Hemorheological responses to an acute bout of maximal exercise in Veterans with Gulf War Illness.

BACKGROUND: Altered red blood cell (RBC) deformability has been reported in Veterans with Gulf War Illness (GWI) who endorse exercise-induced symptom exacerbation and fatigue. However, it is unknown whether altered RBC deformability is worsened secondary to exercise. OBJECTIVE: To evaluate RBC deformability in response to maximal exercise in individuals with and without GWI. METHODS: Seventeen Veterans with GWI and 11 controls performed maximal exercise and provided blood samples (pre-, immediately post- and 60-min post-exercise). We calculated RBC deformation at infinite stress (EIMAX), shear stress for half-deformation (SS1/2) and their ratio (SS1/2/EIMAX) via repeated measures ANOVA with group and time as factors. RESULTS: A moderate interaction effect (p = 0.08, η2p = 0.10), large main effect for group (p = 0.02, η2p = 0.19) and moderate main effect for time (p = 0.20, η2p = 0.06) were observed for EIMAX, but only the main effect for group reached statistical significance. Changes in SS1/2 and SS1/2/EIMAX over time were similar between cases and controls as were main effects. CONCLUSIONS: Veterans with GWI had more deformable RBCs in comparison to controls that was unaffected by maximal exercise. Future studies to confirm our findings and identify associated mechanisms are warranted.

Abnormal rheological properties of red blood cells as a potential marker of Gulf War Illness: A preliminary study.

BACKGROUND: Veterans with Gulf War Illness (GWI) experience chronic symptoms that include fatigue, pain, and cognitive impairment. This symptom cluster may be the consequence of impaired tissue oxygen delivery due to red blood cell (RBC) dysfunction. OBJECTIVE: The purpose of this preliminary study was to determine whether the microrheological behavior of RBCs is altered in GWI. METHODS: We recruited 17 cases of GWI (GWI+) and 10 age matched controls (GWI-), and examined RBC deformability and aggregation via ektacytometry along with measurement of complete blood counts. RESULTS: RBCs were more deformable in GWI+, as indicated by higher elongation indices particularly at higher shear stress values (5.33, 9.49, and 16.89) when compared to GWI-. Aggregation formation, stability and kinetics were similar between GWI+and GWI-. Complete blood counts were also similar, with the exception of mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), and RBC distribution width (RDW) which was elevated in GWI+. CONCLUSIONS: In this preliminary study, we observed increased deformability along with increased MCH, MCHC and RDW in veterans with GWI+, which may contribute to the symptomatology of GWI. Further research is required to confirm our findings and the role of RBC microrheology in GWI.

Correction: Role of mitochondrial DNA damage and dysfunction in veterans with Gulf War Illness.

[This corrects the article DOI: 10.1371/journal.pone.0184832.].

Role of mitochondrial DNA damage and dysfunction in veterans with Gulf War Illness.

Gulf War Illness (GWI) is a chronic multi-symptom illness not currently diagnosed by standard medical or laboratory test that affects 30% of veterans who served during the 1990-1991 Gulf War. The clinical presentation of GWI is comparable to that of patients with certain mitochondrial disorders-i.e., clinically heterogeneous multisystem symptoms. Therefore, we hypothesized that mitochondrial dysfunction may contribute to both the symptoms of GWI as well as its persistence over time. We recruited 21 cases of GWI (CDC and Kansas criteria) and 7 controls to participate in this study. Peripheral blood samples were obtained in all participants and a quantitative polymerase chain reaction (QPCR) based assay was performed to quantify mitochondrial and nuclear DNA lesion frequency and mitochondrial DNA (mtDNA) copy number (mtDNAcn) from peripheral blood mononuclear cells. Samples were also used to analyze nuclear DNA lesion frequency and enzyme activity for mitochondrial complexes I and IV. Both mtDNA lesion frequency (p = 0.015, d = 1.13) and mtDNAcn (p = 0.001; d = 1.69) were elevated in veterans with GWI relative to controls. Nuclear DNA lesion frequency was also elevated in veterans with GWI (p = 0.344; d = 1.41), but did not reach statistical significance. Complex I and IV activity (p > 0.05) were similar between groups and greater mtDNA lesion frequency was associated with reduced complex I (r2 = -0.35, p = 0.007) and IV (r2 = -0.28, p < 0.01) enzyme activity. In conclusion, veterans with GWI exhibit greater mtDNA damage which is consistent with mitochondrial dysfunction.

Use of an alarm pheromone against ants for gaining access to aphid/scale prey by the red velvet mite Balaustium sp. (Erythraeidae) in a honeydew-rich environment.

