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Acute damage to the lung may originate from various direct and indirect reasons. Direct lung injury may be caused by pneumonia, near-drowning, aspiration, inhalation of toxic gases etc., while indirect lung injury is secondary, following any severe extra-pulmonary disease, e.g. sepsis, acute pancreatitis, or severe trauma. Due to a complex pathophysiology of the acute lung injury, the treatment is also extremely complicated and except for lung-protective ventilation there have been no specific treatment approaches recommended. An urgent need for a reliable and sufficiently effective treatment forces the researchers into testing novel therapeutic strategies. However, most of these determinations should be done in the laboratory conditions using animals. Complex methods of preparation of various experimental models of the acute lung injury has gradually developed within decades. Nowadays, there have been the models of direct, indirect, or mixed lung injury well established, as well as the models evoked by a combination of two triggering factors. Although the applicability of the results from animal experiments to patients might be limited by many factors, animal models are essential for understanding the patho-physiology of acute lung injury and provide an exceptional opportunity to search for novel therapeutical strategies.

Asthma is a heterogenous disease which pathophysiology is still poorly understood. Asthma was traditionally divided into allergic (extrinsic) and non-allergic (intrinsic) types, while patients with allergic type responded better to corticosteroids. Since 2013 the definition of asthma has changed. Recently, better insight into clinical consi -derations and underlying inflammatory phenotypes has been gained. Defining these phenotypes has already led to more specific clinical trials and, therefore, to more personalized and successfully targeted therapy. For future, much more effort is put in identifying new phenotype-specific biomarkers which could be helpful in stratification of heterogeneous patients with asthma.

Severe meconium aspiration syndrome (MAS) in the neonates often requires a ventilatory support. As a method of choice, a conventional mechanical ventilation with small tidal volumes (VT

Background: Roflumilast as a phosphodiesterase 4 inhibitor has shown to increase lung functions and decrease the number of exacerbations in chronic obstructive lung disease. In this study, its ability to decrease the airway hyperresponsiveness in a model of eosinophil inflammation was evaluated. Methods: Healthy adult male guinea pigs were divided into groups as follows: the first group was considered as a healthy control group (without sensitization and therapy), animals in the second group were sensitized with ovalbumin, but left without further treatment, and the animals in the third group were sensitized with ovalbumin and treated with roflumilast perorally for 7 consecutive days. In vivo airway reactivity was evaluated using double-chamber whole body plethysmograph and measuring the specific airway resistance after nebulization of histamine aerosol. In vitro experiments were performed with tissue strips of trachea and lungs in organ bath, where their contractile responses to cumulative doses of acetylcholine and histamine were registered. The numbers of inflammatory cells in blood and bronchoalveolar lavage fluid were measured using standard staining. Results: Guinea pigs with roflumilast treatment showed decreased in vivo and in vitro airway reactivity associated with suppressed recruitment of inflammatory cells (especially eosinophils) in blood and bronchoalveolar lavage fluid. Conclusion: Roflumilast has demonstrated the therapeutic potential in the model of ovalbumin induced eosinophil inflammation typically present in patients with bronchial asthma.

In severe respiratory insufficiency, neonatal and pediatric patients should be ventilated artificially by a ventilator. Aim of this experimental study was to evaluate whether the newly developed ventilator Chirana Aura V may effectively ventilate the lungs of animals with two different models of acute lung injury: acute respiratory distress syndrome (ARDS) induced by repetitive saline lavage and meconium aspiration syndrome (MAS) induced by intratracheal instillation of neonatal meconium. The experiments were performed on 10 adult rabbits (New Zealand white). In ARDS group (n=5), the lungs were repetitively lavaged with saline (30 ml/kg) until partial pressure of oxygen (PaO2) in arterial blood was under 26.7 kPa at inspiratory fraction of oxygen FiO2=1.0. In MAS group (n=5), animals were instilled 4 ml/kg of suspension of human meconium (25 mg/ml). When the model of acute lung injury was developed, animals were ventilated for additional 2 hours with pressure control ventilation (PCV) regime by ventilator Chirana Aura V. Ventilatory parameters, blood gases, acid-base balance, end-tidal CO2, O2 saturation of hemoglobin, oxygenation indexes, ventilation efficiency index, dynamic lung compliance, and right-to-left pulmonary shunts were measured and calculated in regular time intervals. In both experimental groups, used ventilatory settings provided acceptable gas exchange within the period of observation. Thus, the results indicate that ventilator Chirana Aura V might be suitable for ventilation of animal models of acute lung injury. However, further pre-clinical investigation is needed before its use may be recommended in neonatal and/or pediatric patients with acute lung injury.

