Josefin Paulsson

Expression of neutrophil SOD2 is reduced after lipopolysaccharide stimulation: a potential cause of neutrophil dysfunction in chronic kidney disease

BACKGROUND Neutrophils from patients with chronic kidney disease (CKD) are dysfunctional and thus a contributing factor to the risk of infections. The mechanisms for leucocyte dysfunction in CKD are not fully understood. It is known that lipopolysaccharide (LPS) activates transcription of several genes encoding proinflammatory cytokines. We therefore aimed to study the effect of LPS on neutrophil expression of genes related to the inflammatory response to address the hypothesis that LPS-induced gene transcriptions are altered in CKD patients. METHODS We analysed gene expression of LPS-stimulated neutrophils from 30 patients with CKD and 15 healthy controls. Superoxide dismutase-2 (SOD2), IL1A, IL-1R1, IL-1R2 and IL8RA gene expression from both neutrophils and differentiated HL60 cells were measured by quantitative polymerase chain reaction. Differentiated HL60 cells were stimulated with phorbol-12-myristate-7-acetate (PMA) after inhibition of SOD2 by small interfering RNA followed by respiratory burst assessment using flow cytometry. RESULTS LPS stimulation induced a significant mobilization of CD11b on neutrophils from CKD and healthy controls. Upregulation of SOD2, IL1A, IL-1R1 and IL-1R2 gene expression in neutrophils from healthy controls after LPS stimulation was contrasted by no change in gene transcription (IL-1R1 and IL-1R2) or even a downregulation in patients with CKD (SOD2 and IL1A). Inhibition of SOD2 reduced the PMA-induced respiratory burst and IL1A, IL-1R1, IL-1R2 and IL8RA gene expression in neutrophil-differentiated HL60 cells. CONCLUSIONS Because of the critical role of SOD2 in the generation of hydrogen peroxide during phagocytosis, downregulation of SOD2 gene expression after LPS stimulation in neutrophils from patients with CKD indicates a potential mechanism for neutrophil dysfunction and cytokine dysregulation in these patients.

Activation of Wnt/β-Catenin Pathway in Monocytes Derived from Chronic Kidney Disease Patients

Patients with chronic kidney disease (CKD) have significantly increased morbidity and mortality resulting from infections and cardiovascular diseases. Since monocytes play an essential role in host immunity, this study was directed to explore the gene expression profile in order to identify differences in activated pathways in monocytes relevant to the pathophysiology of atherosclerosis and increased susceptibility to infections. Monocytes from CKD patients (stages 4 and 5, estimated GFR <20 ml/min/1.73 m2) and healthy donors were collected from peripheral blood. Microarray gene expression profile was performed and data were interpreted by GeneSpring software and by PANTHER tool. Western blot was done to validate the pathway members. The results demonstrated that 600 and 272 genes were differentially up- and down regulated respectively in the patient group. Pathways involved in the inflammatory response were highly expressed and the Wnt/β-catenin signaling pathway was the most significant pathway expressed in the patient group. Since this pathway has been attributed to a variety of inflammatory manifestations, the current findings may contribute to dysfunctional monocytes in CKD patients. Strategies to interfere with this pathway may improve host immunity and prevent cardiovascular complications in CKD patients.

IL-8 from Local Subcutaneous Wounds Regulates CD11b Activation

The cellular and soluble mediators of a dermal inflammation can be studied by the skin chamber technique. The aim of this study was to address the physiological effect of soluble mediators, released into the skin chamber, with special focus on neutrophil CD11b activation. Mediators released at the inflammatory site were studied by Milliplex and enzyme‐linked immunosorbent assay (ELISA) and correlated with transmigration and CD11b activation in vivo and in vitro. Transmigration was studied by the skin chamber technique and by the transwell method, and expression of the CBRM1/5 epitope on activated CD11b was analysed by flow cytometry following in vivo and in vitro incubation with chamber fluid or recombinant interleukin‐8 (IL‐8). Leucocyte in vivo and in vitro transmigration both correlated with the concentrations of IL‐1β, tumour necrosis factor alpha (TNFα) and IL‐8 at P < 0.05 (R > 0.7). Furthermore, CD11b was activated, in terms of exposure of the activation epitope, on neutrophils after 30 min of in vitro incubation with chamber fluid and correlated solely with the concentration of IL‐8, P < 0.05 (R = 0.72). In vitro incubation with recombinant IL‐8 confirmed a concentration‐dependent expression of the activation epitope; however, induction of CBRM1/5 by recombinant IL‐8 required a concentration that was significantly higher compared with that in chamber fluid. In addition, the CBRM1/5 epitope was analysed on in vivo extravasated neutrophils that displayed a significantly higher expression compared with circulating neutrophils, P = 0.04. We conclude that IL‐8 is the major factor regulating the expression of CD11b activation epitope in neutrophils.

