduce an agent-based model describing T cell movements and their interactions with DCs, leading to activation and expansion of cognate T cell clones, in a two-dimensional representation of the lymph node paracortex. The primary objective was to test the putative role of T cell chemotaxis toward DCs, and quantitatively assess the impact of chemotaxis with respect to T cell priming efficacy. Firstly, we evaluated whether chemotaxis of naïve T cells toward a nearest DC may accelerate the scanning process, by quantifying, through simulations, the number of unique T cell-DC contact events. We demonstrate that, in the presence of naïve T cell-to-DC chemoattraction, a higher total number of contacts occurs, as compared to a T cell random walk scenario. However, the forming swarm of naïve T cells, as these cells get attracted to the neighborhood of a DC, may then physically restrict access of additional T cells to the DC, leading to an actual decrease in the cumulative number of unique contacts between naïve T cells and DCs. Secondly, we investigated the potential role of chemotaxis in maintaining cognate T cell clone expansion. The time course of cognate T cells number in the system was used as a quantitative characteristic of the expansion. Model-based simulations indicate that inclusion of chemotaxis, which is selective for already activated (but not naïve) antigen-specific T cells, may strongly accelerate the time of immune response occurrence, which subsequently increases the overall amplitude of the T cell clone expansion process.

The immune function of the chicken spleen depends on its different compartments of red and white pulps, but little is known about the mechanism underlying lymphocyte homing towards the different compartments. In the present study, the role of lymphocyte homing in the chicken spleen was investigated during lipopolysaccharide (LPS) stimulation. Morphological analysis demonstrated the cuboidal endothelial cells of the splenic sheathed capillary facilitated the passage of lymphocyte homing to the chicken spleen. The tissue-specific adhesion molecules- vascular cell adhesion molecule-1 (VCAM-1) and mucosal addressin cell adhesion molecule-1 (MADCAM-1) expressed on the sheathed capillary, which suggested the high endothelial venule (HEV)-like vessels of the chicken spleen. Electron microscope analysis showed LPS activated the endothelium of the sheathed capillary and recruited lymphocytes to the chicken spleen. Transferring of 5, 6- carboxyfluorescein diacetate, succinimidyl ester (CFSE) labeled lymphocytes depicted the rout of lymphocyte homing to the compartments of the chicken spleen was from the white pulp to the red pulp. Furthermore, the mRNA and protein levels of adhesion molecular integrin β1 and VCAM-1 increased after LPS stimulation. The mechanism underlying the integrin β1 and VCAM-1 during LPS stimulation might be associated with the integrin linked kinase (ILK)- dependent regulation of protein kinase B (PKB/AKT). This study firstly shows lymphocyte homing in the chicken spleen after LPS-induced inflammation. These results contribute to our knowledge of comparative immunology and provide a better means for investigating the pharmacological strategies concerning the possible role of lymphocyte homing in inflammation and immunological reactions in infectious disease.

Migration of inflammatory cells from the blood to the central nervous system (CNS) is crucial for development of multiple sclerosis (MS). Inhibition of this process would allow to control disease activity. The first step confirming this approach would be the analysis of the impact of effective MS relapse therapy on migration of effector T cells. The aim of the study was to analyze the influence of methylprednisolone (MP) on the migratory activity of effector CD4+ T cells from MS patients. Moreover, to study the potential mechanism of this process we studied expression of chemokine receptors on migrating cells.
METHODS: Peripheral blood samples were obtained from relapsing-remitting MS (RR-MS) patients during relapse (n=23) and from control group (n=23). After isolation CD4+ T cells were incubated with various concentrations of MP. Then they were stimulated in chemotaxis assay with chemokines CCL3 or CXCL10 or were used to CCR1 and CXCR3 expression analysis.
RESULTS: CXCL10- and CCL3-stimulated migration of CD4+ T cells was significantly increased in MS. MP was able to reduce in vitro migration of effector T cells induced by CXCL10, but not by CCL3. Inhibition by MP was dose-dependent. Expression of analyzed chemokine receptors was unaltered after MP incubation.
CONCLUSIONS: MP reduced CD4+ T cells migration induced by CXCL10 without affecting CXCR3 expression. These observations demonstrate one of the potential mechanisms of MP action in MS, distinct from inducing cell apoptosis, and suggests the new targets for development of more effective MS treatments.

Chemokines are essential mediators of leukocyte movement in vivo. In vitro assays of leukocyte migration cannot mimic the complex interactions with other cell types and matrix needed for cells to extravasate and migrate into tissues. Therefore, in vivo strategies to study the effects and potential relevance of chemokines for the migration of particular leukocyte subsets are necessary. Here, we describe methods to study the effects and endogenous role of chemokine in mice. Advantages and pitfalls of particular models are discussed and we focus on description in model\'s joint and pleural cavity inflammation and the effects and relevance of CXCR2 and CCR2 ligands on cell migration.

