Age and environmental factors predict psychological symptoms in adolescent refugees during the initial post-resettlement phase

BACKGROUND

Adolescent refugees are at high risk of developing mental disorders but are often not recognised early. This pilot study aimed to identify early putative risk factors associated with psychological symptoms in newly resettled refugee youth at potential risk of subsequently developing mental disorders.

METHODS

Newly resettled adolescent refugees were recruited through English language schools in Melbourne, Australia. Participants were assessed with the MINI-Kid, Achenbach Youth Self-Report and Reaction of Adolescents to Traumatic Stress scale. Parents completed a mental health screening separately. Linear regression models were used to identify predictive factors associated with symptom ratings.

RESULTS

Seventy-eight, ostensibly well, refugee adolescents (mean age = 15.0 ± 1.6 years) resettled in Australia for 6.1 ± 4.2 months were assessed. Levels of anxiety, depression and post-traumatic stress symptoms were considerably lower than in mainstream population data. Prior displacement was a key determinant of symptomatology. Transitory displacement, irrespective of duration, was associated with elevated scores for depression (t (47) = -4.05, p < 0.0001), avoidance/numbing (U = 466, p < .05) and total trauma (U = 506, p < .05) symptoms. Older age was a unique predictor of depression (F (1,74) = 8.98, p < .01), internalising (F(1,74) = 6.28, p < .05) and total (F(1,74) = 4.10, p < .05) symptoms, whilst parental depression symptoms (t = 2.01, p < 0.05), displacement (t = 3.35, p < 0.01) and, expectedly, trauma exposure (t = 3.94, p < 0.001) were unique predictors of post-traumatic stress symptoms.

CONCLUSIONS

Displaced status, older age, and parental symptoms predicted psychological symptoms in adolescent refugees in an initial relatively asymptomatic post-resettlement phase. The early recognition of at-risk refugee youth may provide an opportunity for preventative mental health interventions.

Moral injury related to immigration detention on Nauru: a qualitative study

BACKGROUND

Immigration detention is associated with detrimental mental health outcomes but little is known about the underlying psychological processes. Moral injury, the experience of transgression of moral beliefs, may play an important role.

OBJECTIVE

Our aim was to explore moral injury appraisals and associated mental health outcomes related to immigration detention on Nauru.

METHODS

In this retrospective study, we conducted in-depth interviews with 13 individuals who had sought refuge in Australia and, due to arriving by boat, had been transferred to immigration detention on Nauru. At the time of the study, they lived in Australia following medical transfer. We used reflexive thematic analysis to develop themes from the data.

RESULTS

Major themes included 1) how participants' home country experience and the expectation to get protection led them to seek safety in Australia; 2) how they experienced deprivation, lack of agency, violence, and dehumanization after arrival, with the Australian government seen as the driving force behind these experiences; and 3) how these experiences led to feeling irreparably damaged. The participant statement 'In my country they torture your body but in Australia they kill your mind.' conveyed these three key themes in our analysis.

CONCLUSION

Our findings suggest that moral injury may be one of the processes by which mandatory immigration detention can cause harm. Although refugees returned to Australia from offshore detention may benefit from interventions that specifically target moral injury, collective steps are needed to diminish deterioration of refugee mental health. Our results highlight the potentially deleterious mental health impact of experiencing multiple subtle and substantial transgressions of one's moral frameworks. Policy makers should incorporate moral injury considerations to prevent eroding refugee mental health.