Leukocyte proliferation and immune modulator production in patients with chronic kidney disease.

Introduction In Chronic Kidney Disease (CKD), immune cells are affected by uremic retention toxins. Given this effect, we analyzed lymphocyte proliferative response and immune modulators production following in vitro stimulation. Methods Whole blood was drawn from healthy controls, patients with eGFR <20 ml/min/1.73 m2 (Pre-dialysis, CKD stages 4 and 5) and hemodialysis patients (stage 5D). Peripheral cells were incubated for six days with pokeweed mitogen, concanavalin A, Staphylococcus enterotoxin A or influenza A vaccine. Peripheral lymphocyte proliferation was then analyzed by the “Flow-cytometric Assay of Specific Cell-mediated Immune response in Activated whole blood” (FASCIA) method, and cytokine profile in the cell supernatants was analyzed by the Milliplex multi-array method. Results The absolute number of lymphoblasts in response to mitogenic stimulation and the number of cells in each CD4+ and CD8+ subpopulation were similar comparing the three groups, except for a single decline in number of lymphoblasts after stimulation with Staphylococcus enterotoxin A, comparing dialysis patients with healthy controls. Levels of interleukin (IL)-2 (p=0.026), -10 (p=0.019) and -15 (p=0.027) in the Staphylococcus enterotoxin A-stimulated supernatant were lower in hemodialysis patients compared to healthy controls. Levels of IL-15 (p=0.017) from pre-dialysis patients and levels of IL-5 (p=0.019) from hemodialysis patients in influenza A vaccine-stimulated supernatants were also lower compared to controls. In pokeweed mitogen–stimulated supernatant, IL-2 levels (p=0.013) were lower in hemodialysis patients compared to pre-dialysis patients. TNF-α, IL-10, IL-12, IL-15, IL-8, MCP-1, IP-10, IFN-α2, IL-1α and eotaxin levels were all significantly higher in plasma obtained from CKD patients. Conclusion Our results suggest that T-cells from CKD patients have similar proliferative response to stimulation compared with healthy individuals. Moreover, however the immune cells show inability to produce selected cytokines, most likely due to the uremic milieu or dialysis procedure.

Neutrophil activation during transmigration in vivo and in vitro: A translational study using the skin chamber model

Neutrophil transmigration can be studied in vitro by use of the transwell model and in vivo by the skin chamber model. Activation during transmigration involves translocation of secretory vesicles and granules to the plasma- and phagolysosome membranes. In this study, we compared the skin chamber model with the transwell model, focusing on the mobilization of CR1 (CD35), CR3 (CD11b/CD18) and CD63 from intracellular vesicles and granules. In addition, functional responses towards a bacterial related stimulus, formyl-methionyl-leucyl-phenylalanine (fMLP), in terms of CR3 expression and production of reactive oxygen species (ROS) were assessed. Discrepancies between the skin chamber model and the transwell model were observed. The expression of CR1 increased following in vivo transmigration (p<0.001) and, in contrast, decreased following in vitro transmigration (p=0.004). Furthermore, CR1 was mobilized following an isolation procedure included in the transwell model. The expression of CR3 increased following both in vivo (p<0.001) and in vitro (p=0.03) transmigration. However, in vitro transmigration did not influence the fMLP induced CR3 expression which was significantly increased following in vivo transmigration (p=0.01). In addition, the fMLP induced production of ROS was significantly reduced following in vitro transmigration (p=0.002) but unaltered after in vivo transmigration, indicating differences between the impact of the two systems on cellular activation. The observed discrepancies between the two models might be partly explained by granule mobilization and neutrophil priming, induced during the isolation procedure included in the transwell model, which results in an altered cellular activation. Therefore, mobilization of granules needs to be accounted for when interpreting data from different model systems.

Monocyte and Neutrophil Chemotactic Activity at the Site of Interstitial Inflammation in Patients on High-Flux Hemodialysis or Hemodiafiltration

Background/Aims: We have observed a difference between patients on low-flux hemodialysis (HD) or peritoneal dialysis and patients on hemodiafiltration (HDF) or high-flux HD in the capacity of transmigrated leukocytes to mobilize CD11b in response to inflammatory stimuli compared with healthy subjects. This could be due to different interstitial chemokine concentrations. Methods: We measured concentrations of circulating and interstitial macrophage inflammatory protein-1α (MIP-1α), matrix metalloproteinase-9 (MMP-9)/neutrophil gelatinase-associated lipocalin (NGAL), monocyte chemoattractant protein-1 (MCP-1) and interleukin-8 (IL-8) in 10 patients on HDF or high-flux HD and 11 healthy subjects by using immunoassay. Results: The interstitial concentrations of MIP-1α, MMP-9/NGAL and IL-8 were similar in patients and healthy subjects, while the corresponding concentration of MCP-1 was significantly higher in patients on HDF or high-flux HD as compared with healthy subjects (p < 0.01). Conclusion: We suggest that an equal or higher concentration of chemokines in the interstitium in patients with HDF or high-flux HD might be one mechanism responsible for the preserved function of transmigrated leukocytes.

