Chemokines mediate ethanol-induced exacerbations of murine cockroach allergen asthma.

Asthma imposes considerable patient and economic burdens, with the most severe cases causing the greatest affliction. Identifying stimuli that worsen asthma severity is an essential step to controlling both disease morbidity and the lessening economic impact. This study provides the first mechanistic investigation into how acute ethanol exposure will increase asthma severity in a murine model of mild cockroach allergen (CRA)-induced asthma. Outbred mice were sensitized to induce mild allergic asthma, with intratracheal CRA exposures on days 0 and 14. On day 21 mice were gavaged with water or 32% ethanol, and the third allergen exposure was given 30 min post-gavage. Asthmatic responses were measured at several time-points up to 42 h after the third allergen challenge. Ethanol-gavaged mice showed increased asthma severity within 90 min post-allergen challenge, with exacerbations lasting for 24 h. Ethanol caused greater airways obstruction, including an eightfold increase in epithelial cell mucin and increased mucus plugs, resulting in a 50% reduction in bronchiole patency. Ethanol gavage also induced significant increases in airways hyperreactivity. While T helper type 1 (Th1) and Th2 cytokines were not altered by ethanol gavage, pulmonary neutrophil and eosinophil recruitment were augmented. This increase was associated with increased chemokine production. Administration 2 h prior to ethanol gavage of a neutralizing antibody cocktail to keratinocyte-derived chemokine, macrophage inflammatory protein-2, eotaxin-1 and eotaxin-2 prevented ethanol-induced eosinophil recruitment and airways hyperreactivity. These data provide evidence that acute alcohol exposure immediately prior to a mild allergen-triggered asthmatic episode will exacerbate asthma severity mediated by increased production of chemokines.

Febrile reactions occurring with second cycle of high-dose melphalan and SCT in patients with AL amyloidosis: a 'melphalan recall' reaction.

Aggressive treatment with high-dose i.v. melphalan followed by auto-SCT (HDM/SCT) is effective in inducing hematological and clinical remissions, and in extending survival in AL amyloidosis. Tandem cycles of HDM/SCT have been shown to increase hematologic complete response rates in patients with AL amyloidosis. Between April 1994 and July 2008, 57 patients with AL amyloidosis at the Boston University Medical Center were treated with a second cycle of HDM/SCT after failing to achieve a complete response after a first transplantation. A total of 11 of 57 patients (19%) treated with tandem transplantation developed high fever 12-24 h after melphalan administration. The average peak temperature was 39.1 degrees C. Other clinical features include hypotension, acute renal failure and skin rash. No infectious etiology was identified. One of the patients had serum available for measurement of cytokines before, during and after the febrile reaction. The concentration of several pro-inflammatory cytokines, including IL-6 and TNFalpha, increased significantly, showing a clear physiological response correlating with the clinical findings. We conclude that an unusual cytokine-mediated febrile reaction can occur in patients with AL amyloidosis exposed to a second cycle of high-dose melphalan, which we have termed a 'melphalan recall' reaction.

Anti-tumor necrosis factor-alpha antibody treatment reduces pulmonary inflammation and methacholine hyper-responsiveness in a murine asthma model induced by house dust.