Abstract Objective Oxygen therapy is used for the treatment of various diseases, but prolonged exposure to high concentrations of O2 is also associated with formation of free radicals and oxidative damage. Methods In the present study we compared α-ketoglutarate dehydrogenase (KGDH) activity and mitochondrial oxidative damage in the hearts of guinea pigs after long-term (17 and 60 h) oxygenation with 100% normobaric O2 and with partially negatively (O2 neg) or positively (O2 posit) ionized oxygen. Results Inhalation of O2 led to significant loss in KGDH activity and thiol group content and accumulation of bityrosines. Inhalation of O2 neg was accompanied by more pronounced KGDH inhibition, possibly due to additional formation of protein-lipid conjugates. In contrast, O2 posit prevented loss in KGDH activity and diminished mitochondrial oxidative damage. Conclusions These findings suggest that oxygen treatment is associated with impairment of heart energy metabolism and support the view that inhalation of O2 posit optimizes the beneficial effects of oxygen therapy.

Abstract Beside neonatal respiratory distress syndrome, secondary surfactant deficiency may occur in patients with mature lungs. Recent studies revealed quantitative and qualitative changes of lung surfactant in pulmonary thromboembolism (PTE) concerning the total phospholipids content in BAL fluid, alterations in surfactant phospholipids classes and a large-to-small aggregates ratio. Reduced expression of surfactant protein A (SP-A) mRNA and SP-A in lung tissue after pulmonary embolism was found. Serum levels of SP-A were significantly higher in patients with PTE than in other lung diseases, except COPD. Surfactant changes in PTE may result from damage of type II cells by hypoxia, leakage of plasma proteins into the airspaces and/or by reactive oxygen species. They can contribute to lung atelectasis and edema, and a further reduction in oxygen saturation as seen in clinical picture of PTE. Surfactant changes are reliable marker of lung injury that might become a prognostic indicator in patients with pulmonary thromboembolism.

Pulmonary surfactant serves as a barrier to respiratory epithelium but can also regulate airway smooth muscle (ASM) tone. Surfactant (SF) relaxes contracted ASM, similar to β2‐agonists, anticholinergics, nitric oxide, and prostanoids. The exact mechanism of surfactant relaxation and whether surfactant relaxes hyperresponsive ASM remains unknown. Based on previous research, relaxation requires an intact epithelium and prostanoid synthesis. We sought to examine the mechanisms by which surfactant causes ASM relaxation. Organ bath measurements of isometric tension of ASM of guinea pigs in response to exogenous surfactant revealed that surfactant reduces tension of healthy and hyperresponsive tracheal tissue. The relaxant effect of surfactant was reduced if prostanoid synthesis was inhibited and/or if prostaglandin E2‐related EP2 receptors were antagonized. Atomic force microscopy revealed that human ASM cells stiffen during contraction and soften during relaxation. Surfactant softened ASM cells, similarly to the known bronchodilator prostaglandin E2 (PGE2) and the cell softening was abolished when EP4 receptors for PGE2 were antagonized. Elevated levels of PGE2 were found in cultures of normal human bronchial epithelial cells exposed to pulmonary surfactant. We conclude that prostaglandin E2 and its EP2 and EP4 receptors are likely involved in the relaxant effect of pulmonary surfactant in airways. [ABSTRACT FROM AUTHOR]

Pulmonary surfactant has a relaxing effect on the airway smooth muscle (ASM), which suggests its role in the pathogenesis of respiratory diseases associated with hyperreactivity of the ASM, such as asthma and chronic obstructive pulmonary disease (COPD). The ASM tone may be directly or indirectly modified by bacterial wall component lipopolysaccharide (LPS). This study elucidated the effect of LPS on the ASM reactivity and the role of surfactant in this interaction. The experiments were performed using ASM of adult guinea pigs by in vitro method of tissue organ bath (ASM unexposed-healthy or exposed to LPS under in vitro conditions) and ASM of animals intraperitoneally injected with LPS at a dose 1 mg/kg of b.w. once a day during 4-day period. Variable response of LPS was controlled by cyclooxygenase inhibitor indomethacin and relaxing effect of exogenous surfactant was studied using leukotriene and histamine receptor antagonists. The exogenous surfactant has relaxing effect on the ASM, but does not reverse LPS-induced smooth muscle contraction. The results further indicate participation of prostanoids and potential involvement of leukotriene and histamine H1 receptors in the airway smooth muscle contraction during LPS exposure. [ABSTRACT FROM AUTHOR]