BACKGROUND: Phospholipase A2 (PLA2) is associated with a variety of inflammatory processes related to polymorphonuclear neutrophil (PMN)-endothelial cell interactions. However, the cellular and molecular mechanisms underlying the interactions and the causative isoform(s) of PLA2 remain elusive. In addition, we recently showed that calcium-independent PLA2γ (iPLA2γ), but not cytosolic PLA2 (cPLA2), is responsible for the cytotoxic functions of human PMN including respiratory bursts, degranulation, and chemotaxis. We therefore hypothesized that iPLA2γ is a prerequisite for the PMN recruitment cascade into the site of inflammation. The aim of this study was to elucidate the roles of the three major phospholipases A2, iPLA2, cPLA2 and secretory PLA2, in leukocyte rolling and adherence and in the surface expression of β2-integrins in vivo and in vitro in response to well-defined stimuli.
METHODS: Male Wistar rats were pretreated with PLA2 inhibitors selective for iPLA2β, iPLA2γ, cPLA2, or secretory PLA2. Leukocyte rolling/adherence in the mesenteric venules superfused with platelet-activating factor (PAF) were quantified by intravital microscopy. Furthermore, isolated human PMNs or whole blood were incubated with each PLA2 inhibitor and then activated with formyl-methionyl-leucyl-phenylalanine (fMLP) or PAF. PMN adherence was assessed by counting cells bound to purified fibrinogen, and the surface expression of lymphocyte function-associated antigen 1 and macrophage antigen 1 (Mac-1) was measured by flow cytometry.
RESULTS: The iPLA2γ-specific inhibitor almost completely inhibited the fMLP/PAF-induced leukocyte adherence in vivo and in vitro and also decreased the fMLP/PAF-stimulated surface expression of Mac-1 by 60% and 95%, respectively. In contrast, the other inhibitors did not affect these cellular functions.
CONCLUSIONS: iPLA2γ seems to be involved in leukocyte/PMN adherence in vivo and in vitro as well as in the up-regulation of Mac-1 in vitro in response to PAF/fMLP. This enzyme is therefore likely to be a major regulator in the PMN recruitment cascade.

OBJECTIVE: Bone marrow mononuclear cells (BM-MNCs) and bone marrow-derived mesenchymal stem stromal cells (BM-MSCs) could have therapeutic potential for numerous conditions, including ischemia-related injury. Cells transplanted intravascularly may become entrapped in the lungs, which potentially decreases their therapeutic effect and increases the risk for embolism.
METHODS: Twelve pigs were divided into groups of 3 and received (99m)Tc- hydroxymethyl-propylene-amine-oxime-labeled autologous BM-MNCs or allogeneic BM-MSCs by either intravenous (IV) or intra-arterial (IA) transplantation. A whole body scan and single photon emission computed tomography/computed tomography (SPECT/CT) were performed 8 h later, and tissue biopsies were collected for gamma counting. A helical CT scan was also performed on 4 pigs to detect possible pulmonary embolism, 2 after IV BM-MSC injection and 2 after saline injection.
RESULTS: The transplantation route had a greater impact on the biodistribution of the BM-MSCs than the BM-MNCs. The BM-MNCs accumulated in the spleen and bones, irrespective of the administration route. The BM-MSCs had relatively higher uptake in the kidneys. The IA transplantation decreased the deposition of BM-MSCs in the lungs and increased uptake in other organs, especially in the liver. Lung atelectases were frequent due to mechanical ventilation and attracted transplanted cells. CT did not reveal any pulmonary embolism.
CONCLUSIONS: Both administration routes were found to be safe, but iatrogenic atelectasis might be an issue when cells accumulate in the lungs. The IA administration is effective in avoiding pulmonary entrapment of BM-MSCs. The cell type and administration method both have a major impact on the acute homing.

BACKGROUND: Granulocyte transfusion from healthy donors is used in the treatment of patients with granulocyte function defects, or transient neutropenia and severe bacterial or fungal infections resistant to maximal antimicrobial treatment.
METHODS: This study evaluated the performance and safety of the newly developed granulocyte collection protocol of the Spectra Optia in a prospective, multicenter, open-label, randomized, paired crossover trial compared with the COBE Spectra apheresis system in a population of 32 evaluable healthy subjects. All subjects received granulocyte-colony-stimulating factor and dexamethasone before collection.
RESULTS: Granulocyte procedures from Spectra Optia apheresis procedures had an approximately 23% higher polymorphonuclear (PMN) collection efficiency (CE) than the COBE Spectra collections (mean, 53.7% vs. 43.2%; p < 0.01), while the platelet CE (10.9% vs. 10.8%, respectively) and hematocrit (7.4% vs. 7.4%) were comparable between collections on both devices. Spectra Optia collections generated a higher total PMN yield per liter of blood processed than those produced by the COBE Spectra (with means of 8.6 × 10(10) vs. 6.8 × 10(10) , respectively). Granulocyte viability was more than 99% with both devices, and chemotaxic and bacterial killing activities of circulating versus collected granulocytes were similarly preserved. Fewer operator adjustments were required with Spectra Optia and there was no significant difference in the number or intensity of adverse events between instruments.
CONCLUSIONS: CE of the granulocyte collection procedure with the Spectra Optia was approximately 10 percentage points higher than with the COBE Spectra, required less operator involvement, and is safe for clinical implementation.