BACKGROUND/AIMS: Recent studies documented that sensitization and exposure to cockroach allergens significantly increase children's asthma morbidity as well as severity, especially among inner city children. TNF-alpha has been postulated to be a critical mediator directly contributing to the bronchopulmonary inflammation and airway hyper-responsiveness in asthma. This study investigated whether an anti-TNF-alpha antibody would inhibit pulmonary inflammation and methacholine (Mch) hyper-responsiveness in a mouse model of asthma induced by a house dust extract containing both endotoxin and cockroach allergens. METHODS: A house dust sample was extracted with phosphate-buffered saline and then used for immunization and two additional pulmonary challenges of BALB/c mice. Mice were treated with an intravenous injection of anti-TNF-alpha antibody or control antibody 1 h before each pulmonary challenge. RESULTS: In a kinetic study, TNF-alpha levels within the bronchoalveolar lavage (BAL) fluid increased quickly peaking at 2 h while BAL levels of IL-4, IL-5, and IL-13 peaked at later time-points. Mch hyper-responsiveness was measured 24 h after the last challenge, and mice were killed 24 h later. TNF inhibition resulted in an augmentation of these Th2 cytokines. However, the allergic pulmonary inflammation was significantly reduced by anti-TNF-alpha antibody treatment as demonstrated by a substantial reduction in the number of BAL eosinophils, lymphocytes, macrophages, and neutrophils compared with rat IgG-treated mice. Mch hyper-responsiveness was also significantly reduced in anti-TNF-alpha antibody-treated mice and the pulmonary histology was also significantly improved. Inhibition of TNF significantly reduced eotaxin levels within the lung, suggesting a potential mechanism for the beneficial effects. These data indicate that anti-TNF-alpha antibody can reduce the inflammation and pathophysiology of asthma in a murine model of asthma induced by a house dust extract.

Endothelial barrier dysfunction caused by LPS correlates with phosphorylation of HSP27 in vivo.

Lung edema during sepsis is triggered by formation of gaps between endothelial cells followed by macrophage infiltration. Endothelial gap formation has been proposed to involve changes in the structure of the actin filament cytoskeleton. Heat shock protein 27 (HSP27) is believed to modulate actin filament dynamics or structure, in a manner dependent on its phosphorylation status. We hypothesized that HSP27 may play a role in endothelial gap formation, by affecting actin dependent events in endothelial cells. As there has been no report concerning HSP27 in lung edema in vivo, we examined induction and phosphorylation of HSP27 in lung following LPS injection, as a model of sepsis. In lung, HSP27 mainly localized in capillary endothelial cells of the alveolus, and in smooth muscle cells of pulmonary arteries. HSP27 became significantly more phosphorylated at 3 h after LPS treatment, while the distribution of HSP27 remained unchanged. Pre-treatment with anti-TNFalpha antibody, which has been shown to reduce lung injury, blocked increases in HSP27 phosphorylation at 3 h. HSP27 phosphorylation was also increased in cultured rat pulmonary arterial endothelial cells (RPAEC) by treatment with TNFalpha, LPS, or H2O2. This phosphorylation was blocked by pre-treatment with SB203580, an inhibitor of the upstream kinase, p38 MAP kinase. Increased endothelial permeability caused by H2O2 in vitro was also blocked by SB203580. The amount of actin associated with HSP27 was reduced after treatment with LPS, or H2O2. In summary, HSP27 phosphorylation temporally correlated with LPS induced pathological endothelial cell gap formation in vivo and in a cell culture model system. This is the first report of increased HSP27 phosphorylation associated with pathological lung injury in an animal model of sepsis.

Reproducibility of a novel model of murine asthma-like pulmonary inflammation.

Sensitization to cockroach allergens (CRA) has been implicated as a major cause of asthma, especially among inner-city populations. Endotoxin from Gram-negative bacteria has also been investigated for its role in attenuating or exacerbating the asthmatic response. We have created a novel model utilizing house dust extract (HDE) containing high levels of both CRA and endotoxin to induce pulmonary inflammation (PI) and airway hyperresponsiveness (AHR). A potential drawback of this model is that the HDE is in limited supply and preparation of new HDE will not contain the exact components of the HDE used to define our model system. The present study involved testing HDEs collected from various homes for their ability to cause PI and AHR. Dust collected from five homes was extracted in phosphate buffered saline overnight. The levels of CRA and endotoxin in the supernatants varied from 7.1 to 49.5 mg/ml of CRA and 1.7-6 micro g/ml of endotoxin in the HDEs. Following immunization and two pulmonary exposures to HDE all five HDEs induced AHR, PI and plasma IgE levels substantially higher than normal mice. This study shows that HDE containing high levels of cockroach allergens and endotoxin collected from different sources can induce an asthma-like response in our murine model.

Neutralization of Gro alpha and macrophage inflammatory protein-2 attenuates renal ischemia/reperfusion injury.

