Effects of aerobic exercise on molecular aspects of asthma: involvement of SOCS-JAK-STAT.

BACKGROUND: Aerobic training (AT) decreases airway inflammation in asthma, but the underlying cellular and molecular mechanisms are not completely understood. Thus, this study evaluated the participation of SOCS-JAK-STAT signaling in the effects of AT on airway inflammation, remodeling and hyperresponsiveness in a model of allergic airway inflammation. METHODS: C57Bl/6 mice were divided into Control (Co), Exercise (Ex), HDM (HDM), and HDM+Exercise (HDM+ Ex). Dermatophagoides pteronyssinus (100ug/mouse) were administered oro-tracheally on days 0, 7, 14, 21, 28, 35, 42 and 49. AT was performed in a treadmill during 4 weeks in moderate intensity, from day 24 until day 52. RESULTS: AT inhibited HDM-induced total cells (p<0.001), eosinophils (p<0.01), neutrophils (p<0.01) and lymphocytes (p<0.01) in BAL, and eosinophils (p<0.01), neutrophils (p<0.01) and lymphocytes (p<0.01) in peribronchial space. AT also reduced BAL levels of IL-4 (p<0.001), IL-5 (p<0.001), IL-13 (p<0.001), CXCL1 (p<0.01), IL-17 (p<0.01), IL-23 (p<0.05), IL-33 (p<0.05), while increased IL- 10 (p<0.05). Airway collagen fibers (p<0.01), elastic fibers p<0.01) and mucin (p<0.01) were also reduced by AT. AT also inhibited HDM-induced airway hyperresponsiveness (AHR) to methacholine 6,25mg/ml (p<0.01), 12,5mg/mL (p<0.01), 25mg/mL (p<0.01) and 50mg/mL (p<0.01). Mechanistically, AT reduced the expression of STAT6 (p<0.05), STAT3 (p<0.001), STAT5 (p<0.01) and JAK2 (p<0.001), similarly by peribronchial leukocytes and by airway epithelial cells. SOCS1 expression (p<0.001) was upregulated in leukocytes and in epithelial cells, SOCS2 (p<0.01) was upregulated in leukocytes and SOCS3 down-regulated in leukocytes (p<0.05) and in epithelial cells (p<0.001). CONCLUSIONS: AT reduces asthma phenotype involving SOCSJAK- STAT signaling.

The eggshell features and clutch viability of the broad-snouted caiman (Caiman latirostris) are associated with the egg burden of organochlorine compounds.

Organochlorine compounds (OCCs) are toxic and have been identified as endocrine-disrupting chemicals (EDCs). The broad-snouted Caiman (Caiman latirostris) is an oviparous species widely distributed in South America with potential to accumulate OCCs. The eggshell is formed during passage of the eggs through the oviduct. Since the oviduct is a target of hormone actions, exposure to OCCs could modify eggshell quality, thus affecting clutch viability. Eight clutches were collected from wetlands of Parana River tributaries, in north-eastern Argentina. Two to four eggs per clutch were used to establish the burden of OCCs, eggshell thickness and eggshell porosity. The remaining eggs were incubated in controlled conditions. Ten days after hatching, hatchling survival was assessed. Organochlorine pesticide residues (OCPs) were found in all clutches, while polychlorinated biphenyls (PCBs) were present in all but one clutch. The principal contributors to the OCP burden were members of the DDT family and oxychlordane. Eggshell thickness was 400.9±6.0 µm and, unexpectedly, no association between eggshell thickness and the OCC burden was found. The number of pores in the outer surface was 25.3±4.3 pores/cm². A significant inverse correlation between porosity and OCC burden was found (Pearson r= -0.81, p= 0.01). Furthermore, a decrease in caiman survival with decreased pore density was observed (Pearson r= 0.73, p= 0.04). Our findings highlight another potential negative impact of current and past use of OCCs on wildlife species.

Cardiac and pulmonary arterial remodeling after sinoaortic denervation in normotensive rats.