This study shows that honeydew prompts arrestment and reduced activity, but not attraction, by the mite Balaustium sp. nr. putmani. When presented with short-range, two-choice bioassays, mites ceased their characteristic rapid crawling activity when they encountered honeydew-treated surfaces, resulting in them clustering around the honeydew. Approximately 80% of mites were retained by honeydew, with responses being independent of both mite life-history stage and source of honeydew (coccid scale insect or aphid). No obvious crawling movements or redirection of running path were made to the honeydew by the mites, implying the lack of any kind of attractant. Response of mites to single-sugar presentations of the main honeydew components--glucose, sucrose, fructose and trehalose--(0.001-0.1 mmol l(-1)) were inconsistent and failed to reproduce the arrestment/clustering associated with raw honeydew, suggesting that none of these sugars is an active arrestant ingredient. Formation of feeding clusters on honeydew does not contribute to enhancing water conservation by suppressing net transpiration (water loss) rates of individual mites as group size increases, indicating that the clustering is an artifact of arrestment. We hypothesize that release of neryl formate by the mites reduces negative interactions with the local ant species commonly associated with honeydew. We hypothesize that honeydew serves as: (1) a cue that facilitates discovery of scale/aphid prey; (2) a retainer on plants where these prey are present, signaling abundance and quality; and (3) an alternative and supplemental food source like that noted for other plant-inhabiting predatory mites. Neryl formate serves as an alarm pheromone and foul-tasting allomonal defense secretion that prevents predation of mites by ants that co-exist with aphid/scale insects in these honeydew-rich habitats.

Alteration of alpha-spectrin ubiquitination after hemorrhagic shock.

BACKGROUND: RBC deformability after trauma and hemorrhagic shock (T/HS) leads to the microcirculatory dysfunction and clinical manifestations of organ failure. However, the cellular mechanism of this phenomenon remains unknown. Spectrins are important for the shape and physical properties of erythrocytes, such as deformability and resistance to mechanical stress. Previous studies have shown that erythrocyte alpha-spectrin is ubiquitinated. Studies of sickled cells and aged erythrocytes, 2 conditions known to have decreased RBC deformability, have shown decreased alpha-spectrin ubiquitination, which may contribute to the inability of these cells to change shape. It was hypothesized that decreased alpha-spectrin ubiquitination could participate in the mechanism(s) whereby T/HS erythrocytes become less deformable. METHODS: The level of alpha-spectrin ubiquitination in erythrocytes isolated from T/HS rats was determined and compared with erythrocytes from control sham-shocked (T/SS) animals. After T/SS (n = 4) or T/HS (n = 7), alpha- and beta-spectrin subunits were isolated using a low ionic-strength buffer at 37 degrees C for 30 minutes. The relative amount of ubiquitinated alpha-spectrin was evaluated by Western blotting using a monoclonal antibody to ubiquitin. RESULTS: The relative level of alpha-spectrin ubiquitination (normalized to total alpha-spectrin in the same preparation) was found to be significantly decreased after T/HS (.319 +/- .03) compared with T/SS control erythrocytes (.485 +/- .06, P < .05). To evaluate the content and relative amounts of the other membrane proteins, the profiles of T/HS and T/SS erythrocytes were compared by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. This did not reveal any significant quantitative differences between T/SS and T/HS spectrin or other membrane proteins. CONCLUSIONS: The finding of decreased alpha-spectrin ubiquitination after T/HS suggests that this mechanism could contribute to increased rigidity of the erythrocyte membrane.

Augmented erythrocyte band-3 phosphorylation in septic mice.

Infection-induced RBC dysfunction has been shown to play a role in the modulation of host response to injury and infection. The underlying biochemical mechanisms are not known. This study investigated alterations in RBC band-3 phosphorylation status and its relationship to anion exchange activity in vitro as well as under in vivo septic conditions induced by cecal ligation and puncture (CLP) in mice. Pervanadate treatment in vitro increased band-3 tyrosine phosphorylation that was accompanied by decreased RBC deformability and anion exchange activity. Following sepsis, band-3 tyrosine phosphorylation in whole RBC ghosts as well as in cytoskeleton-bound or soluble RBC protein fractions were elevated as compared to controls. Although anion exchange activity was similar in RBCs from septic and control animals, band-3 interaction with eosin-5-maleimide (EMA), which binds to band-3 lysine moieties, was increased in cells from septic animals as compared to controls, indicating that sepsis altered band 3 organization within the RBC membrane. Since glucose-6-phosphate dehydrogenase is a major antioxidant enzyme in RBC, in order to assess the potential role of oxidative stress in band-3 tyrosine phosphorylation, sepsis-induced RBC responses were also compared between WT and (G6PD) mutant animals (20% of normal G6PD activity). Band-3 membrane content and EMA staining were elevated in G6PD mutant mice compared to WT under control non-septic conditions. Following sepsis, G6PD mutant animals showed lessened responses in band-3 tyrosine phosphorylation and EMA staining compared to WT. RBC anion exchange activity was similar between mutant and WT animals under all tested conditions. In summary, these studies indicate that sepsis results in elevated band-3 tyrosine phosphorylation and alters band-3 membrane organization without grossly affecting RBC anion exchange activity. The observations also suggest that factors other than oxidative stress are responsible for the sepsis-induced increase in RBC band-3 tyrosine phosphorylation.