Previous studies have provided strong evidence for a role for neutrophils in mediating pathology during reperfusion of ischemic tissues. CXC chemokines including interleukin-8, KC/Gro alpha, and macrophage inflammatory protein (MIP)-2, direct neutrophils to tissue sites of inflammation. In the current study we tested the efficacy of antibodies to KC/Gro alpha and MIP-2 in inhibiting neutrophil infiltration into kidneys during reperfusion after 1 hour of warm ischemia using a mouse model. KC mRNA and protein were produced within 3 hours after reperfusion of the ischemic kidneys. MIP-2 mRNA and protein were twofold to fourfold lower than KC and were at low levels until 9 hours after reperfusion. Only 60% of mice subjected to ischemia/reperfusion injury survived to day 3 after reperfusion. Treatment with rabbit neutralizing antibodies to both KC and MIP-2 inhibited neutrophil infiltration into ischemic kidneys during reperfusion, restored renal function as assessed by decreased serum creatinine and urea nitrogen levels to near normal levels, and resulted in complete survival of treated animals. Finally, treatment with both antibodies significantly reduced histologically graded pathology of kidneys subjected to ischemia/reperfusion injury. Collectively, the results indicate the efficacy of neutralizing the chemokines directing neutrophils into ischemic kidneys during reperfusion to inhibit this infiltration and attenuate the resulting pathology.

Differences in normal values for murine white blood cell counts and other hematological parameters based on sampling site.

OBJECTIVE AND DESIGN: The effect of blood sampling site on the hemogram and neutrophil adhesion molecules was examined in BALB/c mice. MATERIALS AND METHODS: Blood samples were drawn from the tail, eye, and heart during anesthesia with ketamine and xylazine. Cell numbers were quantified with an automated counter and flow cytometry was used to quantify CD11b and CD18. RESULTS: Total white blood cell (WBC) counts were highest from tail, lower from eye, and significantly lower from heart blood. In general, differences between tail and heart counts reflected changes in all cell types. RBCs, platelets and hematocrits were significantly increased in tail compared to heart blood. Although CD18 levels were not different, CD11b was significantly higher on neutrophils from tail compared to heart blood. CONCLUSIONS: In anesthetized BALB/c mice, sampling site readily influences blood counts and neutrophil CD11b. The findings underscore the need to standardize sampling site when measuring these parameters.

CXC chemokine redundancy ensures local neutrophil recruitment during acute inflammation.

Previous publications demonstrated that elevated systemic levels of interleukin (IL)-8 decrease local neutrophil recruitment. We tested whether sustained, high plasma levels of IL-8 would prevent local inflammation after inflammatory insults. Mice carrying the transgene for human IL-8 were separated on the basis of their plasma levels of IL-8 into IL-8-positive (plasma levels >90 ng/ml) and IL-8-negative (IL-8 below detection). Presence of the IL-8 transgene did not improve survival or morbidity nor did it alter peritoneal neutrophil recruitment induced by the cecal ligation and puncture model of sepsis. In an acute lung injury model created by intratracheal injection of acid, IL-8-positive mice showed no reduction in alveolar neutrophil recruitment. There was no difference in the local recruitment of neutrophils when either thioglycollate or glycogen was injected intraperitoneally. We examined the chemotactic response to murine chemokines to test how neutrophil recruitment occurs in the setting of elevated plasma IL-8 and found that neutrophils from both IL-8-positive and -negative mice respond equally well to recombinant KC or macrophage inflammatory protein (MIP)-2. We measured KC and MIP-2 in the peritoneum after thioglycollate injection and demonstrated that IL-8-positive mice have significantly higher levels of the chemokines compared to the IL-8-negative mice. Antibody inhibition of KC and MIP-2 in the IL-8-positive mice significantly decreased peritoneal neutrophil recruitment in response to thioglycollate, clarifying their important role in the local neutrophil recruitment. Our data demonstrate that despite the presence of high plasma levels of IL-8, neutrophils may still be recruited to sites of local inflammation because of chemokine redundancy.

Eotaxin represents the principal eosinophil chemoattractant in a novel murine asthma model induced by house dust containing cockroach allergens.