To strive, to seek, to find, and not to yield: Narratives on the road to asylum

This study aimed to explore the ecological influences on subjective well-being identified by current and former community-dwelling asylum seekers engaged in the process of Refugee Status Determination in Australia. This article presents the qualitative component of a prospective mixed-methods study of 131 asylum seekers and refugees (T1, N = 131; T2, N = 56). The Framework Analysis method was employed to qualitatively analyse the narrative data derived from 187 semi-structured interviews documenting pre-, peri-, and post-migration experiences, and the impact of Australia's asylum policies and procedures. Four overarching themes comprising 15 sub-themes emerged: The Refugee Status Determination process (Waiting; Uncertainty; Worry); Psychosocial factors (Un/employment & gainful activity; Medicare; Accommodation; Family separation & loneliness; Loss); Health and well-being (Mental health; Physical health & somatic issues; Hopelessness; Helplessness); and Protective factors (Hope; Support & social connectivity; Religion). The complex interface between the Refugee Status Determination process, un/employment, and mental health concerns was the most salient finding. Policy implications are discussed in relation to the application of the Convention and Protocol Relating to the Status of Refugees and the Guidelines on the Judicial Approach to Expert Medical Evidence.

Development and validation of a mental health screening tool for asylum-seekers and refugees: the STAR-MH

BACKGROUND

There is no screening tool for major depressive disorder (MDD) or post-traumatic stress disorder (PTSD) in asylum-seekers or refugees (ASR) that can be readily administered by non-mental health workers. Hence, we aimed to develop a brief, sensitive and rapidly administrable tool for non-mental health workers to screen for MDD and PTSD in ASR.

METHODS

The screening tool was developed from an extant dataset (n = 121) of multiply screened ASR and tested prospectively (N = 192) against the M.I.N.I. (Mini International Neuropsychiatric Interview) structured psychiatric interview. Rasch, Differential Item Functioning and ROC analyses evaluated the psychometric properties and tool utility.

RESULTS

A 9-item tool with a median administration time of six minutes was generated, comprising two 'immediate screen-in' items, and a 7-item scale. The prevalence of PTSD &/or MDD using the M.I.N.I. was 32%, whilst 99% of other diagnosed mental disorders were comorbid with one or both of these. Using a cut-score of ≥2, the tool provided a sensitivity of 0.93, specificity of 0.75 and predictive accuracy of 80.7%.

CONCLUSIONS

A brief sensitive screening tool with robust psychometric properties that was easy to administer at the agency of first presentation was developed to facilitate mental health referrals for asylum-seekers and new refugees.

Social factors ameliorate psychiatric disorders in community-based asylum seekers independent of visa status

The impact of industrialised host nations' deterrent immigration policies on the mental health of forced migrants has not been well characterised. The present study investigated the impact of Australia's refugee determination process (RDP) on psychiatric morbidity in community-based asylum-seekers (AS) and refugees. Psychiatric morbidity was predicted to be greater in AS than refugees, and to persist or increase as a function of time in the RDP. The effect on mental health of demographic and socio-political factors such as health cover and work rights were also investigated. Psychiatric morbidity was measured prospectively on five mental health indices at baseline (T1, n=131) and an average of 15.7 months later (T2, n=56). Psychiatric morbidity in AS significantly decreased between time points such that it was no longer greater than that of refugees at T2. Caseness of PTSD and demoralisation reduced in AS who gained protection; however, those who maintained asylum-seeker status at T2 also had a significant reduction in PTS and depression symptom severity. Reduced PTS and demoralisation symptoms were associated with securing work rights and health cover. Living in the community with work rights and access to health cover significantly improves psychiatric symptoms in forced migrants irrespective of their protection status.

Fibronectin polymerization stimulates cell growth by RGD-dependent and -independent mechanisms