Persistent HIF-1alpha activation in gut ischemia/reperfusion injury: potential role of bacteria and lipopolysaccharide.

In both animal models of hemorrhagic shock and clinical settings, shock-induced gut ischemia has been implicated in the development of the systemic inflammatory response syndrome and distant organ injury, yet the factors transducing these events remain to be fully determined. Because hypoxia-inducible factor (HIF-1), a transcription factor composed of oxygen-labile HIF-1alpha and constitutive HIF-1beta subunits, regulates the physiologic/pathophysiologic response to hypoxia and ischemia, we examined the HIF-1 response in two rat models of gut ischemia-reperfusion. We found that ileal nuclear HIF-1alpha protein levels were induced in rats subjected to trauma (laparotomy) plus hemorrhagic shock for 90 min relative to their trauma sham-shock and naïve counterparts and that this trauma hemorrhagic shock-induced mucosal HIF-1alpha protein response persisted after 1 h and 3 h of reperfusion. Likewise, in a model of isolated gut ischemia-reperfusion injury, where the superior mesenteric artery was occluded for 45 min, nuclear HIF-1alpha were induced in the gut mucosa relative to their sham counterparts and persisted after 1 h and 3 h or reperfusion. Similar to the in vivo response, in vitro hypoxia induced HIF-alpha expression in three different enterocyte cell lines (rat IEC-6 and human Caco-2 and HT-29 cell lines). However, in contrast to the in vivo response, HIF-1 expression rapidly disappeared on subsequent reoxygenation. Because in vivo enterocytes are exposed to bacteria, we tested whether the in vitro HIF-1alpha response would persist on reoxygenation if the enterocytes were cocultured with bacteria. P. aeruginosa, an enteric bacterium, markedly induced enterocyte HIF-1alpha protein levels under normoxic conditions. Furthermore, the addition of P. aeruginosa during either the hypoxic or reoxygenation phase prevented the degradation of HIF-1alpha protein levels. Moreover, the observation that lipopolysaccharide induced HIF-1alpha expression in a time-dependent manner in IEC-6 cells indicated that the induction of HIF-1 by exposure to P. aeruginosa is not dependent on bacterial viability. In conclusion, these results suggest that HIF-1alpha activation is an early reperfusion-independent event in models of gut ischemia-reperfusion and that this HIF-1alpha response is potentiated by the presence of P. aeruginosa or lipopolysaccharide.

Red blood cell dysfunction in septic glucose-6-phosphate dehydrogenase-deficient mice.

Glucose-6-phosphate dehydrogenase (G-6-PDH) deficiency is the most common known human genetic polymorphism. This study tested the hypothesis that G-6-PDH deficiency worsens sepsis-induced erythrocyte dysfunction. Sepsis (24 h) was induced by cecal ligation and puncture in wild-type (WT) and G-6-PDH-deficient (G-6-PDH activity 15% of WT) mice. Erythrocyte responses were tested in whole blood as well as in subpopulations of circulating erythrocytes. Whereas erythrocyte deformability was similar in unchallenged deficient and WT animals, sepsis decreased erythrocyte deformability that was more pronounced in deficient than WT animals. Sepsis also resulted in anemia and hemolysis in deficient compared with WT animals. Mean corpuscular hemoglobin content and erythrocyte deformability decreased in younger erythrocyte subpopulations from septic deficient compared with WT animals. Sepsis decreased the reduced-to-oxidized glutathione ratio in erythrocytes from both deficient and WT animals; however, plasma glutathione increased more in deficient than in WT animals. Erythrocyte content of band 3 associated with the cytoskeleton was elevated in deficient compared with WT erythrocytes. The antioxidant N-acetyl-l-cysteine in vivo alleviated the sepsis-induced decrease in erythrocyte deformability in deficient animals compared with sham-operated control animals. This study demonstrates that a mild degree of G-6-PDH deficiency (comparable to the human class III G-6-PDH deficiencies) worsens erythrocyte dysfunction during sepsis. Increased erythrocyte rigidity and tendency for hemolysis together with alterations in band 3-spectrin interactions may contribute to the immunomodulatory effects of G-6-PDH deficiency observed after major trauma and infections in humans.

