Macrophages from a type 1 diabetes mouse model present dysregulated Pl3K/AKT, ERK 1/2 and SAPK/JNK levels

Diabetes causes dysregulation in signal transduction in immune cells leading to an impaired response to pathogens. Herein, we investigated the impact of type 1 diabetes (T1D) in bone marrow-derived macrophages (BMDM), using male non-diabetic and diabetic C57BL/6 mice (alloxan 60 mg/kg, i.v., CEUA/FCF/USP - 467). Diabetic BMDM expressed impaired phosphoinositide 3-kinase (PI3K), being lower p-PI3K p55 levels and higher levels of PI3K p110 alpha, whereas protein kinase B (PKB/Akt) (Ser-473 and Thr-308), extracellular signal-regulated kinases (ERK 1/2), and stress-activated protein kinase (SAPK/JNK) were enhanced compared to non-diabetic BMDM. Further evaluation of the responsiveness to lipopolysaccharide (LPS; 0.1 and 1 ug/mL), diabetic BMDM and peritoneal macrophage secreted dysregulated levels of tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-10 levels. In 24 h, diabetic BMDM stimulated by LPS presented lower metabolic activity, with no differences in cell surveillance. Therefore, LPS re-stimulation (0.1 ug/mL) in diabetic BMDM resulted in higher secretion of TNF-α compared to non-diabetic BMDM. However, diabetic peritoneal macrophages secreted similar IL-6 levels in the first and additional 24 h of LPS stimulation. In general, our results demonstrated that diabetes exerts an impact in both BMDM and peritoneal macrophages ability to secrete cytokine under LPS stimulation.

Insulin Modulates Paracoccidioides brasiliensis-Induced Inflammation by Restoring the Populations of NK Cells, Dendritic Cells, and B Lymphocytes in Lungs

Paracoccidioidomycosis, a key issue for Brazilian health service, can be aggravated in patients with impaired immunological responses, such as diabetic patients. We evaluated the role of insulin in inflammatory parameters in diabetic and nondiabetic mice using a systemic mycosis Paracoccidioides brasiliensis (Pb) model. Diabetic C57BL-6 mice and controls were infected with Pb18 and treated with insulin for 12 days prior to experiments. After 55 days, infected diabetic mice exhibited fewer leukocytes in both peritoneal lavage fluid (PeLF) and bronchoalveolar lavage fluid and reduced secretion of interleukin- (IL-) 6 in lungs. In addition, diabetic mice presented a reduced influx of TCD4+ cells, TCD8+ cells, B lymphocytes, NK cells, and dendritic cells compared to control infected groups. Insulin treatment restored the leukocyte number in PeLF and restored the presence of B lymphocytes, dendritic cells, and NK cells in lungs of diabetic animals. The data suggest that diabetic mice present impaired immunological response to Pb18 infection and insulin modulates inflammation by reducing IL-6 levels in lung and CINC-1 levels in spleen and liver homogenates, restoring leukocyte concentrations in PeLF and also restoring populations of dendritic cells and B lymphocytes in lungs of diabetic mice, permitting the host to better control the infection.

Is there a therapeutic window for pentoxifylline after the onset of acute pancreatitis?

PURPOSE

To investigate the effects of pentoxifylline (PTX) in experimental acute pancreatitis (AP) starting drug administration after the induction of the disease.

METHODS

One hundred male Wistar rats were submitted to taurocholate-induced AP and divided into three groups: Group Sham: sham-operated rats, Group Saline: AP plus saline solution, and Group PTX: AP plus PTX. Saline solution and PTX were administered 1 hour after induction of AP. At 3 hours after AP induction, peritoneal levels of tumor necrosis factor (TNF)-α, and serum levels of interleukin (IL)-6 and IL-10 levels were assayed by Enzyme-Linked Immunosorbent Assay (ELISA). Determinations of lung myeloperoxidase activity (MPO), histological analysis of lung and pancreas, and mortality study were performed.

RESULTS

PTX administration 1 hour after induction of AP caused a significant decrease in peritoneal levels of TNF-α and in serum levels of IL-6 and IL-10 when compared to the saline group. There were no differences in lung MPO activity between the two groups with AP. A decrease in mortality was observed in the PTX treatment compared to the saline group.

CONCLUSIONS

Administration of PTX after the onset of AP decreased the systemic levels of proinflammatory cytokines, raising the possibility that there is an early therapeutic window for PTX after the initiation of AP.

Diagnostic methods in sepsis: the need of speed

OBJECTIVE

Sepsis is a common condition encountered in hospital environments. There is no effective treatment for sepsis, and it remains an important cause of death at intensive care units. This study aimed to discuss some methods that are available in clinics, and tests that have been recently developed for the diagnosis of sepsis.

METHODS

A systematic review was performed through the analysis of the following descriptors: sepsis, diagnostic methods, biological markers, and cytokines.

RESULTS

The deleterious effects of sepsis are caused by an imbalance between the invasiveness of the pathogen and the ability of the host to mount an effective immune response. Consequently, the host's immune surveillance fails to eliminate the pathogen, allowing it to spread. Moreover, there is a pro-inflammatory mediator release, inappropriate activation of the coagulation and complement cascades, leading to dysfunction of multiple organs and systems. The difficulty achieve total recovery of the patient is explainable. There is an increased incidence of sepsis worldwide due to factors such as aging population, larger number of surgeries, and number of microorganisms resistant to existing antibiotics.