Many aspects of cell behavior are regulated by cell-extracellular matrix interactions, including cell migration and cell growth. We previously showed that the addition of soluble fibronectin to collagen-adherent fibronectin-null cells enhances cell growth. This growth-promoting effect of fibronectin depended upon the deposition of fibronectin into the extracellular matrix; occupancy and clustering of fibronectin-binding integrins was not sufficient to trigger enhanced cell growth. To determine whether the binding of integrins to fibronectin's RGD site is required for fibronectin-enhanced cell growth, the ability of fibronectin lacking the integrin-binding RGD site (FN(Delta)RGD) to promote cell growth was tested. FN(Delta)RGD promoted cell growth when used as an adhesive substrate or when added in solution to collagen-adherent fibronectin-null cells. Addition of FN(Delta)RGD to collagen-adherent fibronectin-null cells resulted in a 1.6-1.8x increase in cell growth in comparison with cells grown in the absence of fibronectin. The growth-promoting effects of FN(Delta)RGD and wild-type fibronectin were blocked by inhibitors of fibronectin polymerization, including the anti-fibronectin antibody, L8. In addition, FN(Delta)RGD-induced cell growth was completely inhibited by the addition of heparin, and was partially blocked by either heparitinase-treatment or by addition of recombinant fibronectin heparin-binding domain. Heparin and heparitinase-treatment also partially blocked the growth-promoting effects of wild-type fibronectin, as well as the deposition of wild-type fibronectin into the extracellular matrix. These data suggest that cell surface heparan-sulfate proteoglycans contribute to the growth-promoting effects of FN(Delta)RGD and wild-type fibronectin. Addition of heparin, treatment with heparitinase, or incubation with monoclonal antibody L8 all inhibited the formation of short linear FN(Delta)RGD fibrils on the cell surface. Inhibitory (beta)1 integrin antibodies had no effect on FN(Delta)RGD fibril formation, FN(Delta)RGD-induced cell growth, or cell adhesion on FN(Delta)RGD-coated substrates. These data suggest that fibronectin fibril formation can promote cell growth by a novel mechanism that is independent of RGD-integrin binding, and that involves cell surface proteoglycans.

Stimulation of integrin-mediated cell contractility by fibronectin polymerization

Ligation of integrins with extracellular matrix molecules induces the clustering of actin and actin-binding proteins to focal adhesions, which serves to mechanically couple the matrix with the cytoskeleton. During wound healing and development, matrix deposition and remodeling may impart additional tensile forces that modulate integrin-mediated cell functions, including cell migration and proliferation. We have utilized the ability of cells to contract floating collagen gels to determine the effect of fibronectin polymerization on mechanical tension generation by cells. Our data indicate that fibronectin polymerization promotes cell spreading in collagen gels and stimulates cell contractility by a Rho-dependent mechanism. Fibronectin-stimulated contractility was dependent on integrin ligation; however, integrin ligation by fibronectin fragments was not sufficient to induce either tension generation or cell spreading. Furthermore, treatment of cells with polyvalent RGD peptides or pre-polymerized fibronectin did not stimulate cell contractility. Fibronectin-induced contractility was blocked by agents that inhibit fibronectin polymerization, suggesting that the process of fibronectin polymerization is critical in triggering cytoskeletal tension generation. These data indicate that Rho-mediated cell contractility is regulated by the process of fibronectin polymerization and suggest a novel mechanism by which extracellular matrix fibronectin regulates cytoskeletal organization and cell function.

Inhibition of fibronectin matrix assembly by the heparin-binding domain of vitronectin

The deposition of fibronectin into the extracellular matrix is an integrin-dependent, multistep process that is tightly regulated in order to ensure controlled matrix deposition. Reduced fibronectin deposition has been associated with altered embryonic development, tumor cell invasion, and abnormal wound repair. In one of the initial steps of fibronectin matrix assembly, the amino-terminal region of fibronectin binds to cell surface receptors, termed matrix assembly sites. The present study was undertaken to investigate the role of extracellular signals in the regulation of fibronectin deposition. Our data indicate that the interaction of cells with the extracellular glycoprotein, vitronectin, specifically inhibits matrix assembly site expression and fibronectin deposition. The region of vitronectin responsible for the inhibition of fibronectin deposition was localized to the heparin-binding domain. Vitronectin's heparin-binding domain inhibited both beta(1) and non-beta(1) integrin-dependent matrix assembly site expression and could be overcome by treatment of cells with lysophosphatidic acid, an agent that promotes actin polymerization. The interaction of cells with the heparin-binding domain of vitronectin resulted in changes in actin microfilament organization and the subcellular distribution of the actin-associated proteins alpha-actinin and talin. These data suggest a mechanism whereby the heparin-binding domain of vitronectin regulates the deposition of fibronectin into the extracellular matrix through alterations in the organization of the actin cytoskeleton.

