Chemokines as mediators of diseases related to surgical conditions

IL-1 regulates in vivo C—X—C chemokine induction and neutrophil sequestration following endotoxemia

The influx of neutrophils into tissues in response to inflammatory stimuli involves C—X—C chemokines. Interleukin-1 (IL-1) stimulates chemokine production in vitro , but its role in vivo on chemokine production is not as clearly understood. We hypothesized that IL-1 mediates in vivo tissue C—X—C chemokine production induced by systemic lipopolysaccharide (LPS). IL-1 activity was blockedbyIL-1 receptor antagonist (IL-1Ra). Rats were injected with Salmonella typhi LPS (0.5 mg/kg) with and without prior administration of IL-1Ra. Cytokine-induced neutrophil chemoattractant-1 (CINC-1) and macrophage inflammatory protein-2 (MIP-2) protein and mRNA levels, tissue neutrophil accumulation, and indices of organ injury were measured. LPS administration resulted in increased plasma, lung, and liver IL-1β that was decreased by IL-1Ra. LPS also induced an increase in plasma, lung, and liver CINC-1 and MIP-2 protein and mRNA. However, IL-1Ra had no effect on LPS-induced plasma or lung tissue CINC-1 levels. In contrast, IL-1Ra pretreatment did significantly decrease CINC-1 protein expression in the liver (45% decrease) and MIP-2 protein expression in plasma (100% decrease), lung (72% decrease) and liver (100% decrease) compared to LPS-treated controls. Steady-state mRNA levels by Northern blot analysis of both CINC-1 and MIP-2 in lung and liver were similar to the protein findings. Pretreatment with IL-1Ra also resulted in a 47% and 59% decrease in lung and liver neutrophil accumulation, respectively, following LPS. In addition, indices of both lung and liver injury were decreased in animals pretreated with IL-1Ra. In summary, LPS induces IL-1β and MIP-2 expression in the lung and liver, both of which are IL-1 dependent. Although lung neutrophil accumulation in both lung and liver after LPS is also IL-1 mediated, lung CINC-1 levels were unaffected by IL-1Ra. These data suggest that IL-1 regulates tissue chemokine expression and neutrophil accumulation after LPS.

Chemokine upregulation in response to anal sphincter and pudendal nerve injury: potential signals for stem cell homing

PURPOSE

Stromal derived factor-1 (SDF-1) and monocyte chemotactic protein-3 (MCP-3) are signals forcing the migration of bone marrow-derived stem cells to ischemic tissue. This study investigates SDF-1 and MCP-3 expression following direct injury to the anal sphincter and pudendal nerve and to determine if these same mechanisms have any role.

METHODS

Chemokine expression was studied after anal sphincter injury in female rats after either a sphincterotomy (n = 15), pudendal nerve crush (PNC; n = 15), sham pudendal nerve crush (n = 15), or acted as unmanipulated controls (n = 5). Analysis was done at 1 h and 10 and 21 days after injury.

RESULTS

After injury, SDF-1 expression increased 40.2 ± 6.42 (P = 0.01) at 1 h and 28.2 ± 2.37 (P = 0.01) at 10 days, respectively, compared to controls. Likewise, MCP-3 expression increased 40.8 ± 8.17 (P = 0.02) at the same intervals compared to controls. After PNC, SDF-1 expression increased 46.4 ± 6.01 (P = 0.02) and 50.6 ± 10.11 (P = 0.01), and MCP-3 expression increased 46.3 ± 7.76 (P = 0.03) and 190.8 ± 22.15 (P = 0.01), respectively, at the same time intervals compared to controls. However, when PNC was compared to sham injured, a significant increase was seen in SDF-1 and MCP-3 at 10 days. At 21 days, PNC compared to sham injured was significantly low in expression for both SDF-1 and MCP-3 (P < 0.05).

CONCLUSIONS

Direct anal sphincter injury results in higher levels of SDF-1 and MCP-3 expression soon after injury, whereas denervation via pudendal nerve crush results in greater SDF-1 and MCP-3 expression 10 days after injury. Chemokine overexpression suggests the potential for cell-based therapeutic strategies.