Activation of Basophils Is a New and Sensitive Marker of Biocompatibility in Hemodialysis

The hemodialysis procedure involves contact between peripheral blood and the surface of dialyzer membranes, which may lead to alterations in the pathways of innate and adaptive immunity. We aimed to study the effect of blood–membrane interaction on human peripheral basophils and neutrophils in hemodialysis with high- and low-permeability polysulfone dialyzers. The surface expression of CD203c (basophil selection marker) and CD63 (activation marker) after activation by the bacterial peptide formyl-methionyl-leucyl-phenylalanine (fMLP) or anti-Fcε receptor I (FcεRI) antibody and the absolute number of basophils was investigated before and after hemodialysis with each of the dialyzers. Moreover, the expression on neutrophils of CD11b, the CD11b active epitope, and CD88 was analyzed in the same groups of individuals. The expression of CD63 in basophils following activation by fMLP was significantly higher in the patient group compared with that in healthy controls, but no differences were observed after activation by anti-FcεRI. During the hemodialysis procedure, the low-flux membrane induced up-regulation of CD63 expression on basophils, while passage through the high-flux membrane did not significantly alter the responsiveness. In addition, the absolute number of basophils was unchanged after hemodialysis with either of the dialyzers and compared with healthy controls. We found no significant differences in the expression of the neutrophil activation markers (CD11b, the active epitope of CD11b, and CD88) comparing the two different dialyzers before and after dialysis and healthy controls. Together, these findings suggest that alterations in basophil activity may be a useful marker of membrane bioincompatibility in hemodialysis.

In vivo extravasated human monocytes have an altered expression of CD16, HLA-DR, CD86, CD36 and CX(3)CR1.

The phenotypic alterations in monocytes induced by extravasation in vivo are still largely unknown. We addressed the question whether a general phenotype of extravasated monocytes exists and whether this phenotype differs between healthy individuals and statin treated patients with coronary artery disease (CAD). In vivo extravasated monocytes from CAD patients and healthy controls were collected by use of the skin blister method and compared with peripheral circulating monocytes by flow cytometry. The number of CD14+CD16+ monocytes were significantly higher in the skin blister compared with peripheral circulation in both patients (P < 0.001) and controls (P = 0.005). In vivo extravasated monocytes had in comparison with peripheral monocytes a lower expression of CX3CR1, a higher expression of HLA‐DR, CD86 and CD36 and a higher binding of acetylated low density lipoprotein (acLDL) (significant for all markers). Skin blister fluid from CAD patients, compared with healthy controls, induced a 20% increase in monocyte CD36 expression (P = 0.008) following 18 h of in vitro incubation. The results indicate that the integrated response to the in vivo extravasation process is similar in statin treated stable CAD patients and healthy controls, with respect to phenotypic alterations. Such differences in CAD patients may, however, occur as a response to the inflammatory milieu.

In vivo transmigrated monocytes from patients with stable coronary artery disease have a reduced expression of CD11b

Coronary artery disease (CAD) is characterized by infiltration of monocyte derived cells in the intima of the vessel wall. We hypothesized that accumulation of these cells is caused partly by an altered monocyte transmigration process in CAD. To gain insight into this issue we applied the skin blister method that allows collection of in vivo transmigrated cells at sites of local inflammation. Nineteen patients with stable CAD and 19 matched controls were enrolled. Markers of inflammation and gradients of chemokines, as well as adhesion molecule expression and up‐regulation capacity, were studied. The expression of inflammatory markers, such as C‐reactive protein, interleukin (IL)‐6, tumour necrosis factor‐α and IL‐10, was similar in patients and controls, indicating that patients were in a stable phase of the disease. Expression of adhesion molecules, CD11b and very late activation antigen‐4, on peripheral monocytes did not differ between patients and controls. However, following in vivo transmigration, monocytes in patients with CAD had a significantly reduced expression and mobilization of CD11b. The effect on CD11b could not be reproduced by in vitro stimulation with blister fluid, representing a local inflammatory milieu, or in an in vitro system of transmigration. These findings point towards differences in monocyte CD11b expression and availability at an inflammatory site between patients with CAD and healthy controls.