Fibronectin matrix assembly enhances adhesion-dependent cell growth

Cell growth control in non-transformed cells depends, in part, on adhesive interactions with the extracellular matrix. Following injury, excess or altered fibronectin deposition into the extracellular matrix may contribute to the pathogenesis of fibrosis and atherosclerosis by triggering changes in specific cell functions associated with wound repair, including cell proliferation and migration. To assess the role of fibronectin polymerization on cell growth, we isolated mouse embryonic cells that lack endogenous fibronectin (fibronectin-null cells) and established them in culture under serum-free conditions. These fibronectin-null cells do not produce any detectable fibronectin, but are capable of assembling a fibronectin matrix when cultured in the presence of exogenously added fibronectin. Our data indicate that adhesion-dependent growth in fibronectin-null cells is dramatically increased (&gt;2-5x) by culturing cells in the presence of fibronectin. This fibronectin-induced cell growth was blocked by inhibiting fibronectin matrix assembly. Arg-Gly-Asp peptides or fragments of fibronectin that contain the Arg-Gly-Asp cell binding site promoted clustering of the (α)5beta1 integrin in focal adhesions, but did not enhance cell growth. These data indicate that the polymerization of fibronectin into the extracellular matrix positively regulates cell growth, and that occupancy and clustering of fibronectin-binding integrins alone are not sufficient to trigger increased cell growth.

Activation of distinct alpha5beta1-mediated signaling pathways by fibronectin's cell adhesion and matrix assembly domains

The interaction of cells with fibronectin generates a series of complex signaling events that serve to regulate several aspects of cell behavior, including growth, differentiation, adhesion, and motility. The formation of a fibronectin matrix is a dynamic, cell-mediated process that involves both ligation of the alpha5beta1 integrin with the Arg-Gly-Asp (RGD) sequence in fibronectin and binding of the amino terminus of fibronectin to cell surface receptors, termed "matrix assembly sites," which mediate the assembly of soluble fibronectin into insoluble fibrils. Our data demonstrate that the amino-terminal type I repeats of fibronectin bind to the alpha5beta1 integrin and support cell adhesion. Furthermore, the amino terminus of fibronectin modulates actin assembly, focal contact formation, tyrosine kinase activity, and cell migration. Amino-terminal fibronectin fragments and RGD peptides were able to cross-compete for binding to the alpha5beta1 integrin, suggesting that these two domains of fibronectin cannot bind to the alpha5beta1 integrin simultaneously. Cell adhesion to the amino-terminal domain of fibronectin was enhanced by cytochalasin D, suggesting that the ligand specificity of the alpha5beta1 integrin is regulated by the cytoskeleton. These data suggest a new paradigm for integrin-mediated signaling, where distinct regions within one ligand can modulate outside-in signaling through the same integrin.

A novel role for the integrin-binding III-10 module in fibronectin matrix assembly