The septic abscess wall: a cytokine-generating organ associated with portal venous cytokinemia, hepatic outflow fibrosis, sinusoidal congestion, inflammatory cell sequestration, hepatocellular lipid deposition, and focal cell death.

An acute septic inflammatory response with access to the portal circulation was created in a rat model using an intra-abdominal abscess composed of a sterile agar pellet, or one contaminated with 102 Escherichia coli (E. coli) and 109 Bacteriodes fragilis (B. fragilis). After 3 days postimplantation, a well-formed intra-abdominal abscess occurred whose wall showed IL-6 DNA by PCR and IL-6 mRNA by in situ hybridization. Portal venous blood draining into the liver from the intra-abdominal abscess had increased levels of TNF-alpha, IL-1beta, and IL-6 in both sterile and septic groups compared with a control normal animal group. Increased levels of these cytokines were also found in suprahepatic inferior vena caval blood, but were correlated with the higher portal vein levels, suggesting a gradient from abscess wall to portal vein into the systemic circulation via the liver. Liver histology demonstrated sinusoidal congestion centering on the central vein, growing worse with progression from normal in control, to sterile, to septic. Similarly, the degree of intrahepatic myeloperoxidase-positive inflammatory cell infiltration and hepatocellular lipid deposition and apoptosis also increased from control, to sterile, to septic. Gene expression by in situ hybridization demonstrated a significant increase in IL-6 and fibrinogen mRNAs in cells surrounding the central vein in sterile and septic animals, being greatest in animals with sepsis, associated with an increased deposition of collagen in the central vein area, most prominent in the septic liver. The pericentral vein cells with IL-6 and fibrinogen mRNA increases paralleled the increases in cells containing IL-6 and fibrinogen mRNAs in the abscess walls of sterile and septic animals, respectively. The data suggest that an intra-abdominal abscess, especially when contaminated with gram-negative bacteria, induces mRNA-generated cytokine responses in the abscess wall that are related to increased portal venous levels of the inflammatory cytokines TNF-alpha, IL-1beta, and IL-6 perfusing the liver. These, in turn, induce localized production of IL-6 and fibrinogen mRNAs in cells at the central vein area with resultant outflow fibrosis and increased inflammatory cell sequestration within the liver lobular sinuses. This is associated with a generalized inflammatory response and intrahepatic portal sinusoid congestion. There is also increased hepatocellular lipid deposition and apoptosis. Thus, the cytokine production of the abscess wall itself appears to be a major mediator of the septic hepatic response.

Appearance of an erythrocyte population with decreased deformability and hemoglobin content following sepsis.

With the use of the cecal ligation and puncture model in mice, this study tested whether sepsis-induced decreased erythrocyte deformability is restricted to a subpopulation of cells. Erythrocyte subpopulations were isolated by centrifugal elutriation. Lineweaver-Burk conversion of deformability-response curves to shear stress was used to determine the shear stress at half-maximal cell elongation (K(EI)) and maximal cell elongation (EI(max)). Sepsis decreased erythrocyte deformability in whole blood. K(EI) values were elevated (2.7 vs. 2.1 Pa) and EI(max) values decreased (0.56 vs. 0.50) in sepsis compared with sham mice. K(EI) values for cells eluted at 7 ml/min (smallest and oldest cells) were similar; however, K(EI) values for cells eluted at 8 ml/min were greater in septic than sham animals (2.50 vs. 2.10). Younger and larger subpopulations of erythrocytes (eluted at 9, 10, and 11 ml/min) also showed a tendency of decreased deformability in sepsis. Mean corpuscular hemoglobin content was decreased in cells eluted at 7 and 8 ml/min in sepsis (4.5 and 10.2 pg) compared to sham (7.4 and 11.4 pg) mice. This study indicates that an erythrocyte subpopulation that represents 20% of circulating cells shows the most pronounced decrease in cell deformability during sepsis. Increased rigidity together with decreased corpuscular hemoglobin content in these cells may contribute to microcirculatory dysfunction and immune modulation during sepsis.