Asthma represents a serious health problem particularly for inner city children, and recent studies have identified that cockroach allergens trigger many of these asthmatic attacks. This study tested the concept that asthma-like pulmonary inflammation may be induced by house dust containing cockroach allergens. An aqueous extract was prepared from a house dust sample containing endotoxin and high levels of cockroach allergens. BALB/c mice were immunized with the house dust extract (HDE) and received two additional pulmonary challenges. Bronchoalveolar lavage (BAL) eosinophil counts and eotaxin levels were significantly increased in immunized mice exposed to the HDE, whereas neutrophils were the predominant BAL inflammatory cell in the unimmunized mice. Kinetics studies in immunized mice demonstrated a peak pulmonary inflammatory response 48 h after the last challenge. The allergic response in this model was further confirmed by histological and physiological studies demonstrating a significant influx of eosinophils and lymphocytes in the peribronchial area, and severe airway hyperreactivity through whole-body plethysmography. The specificity of the response was established by immunizing with HDE and challenging with purified cockroach allergen, which induced pulmonary eosinophilia and airway hyperreactivity. Ab inhibition of eotaxin significantly inhibited the number of BAL eosinophils. These data describe a novel murine model of asthma-like pulmonary inflammation induced by house dust containing endotoxin and cockroach allergens and further demonstrate that eotaxin represents the principal chemoattractant for the recruitment of the pulmonary eosinophils.

Early chemokine cascades in murine cardiac grafts regulate T cell recruitment and progression of acute allograft rejection.

The identification of early inflammatory events after transplant in solid tissue organ grafts that may direct T cell recruitment and promote acute allograft rejection remain largely unknown. To better understand temporal aspects of early inflammatory events in vascularized organ grafts, we tested the intragraft expression of four different chemokines in heterotopically transplanted A/J (H-2(a)) and syngeneic heart grafts in C57BL/6 (H-2(b)) recipient mice from 1.5 to 48 h after transplant. Similar temporal expression patterns and equivalent levels of chemokine expression were observed in both syngeneic and allogeneic cardiac allografts during this time period. Expression of the neutrophil chemoattractant growth-related oncogene alpha (KC) was observed first and reached peak levels by 6 h after transplant and was followed by the monocyte/macrophage chemoattractant protein-1 (JE) and then macrophage inflammatory proteins 1beta and 1alpha. Administration of rabbit KC antiserum to allograft recipients within 30 min of cardiac transplantation attenuated downstream events including intra-allograft expression of the T cell chemoattractants IFN-gamma-inducible protein-10 and monokine induced by IFN-gamma, cellular infiltration into the allograft, and graft rejection. Similarly, depletion of recipient neutrophils at the time of transplantation significantly extended allograft survival from day 8 to 10 in control-treated recipients up to day 21 after transplant. These results indicate the induction of highly organized cascades of neutrophil and macrophage chemoattractants in cardiac grafts and support the proposal that early inflammatory events are required for optimal recruitment of T cells into allografts during the progression of acute rejection of cardiac allografts.

Development and optimization of cytokine ELISAs using commercial antibody pairs.

The measurement of cytokines in plasma and other fluids often requires the use of an enzyme-linked immunosorbant assay (ELISA). In the research environment, a valuable assay is one that yields reliable results in the shortest amount of time for the least cost. To achieve this goal, a protocol has been outlined to develop sandwich ELISAs for cytokines using commercial antibodies. These guidelines for ELISA development include selecting antibody concentrations, choosing an appropriate buffer, reducing plasma interference and evaluating the optimal length for incubation periods. In addition, the protocol for a rapid IL-6 ELISA is presented. This ELISA allows measurement of IL-6 in a reduced amount of time by raising the concentration of antibodies used and increasing the temperature for incubation. By following the guidelines presented, cost-effective, cytokine ELISAs can be developed that yield low background, detect a wide range of concentrations, and are suitable for use in the research setting.

Protegrin-1 enhances bacterial killing in thermally injured skin.

