Hormonal control of inflammatory responses

Oxidative stress, hormones, and effects of natural antioxidants on intestinal inflammation in inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic, relapsing gastrointestinal (GI) disorder characterized by intestinal inflammation. The etiology of IBD is multifactorial and results from a complex interplay between mucosal immunity, environmental factors, and host genetics. Future therapeutics for GI disorders, including IBD, that are driven by oxidative stress require a greater understanding of the cellular and molecular mechanisms mediated by reactive oxygen species (ROS). In the GI tract, oxidative stressors include infections and pro-inflammatory responses, which boost ROS generation by promoting the production of pro-inflammatory cytokines. Nuclear factor kappa B (NF-κB) and nuclear factor erythroid 2-related factor 2 (Nrf2) represent two important signaling pathways in intestinal immune cells that regulate numerous physiological processes, including anti-inflammatory and antioxidant activities. Natural antioxidant compounds exhibit ROS scavenging and increase antioxidant defense capacity to inhibit pro-oxidative enzymes, which may be useful in IBD treatment. In this review, we discuss various polyphenolic substances (such as resveratrol, curcumin, quercetin, green tea flavonoids, caffeic acid phenethyl ester, luteolin, xanthohumol, genistein, alpinetin, proanthocyanidins, anthocyanins, silymarin), phenolic compounds including thymol, alkaloids such as berberine, storage polysaccharides such as tamarind xyloglucan, and other phytochemicals represented by isothiocyanate sulforaphane and food/spices (such as ginger, flaxseed oil), as well as antioxidant hormones like melatonin that target cellular signaling pathways to reduce intestinal inflammation occurring with IBD.

White Matter Microstructural Differences in Youth With Classical Congenital Adrenal Hyperplasia

CONTEXT

Gray matter morphology in the prefrontal cortex and subcortical regions, including the hippocampus and amygdala, are affected in youth with classical congenital adrenal hyperplasia (CAH). It remains unclear if white matter connecting these aforementioned brain regions is compromised in youth with CAH.

OBJECTIVE

To examine brain white matter microstructure in youth with CAH compared to controls.

DESIGN

A cross-sectional sample of 23 youths with CAH due to 21-hydroxylase deficiency (12.9 ± 3.5 year; 61% female) and 33 healthy controls (13.1 ± 2.8 year; 61% female) with 3T multishell diffusion-weighted magnetic resonance brain scans.

MAIN OUTCOME MEASURES

Complementary modeling approaches, including diffusion tensor imaging (DTI) and neurite orientation dispersion and density imaging (NODDI), to examine in vivo white matter microstructure in six white matter tracts that innervate the prefrontal and subcortical regions.

RESULTS

DTI showed CAH youth had lower fractional anisotropy in both the fornix and stria terminalis and higher mean diffusivity in the fornix compared to controls. NODDI modeling revealed that CAH youth have a significantly higher orientation dispersion index in the stria terminalis compared to controls. White matter microstructural integrity was associated with smaller hippocampal and amygdala volumes in CAH youth.

CONCLUSIONS

These patterns of microstructure reflect less restricted water diffusion likely due to less coherency in oriented microstructure. These results suggest that white matter microstructural integrity in the fornix and stria terminalis is compromised and may be an additional related brain phenotype alongside affected hippocampus and amygdala neurocircuitry in individuals with CAH.

Inflammation, immunosuppressive microenvironment and breast cancer: opportunities for cancer prevention and therapy

Breast cancer is the most commonly diagnosed malignancy and a leading cause of cancer-related death in women worldwide. It also exhibits pronounced racial disparities in terms of incidence and clinical outcomes. There has been a growing interest in research community to better understand the role of the microenvironment in cancer. Several lines of evidence have highlighted the significance of chronic inflammation at the local and/or systemic level in breast tumor pathobiology. Inflammation can influence breast cancer progression, metastasis and therapeutic outcome by establishing a tumor supportive immune microenvironment. These processes are mediated through a variety of cytokines and hormones that exert their biological actions either locally or distantly via systemic circulation. Targeting of immune and inflammatory pathways has met tremendous success in some cancers underscoring the importance of research to further our understanding of these systems in breast cancer. This knowledge can be helpful not only in the development of novel prevention and therapeutic strategies, but also help in better prediction of therapeutic responses in patients. This review summarizes some of the significant findings on the role of inflammation in breast cancer to gain collective molecular and mechanistic insights. We also discuss ongoing efforts and future outlook to exploit the existing knowledge for improved breast cancer management.