Blood pressure variability (BPV) and baroreflex dysfunction may contribute to end-organ damage process. We investigated the effects of baroreceptor deficit (10 weeks after sinoaortic denervation - SAD) on hemodynamic alterations, cardiac and pulmonary remodeling. Cardiac function and morphology of male Wistar intact rats (C) and SAD rats (SAD) (n=8/group) were assessed by echocardiography and collagen quantification. BP was directly recorded. Ventricular hypertrophy was quantified by the ratio of left ventricular weight (LVW) and right ventricular weight (RVW) to body weight (BW). BPV was quantified in the time and frequency domains. The atrial natriuretic peptide (ANP), alpha-skeletal actin (α-skelectal), collagen type I and type III genes mRNA expression were evaluated by RT-PCR. SAD did not change BP, but increased BPV (11±0.49 vs. 5±0.3 mmHg). As expected, baroreflex was reduced in SAD. Pulmonary artery acceleration time was reduced in SAD. In addition, SAD impaired diastolic function in both LV (6.8±0.26 vs. 5.02±0.21 mmHg) and RV (5.1±0.21 vs. 4.2±0.12 mmHg). SAD increased LVW/BW in 9% and RVW/BW in 20%, and augmented total collagen (3.8-fold in LV, 2.7-fold in RV, and 3.35-fold in pulmonary artery). Also, SAD increased type I (~6-fold) and III (~5-fold) collagen gene expression. Denervation increased ANP expression in LV (75%), in RV (74%) and increased α-skelectal expression in LV (300%) and in RV (546%). Baroreflex function impairment by SAD, despite not changing BP, induced important adjustments in cardiac structure and pulmonary hypertension. These changes may indicate that isolated baroreflex dysfunction can modulate target tissue damage.

Baroreflex deficit blunts exercise training-induced cardiovascular and autonomic adaptations in hypertensive rats.

1. Baroreceptors regulate moment-to-moment blood pressure (BP) variations, but their long-term effect on the cardiovascular system remains unclear. Baroreceptor deficit accompanying hypertension contributes to increased BP variability (BPV) and sympathetic activity, whereas exercise training has been associated with an improvement in these baroreflex-mediated changes. The aim of the present study was to evaluate the autonomic, haemodynamic and cardiac morphofunctional effects of long-term sinoaortic baroreceptor denervation (SAD) in trained and sedentary spontaneously hypertensive rats (SHR). 2. Rats were subjected to SAD or sham surgery and were then further divided into sedentary and trained groups. Exercise training was performed on a treadmill (five times per week, 50-70% maximal running speed). All groups were studied after 10 weeks. 3. Sinoaortic baroreceptor denervation in SHR had no effect on basal heart rate (HR) or BP, but did augment BPV, impairing the cardiac function associated with increased cardiac hypertrophy and collagen deposition. Exercise training reduced BP and HR, re-established baroreflex sensitivity and improved both HR variability and BPV. However, SAD in trained SHR blunted all these improvements. Moreover, the systolic and diastolic hypertensive dysfunction, reduced left ventricular chamber diameter and increased cardiac collagen deposition seen in SHR were improved after the training protocol. These benefits were attenuated in trained SAD SHR. 4. In conclusion, the present study has demonstrated that the arterial baroreflex mediates cardiac disturbances associated with hypertension and is crucial for the beneficial cardiovascular morphofunctional and autonomic adaptations induced by chronic exercise in hypertension.

Structural alterations in adult rat carotid bodies exposed to hyperbaric oxygenation.