Acute respiratory distress syndrome (ARDS) is characterized by acute hypoxemia, neutrophil-mediated inflammation, and lung edema formation. Whereas lung damage might be alleviated by nitric oxide (NO), goal of this study was to evaluate if intratracheal NO donor S-nitroso-N-acetylpenicillamine (SNAP) can positively influence the lung functions in experimental model of ARDS. New Zealand rabbits with respiratory failure induced by saline lavage (30 ml/kg, 9±3 times) were divided into: ARDS group without therapy, ARDS group treated with SNAP (7 mg/kg i.t.), and healthy Control group. During 5 h of ventilation, respiratory parameters (blood gases, ventilatory pressures) were estimated. After anesthetics overdosing, left lung was salinelavaged and cell count, cell viability and protein content in bronchoalveolar lavage fluid (BALF) were measured. Right lung tissue was used for estimation of wet/dry weight ratio, concentration of NO metabolites, and histomorphological investigation. Repetitive lung lavage induced lung injury, worsened gas exchange, and damaged alveolar-capillary membrane. Administration of SNAP reduced cell count in BALF, lung edema formation, NO metabolites, and histopathological signs of injury, and improved respiratory parameters. Treatment with intratracheal SNAP alleviated lung injury and edema and improved lung functions in a saline-lavaged model of ARDS suggesting a potential of NO donors also for patients with ARDS. [ABSTRACT FROM AUTHOR]

Inflammation associated with acute respiratory distress syndrome (ARDS) can damage the alveolar epithelium and surfactant and worsen the respiratory failure. Glucocorticoids (GC) appear to be a rational therapeutic approach, but the effect is still unclear, especially for early administration and low-dose. In this study we compared two low doses of dexamethasone in early phase of surfactant-depleted model of acute respiratory distress syndrome (ARDS). In the study, lung-lavaged New Zealand rabbits with respiratory failure (PaO2<26.7 kPa in FiO2 1.0) were treated with intravenous dexamethasone (DEX): 0.5 mg/kg (DEX-0.5) and 1.0 mg/kg (DEX-1.0), or were untreated (ARDS). Animals without ARDS served as controls. Respiratory parameters, lung edema, leukocyte shifts, markers of inflammation and oxidative damage in the plasma and lung were evaluated. Both doses of DEX improved the lung function vs. untreated animals. DEX-1.0 had faster onset with significant improvement in gas exchange and ventilation efficiency vs. DEX-0.5. DEX-1.0 showed a trend to reduce lung neutrophils, local oxidative damage, and levels of TNFa, IL-6, IL-8 more effectively than DEX-0.5 vs. ARDS group. Both dosages of dexamethasone significantly improved the lung function and suppressed inflammation in early phase ARDS, while some additional enhancement was observed for higher dose (1 mg/kg) of DEX. [ABSTRACT FROM AUTHOR]

Damage of alveolar-capillary barrier, inflammation, oxidative injury, and lung cell apoptosis represent the key features of acute lung injury (ALI). This study evaluated if selective phosphodiesterase (PDE)-4 inhibitor roflumilast can reduce the mentioned changes in lavage-induced model of ALI. Rabbits with ALI were divided into 2 groups: ALI without therapy (A group) and ALI treated with roflumilast i.v. (1 mg/kg; A+R group). One group of healthy animals without ALI served as ventilated controls (C group). All animals were oxygen-ventilated for further 4 h. At the end of experiment, total and differential counts of cells in bronchoalveolar lavage fluid (BALF) and total and differential counts of white blood cells were estimated. Lung edema formation was assessed from determination of protein content in BALF. Pro-inflammatory cytokines (TNFα, IL-6 and IL-8) and markers of oxidation (3-nitrotyrosine, thiobarbituricacid reactive substances) were detected in the lung tissue and plasma. Apoptosis of lung cells was investigated immunohistochemically. Treatment with roflumilast reduced leak of cells, particularly of neutrophils, into the lung, decreased concentrations of cytokines and oxidative products in the lung and plasma, and reduced lung cell apoptosis and edema formation. Concluding, PDE4 inhibitor roflumilast showed potent anti-inflammatory actions in this model of ALI. [ABSTRACT FROM AUTHOR]