Pharmacological study of anti-inflammatory activity of aqueous extracts of Mikania glomerata (Spreng.) and Mikania laevigata (Sch. Bip. ex Baker)

ETHNOPHARMACOLOGICAL RELEVANCE

Mikania glomerata Spreng. (MG) and Mikania laevigata Sch. Bip. ex Baker (ML), popularly known as guaco, are medicinal plants similar in morphology, chemical composition and medicinal uses. Both species are often used and sold without distinction; however, it is believed that their chemical composition is different.

AIM

Thus, the aim of this study is to investigate if the aqueous extract of MG and ML present similar anti-inflammatory activity to the point of being used interchangeably.

MATERIAL AND METHODS

Different doses of both extracts and coumarin were given to rats in different experimental models to assess the anti-inflammatory activity between these two species. For this, the animals were submitted to paw edema, pleurisy and degranulation of peritoneal mast cell and the extracts were also characterized by Ultra High Efficiency Liquid Chromatography coupled to Mass Spectrometry (UHPLC-MS).

RESULTS

The chromatographic method showed that ML presents ten times more coumarin than MG. Oral administration of MG, ML and coumarin inhibited paw edema induced by carrageenan (400 mg/kg, 55% inhibition; 400 mg/kg, 57% inhibition; 75 mg/kg, 38% inhibition; p < 0.05, respectively). MG, ML and coumarin treatment also inhibited the edema induced by compound 48/80 (400 mg/kg, 56% inhibition; 400 mg/kg, 69% inhibition; 75 mg/kg, 40% inhibition; p < 0.05, respectively). MG, ML and coumarin did not prevent mast cell degranulation and the consequent histamine release in Wistar rat peritoneal mast cells induced by compound 48/80. MG did not inhibit cell infiltration in pleurisy nor the highest dose tested, while ML decreased the leukocyte migration (200 and 400 mg/kg, 23% and 30% inhibition; p < 0.001, respectively) and, to a lesser extent, coumarin also reduced cell infiltration (10, 50 and 75 mg/kg; 15%, 16% and 17% inhibition; p < 0.001, respectively).

CONCLUSION

The variation of the results of the anti-inflammatory activity found in M. glomerata and M. laevigata demonstrates that these two species should not be used interchangeably. Coumarin, as already proven, has anti-inflammatory action however, we have suggested that it probably is not the only component responsible for this therapeutic effect in the extracts.

Endocrine Regulation of Lymphocyte Trafficking In Vitro

Lymphocyte recruitment in inflammation can be influenced by many molecules including cytokines, chemokines, and adipokines. In our lab, we have examined the effects of the adipokines leptin and adiponectin on lymphocyte migration, and observed modulation of this process. Lymphocyte behavior can be assessed in the lab under static conditions, or can be studied under flow, simulating in vivo conditions. In this chapter, in vitro methods for analyzing adhesion and migration of lymphocytes isolated from blood are described in detail. In static adhesion and migration assays, lymphocytes are allowed to settle on top of endothelial cell monolayers cultured in plates for a desired period of time. In the flow-based assay, lymphocytes are perfused over the endothelium at a continuous rate through microchannels which are commercially available. Depending on the choice of method employed, the efficiency of lymphocytes to adhere to and migrate across the endothelial cell monolayer under different conditions can be evaluated. Static assays are less complex and are of higher throughput. However, these assays provide less detailed information regarding lymphocyte behaviors. On the other hand, the flow-based assays are more difficult to perform, but are more physiologically relevant due to the presence of flow and yield more detailed information about lymphocyte activities such as capture, immobilization, and migration in real-time.

Effects of equivalent sympathetic activation during hypoglycemia on endothelial function and pro-atherothrombotic balance in healthy individuals and obese standard treated type 2 diabetes

OBJECTIVE

Recent studies in type 2 diabetes have reported an association between hypoglycemia and severe cardiovascular adverse events, which are relatively increased in standard versus intensively treated individuals. The aim of this study was to determine the effects of equivalent sympathetic nervous system (SNS) activity during moderate hypoglycemia on in-vivo endothelial function, pro-inflammatory, pro-atherothrombotic, and pro-coagulant responses in healthy and standard treated type 2 diabetes individuals.

RESEARCH DESIGN AND METHODS

Eleven type 2 diabetes and 16 healthy individuals participated in single 2day studies. Day 1 involved a 2h hyperinsulinemic/euglycemic clamp and day 2, a 2h hyperinsulinemic/hypoglycemic clamp of 3.2±1mmol/L in type 2 diabetes and (2.9±0.1mmol/L) in healthy individuals.