UNLABELLED: Inhibition of carotid body (CB) function is the main mechanism involved in the attenuation of respiratory drive observed during hyperoxia. However, only a few studies at 5.0 atmospheres absolutes (ATA) have analyzed carotid body structure or function in hyperbaric oxygenation (HBO2) situations. We hypothesized that rats will present CB structural alterations when exposed to different lower hyperbaric oxygen doses enough to alter their chemosensory response to hypoxia. METHODS: Twenty-one adult male Wistar rats, divided into three groups, were maintained in room air or exposed to O2 at 2.4 or 3.0 ATA for six hours. Histological, ultrastructural and immunohistochemical analyses for neuronal nitric oxide synthase (nNOS) and F2-isoprostane were performed in the excised CBs. RESULTS: Histological analyses revealed signs of intracellular edema in animals exposed to both conditions, but this was more marked in the 3.0 ATA group, which showed ultrastructural alterations at the mitochondrial level. There was a significant increase in the volume density of intraglomic-congested capillaries in the 3.0 ATA group associated with an arteriolar vasoconstriction. In the 2.4 ATA group, there was a relative increase of glomic light cells and a decrease of glomic progenitor cells. Additionally, there was a stronger immunoreactivity for F2-isoprostane in the 3.0 ATA O2-exposed carotid bodies. The glomic cells stained positive for nNOS, but no difference was observed between the groups. Our results show that high O2 exposures may induce structural alterations in glomic cells with signs of lipid peroxidation. We further suggest that deviation of blood flow toward intraglomic capillaries occurs in hyperbaric hyperoxia.

Molecular and ultrastructural studies of the fibrotic lesions of bovine focal proliferative fibrogranulomatous panniculitis (Lechiguana).

This work aimed to investigate some aspects related to the pathogenicity of Lechiguana, a bovine fibroproliferative lesion characterized by rapid collagen accumulation. Light and transmission electron microscopy and in situ hybridization studies were performed in order to elucidate the fibrogenic activity of this lesion. The characterization of fibroblastic plasticity in the lesion was done by immunohistochemical study for alpha-smooth-muscle cell actin. The ovoid-shaped cells presented positive reaction for alpha-smooth-muscle cell actin in their cytoplasm and, at the electron-microscopic level demonstrated basal lamina-like material adjacent to the external surface and collagen fibrils that corresponded to a cell population phenotypically similar to the myofibroblast. We also investigated alpha1 collagen type I mRNA at different times of evolution of Lechiguana lesions, using isotopic and non-isotopic in situ hybridization. The results strongly suggest the involvement of a myofibroblast-like cell population that expresses mRNA for type I collagen and is probably associated with the increase of collagen deposition.

Ultrastructural, immunohistochemical and biochemical analysis of glycosaminoglycans and proteoglycans in the mouse pubic symphysis during pregnancy.

During pregnancy, an interpubic ligament is formed in the mouse pubic symphysis. In late stages, this ligament undergoes "relaxation" to allow proper delivery, which is expected on the 19th day. Proteoglycans and hyaluronic acid play an important role in the remodeling of the extracellular matrix in these tissues. Glycosaminoglycans and proteoglycans were studied by electron microscopic, immunohistochemical and biochemical methods in samples of mouse pubic symphysis from the 12th to 18th day of pregnancy. At the ultrastructural level, using cuprolinic blue and enzymatic digestion by chondroitin lyases, two types of proteoglycan filaments were observed in the fibrocartilage on the 12th day, as well as in D 15, D 17 and D 18 pubic ligaments. The only sulfated glycosaminoglycan in these filaments was chondroitin sulfate, as shown by chondroitin lyase treatment. Their electrophoretic mobility, before and after enzymatic degradation, corroborated this inference. The ratio of chondroitin sulfate/dry weight of symphysis showed two phases of increase: between D12 and D 15, and between D 17 and D 18. We suggest that the first corresponds mainly to an increase in decorin when the ligament is formed, and the second to versican, during "relaxation". Versican and hyaluronic acid, working as water holding molecules would be responsible for the hydration of the ligament at the end of pregnancy, allowing an increase in resiliency. The presence of hyaluronic acid was confirmed by labeling with HA-probe in the perichondrium, fibrocartilage and ligament. The role of collagen fibers as physical restrictors of the complete expansion of glycosaminoglycans and hyaluronic acid in tissue is discussed.