Fibronectin matrix assembly is a cell-dependent process which is upregulated in tissues at various times during development and wound repair to support the functions of cell adhesion, migration, and differentiation. Previous studies have demonstrated that the alpha 5 beta 1 integrin and fibronectin's amino terminus and III-1 module are important in fibronectin polymerization. We have recently shown that fibronectin's III-1 module contains a conformationally sensitive binding site for fibronectin's amino terminus (Hocking, D.C., J. Sottile, and P.J. McKeown-Longo. 1994. J. Biol. Chem. 269: 19183-19191). The present study was undertaken to define the relationship between the alpha 5 beta 1 integrin and fibronectin polymerization. Solid phase binding assays using recombinant III-10 and III-1 modules of human plasma fibronectin indicated that the III-10 module contains a conformation-dependent binding site for the III-1 module of fibronectin. Unfolded III-10 could support the formation of a ternary complex containing both III-1 and the amino-terminal 70-kD fragment, suggesting that the III-1 module can support the simultaneous binding of III-10 and 70 kD. Both unfolded III-10 and unfolded III-1 could support fibronectin binding, but only III-10 could promote the formation of disulfide-bonded multimers of fibronectin in the absence of cells. III-10-dependent multimer formation was inhibited by both the anti-III-1 monoclonal antibody, 9D2, and amino-terminal fragments of fibronectin. A fragment of III-10, termed III-10/A, was able to block matrix assembly in fibroblast monolayers. Similar results were obtained using the III-10A/RGE fragment, in which the RGD site had been mutated to RGE, indicating that III-I0/A was blocking matrix assembly by a mechanism distinct from disruption of integrin binding. Texas red-conjugated recombinant III-1,2 localized to beta 1-containing sites of focal adhesions on cells plated on fibronectin or the III-9,10 modules of fibronectin. Monoclonal antibodies against the III-1 or the III-9,10 modules of fibronectin blocked binding of III-1,2 to cells without disrupting focal adhesions. These data suggest that a role of the alpha 5 beta 1 integrin in matrix assembly is to regulate a series of sequential self-interactions which result in the polymerization of fibronectin.

Fibronectin's III-1 module contains a conformation-dependent binding site for the amino-terminal region of fibronectin

Cultured fibroblasts express binding sites for the amino-terminal region of fibronectin on their cell surface that mediate the assembly of soluble fibronectin into disulfide-stabilized fibrils. These binding sites have been termed matrix assembly sites and have been studied in binding assays using a 125I-labeled 70-kDa fragment derived from the amino terminus of fibronectin. In an attempt to isolate the protein(s) responsible for binding the 70-kDa fragment, cell surface proteins were cleaved from fibroblast monolayers by mild trypsinization. Trypsinization of monolayers generated a series of fibronectin fragments that bound the 125I-labeled 70-kDa fragment by ligand blot assay and affinity chromatography. All of the fibronectin fragments that bound the 70-kDa fragment contained the III-1 module. In solid phase binding assays, the 125I-labeled 70-kDa fragment bound preferentially to reduced fibronectin as compared with unreduced fibronectin fragments. Binding of the 125I-labeled 70-kDa fragment to reduced fibronectin was inhibited by a monoclonal antibody directed against the III-1 domain. Isolated III-1, however, did not bind the 125I-labeled 70-kDa fragment when adsorbed to plastic tissue culture wells. Heat denaturation of III-1 prior to adsorption conferred 70-kDa fragment binding properties on the isolated module. The 125I-labeled 70-kDa fragment did not bind to heat-denatured III-2, suggesting that 70-kDa fragment binding was a property of the III-1 module and not a general characteristic of all type III modules. The binding of 125I-labeled 70-kDa fragment to III-1 was of high affinity (KD = 1.8 x 10(-8) M). These results indicate that a binding site for the 70-kDa amino terminus of fibronectin is contained within a cryptic site found in the first type III module of fibronectin. Unfolding of the III-1 module on the cell surface may control matrix assembly site expression and represent an important step in the initiation of cell-dependent fibronectin polymerization.

Tumor necrosis factor-alpha alters pulmonary vasoreactivity via neutrophil-derived oxidants

We postulated that tumor necrosis factor-alpha (TNF) "primes" the lung for the development of pulmonary vasoconstriction and edema by inducing the release of polymorphonuclear leukocyte (PMN)-derived reactive oxidant species (ROS). Guinea pigs were injected with TNF (1.6 x 10(5) U/kg ip), and the lungs isolated 18 h later. Compared with controls, TNF pretreatment resulted in 1) greater increases in lung weight and capillary pressure in response to the thromboxane A2 mimetic U-46619 (365 pmol/min) and 2) an increase in the dose of acetylcholine (ACh) causing 50% of maximal dilation (EC50). The vascular effects of TNF were associated with 1) decreased lung effluent nitrite (NO2-, oxidation product of nitric oxide), 2) increased lung effluent superoxide (O2-), and 3) increased lung myeloperoxidase (MPO). Superoxide dismutase (SOD, 10 U/ml) prevented 1) the effects of TNF on the hemodynamic responses to U-46619 and ACh and 2) the TNF-induced decrease in NO2-. The effects of TNF on lung MPO and effluent O2- were prevented using cyclophosphamide intraperitoneally (100 mg/kg 5 days before, and 50 mg/kg 1 day before, treatment with TNF or control). The data suggest that ROS generated from PMN mediate the decrease in nitric oxide and altered pulmonary vasoreactivity induced by TNF.