OBJECTIVE: Septic complications and the emergence of drug-resistant microbes represent serious risks to patients. Recently, naturally occurring peptides have been discovered that possess potent and broad-spectrum antimicrobial activity. Protegrin-1 is particularly attractive for clinical use in human wounds because, unlike defensins, protegrin-1 retains broad antimicrobial and antifungal activity at physiologic salt concentration and in the presence of serum. The objective of this study was to examine the efficacy of protegrin-1 in killing multiple drug-resistant microbes isolated from human burn patients. DESIGN: For thein vitroexperiment, bilayer radial diffusion was performed comparing standard antibiotics with protegrin-1 on multiple-drug-resistant microbial organisms isolated from infected burn wounds. In vivo, rats received a 20% total body surface area partial-thickness burn by immersion in 60 degrees C water for 20 secs followed by wound seeding with 106 colony forming units of Silvadene-resistant Pseudomonas aeruginosa. SETTING: University of Michigan research laboratory. SUBJECTS: Adult, male Sprague-Dawley rats. INTERVENTIONS: Rats were randomized into three groups: those receiving synthetic protegrin-1, acetic acid (carrier), or gentamicin (positive control). Protegrin-1 was administered by topical application or intradermal injection. Wound tissues were harvested aseptically at different time points for quantitative bacterial counts. MEASUREMENTS AND MAIN RESULTS: In vivo and in vitro experiments revealed rapid and significant decreases in bacterial counts for protegrin-1-treated groups compared with controls. CONCLUSIONS: This study shows that protegrin-1 potentially may be used as an alternative or adjunct therapy to standard agents used to treat wound infections.

Combination immunotherapy with soluble tumor necrosis factor receptors plus interleukin 1 receptor antagonist decreases sepsis mortality.

OBJECTIVE: Inhibition of tumor necrosis factor (TNF) or interleukin 1 (IL-1) alone has not improved sepsis survival in human clinical trials; therefore, it has been suggested that blockade of both may be successful. We tested whether combination immunotherapy would improve survival in mice subjected to a lethal lipopolysaccharide (LPS) challenge or the sepsis model of cecal ligation and puncture. DESIGN: Mice were treated with the combination immunotherapy and challenged with either a lethal dose of lipopolysaccharide or a septic challenge induced by cecal ligation and puncture. SETTING: University research laboratory. SUBJECTS: Adult, female Balb/c mice. INTERVENTIONS: Mice were treated with the combination of the IL-1 receptor antagonist plus a polyethylene glycol-linked dimer of the TNF soluble receptor. MEASUREMENTS AND MAIN RESULTS: LPS lethality was reduced in the treated mice with a decrease in biologically active TNF in the plasma and peritoneal fluid. In the cecal ligation and puncture (CLP) model of sepsis, this combination immunotherapy for 1 day decreased plasma and peritoneal levels of IL-6 and the murine chemokines KC and MIP-2. However, treatment did not result in a reduction in the hypothermia or peripheral blood alterations that occur after CLP, and the 1-day therapy did not result in an improvement in survival. In contrast, when combination immunotherapy was extended to 3 days there was a significant improvement in survival. CONCLUSIONS: These data demonstrate that inhibition of both TNF and IL-1 will decrease the lethality of sepsis initiated by CLP if the combination immunotherapy is provided for a sufficient amount of time.

Differential local and systemic regulation of the murine chemokines KC and MIP2.

We characterized the relative biological activity and expression of two murine chemokines that may serve as functional homologues for human IL-8, KC, and macrophage inflammatory protein 2 (MIP2). Recombinant chemokines were produced in bacterial expression systems and antibodies specific for KC or MIP2 were raised. In vitro assays showed that KC elicited 4-fold greater neutrophil chemotaxis compared with MIP2, while MIP2 elicited significantly greater release of elastase. Lipopolysaccharide- (LPS) stimulated macrophages (8 h) secreted more MIP2 (approximately 10 ng/mL) compared with KC (approximately 4 ng/ml) and expression of either murine chemokine was independent of TNFalpha or IL-1beta production. Thioglycollate (thio) and glycogen (gly) induced peritonitis produced more KC (thio = 7.1 and gly = 2.5 ng/mL) in the peritoneum compared with MIP2 (thio = 4.5 and gly = 0.3 ng/mL). Plasma KC levels were very high after either challenge (approximately 24 ng/mL), which was >50-fold more than the systemic increase in MIP2 (approximately 0.3 ng/mL). Our data demonstrate that while KC and MIP2 have similar in vitro production characteristics, KC appears to be a more potent and systemically distributed chemokine during acute in vivo inflammation, while MIP2 expression appears limited to localized expression.