Acute lung injury (aLI) is associated with deterioration of alveolar-capillary lining and transmigration and activation of inflammatory cells. sildenafil, phosphodiesterase 5 (Pde5) inhibitor, inhibits degradation of cyclic guanosine monophosphate (cGMP) by competing with cGMP for binding site of Pde5. Positive effects of sildenafil treatment result from influencing proliferation of regulatory T cells and production of proinflammatory cytokines and autoantibodies as well as from modulation of platelet activation, angiogenesis, and pulmonary vasoreactivity. This study evaluated if intravenous sildenafil can influence inflammation, edema formation, apoptosis, and respiratory parameters in rabbits with a model of aLI induced by repetitive lung lavage by saline (30 ml/kg). animals were divided into 3 groups: aLI without therapy (aLI), aLI treated with sildenafil intravenously (1 mg/kg; aLI + sil), and healthy ventilated controls (Control) which were oxygen-ventilated for 4 hours following treatment administration. during this period, respiratory parameters (ventilatory pressures, lung compliance, blood gases, oxygenation indexes etc.) were regularly measured. at the end of experiment, animals were overdosed by anesthetics. The left lung was saline-lavaged and total and differential cell counts and protein content in the bronchoalveolar lavage fluid (BaL) were estimated. The right lung was used for determination of lung edema formation expressed as wet/dry lung weight ratio, for detection of inflammation and oxidative stress markers by eLIsa methods, and for detection of lung epithelial cells apoptosis by TuneL methods and level of caspase-3. sildenafil treatment reduced leak of cells (P < 0.05), particularly of neutrophils (P < 0.001) into the lung, release of pro-inflammatory mediators (TnF-a, P < 0.001; IL-8 and IL-6, P < 0.01), level of nitrite/nitrate (P < 0.001), markers of oxidative damage (3-nitrotyrosine and malondialdehyde, both P < 0.01), lung edema formation (P < 0.01), protein content in BaL (P < 0.001), and apoptosis of epithelial cells (P < 0.01), and improved respiratory parameters. Concluding, the results indicate a future potential of Pde5 inhibitors also for the therapy of aLI. [ABSTRACT FROM AUTHOR]

Nitric oxide (NO) is an important endogenous mediator with significant role in the respiratory system. Many endogenous and exogenous factors influence the synthesis of NO and its level is significantly changed during the inflammation. Analysis of nasal nitric oxide (nNO) is not validated so far as the diagnostic method. There is a lack of reference values with possible identification of factors modulating the nNO levels. In healthy adult volunteers (n=141) we studied nasal NO values by NIOX MINO® (Aerocrine, Sweden) according to the recommendations of the ATS & ERS. Gender, age, height, body weight, waist-to-hip ratio, FEV1/FVC, PEF and numbers of leukocytes, eosinophils, basophils and monocytes were studied as potential variables influencing the levels of nNO. The complexity of the results allowed us to create a homogenous group for nasal NO monitoring and these data can be used further as the reference data for given variables. Because of significant correlation between nNO and exhaled NO, our results support the "one airway - one disease" concept. Reference values of nasal NO and emphasis of the individual parameters of tested young healthy population may serve as a starting point in the non-invasive monitoring of the upper airway inflammation. [ABSTRACT FROM AUTHOR]

Meconium aspiration syndrome (MAS) in newborns is characterized mainly by respiratory failure due to surfactant dysfunction and inflammation. Previous meta-analyses did not prove any effect of exogenous surfactant treatment nor glucocorticoid administration on final outcome of children with MAS despite oxygenation improvement. As we supposed there is the need to intervene in both these fields simultaneously, we evaluated therapeutic effect of combination of exogenous surfactant and selective inhibitor of NF-κB (IKK-NBD peptide). Young New Zealand rabbits were instilled by meconium suspension and treated by surfactant alone or surfactant in combination with IKK-NBD, and oxygen-ventilated for 5 h. PaO2/FiO2, oxygenation index, oxygen saturation and ventilation efficiency index were evaluated every hour; post mortem, total and differential leukocyte counts were investigated in bronchoalveolar lavage fluid (BALF) and inflammatory, oxidative and apoptotic markers were assessed in lung tissue homogenates. Exogenous surfactant combined with IKK-NBD improved oxygenation, reduced neutrophil count in BALF and levels of IL-1β, IL-6, p38 MAPK and caspase 3 in comparison with surfactant-only therapy. It seems that inhibition of inflammation may be strong supporting factor in surfactant treatment of MAS. [ABSTRACT FROM AUTHOR]