Tumor necrosis factor-alpha primes pulmonary hemodynamic response to N-formyl-L-methionyl-L-leucyl-L-phenylalanine

We tested the hypothesis that tumor necrosis factor-alpha (TNF-alpha) primes the hemodynamic response to the neutrophil agonist N-formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP) in lungs isolated from guinea pigs. Lungs were isolated from animals 18 h after injection of TNF-alpha (3.20 x 10(5) U/kg ip). The infusion of FMLP (300 nM) into lungs isolated after the intraperitoneal administration of TNF-alpha resulted in increases in lung weight, lung (wet-dry)-to-dry weight ratio [(wet-dry)/dry wt], pulmonary capillary pressure, lung myeloperoxidase activity and perfusate thromboxane (Tx)B2 levels. Animals pretreated with the maximal possible amount of endotoxin in the TNF-alpha (1.7 pg endotoxin) did not respond to FMLP. WEB-2086 (37 microM), a platelet-activating factor (PAF) receptor antagonist, added to the perfusate attenuated the hemodynamic and TxA2 response to FMLP. Dazoxiben (0.5 mM), a TxA2 synthetase inhibitor, prevented the FMLP effect. Polyethylene glycol (PEG)-catalase (500 U/ml) added to the perfusate did not affect the FMLP response; however, PEG-catalase (10(5) U/kg) given intraperitoneally with the TNF-alpha decreased the synergism induced by TNF-alpha with FMLP. The data suggest that TNF-alpha primes the lung to the effects of FMLP by increasing the population of resident neutrophils in the lung and/or by in vivo oxidant generation. The pulmonary hemodynamic response and lung edema induced by FMLP are mediated by PAF and TxA2.

Dextran sulfate inhibits PMN-dependent hydrostatic pulmonary edema induced by tumor necrosis factor

We tested the hypothesis that neutrophil sequestration is required for the development of tumor necrosis factor- (TNF) induced neutrophil- (PMN) dependent pulmonary edema. TNF (3.2 X 10(5) U/kg ip) was injected into guinea pigs 18 h before lung isolation. After isolation, the lung was perfused with a phosphate-buffered Ringer solution. Dextran sulfate (mol wt 500,000) prevented the changes in pulmonary capillary pressure (Ppc; 8.5 +/- 0.8 vs. 12.8 +/- 0.8 cmH2O), lung weight gain (dW; +0.240 +/- 0.135 vs. +1.951 +/- 0.311 g), and pulmonary edema formation or wet-to-dry wt ratio [(W - D)/D; 6.6 +/- 0.2 vs. 8.3 +/- 0.5] at 60 min induced by PMN infusion into a TNF-pretreated lung. The unsulfated form of dextran had no protective effect [Ppc, dW, and (W - D)/D at 60 min: 11.9 +/- 0.9 cmH2O, +1.650 +/- 0.255 g, and 7.3 +/- 0.2, respectively], whereas the use of another anionic compound, heparin, inhibited the TNF + PMN response [Ppc, dW, and (W - D)/D at 60 min: 5.6 +/- 0.4 cmH2O, +0.168 +/- 0.0.052 g, and 6.4 +/- 0.2, respectively]. Isolated lungs showed increased PMN myeloperoxidase (MPO) activity compared with control in TNF-treated lungs at baseline and 60 min after PMN infusion. Dextran sulfate, dextran, and heparin inhibited the increase in MPO activity. The data indicate that inhibition of PMN sequestration alone is not sufficient for the inhibition of PMN-mediated TNF-induced hydrostatic pulmonary edema and that a charge-dependent mechanism mediates the protective effect of dextran sulfate.