Feasibility of biolistic gene therapy in burns.

Skin is an especially attractive target for genetic manipulation because it is readily accessible and easily monitored for both the presence and the expression of inserted genes. This study was designed to assess the feasibility of particle mediated gene transfer to burned skin and to compare the transfection efficiency, anatomic distribution, and duration of transgene expression achievable in normal versus burned skin. Two days following scald injury of varying depths in 60 degrees C water (10 s: superficial partial; 20 s: deep partial; 40 s: full thickness) reporter gene (beta-galactosidase) constructs were delivered using a gene gun at various helium pressures (200-600 psi) to normal and burned skin. A time course study was performed to examine the kinetics of transgene expression. Animals received a superficial partial thickness burn and were sacrificed 12 h, 1, 3, 5, 7, 14, or 21 days after gene transfer. India Ink injection and immunohistochemistry were used to assess the depth of the scald injury. Transfection efficiency was measured in skin homogenates 24 h after gene transfer by morphometric and chemoluminescent assays. We found that the extent of tissue damage was directly related to the duration of heat source exposure. Reporter gene activity was significantly higher in superficial partial thickness burns compared to normal controls and gradually declined with increasing tissue injury. No activity was seen in the full thickness burn group. Beta-galactosidase activity reached a maximum level 12 h after gene transfer in both normal and superficial partial thickness burned skin with no levels seen after 5 days post-transfection. These findings indicate that particle-mediated gene transfer in thermally injured skin is feasible and may provide a means of introducing biologic agents into injured tissue capable of enhancing bacterial clearance and improving wound healing.

Critical role of CD14 for production of proinflammatory cytokines and cytokine inhibitors during sepsis with failure to alter morbidity or mortality.

We investigated the immunopathophysiologic responses during sepsis induced by cecal ligation and puncture (CLP) in CD4-deficient (CD14 knockout [CD14KO]) mice. Our studies were designed to specifically test the role of CD14 in the inflammatory response to sepsis and to ascertain if alterations would improve morbidity or mortality. Sepsis was induced using the CLP model with appropriate antibiotic treatment. The severity of sepsis increased in the CD14KO mice with increasing puncture size (18 gauge [18G], 21G, and 25G). Following CLP, body temperature (at 12 h) and gross motor activity levels of the sham and 25G CLP groups recovered to normal, while the 21G and 18G CLP groups exhibited severe hypothermia coupled with decreased gross motor activity and body weight. There were no significant differences in survival, temperature, body weight, or activity levels between CD14KO and control mice after 21G CLP. However, CD14KO mice expressed two- to fourfold less pro-inflammatory (interleukin-1beta [IL-1beta], tumor necrosis factor [TNF], and IL-6) and anti-inflammatory (IL-10, IL-1 receptor antagonist, and TNF receptors I and II) cytokines in the blood after 21G CLP. Plasma levels of the chemokines macrophage inflammatory protein 2alpha and KC were similarly reduced in CD14KO mice. A similar trend of decreased cytokine and cytokine inhibitor levels was observed in the peritoneal cavity of CD14KO mice. Our results indicate that the CD14 pathway of activation plays a critical role in the production of both pro-inflammatory cytokines and cytokine inhibitors but has minimal impact on the morbidity or mortality induced by the CLP model of sepsis.

Under-resuscitation of near-lethal uncontrolled hemorrhage: effects on mortality and end-organ function at 72 hours.