Suppression of Perfluoroisobutylene Induced Acute Lung Injury by Pretreatment with Pyrrolidine Dithiocarbamate

Perfluoroisobutylene (PFIB) is produced as a main by-product in large quantities by the fluoropolymer industry. As a highly toxic compound, even the case of brief inhalation of PFIB can result in acute lung injury (ALI), pulmonary edema and even death. To test for any preventive or therapeutic effects of pyrrolidine dithiocarbamate (PDTC), a NF-kappaB activation inhibitor, against PFIB inhalation-induced ALI, mice were exposed in a flow-past exposure system to PFIB and the prophylactic and therapeutic effects of PDTC were studied. The inhibitory effects of PDTC on ALI, the activation of NF-kappaB, as well as the expression of cytokines (IL-1beta and IL-8) after PFIB exposure were evaluated. The results demonstrated that pretreatment with PDTC (120 mg/kg, 30 min before PFIB exposure) could significantly lower the lung coefficient (wet lung-to-body weight ratio, dry lung-to-body weight ratio, water content in the lung, and lung wet-to-dry weight ratio) and protein content in bronchoalveolar lavage fluid (BALF), but no effects of PDTC were found when PDTC was treated after PFIB inhalation, suggesting a preventative effect rather than a therapeutic effect of PDTC. Furthermore, the above preventative effects of PDTC (when given at 30 min before PFIB exposure) on PFIB-induced lung injury were achieved in a dose-dependent manner. In support of these preventive effects of PDTC, our toxicological studies demonstrated that PFIB-inhalation induced a quick activation of NF-kappaB (0.5 h post PFIB exposure) and expression of IL-1beta and IL-8 (0.5 h and 1 h post PFIB exposure, respectively). Pretreatment with PDTC (120 mg/kg, 30 min before PFIB exposure) resulted in a significant inhibitive effect on the activation of NF-kappaB (0.5 h post PFIB exposure) and expression of IL-1beta and IL-8 (1 h post PFIB exposure). The mortality, the extent of lung injury of the mice indexed by lung coefficients, the content of total protein and albumin in BALF, as well as the lung histopathologic changes, were dramatically alleviated in PFIB exposure after pretreatment with PDTC, clearly suggesting that PDTC has a prophylactic role against PFIB inhalation-induced ALI, and that NF-kappaB activation might play a central role in initiating an acute inflammatory response and in causing injury to the lungs after PFIB inhalation.

CXC-chemokine stimulation of neutrophils correlates with plasma levels of myeloperoxidase and lactoferrin and contributes to clinical outcome after pediatric cardiac surgery

Several CXC-chemokines, of which interleukin (IL)-8 is the prototype, are potent neutrophil chemotactic and activating cytokines, inducing the secretion of granule proteins and the generation of reactive oxygen intermediates that may cause tissue damage and amplify inflammatory responses. Here, we investigated whether chemokines play a key role in the inflammatory process following cardiac surgery with cardiopulmonary bypass (CPB) in children. We performed an observational prospective clinical study of 40 pediatric patients before, during, and after open heart surgery with CPB. Plasma levels of chemokines, myeloperoxidase (MPO), and lactoferrin were measured by immunoassays. Cell surface receptors were detected by flow cytometry. Plasma levels of IL-8 were increased after CPB, correlating strongly with a reduction of expression of the CXC-chemokine receptors (CXCR) 1 and 2 on neutrophils indicating in vivo activation of neutrophils by IL-8. Other CXC-chemokines with Glu-Leu-Arg motif showed no correlation with CXCR1 or CXCR2 expression. Two components of neutrophilic granules, MPO and lactoferrin, were strongly elevated postoperatively, and the levels of both were correlated with IL-8. Levels of monocyte chemoattractant protein (MCP)-1 were increased postoperatively, correlating with a reduction of CCR2 expression and an increase of CD11b expression on monocytes, suggesting monocyte activation by MCP-1. The early postoperative course was complicated in patients with an increase of these inflammatory parameters. Impaired cardiovascular function correlated with increased levels of IL-8 and activation of neutrophils and was most prominent in patients with a long time on CPB and in those with cyanotic heart lesions. In conclusion, MCP-1 is involved in the regulation of chemotaxis and function of monocytes during and early after the end of CPB. Activation of neutrophils and down-regulation of CXCR1 and CXCR2 were predominantly caused by IL-8. This activation implies release of components of neutrophilic granules and correlates with the need for inotropic support.

RECOMBINANT HUMAN ERYTHROPOIETIN STIMULATES ANGIOGENESIS AND HEALING OF ISCHEMIC SKIN WOUNDS

Wound healing in ischemic tissues such as flap margins due to inadequate blood supply is still a source of considerable morbidity in surgical practice. Adequate tissue perfusion is particularly important in wound healing. We investigated the effects of recombinant human erythropoietin (rHuEPO) on wound healing in an ischemic skin wound model. Sixty-three Sprague-Dawley rats were used. Normal incisional wound and H-shaped double flaps were used as the wound models. Animals were treated with rHuEPO (400 IU/kg) or its vehicle. Rats were killed on different days (3, 5, and 10 days after skin injury) and the wounded skin tissues were used for immunohistochemistry and for analysis of vascular endothelial growth factor content and collagen content. Tissue transglutaminase immunostaining of histological specimens was used as a vascular marker to determine the level of microvessel density. The results showed a higher level of vascular endothelial growth factor protein and an increased microvessel density in ischemic wounds with rHuEPO treatment than the normal incisional wounds and ischemic control wounds. Collagen content was higher in the incisional wounds and in the ischemic wounds with rHuEPO treatment compared with the ischemic control wounds. Our results suggest that erythropoietin may be an effective therapeutic approach in improving healing in ischemic skin wounds.