Mechanisms of pulmonary edema induced by tumor necrosis factor-alpha

We tested the hypothesis that human recombinant tumor necrosis factor-alpha (TNF) promotes pulmonary edema by neutrophil-dependent effects on the pulmonary vasculature. The isolated guinea pig lung was perfused with phosphate-buffered Ringer's solution with or without human neutrophils. The infusion of neutrophils (9 x 10(6) total) into lungs isolated after the in vivo administration of TNF (3.2 x 10(5) units/kg) resulted in weight gain (+1.951 +/- 0.311 g versus -0.053 +/- 0.053 g in control) and an increase in the lung (wet-dry)-to-dry weight ratio (8.3 +/- 0.5 versus 6.0 +/- 0.2 in control), indicating the formation of pulmonary edema. The neutrophil-dependent pulmonary edema induced by TNF was associated with a combination of increased capillary permeability (capillary filtration coefficient [Kf,c], 0.170 +/- 0.048 g/min/cm H2O/g at 30 minutes versus 0.118 +/- 0.008 g/min/cm H2O/g at baseline) and increased pulmonary capillary pressure (Ppc, 12.8 +/- 0.8 cm H2O at 60 minutes versus 6.0 +/- 0.3 cm H2O at baseline). The Ppc increase was mediated by thromboxane A2 (TXA2) because the TXA2 synthetase inhibitor Dazoxiben (0.5 mM) prevented the effect (Ppc, 6.7 +/- 0.6 cm H2O at 60 minutes with Dazoxiben), and thromboxane B2 (TXB2) levels were increased in the pulmonary venous effluent (5,244 +/- 599 pg/ml at 60 minutes versus 60 +/- 13 pg/ml at baseline). Studies using WEB-2086 (37 microM), a platelet activating factor (PAF) receptor antagonist, indicated that PAF mediated the increased vascular permeability (Kf,c, 0.107 +/- 0.014 g/min/cm H2O/g at 30 minutes using WEB-2086) and, in part, the increased Ppc (Ppc, 8.4 +/- 0.7 cm H2O at 60 minutes using WEB-2086). In addition, alterations of endothelial peripheral actin bands were noted after TNF administration. The data indicate that TNF induces neutrophil-dependent pulmonary edema associated with increased Ppc (mediated by TXA2 and PAF), increased Kf,c (mediated by PAF), and changes in endothelial peripheral actin bands.

Mechanisms of pulmonary edema induced by a diacylglycerol second messenger

We investigated the effect of dioctanoylglycerol (DOG), a second messenger of protein kinase C (PKC) activation, in the absence and presence of neutrophils in isolated perfused guinea pig lung. DOG was given after a base-line isogravimetric steady-state period. Pulmonary capillary pressure (Ppc) and change in lung weight (delta W) were monitored at 15, 30, and 60 min. Capillary filtration coefficient (Kf,c, an index of vascular permeability) was measured during base-line period and at 30 min. DOG increased the Ppc and delta W at 30 and 60 min, and the Kfc at 30 min. Monooctanoylglycerol, a monoacylglycerol that does not activate PKC, had no effect on Ppc, Kf,c, and delta W. Pretreatment with two different PKC inhibitors, 1-(5-isoquinolinylsulfonyl)-2-methyl piperazine or staurosporin, prevented the pulmonary response to DOG. With neutrophils present, DOG caused greater increases in delta W and the (wet-dry)-to-dry wt ratio compared with DOG group. Response to DOG+ neutrophils was due to oxygen radical production because it was prevented by pretreatment with catalase and because DOG increased superoxide release from neutrophils. PKC activation using DOG in the isolated lung results in pulmonary edema mediated by increases in capillary pressure and vascular permeability. Lung weight-gain response to DOG is greater in the presence of neutrophils. Response to DOG+ neutrophils is mediated by oxygen radicals.