RESULTS

ICAM-1, VCAM-1, P-selectin, PAI-1, VEGF and endothelin-1 (ET-1) fell during hyperinsulinemic euglycemia but increased during hypoglycemia in type 2 diabetes and healthy individuals. Epinephrine and norepinephrine levels were equivalent during hypoglycemia in type 2 DM and healthy individuals. However, despite similar SNS drive but milder and hypoglycemia there were greater ICAM-1, VCAM-1, PAI-1, VEGF and ET-1 responses in the type 2 diabetes group. Endogenous and exogenous nitric oxide mediated arterial vasodilation were also impaired only during hypoglycemia in type 2 diabetes.

CONCLUSION

We conclude that, milder hypoglycemia but equivalent SNS activation results in more diffuse endothelial dysfunction and a greater pro-inflammatory, pro-atherothrombotic and pro-coagulant state in standard treated type 2 diabetes as compared to healthy individuals.

Different inflammatory stimuli in the footpad of mice influence the kinetics of resident peritoneal cells

OBJECTIVES

Evidence from the literature that inflammation is a systemic biological phenomenon prompted us to investigate whether inoculation of different irritants to the footpad of mice might influence the kinetics of resident peritoneal cells.

METHODS

Mice were inoculated in the footpad at different time intervals with Mycobacterium bovis bacillus Calmette-Guerin (BCG), Ehrlich ascitic tumor cells or lipopolysaccharide (LPS), and resident peritoneal cells were analyzed by flow cytometry.

RESULTS

The results indicate that different stimuli induced different responses in resident peritoneal cells. FoxP3 positive regulatory T cells increased drastically in number after BCG inoculation. Conversely, tumor cell inoculation induced a decrease in FoxP3-positive T cells in the peritoneal cavity, although this effect was not statistically significant. Results also show that cells from the paw migrate to the popliteal lymph node and to the peritoneal cavity. Yet, there are cells in the peritoneal cavity that migrate to the popliteal lymph node.

CONCLUSION

These data show that cells from the peritoneal cavity are influenced by pathologies in remote regions of the animal. How this novel phenomenon influences overall immune responses, courses of infection and tumor growth are open to further investigation.

Paradoxical effects of brain death and associated trauma on rat mesenteric microcirculation: an intravital microscopic study

OBJECTIVE

Experimental findings support clinical evidence that brain death impairs the viability of organs for transplantation, triggering hemodynamic, hormonal, and inflammatory responses. However, several of these events could be consequences of brain death-associated trauma. This study investigated microcirculatory alterations and systemic inflammatory markers in brain-dead rats and the influence of the associated trauma.

METHOD

Brain death was induced using intracranial balloon inflation; sham-operated rats were trepanned only. After 30 or 180 min, the mesenteric microcirculation was observed using intravital microscopy. The expression of Pselectin and ICAM-1 on the endothelium was evaluated using immunohistochemistry. The serum cytokine, chemokine, and corticosterone levels were quantified using enzyme-linked immunosorbent assays. White blood cell counts were also determined.

RESULTS

Brain death resulted in a decrease in the mesenteric perfusion to 30%, a 2.6-fold increase in the expression of ICAM-1 and leukocyte migration at the mesentery, a 70% reduction in the serum corticosterone level and pronounced leukopenia. Similar increases in the cytokine and chemokine levels were seen in the both the experimental and control animals.

CONCLUSION

The data presented in this study suggest that brain death itself induces hypoperfusion in the mesenteric microcirculation that is associated with a pronounced reduction in the endogenous corticosterone level, thereby leading to increased local inflammation and organ dysfunction. These events are paradoxically associated with induced leukopenia after brain damage.

Insulin modulates inflammatory and repair responses to elastase-induced emphysema in diabetic rats

As pulmonary emphysema and diabetes mellitus are common diseases, concomitance of both is correspondingly expected to occur frequently. To examine whether insulin influences the development of inflammation in the alveolar septa, diabetic male Wistar rats (alloxan, 42 mg/kg, i.v., n = 37) and matching controls (n = 31) were used. Ten days after alloxan injection, diabetic and control rats were instilled with physiologic saline solution containing porcine pancreatic elastase (PPE, 0.25 IU/0.2 ml, right lung) or saline only (left lung). The following analyses were performed: (i) number of leucocytes in the bronchoalveolar lavage (BAL) fluid of the animals, 6 h after PPE/saline instillation (early time point); and (ii) mean alveolar diameter (μm) and quantification of elastic and collagen fibres (%) 50 days after PPE/saline instillation (late time point). Relative to controls, alloxan-induced diabetic rats showed a 42% reduction in the number of neutrophils in BAL fluid, a 20% increase in the mean alveolar diameter and a 33% decrease in elastic fibre density in the alveolar septa. Treatment of diabetic rats with 4 IU neutral protamine Hagedorn (NPH) insulin, 2 h before elastase instillation, restored the number of neutrophils in the BAL fluid. The mean alveolar diameter and elastic fibre content in alveolar septa matched the values observed in control rats if diabetic rats were treated with 4 IU NPH insulin 2 h before instillation followed by 2 IU/day for the next 50 days. Density of collagen fibres did not differ between the various groups. Thus, the data presented suggest that insulin modulates the inflammatory and repair responses in elastase-induced emphysema, and assures normal repair and tissue remodelling.