Keratinocyte growth factor pretreatment is associated with decreased macrophage inflammatory protein-2alpha concentrations and reduced neutrophil recruitment in acid aspiration lung injury

A two-hit model of acid aspiration was used to examine the effect of keratinocyte growth factor (KGF) on chemokine levels and neutrophil recruitment into the lung. Mice were subjected to cecal ligation and puncture and then either KGF or saline, intratracheally (i.t.). Forty-eight hours later, the mice were given i.t. acid. After 8 h, neutrophil counts in bronchoalveolar lavage (BAL) fluid were significantly decreased in animals pretreated with KGF (23 +/- 4 x 10(3)/mouse) compared with saline (74 +/- 2 x 10(3)/mouse). In addition, the BAL fluid IL-6 levels were decreased in the KGF-treated group (88+/- 44 pg/mL) compared with the saline group (166 +/- 34 pg/mL). To examine the mechanism behind the KGF-induced reduction in neutrophil influx, the murine chemokines KC and macrophage inflammatory protein (MIP)-2alpha were measured. KC levels in plasma and BAL fluid were not significantly different between the treatment groups. Likewise, levels of MIP-2alpha in plasma were not affected by KGF treatment. However, 8 h after acid aspiration, MIP-2alpha concentrations were significantly lower in the KGF-treated group. The ratio of MIP-2alpha in BAL fluid versus plasma was lower in the KGF group (0.72 +/- 0.28) than in the saline group at 3 h (2.23 +/- 0.93) and also significantly lower in the KGF group (3.02 +/- 0.78) compared with the saline group (6.23 +/- 1.19) at 8 h. In this study, KGF pretreatment after acid aspiration was associated with reduced neutrophil recruitment into the lung and a decrease in MIP-2alpha gradients between BAL fluid and plasma.

Coagulation/fibrinolysis abnormality and vascular endothelial damage in the pathogenesis of thrombocytopenic multiple organ failure

OBJECTIVE

Until recently, attention has been directed to disseminated intravascular coagulation as a cause of multiple organ failure (MOF). On the other hand, it has now become clear that humoral mediators play important roles in the pathogenesis of MOF. Therefore, we performed the present study in patients with thrombocytopenic MOF to investigate the relationship between various humoral mediators and vascular endothelial damage reported to be triggered by such humoral mediators in the pathogenesis of MOF.

DESIGN

A retrospective clinical study.

SETTING

Intensive care unit of a university hospital.

PATIENTS

The study included 18 thrombocytopenic patients whose conditions progressed to septic MOF (MOF group) and 20 others who did not progress to MOF (non-MOF group). The MOF group and non-MOF group were also presented with infection and with platelet counts of <100,000/mm3.

MEASUREMENTS AND MAIN RESULTS

The MOF group had fibrinolysis abnormality, as indicated by increased plasminogen activator inhibitor-1 level. On the other hand, the MOF group had increased polymorphonuclear elastase and polymorphonuclear-mediated fibrinogen degradation product levels with consequent prolonged elevation of thrombomodulin. In addition, both polymorphonuclear elastase and polymorphonuclear-fibrinogen degradation products were significantly positively correlated with thrombomodulin in the MOF group, but no such positive correlation was observed between interleukin-6 or plasminogen activator inhibitor-1 and thrombomodulin. In the non-MOF group, on the other hand, thrombomodulin exhibited no significant positive correlation with polymorphonuclear elastase, polymorphonuclear-fibrinogen degradation products, interleukin-6, or plasminogen activator inhibitor-1.

CONCLUSIONS

Our study provided evidence that vascular endothelial damage was the primary cause of organ failures in patients with thrombocytopenic MOF and that humoral mediators played a major role in the development of vascular endothelial damage in such patients. These results suggest that it is important to treat thrombocytopenic MOF as a condition of vascular endothelial damage, with weight placed on countermeasures against disorders of humoral mediators.

MOB-1 and TNF-alpha interact to induce microvascular lung injury

We have recently identified the alpha-chemokine mob-1 as a highly inducible gene in several rat models of microvascular lung injury, whose expression was suppressed by inhibition of tumor necrosis TNF-alpha (TNF-alpha). This work provides further insight into the relationship between mob-1 and TNF-alpha in the development of lung injury assessed by pulmonary edema and leukosequestration. First, pulmonary mob-1 and TNF-alpha were upregulated in animals subjected to lung injury produced by the intratracheal administration of recombinant TNF-alpha and recombinant mob-1, respectively. Second, mob-1 inhibition by intratracheal anti-mob-1 antibody attenuated lung injury induced by recombinant TNF-alpha. Third, pretreatment with anti-TNF-alpha monoclonal antibody administered intratracheally abrogated recombinant mob-1-induced microvascular lung injury. In vitro, mob-1 and TNF-alpha increased each other's production in RAW 264.7 cells and mob-1 or TNF-alpha inhibition prevented endotoxin-induced upregulation of TNF-alpha or mob-1, respectively, from these cells. Together, these data suggest that mob-1 and TNF-alpha interact to promote lung inflammation.