Histochemical and ultrastructural study of collagen fibers in mouse pubic symphysis during late pregnancy.

Reference is usually made to the parallel orientation towards the main line of exerted tension at the pubic joint in mice, for supporting forces applied to the joint. Despite the wealth of morphological information about the extracellular matrix in this joint, little is known regarding the involvement of the crimp of collagen fibers in the dramatic transformations occurring in this region during the last 3 days of pregnancy. Examination of the collagenous architecture suggests that the biomechanical properties are directly related to fibril diameters, composition of ground substance and changes in the bundle morphology, particularly in the crimp structure. The purpose of this study was to further describe the transformation of the collagen fibers of the pubic symphysis during late mouse pregnancy. We examined the architecture of collagen fibers in the symphysis and pubic ligament through the Picrosirius-polarization method and also through scanning electron microscopy to directly visualize and measure the crimping from pregnant and virgin mice. The crimp angle and the length of five consecutive crimps were measured according to Patterson-Kane et al. [Connect. Tissue Res. 36 (1997) 253]. It could be demonstrated that the angles progressively decreased and the crimp length increased, denoting that the fibers have untwisted during the relaxation process. Our findings suggest that a disruption of the helical arrangement of the collagen containing fibers may contribute to explaining the rapid remodeling that occurs at the end of pregnancy and that is responsible for an increase in pliancy and length of the pubic ligament in mice.

How to measure the increase in elastic system fibres in the lamina propria of the uterine cervix of pregnant rats.

As the uterus enlarges to accommodate the growing fetus during pregnancy, the cervix behaves essentially as a barrier. During ripening and delivery, it needs to become soft and distensible to allow dilation and the passage of the conceptus. As the transformations of the collagen-containing fibres are known to be essential for ripening and delivery, it has been hypothesized that the elastic system fibres, owing to their intrinsic mechanical properties (reversible extensibility), could be involved in the shape-recovering process immediately after delivery. In sections stained by Weigert's resorcin-fuchsin (with previous oxidation), we describe the elastic system fibres in the lamina propria of the rat uterine cervix. They are distributed following different patterns when in the endocervix or in the ectocervical-vaginal region. A third distinctive pattern (named the 'elastic tendon') is described here for the first time in the uterine-cervical transition. A special morphometrical protocol has been designed in order to overcome problems during the quantification process. Using the so-called intercept counting method, it was possible to demonstrate that the elastic system fibres are increased in the cervix at the end of pregnancy. They may be involved in the immediate shape-recovering of the cervix after delivery as well as in helping to strengthen the anchoring of the epithelium to the lamina propria, thus minimizing birth trauma.

Relation between interstitial myocardial collagen and the degree of clinical impairment in Chagas' disease.

Cardiac performance is negatively associated with interstitial collagen in Chagas' cardiomyopathy. The magnitude of dysfunction is related to the degree of collagen, and this association seems to exhibit a threshold above it if definite cardiac deterioration occurs.

Differential distribution of elastic system fibers in control and bronchoconstricted intraparenchymatous airways in the guinea-pig lung.

The elastic system fibers were studied at the light microscopic level by using Weigert's resorcin-fuchsin method after oxidation. This study was designed to describe the distribution of these fibers in intrapulmonary guinea-pig airways and to characterize their conformational changes during bronchoconstriction induced by methacholine aerosol. Airways present a palisade of elastic system fibers just beneath the epithelial basement membrane; these fibers are also present in the adventitial connective tissue. Thin fibers link the fibers located in the palisade among themselves and also connect them to those fibers located in the bronchial adventitial tissue, by traversing the airway smooth muscle. During bronchoconstriction, the fibers located beneath the epithelial basement membrane are divided into two components: one follows the epithelial invaginations towards airway lumen, while the other population remains attached through airway smooth muscle to the fibers located in the adventitial connective tissue. At the ultrastructural level, the findings corroborated those of the light microscopy and in addition, disclosed that typical mature elastic fibers and also elaunin fibers attach directly to the basal lamina, a feature that has not been reported previously in other tissues studied. This configuration is compatible with the idea that fibers of the elastic system restrict the mucosal folding during bronchoconstriction, and may also provide energy to restore airway configuration to its normal status after contraction.