Role of insulin hormone in modulation of inflammatory phenomena

Evidence demonstrates the involvement of hormones in the development of inflammatory response. Inflammation evokes marked structural alterations of microvasculature, besides migration of leukocytes from microcirculation to the site of lesion. These alterations are caused primarily by release or activation of endogenous mediators, in which hormones play an integral role in this regulatory system. Binding sites for many hormones may be characterized by vascular structures and hematogenous cells involved with the inflammatory response. Quantitative alterations of inflammatory events involving the decrease in microvascular response to inflammatory mediators, deficiency in the leukocyte-endothelium interaction, reduction of cell concentration in the inflammatory exudate, and failure of the phagocyte function of mononuclear cells were observed in insulin- deficient states. Therefore, inflammation is not merely a local response, but rather a process controlled by hormones in which insulin plays an essential role in modulation of these phenomena, and assures tissue repair and remodeling within the limits of normality.

Airway inflammatory events in diabetic-antigen sensitized guinea pigs

Experimental evidence indicates that the relative lack of insulin in an organism results in an overall reduction in inflammatory reactions. This study was planned to determine the inflammatory events in antigen sensitized diabetic guinea pigs. Twenty-five male guinea pigs were categorized into five groups of five each as follows: diabetic, antigen sensitized, antigen sensitized diabetic, insulin-treated antigen sensitized diabetic and control animals. Induction of experimental diabetes and antigen sensitization was performed by injection of streptozotocin and ovalbumin, respectively. Animals were killed by exsanguination and bronchoalveolar lavage was performed. Bronchoalveolar lavage fluid cellular and protein contents were determined. Airway responsiveness to acetylcholine was assessed using isolated tracheal triple-ring. Histopathological examinations were performed on the lungs. Decreases in the airway reactivity in diabetic and antigen sensitized diabetic animals were found compared with antigen sensitized animals. Experimental diabetes also decreased antigen-induced protein leakage into the airspace as well as the accumulation of inflammatory cells (eosinophils, neutrophils, lymphocytes and macrophages) in bronchoalveolar lavage fluid of antigen sensitized animals. Insulin treatment prevented these decreases in protein content and inflammatory cells infiltration in bronchoalveolar lavage fluid observed in the antigen sensitized guinea pigs with diabetes. Histopathological results showed that coinduction of experimental diabetes significantly reduces the number of eosinophils in the lungs of antigen sensitized animals. Again, treatment with insulin increased the number of eosinophils in the antigen sensitized diabetic animals. Experimental diabetes causes were found to decrease the airway reactivity and inflammatory responsiveness induced by antigen sensitization due to a reduction in the insulin levels.

Neutrophil function and metabolism in individuals with diabetes mellitus

Neutrophils act as first-line-of-defense cells and the reduction of their functional activity contributes to the high susceptibility to and severity of infections in diabetes mellitus. Clinical investigations in diabetic patients and experimental studies in diabetic rats and mice clearly demonstrated consistent defects of neutrophil chemotactic, phagocytic and microbicidal activities. Other alterations that have been reported to occur during inflammation in diabetes mellitus include: decreased microvascular responses to inflammatory mediators such as histamine and bradykinin, reduced protein leakage and edema formation, reduced mast cell degranulation, impairment of neutrophil adhesion to the endothelium and migration to the site of inflammation, production of reactive oxygen species and reduced release of cytokines and prostaglandin by neutrophils, increased leukocyte apoptosis, and reduction in lymph node retention capacity. Since neutrophil function requires energy, metabolic changes (i.e., glycolytic and glutaminolytic pathways) may be involved in the reduction of neutrophil function observed in diabetic states. Metabolic routes by which hyperglycemia is linked to neutrophil dysfunction include the advanced protein glycosylation reaction, the polyol pathway, oxygen-free radical formation, the nitric oxide-cyclic guanosine-3'-5'monophosphate pathway, and the glycolytic and glutaminolytic pathways. Lowering of blood glucose levels by insulin treatment of diabetic patients or experimental animals has been reported to have significant correlation with improvement of neutrophil functional activity. Therefore, changes might be primarily linked to a continuing insulin deficiency or to secondary hyperglycemia occurring in the diabetic individual. Accordingly, effective control with insulin treatment is likely to be relevant during infection in diabetic patients.