Acute lung injury (ALI) is associated with deterioration of alveolar-capillary lining and transmigration and activation of inflammatory cells. Whereas a selective phosphodiesterase-4 (PDE4) inhibitor roflumilast has exerted potent anti-inflammatory properties, this study evaluated if its intravenous delivery can influence inflammation, edema formation, and respiratory parameters in rabbits with a lavage-induced model of ALI. ALI was induced by repetitive saline lung lavage (30 ml/kg). Animals were divided into 3 groups: ALI without therapy (ALI), ALI treated with roflumilast i.v. (1 mg/kg; ALI+Rofl), and healthy ventilated controls (Control), and were ventilated for following 4 h. Respiratory parameters (blood gases, ventilatory pressures, lung compliance, oxygenation indexes etc.) were measured and calculated regularly. At the end of experiment, animals were overdosed by anesthetics. Total and differential counts of cells in bronchoalveolar lavage fluid (BAL) were estimated microscopically. Lung edema was expressed as wet/dry lung weight ratio. Treatment with roflumilast reduced leak of cells (P<0.01), particularly of neutrophils (P<0.001), into the lung, decreased lung edema formation (P<0.01), and improved respiratory parameters. Concluding, the results indicate a future potential of PDE4 inhibitors also in the therapy of ALI. [ABSTRACT FROM AUTHOR]

Acute lung injury in the preterm newborns can originate from prematurity of the lung and insufficient synthesis of pulmonary surfactant. This situation is known as respiratory distress syndrome (RDS). In the term neonates, the respiratory insufficiency is related to a secondary inactivation of the pulmonary surfactant, for instance, by action of endotoxins in bacterial pneumonia or by effects of aspirated meconium. The use of experimental models of the mentioned situations provides new information on the pathophysiology of these disorders and offers unique possibility to test novel therapeutic approaches in the conditions which are very similar to the clinical syndromes. Herewith we review the advantages and limitations of the use of experimental models of RDS and meconium aspiration syndrome (MAS) and their value for clinics. [ABSTRACT FROM AUTHOR]

Nitric oxide (NO) is an important endogenous neurotransmitter and mediator. It participates in regulation of physiological processes in different organ systems including airways. Therefore, it is important to clarify its role in the regulation of both airway and vascular smooth muscle, neurotransmission and neurotoxicity, mucus transport, lung development and in the surfactant production. The bioactivity of NO is highly variable and depends on many factors: the presence and activity of NO-producing enzymes, activity of competitive enzymes (e.g. arginase), the amount of substrate for the NO production, the presence of reactive oxygen species and others. All of these can change NO primary physiological role into potentially harmful. The borderline between them is very fragile and in many cases not entirely clear. For this reason, the research focuses on a comprehensive understanding of NO synthesis and its metabolic pathways, genetic polymorphisms of NO synthesizing enzymes and related effects. Research is also motivated by frequent use of exhaled NO monitoring in the clinical manifestations of respiratory diseases. The review focuses on the latest knowledge about the production and function of this mediator and understanding the basic physiological processes in the airways. [ABSTRACT FROM AUTHOR]

Inflammation and other immune responses are involved in the variety of diseases and disorders. The acute response to endotoxemia includes activation of innate immune mechanisms as well as changes in autonomic nervous activity. The autonomic nervous system and the inflammatory response are intimately linked and sympathetic and vagal nerves are thought to have anti-inflammation functions. The basic functional circuit between vagus nerve and inflammatory response was identified and the neuroimmunomodulation loop was called cholinergic anti-inflammatory pathway. Unique function of vagus nerve in the anti-inflammatory reflex arc was found in many experimental and pre-clinical studies. They brought evidence on the cholinergic signaling interacting with systemic and local inflammation, particularly suppressing immune cells function. Pharmacological/ electrical modulation of vagal activity suppressed TNF-α and other proinflammatory cytokines production and had beneficial therapeutic effects. Many questions related to mapping, linking and targeting of vagal-immune interactions have been elucidated and brought understanding of its basic physiology and provided the initial support for development of Tracey's inflammatory reflex. This review summarizes and critically assesses the current knowledge defining cholinergic anti-inflammatory pathway with main focus on studies employing an experimental approach and emphasizes the potential of modulation of vagally-mediated anti-inflammatory pathway in the treatment strategies. [ABSTRACT FROM AUTHOR]