Laboratory studies of uncontrolled hemorrhage demonstrate that under resuscitation (UR) improves short-term survival, but at the expense of tissue perfusion. The long-term effects of UR have not been studied. The purpose of this study was to evaluate survival and the incidence of end-organ injury (EOI), 3 days following moderate and severe UR of uncontrolled hemorrhage. Thirty-four swine (14-24 kg) were assigned to 4 groups: Groups I, II, and III were hemorrhaged to a pulse pressure = 5 mmHg in the presence of a 4-mm aortic tear: Group I (control; n = 6) was not resuscitated; Group II (n = 11) was severely under resuscitated (MAP [mean arterial pressure] = 40 mmHg) for 75 min; Group III (n = 9) was moderately under resuscitated (MAP = 60 mmHg) for 75 min. After 75 min, the aortotomy was repaired, and animals were resuscitated to baseline physiologic parameters. Group IV (sham; n = 8) was instrumented, but not hemorrhaged. Seventy-two-hour mortality was 100%, 36%, 22%, and 0% for Groups I through IV (P = .001 Fisher's exact). Cardiac indices, serum bicarbonate, and systemic oxygen delivery were significantly lower in Group II as compared to Group III during the 75 min of UR (P < 0.05; repeated measures ANOVA). By 72 h, physiologic parameters in surviving animals had returned to baseline levels. Measures of kidney, liver, neurologic, and pulmonary function did not change from baseline. There was no histologic evidence of EOI. In this model, 75 min of UR did not result in EOI. There was a trend toward greater survival, and tissue perfusion was better preserved with moderate as compared to severe UR.

Ratio of local to systemic chemokine concentrations regulates neutrophil recruitment.

CXC chemokines are important regulators of local neutrophil recruitment. In this study, we examined the role of the ratio of local to systemic chemokine concentrations as a significant factor determining local neutrophil recruitment. Thioglycollate was injected intraperitoneally into BALB/c mice resulting in a dose-dependent increase in neutrophil recruitment and local inflammation, as measured by peritoneal levels of interleukin 6. At the high dose of 3% thioglycollate, antibody inhibition of the murine chemokines KC and macrophage inflammatory protein-2 caused a reduction in peritoneal neutrophil recruitment by as much as 93%. A paradoxical effect was observed with a 0.3% thioglycollate intraperitoneal challenge. In this situation, inhibition of KC resulted in a significant increase in peritoneal neutrophils, and inhibition of macrophage inflammatory protein-2 also resulted in increased peritoneal neutrophils. These results were consistent with a reverse chemotactic gradient as described by the ratio of peritoneal to plasma KC levels. A higher ratio (ie, increased peritoneal chemokines compared to plasma) resulted in increased neutrophil recruitment after either the 3% or 0.3% thioglycollate challenge. Our results demonstrate that whereas sufficient local concentrations of chemokines are necessary, a critical factor dictating local neutrophil recruitment is the ratio of the local to the systemic chemokine concentrations.

Interleukin-8 levels and activity in delayed-healing human thermal wounds.

There are numerous causes for slow or delayed wound healing. Because slowly healing wounds are often inflamed, we quantitated the inflammatory chemokine, interleukin-8, produced by slowly healing human burn wounds and compared this to interleukin-8 from healed wounds and normal intact skin. Interleukin-8 levels were increased significantly in unhealed wounds (19.7 ng/ml) compared to healed wounds (7.7 ng/ml) or normal skin (5.7 ng/ml). Interleukin-8 in these ranges was added to adult human keratinocytes and fibroblasts. Interleukin-8 significantly decreased keratinocyte replication but had no effect on fibroblast replication. The rate or final degree of fibroblast populated collagen lattice contraction was inhibited at interleukin-8 concentrations between 10 and 30 ng/ml, but not altered at concentrations below 10 ng/ml and above 100 ng/ml. The concurrent application of indomethacin at 10 microg/ml reversed this interleukin-8 induced inhibition. Interleukin-8 inhibited myosin ATPase activity, apparently by reducing the phosphorylation of nonmuscle myosin light chain. We conclude that elevated levels of interleukin-8 may be found during delayed healing, and these elevated interleukin-8 levels may directly contribute to retarded wound closure.