Compartmentalization of macrophage inflammatory protein-2, but not cytokine-induced neutrophil chemoattractant, in rats challenged with intratracheal endotoxin

An important feature of the pulmonary inflammatory response is that the production of certain cytokines and chemokines is largely confined to the lung. This study investigated the local and systemic responses of macrophage inflammatory protein-2 (MIP-2) and cytokine-induced neutrophil chemoattractant (CINC) in rats administered with either intratracheal or intravenous lipopolysaccharide (LPS). Intratracheal LPS induced a significant increase in MIP-2 in bronchoalveolar lavage (BAL) fluid with no detectable MIP-2 in the plasma. In contrast, CINC was significantly increased in both BAL fluid and the plasma after intratracheal LPS challenge. Cell-associated MIP-2 was increased in the pulmonary-recruited neutrophils (PMNs) but not in the circulating PMNs in rats given intratracheal LPS. Cell-associated CINC was increased in both the recruited and circulating PMNs in these animals. Intravenous LPS caused a marked increase in plasma MIP-2 and CINC, whereas only a small elevation of both MIP-2 and CINC concentrations in BAL fluid was observed. The lack of CINC compartmentalization compared to MIP-2 implies that these C-X-C chemokines are regulated differentially and may have different effects upon polymorphonuclear leukocyte (PMN) recruitment into the alveolar space in response to intrapulmonary LPS or bacterial challenge.

TNF receptor I mediates chemokine production and neutrophil accumulation in the lung following systemic lipopolysaccharide

BACKGROUND

Tumor necrosis factor (TNF)-alpha is a critical effector of lipopolysaccharide (LPS)-induced acute lung injury, and its effects are mediated by two structurally related receptors, RI and RII. Cellular adhesion molecules and C-X-C chemokines (Keratinocyte chemoattractant (KC) and macrophage inflammatory protein [MIP]-2) regulate tissue neutrophil polymorphonuclear neutrophil (PMN) accumulation in a multitude of inflammatory states. We hypothesized that TNFRI signaling dictates PMN accumulation in the lung via regulation of chemokine molecule production. Therefore, the purposes of this study were to (1) delineate LPS-induced lung TNF-alpha production and (2) characterize the contribution of both TNF receptors to lung chemokine production and neutrophil influx following systemic LPS.

METHODS

Wild-type or TNFRI and TNFRII knockout (KO) mice were injected with vehicle (saline) or LPS (Escherichia coli 0.5 mg/kg intraperitoneally). After 2, 4, 6, or 24 h, lungs were analyzed for TNF-alpha and chemokine (KC and MIP-2) protein expression (enzyme-linked immunosorbent assay) and PMN accumulation (myeloperoxidase assay).

RESULTS

There was an increase in total lung TNF-alpha (vehicle, 5.0 +/- 1.2 pg/mg total protein vs LPS, 950 +/- 318; P < 0.05) after LPS. Lung chemokine production and PMN accumulation were also increased compared to vehicle-injected mice. Lung chemokine production and PMN accumulation were significantly lower in TNFRI KO, but not TNFRII KO, mice, despite no difference in TNF-alpha production (TNFRI KO, 925 +/- 301 vs TNFRII KO, 837 +/- 267, P = 0.82).

CONCLUSIONS

Acute lung injury following systemic LPS administration is characterized by increased lung (1) TNF-alpha production, (2) C-X-C chemokine production, and (3) neutrophil accumulation. The maximal effect of LPS-induced lung neutrophil accumulation appears to be dependent upon the TNFRI receptor but not the TNFRII receptor. .

Current topics on cytokine removal technologies

It has been widely accepted that cytokines play important roles in the development of organ failure in various pathophysiological conditions of critically ill patients. Various new technologies, including continuous renal replacement therapy, have been developed for the removal of causative humoral mediators in sepsis or other critical conditions. Nonselective blood purification technologies, such as hemofiltration and plasma exchange, are applied in cytokine removal technology. However, the more selective blood purification technologies, such as adsorption, and the combination of those technologies, should be considered in future applications. Only through a prospective randomized controlled study can it be elucidated whether or not these technologies have efficacy in the treatment of sepsis and critically ill patients with hypercytokinemia. We should join and discuss the design of future clinical trials with a standardized strategy for the evaluation of the technologies.