Acute lung injury (ALI) is characterized by diffuse alveolar damage, inflammation, and transmigration and activation of inflammatory cells. This study evaluated if intravenous dexamethasone can influence lung inflammation and apoptosis in lavage-induced ALI. ALI was induced in rabbits by repetitive saline lung lavage (30 ml/kg, 9±3-times). Animals were divided into 3 groups: ALI without therapy (ALI), ALI treated with dexamethasone i.v. (0.5 mg/kg, Dexamed; ALI+DEX), and healthy non-ventilated controls (Control). After following 5 h of ventilation, ALI animals were overdosed by anesthetics. Total and differential counts of cells in bronchoalveolar lavage fluid (BAL) were estimated. Lung edema was expressed as wet/dry weight ratio. Concentrations of IL-1β, IL-8, esRAGE, S1PR3 in the lung were analyzed by ELISA methods. In right lung, apoptotic cells were evaluated by TUNEL assay and caspase-3 immunohistochemically. Dexamethasone showed a trend to improve lung functions and histopathological changes, reduced leak of neutrophils (P<0.001) into the lung, decreased concentrations of pro-inflammatory IL-1β (P<0.05) and marker of lung injury esRAGE (P<0.05), lung edema formation (P<0.05), and lung apoptotic index (P<0.01), but increased immunoreactivity of caspase-3 in the lung (P<0.001). Considering the action of dexamethasone on respiratory parameters and lung injury, the results indicate potential of this therapy in ALI. [ABSTRACT FROM AUTHOR]

The aim of the study was to evaluate short-term heart rate variability (HRV) as an index of cardiac autonomic control in rats with lipopolysaccharide (LPS)-induced endotoxemia. Animals were injected intraperitoneally with LPS (100 μg/kg b.w.) and control group with an equivalent volume of saline. ECG recordings were done before (base) and 60, 120, 180, 240 and 300 min after LPS or saline administration. HRV magnitude was quantified by time and frequency-domain analysis (mean RR interval, SDRR, RMSSD, spectral powers in low (LF) and high frequency (HF) bands. Heart tissue homogenates and plasma were analyzed to determine interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-α) and oxidative stress level (TBARS). Administration of lipopolysaccharide was followed by continuous rise in colonic body temperature compared to saline-treated controls. Endotoxemia in rats was accompanied by significant decrease in HRV spectral activity in high-frequency range at maximal body temperature (logHFpower: 1.2±0.5 vs. 1.9± 0.6 ms2, P<0.01). Increased IL-6 was found in heart tissue homogenates of LPS rats (8.0±0.6 vs. 26.4±4.8 pg/ml, (P<0.05). In conclusions, reduced HRV in HF band may indicate a decreased parasympathetic activity in LPS-induced endotoxemia as basic characteristics of altered cardiac control during response to endotoxemia. [ABSTRACT FROM AUTHOR]

The study was designed to prove the hypothesis that lipopolysaccharide (LPS)-induced fever elicits the changes in surfactant specific proteins, potentially related to thermal tachypnea. In adult rats fever was induced by intraperitoneal administration of LPS at a dose 100 μg/kg of body weight; control group received saline. Respiratory parameters, arterial blood gases and pH and colonic body temperature (BT) were recorded. Five hours later, surfactant proteins (SP) A, B, C and D were evaluated in bronchoalveolar lavage fluid (BALF) and lung tissue (LT). LPS evoked monophasic thermic response (at 300 min 38.7±0.2 vs. 36.4±0.3 °C, P<0.05) and an increase in minute ventilation due to changes in breathing rate and tidal volume. LPS-instilled animals had higher levels of SP-A and SP-D in LT (P<0.05 and 0.01), and higher SP-D in BALF (P<0.01) than controls. SP-B increased in LT and SP-C in BALF of animals with LPS (both P<0.05 vs. controls). The changes in all surfactant specific proteins are present in LPS-induced fever. Alterations of proteins related to local immune mechanisms (SP-A, SP-D) are probably a part of general inflammatory response to pyrogen. Changes in proteins related to surface activity (SP-B and SP-C) might reflect the effort of the body to stabilize the lungs in thermal challenge. [ABSTRACT FROM AUTHOR]