Bothrops jararaca and Crotalus durissus terrificus venoms elicit distinct responses regarding to production of prostaglandins E2 and D2, and expression of cyclooxygenases

Prostaglandins (PGs), synthesized by cyclooxygenases, play important roles in many pathophysiological processes including inflammation and hyperalgesia. In this study the profiles of PGE(2) and PGD(2) production secondary to injection of Bothrops jararaca venom (BjV), with inflammatory activity or Crotalus durissus terrificus venom (CdtV), with anti-inflammatory and antinociceptive properties, into mice were evaluated, and the ability of these venoms to induce expression of cyclooxygenases-1 (COX-1) and -2 (COX-2) was investigated. Intraperitoneal injection of BjV but not of CdtV induced the release and PGD(2) at 30 min and of PGE(2) from 3 up to 12 h after injection. Moreover, BjV up-regulated expression of COX-2 but not of the constitutive COX-1, suggesting that expressed COX-2 provides more substrate for synthesis of PGs by the respective terminal synthases, being the critical enzyme for PGs production in the late periods of BjV effect. In contrast, CdtV does not have any effect on constitutive COX-1 and do not induce expression of COX-2. Therefore, differences between BjV and CdtV in the ability to regulate PGs synthesis can account for their distinct effects with regard to inflammation. Moreover, inhibition of COX-2 by selective drugs may be of value to counteract the severe local inflammation induced by BjV in the victims.

MODULATION OF LIPOPOLYSACCHARIDE-INDUCED ACUTE LUNG INFLAMMATION

The present study was undertaken to investigate the influence of insulin on lipopolysaccharide (LPS)-induced acute lung injury. Diabetic male Wistar rats (alloxan, 42 mg/kg, i.v., 30 days) and controls were instilled with saline containing LPS (750 microg/0.4 mL) or saline alone. The following analyses were performed 6 h there after: (a) total and differential cell counts in bronchoalveolar lavage (BAL) fluid, (b) quantification of tumor necrosis factor alpha, interleukin (IL) 1beta, IL-10, and cytokine-induced neutrophil chemoattractant 1 in the BAL (enzyme-linked immunosorbent assay), (c)immunohistochemistry for intercellular adhesion molecule 1 and E-selectin on lung vessels, and (d) quantification of metalloproteinases (MMP) 2 and 9 in the BAL (zymography). Relative to controls, diabetic rats exhibited a reduction in the number of neutrophils (80%) and reduced concentrations of tumor necrosis factor alpha (56%), IL-1beta (66%), and IL-10 (35%) after LPS instillation. Cytokine-induced neutrophil chemoattractant 1 levels did not differ between groups. Increased levels of MMP-2 (90%) and MMP-9 (500%) were observed in diabetic rats compared with controls. Treatment of diabetic rats with neutral protamine Hagedorn insulin (4 IU, s.c.), 2 h before LPS instillation, completely restored the number of neutrophils and concentrations of cytokines in the BAL fluid. Despite no significant differences between diabetic and control groups, there was a remarkable increase in intercellular adhesion molecule 1 and E-selectin expression on lung vessels after insulin treatment. Levels of MMP-2 and MMP-9 did not change after treatment with insulin. Levels of corticosterone were equivalent among groups. Data presented suggest that insulin modulates the production/release of cytokines and the expression of adhesion molecules controlling, therefore, neutrophil migration during the course of LPS-induced acute lung inflammation.

Role of insulin on PGE2 generation during LPS-induced lung inflammation in rats

Alterations in arachidonic acid (AA) metabolism have been reported to occur in diabetes mellitus. The present study was carried out to verify if these alterations are due to the relative lack of insulin or to high levels of blood glucose. Male Wistar rats were rendered diabetic by alloxan injection (42 mg/kg, i.v.), 10 or 30 days before the experiments. Some diabetic rats received a single dose (4 IU, s.c.) of NPH insulin 2 h before an intratracheal instillation of lipopolysaccharide (LPS, 750 microg) or saline. Six hours after LPS challenge, the following parameters were analysed: blood glucose levels, total and differential leukocyte counts in bronchoalveolar lavage (BAL) fluid; linoleic acid and AA content in blood neutrophils (HPLC), and levels of prostaglandin (PG)E(2) in BAL (ELISA). Relative to controls, a reduced number of neutrophils (18%) and decreased amounts of PGE(2) (40%) were observed in the BAL fluid of diabetic rats in response to LPS. A single dose of insulin was not able to reduce blood sugar levels to normal values, but instead resulted in the normalization of both leukocyte migration to the lungs and levels of PGE(2). Accordingly, these abnormalities might be primarily linked to a continuing insulin deficiency rather than to secondary hyperglycaemia occurring in the diabetic rat. In conclusion, data presented suggest that insulin might regulate neutrophil migration and generation of PGE(2) during the course of acute lung injury induced by LPS.