Leukocyte infiltration and collagenolysis in cervical tissue from intrapartum sheep.

Sheep uterine cervices and cervical mucus were heavily infiltrated by neutrophils during labour, whereas samples of cervices obtained from non-pregnant controls had no infiltrate. The neutrophilic infiltrate of the sheep uterine cervix at term was not homogeneously distributed throughout the organ: luminal mucus contained more neutrophils than tissues which, in turn, displayed a differential distribution, the superficial subepithelial layer being more heavily infiltrated than the deeper submucous layers. A widespread collagenolysis was observed in the sheep uterine cervix at term. The homogeneous morphological aspect of degradation of collagen fibres throughout the whole cervical stroma contrasted with the above-mentioned differential distribution of neutrophils. On the basis of previous reports showing that collagenolysis follows the leukocytic invasion of human and rat cervices at term, a possible role for the neutrophilic infiltrate of the sheep uterine cervix is discussed.

The role of the collagenous and elastic system fibers in modulating bronchoconstriction

The distribution and conformational changes of the fibers of the collagenous and elastic systems in guinea pig airways after a contractile agonist challenge are described. We observed a distinct pattern of behavior within the mucosal fibers during bronchoconstriction. Part of the fibers of the two systems tend to follow the epithelial invaginations towards the airway lumen, while the remaining ones seem to be attached to the internal smooth muscle. These layers of fibers in the mucosa are interconnected to one another and to the adventitial network by slender fibers. We suggest that the configuration and behavior of these fibers during bronchoconstriction may contribute to airway reopening after the contractile stimulus has ceased. The possible role of this mechanism in the pathophysiology of human asthma is discussed.

Distribution of elastic system fibres in the rat tail tendon and its associated sheaths.

The distribution of elastic, elaunin and oxytalan fibres in tendons and tendon sheaths was studied by means of light and electron microscopy. The different fibres were characterised by comparing their typical ultrastructural pictures with a combination of selective staining techniques for light microscopy with the appropriate enzymatic digestions. Since it was observed that the rat tail tendon and its associated sheaths are not homogeneous structures from the point of view of the distribution of the elastic system fibres, a systematic description of the differential distribution of the oxytalan, elaunin and elastic fibres in the tendon and in the endo-, peri-, epi- and paratendineum is presented. Mature elastic fibres are present in the tendon and in the para-, epi- and endotendineum, whereas these fibres could not be detected in the peritendineum. Very many elaunin fibres are characteristically recognised in the endotendineum; these fibres are present in the peritendineum and in the tendon fascicles too, while the epi- and paratendineum are devoid of elaunin fibres. The peri- and endotendineum contain numerous oxytalan fibres, whereas these fibres are absent from the tendon fascicles and the epi- and paratendineum. The functional implications of the foregoing findings are discussed.

Distribution of elastic system fibers in the peripheral nerves of mammals.

Various nerves of 6 representative species of mammals (including the human) were studied by the comparative association of the selective staining methods of light microscopy with the ultrastructural observation after tannic acid-glutaraldehyde fixation, which provided a reliable means of characterizing the different elastic system fibers. Although mature elastic fibers are not present in nerves, elastic-related fibers are frequently observed: oxytalan fibers are found mainly in the endoneurium, whereas elaunin fibers predominate in the epineurium. These fibers are longitudinally disposed, in a parallel orientation to the axons. The fact that these findings were consistently observed in the nerves of all species studied argues strongly in favor of the existence of a uniform structural pattern of distribution of elastic system fibers in nerves as a general phenomenon in mammals.