Mast cell changes in experimental diabetes: focus on attenuation of allergic events

The prevalence of atopic diseases and diabetes is increasing worldwide though the concurrence of these pathologies in individual patients is found less frequent than it would be predicted. Moreover, co-existence of diabetes and allergy is generally marked by attenuation of their respective symptoms, and effective treatment of one disease exacerbates the other. This review gives an update of the state-of-the-art concerning the intercurrence of allergy and diabetes, particularly focusing on the consequences to the allergen-evoked vascular and cellular changes. It is proposed that the reduction in mast cell numbers and reactivity may be a pivotal mechanism behind the mutual exclusion phenomenon.

Lymphatic system changes in diabetes mellitus: role of insulin and hyperglycemia

BACKGROUND

Diabetic alterations of blood vessels have been well studied, but much less is known about the lymphatic system, which plays an important role in the transport of particles and defensive responses. Accordingly, we investigated lymphatic changes in diabetic rats.

METHODS

Ten, 30 or 60 days after alloxan-induced diabetes (40 mg/kg; i.v.), we studied thoracic duct lymph flow and lymphocyte output, thoracic duct lymph transport of radiotracer particles ((99m)Tc-dextran 500), lymph node uptake and scintigraphic visualization of subcutaneously injected radiotracer particles, as well as the effect of insulin administration and food deprivation.

RESULTS

Diabetes significantly increased thoracic duct lymph flow and the transport of dextran from the footpad subcutaneous tissue. Abnormal lymphocyte output from the thoracic duct occurred in the first 10 days. Uptake of dextran into regional lymph nodes was decreased in diabetes. Insulin per se, although not normalizing blood sugar levels, appeared to recover thoracic duct lymphocyte output and lymph node uptake of (99m)Tc-dextran 500 without affecting the thoracic duct lymph flow or the amount of radiotracer recovered therein. Normalization of glycemia (by food deprivation) restored the lymph flow to control levels without modifying the lymphocyte output. On the other hand, under insulin-restored normoglycemic conditions, both the thoracic duct lymph flow and the lymphocyte output were normalized.

CONCLUSIONS

These findings suggest that variables related to defensive mechanisms, such as lymphocyte recirculation and particles uptake into the lymph nodes can benefit from insulin treatment, whereas glycemic control can benefit transport mechanisms in the lymphatic system, such as lymph flow and lymphatic transport of particles.

Inducible nitric oxide synthase in rat neutrophils: role of insulin

Defective leukocyte-endothelial interactions are observed in experimental diabetes mellitus. Endogenous substances, including nitric oxide (NO), have anti-inflammatory effects within the vasculature by reducing leukocyte adherence to post-capillary venules. The purpose of this study was to examine the activity and expression of NO synthase in neutrophils from alloxan-induced diabetic rats. Glycogen-elicited peritoneal neutrophils were obtained from diabetic rats and matching controls 10, 30, and 180 days after alloxan (42 mg/kg, i.v.) or saline injection. NO synthase activity was determined by the [3H]L-citrulline assay method. Expression of the enzyme was investigated by western blot analysis. Relative to controls, neutrophils obtained from diabetic rats presented a 2-fold increase in the activity of inducible NO synthase (iNOS), accompanied by an increase in the expression of the enzyme depicted by western blot. Treatment of diabetic animals with NPH insulin (2 IU/day, for 3 days) reduced both the activity and expression of iNOS to normal levels. Results presented suggest that overexpression of the inducible isoform of NO synthase by neutrophils may be responsible, at least in part, for the defects in leukocyte-endothelial interactions in diabetes mellitus.

Influence of tolrestat on the defective leukocyte-endothelial interaction in experimental diabetes

One of the most devastating secondary complications of diabetes is the blunted inflammatory response that becomes evident even in the very early stages of poorly controlled diabetes mellitus. While the etiology of this diminished response is not clearly understood, it has been linked to a decrease in the respiratory burst of neutrophils, as well as a decrease in microvessel response to inflammatory mediators and defective leukocyte-endothelial interactions. Using video microscopy to visualize vessels of the internal spermatic fascia, we have characterized leukocyte-endothelial interactions in alloxan-induced diabetic and in galactosemic rats by quantitating the number of leukocytes rolling along the venular endothelium and the number of leukocytes sticking to the vascular wall after topical application of zymosan-activated plasma or leukotriene B(4) (1 ng/ml), as well as after the application of a local irritant stimulus (carrageenan, 100 microg). We observed that while 33 days of alloxan-induced diabetes or 7 days of galactosemia had no effect on total or differential leukocyte counts and on the wall shear rate, both treatments significantly (P<0.001) reduced the number of leukocytes rolling along the venular endothelium by about 70% and the number of adhered leukocytes in postcapillary venules by 60%. These effects were not observed in diabetic and galactosemic animals treated with an aldose reductase inhibitor. The results suggest that impaired leukocyte-endothelial cell interactions are a consequence of an enhanced flux through the polyol pathway.

Endotoxin-induced acute lung injury in rats. Role of insulin

Reduced inflammatory responses are frequently associated with diabetes mellitus. In order to investigate the influence of diabetes mellitus on the activation of bronchoalveolar cells, diabetic Wistar rats (alloxan, 40 mg/kg, iv, 30 days) and matched controls were exposed to an aerosol of endotoxin (lipopolysaccharide, LPS) or saline. Bronchoalveolar lavage (BAL) was performed 4 h thereafter. Compared with saline, aerosol administration of LPS significantly increased the number of neutrophils in the BAL fluid of control and diabetic rats. Number of mononuclear cells did not change and eosinophils were absent. A marked increase in luminol-dependent chemiluminescence (LDCL) was observed in control group after stimulation of the cells in vitro with zymosan. In contrast, tests performed with cells from diabetic rats showed a 50% reduction in LDCL generation. Full recovery of cell behaviour to match control values was observed after treatment of diabetic animals with insulin, administered before LPS exposure. Furthermore, relative to controls, level of TNF-alpha in the BAL supernatant of diabetic rats was significantly reduced. Values returned to control levels after treatment of diabetic rats with insulin, prior exposure to LPS. In conclusion, data presented suggest that insulin might regulate superoxide generation and TNF-alpha release by leukocytes upon exposure to LPS in vivo.

Allergic airway inflammation in hypothyroid rats

BACKGROUND

Hormones play a modulating role in allergic inflammation. Hyperthyroidism may increase the severity of asthma, and hypothyroidism may ameliorate coexistent asthma. The mechanisms regulating this interaction are not completely understood.

OBJECTIVE

The purpose of this study was to test the hypothesis that thyroid hormones influence the development of allergic airway inflammation after antigen challenge in rats.

METHODS

The experimental design included either sensitized or nonsensitized surgically thyroidectomized and sham-operated rats. Experiments were performed 50 days after surgery. Thyroidectomized rats and sham-operated controls were sensitized by subcutaneous injection of ovalbumin (OVA) and Al(OH)(3) and challenged 14 days later by OVA inhalation. Bronchoalveolar lavages were performed 24 hours after challenge.

RESULTS

Compared with controls, thyroidectomized animals presented markedly decreased cell yields from bronchoalveolar lavage fluid after OVA challenge. The impaired response was not related to changes in the number of circulating leukocytes. Determination of antibody serum concentrations indicated that thyroidectomized rats presented a marked reduction in the level of anti-OVA IgE compared with controls, without significant differences in IgG(1) and IgG(2a) serum concentrations. Reversal of the impaired responses was attained by 16-day treatment of hypothyroid animals with thyroxine, but not by 1- or 3-day treatment.

CONCLUSION

The data presented suggest that the continuing deficiency of thyroid hormones influences the development of the inflammatory component of asthma. This is due, at least in part, to a decrease in the production of IgE.

Antigen-induced pleural eosinophilia is suppressed in diabetic rats: role of corticosteroid hormones

Previous studies have evidenced for the existence of interactive regulatory mechanisms between insulin and steroid hormones in different systems. In this study, we have investigated whether endogenous corticosteroids could be implicated in the hyporeactivity to antigen challenge observed in sensitized diabetic rats. Alloxinated rats showed a long-lasting increase in the blood glucose levels and a reduction in the number of pleural mast cells at 48 and 72 hr, but not at 24 hr after alloxan administration. In parallel, they also showed a significant elevation in the plasma levels of corticosterone together with an increase in the adrenal/body weight ratio. Antigen-evoked eosinophil accumulation appeared significantly reduced in rats pretreated with dexamethasone as well as in those rendered diabetic 72 hr after alloxan. In the same way, naive animals treated with dexamethasone also responded with a significant decrease in the number of pleural mast cells. Interestingly, when sensitized diabetic rats were pretreated with the steroid antagonist RU 38486 a reversion of the reduction in the allergen-induced eosinophil accumulation was noted. We conclude that the down-regulation of the allergic inflammatory response in diabetic rats is close-related to reduction in mast cell numbers and over expression of endogenous corticosteroids.

Aminoguanidine and the prevention of leukocyte dysfunction in diabetes mellitus: a direct vital microscopic study

1. Defective leukocyte-endothelial interactions are observed in experimental diabetes mellitus. The present study investigated the effect of aminoguanidine, an inhibitor of advanced glycation end products formation, on leukocyte-endothelial interactions in alloxan-induced diabetic rats. 2. In rats anaesthetized with sodium pentobarbitone, the internal spermatic fascia was exteriorized and the microcirculation was observed by a closed-circuit TV coupled to a microscope. The number of leukocytes rolling along the venular endothelium and sticking to the vascular wall was determined after topical application of zymosan-activated plasma (1 mg ml(-1)), as well as the number of adherent and migrated cells after an irritative stimulus (carrageenan 100 microg). 3. The diabetic state decreased the number of rolling, sticking and migrated leukocytes. Pretreatment of diabetic animals with aminoguanidine (250 mg kg(-1) day(-1), for 18 days) normalized these values. To be effective, aminoguanidine had to be administered chronically, starting treatment before induction of the diabetic state. 4. The preventive effect was unrelated to the number of circulating leukocytes, or to the hyperglycaemia or to the hyperosmolality secondary to hyperglycaemia. 5. A non-dialyzed (>12,000-Mr) material in plasma from diabetic, but not normal animals, decreased the number of rolling, sticking and migrated leukocytes in recipient rats. This effect was completely abolished by chronic treatment of diabetic plasma donors with aminoguanidine. 6. The results suggest that a protein modified by glycosylation (>12 kDa) is associated with leukocyte dysfunction in diabetes mellitus and that the ability of aminoguanidine to prevent such dysfunction is related to an inhibitory effect on advanced glycation end products formation.

Lack of effect of endogenous corticosteroids on the acute inflammatory reaction (edema) induced by Bothrops jararaca venom (BjV) in rats

Intraplantar injection of 5 or 10 micrograms of BjV caused local edema in rats that was not affected by ablation of adrenal glands. In addition, no changes in plasma corticosterone levels were observed. Simultaneous injections of the venom into both hindpaws of normal animals, or injections made at varying intervals, resulted in local inflammatory reactions of comparable time-course development and analogous magnitude. These data might be related to an inability of the venom to evoke secretion of corticosteroids.

In vivo Mononuclear Phagocyte Migration: Paradoxical Effect of Adrenalectomy

The effect of adrenalectomy on neutrophil and monocyte migration into rat peritoneal and pleural cavities was investigated. Carrageenin- or thioglycollate-induced neutrophil emigration into both cavities was enhanced by adrenalectomy. In contrast, monocyte migration into peritoneal cavities induced by these two stimuli was significantl decreased. In pleural cavities, adrenalectomy enhanced the monocyte migration induced by carrageenin but had no effect on that induced by thioglycollate. Administration of physiological doses of glucocorticoids reversed the effect of adrenalectomy on monocyte migration by both stimuli into both cavities. The results support the hypothesis that endogenous glucocorticotds negatively control neutrophil migration independently of the site or type of stimulus. Their role in monocyte migration is, however, dependent on the site of injury and on the type of inflammatory stimulus. There is no obvious explanation for the divergent influence of endogenous glucocorticoids on the monocyte emigration into peritoneal and pleural cavities observed with different stimuli.

Infection with Toxoplasma gondii does not Alter TNFalpha and IL-6 Secretion by A human Astrocytoma Cell Line

The secretion of tumour necrosis factor-α (TNFα), interleukin-1α (IL-α) and interleukin-6 (IL-6) by a human astrocytoma cell fine was studied 1 h, 3 h, 6 h and 24 h after infection with tachyzoites from three Toxoplasma gondii strains (virulent, RH; cystogentc, 76K and Prugniaud strains). The astrocytoma cell fine constitutively secreted TNFα and IL-6, but no IL-1α. A positive control was obtained by stimulation with phorbol esters inducing a significant increase (p < 0.05) in TNFα and IL- 6 secretion but not in IL-1α, while lipopolysaccharide (alone and after priming), interferon gamma, ionophore A 23187 and sera positive to T. gondii did not induce any increase in cytokine levels. None of the tachyzoites, whatever their virulence, induced a significant increase in cytokine production at any time in the study. Tachyzoites did not inhibit the secretion induced by phorbol esters.