CONCLUSION

The search for new diagnostic markers associated with increased risk of sepsis development and molecules that can be correlated to certain steps of sepsis is becoming necessary. This would allow for earlier diagnosis, facilitate patient prognosis characterization, and prediction of possible evolution of each case. All other markers are regrettably constrained to research units.

Effect of plant neutrophil elastase inhibitor on leucocyte migration, adhesion and cytokine release in inflammatory conditions

BACKGROUND AND PURPOSE

The serine and cysteine peptidase inhibitor, BbCI, isolated from Bauhinia bauhinioides seeds, is similar to the classical plant Kunitz inhibitor, STI, but lacks disulphide bridges and methionine residues. BbCI blocks activity of the serine peptidases, elastase (K(iapp) 5.3 nM) and cathepsin G (K(iapp) 160.0 nM), and the cysteine peptidase cathepsin L (K(iapp) 0.2 nM). These three peptidases play important roles in the inflammatory process.

EXPERIMENTAL APPROACH

We measured the effects of BbCI on paw oedema and on leucocyte accumulation in pleurisy, both induced by carrageenan. Leucocyte-endothelial cell interactions in scrotal microvasculature in Wistar rats were investigated using intravital microscopy. Cytokine levels in pleural exudate and serum were measured by elisa.

KEY RESULTS

Pretreatment of the animals with BbCI (2.5 mg·kg(-1)), 30 min before carrageenan-induced inflammation, effectively reduced paw oedema and bradykinin release, neutrophil migration into the pleural cavity. The number of rolling, adhered and migrated leucocytes at the spermatic fascia microcirculation following carrageenan injection into the scrotum were reduced by BbCI pretreatment. Furthermore, levels of the rat chemokine cytokine-induced neutrophil chemo-attractant-1 were significantly reduced in both pleural exudates and serum from animals pretreated with BbCI. Levels of interleukin-1β or tumour necrosis factor-α, however, did not change.

CONCLUSIONS AND IMPLICATIONS

Taken together, our data suggest that the anti-inflammatory properties of BbCI may be useful in investigations of other pathological processes in which human neutrophil elastase, cathepsin G and cathepsin L play important roles.

The allergic inflammatory reaction in neonatal streptozotocininduced diabetic rats: evidence of insulin resistance and microvascular dysfunction

OBJECTIVE

To investigate the allergic reaction in neonatal streptozotocin (nSTZ)-induced diabetes mellitus.

MATERIAL

Male newborn Wistar rats were made diabetic by the injection of streptozotocin (160 mg/kg, i. p.) and used 8 weeks thereafter.

TREATMENT

Animals were sensitized against ovalbumin (OA, 50 microg and Al(OH)3, 5 mg, s. c.) and challenged 14 or 21 days thereafter.

METHODS

OA-induced airway inflammation and OA-induced pleurisy models were used to investigate leukocyte migration (total and differential leukocyte counts) and lung vascular permeability (Evans blue dye extravasation).

RESULTS

nSTZ-diabetic rats presented glucose intolerance and insulin resistance. Relative to controls, nSTZ rats exhibited a 30% to 50% reduction in lung vascular permeability. Leukocyte infiltration in both models of allergen-induced inflammation, and number of pleural mast cells did not differ between groups.

CONCLUSIONS

Data suggest that the reduction of allergic inflammatory reactions in nSTZ rats is restricted to microvascular dysfunctions and associated, probably, with insulin resistance in lung microvascular endothelium.

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.

Insulin inhibits LPS-induced signaling pathways in alveolar macrophages

The systemic inflammatory response syndrome (SIRS) is triggered by lipopolysaccharide (LPS) from Gram-negative bacteria. Insulin was shown to have a protective role in SIRS related to sepsis. Lungs are particularly affected in this condition and provide a second wave of mediators/cytokines which amplifies SIRS. The aim of the present study was to investigate the effect of insulin on the signaling pathways elicited by LPS in alveolar macrophages (AMs) and its consequence in cellular response to LPS measured as production of tumor necrosis factor (TNF). To this purpose, resident AMs from male Wistar rats were obtained by lung lavage and stimulated by LPS (100 ng/mL). Insulin (1 mU/mL) was added 10 min before LPS. Activation (phosphorylation) of signaling molecules by LPS was analyzed by western blot, 30 min after LPS stimulation. TNF was measured in the AMs culture supernatants by bioassay using L-929 tumor cells. Relative to controls, LPS induced a significant increase in the activation of ERK (3.6-fold), p38 (4.4-fold), Tyr-326 Akt (4.7-fold), Ser-473 Akt (6.9-fold), PKCalpha (4.7-fold) and PKCdelta (2.3-fold). Treatment of AMs with insulin before LPS stimulation, significantly reduced the activation of ERK (54%), p38 (48%), Tyr-326 Akt (64%), Ser-473 Akt (41%), PKCalpha (62%) and PKCdelta (39%). LPS induced TNF production in AMs which was also inhibited by insulin (60%). These results show that insulin down-regulates MAPK, PI3K and PKCs and inhibits a downstream effect of LPS, TNF production, in rat AMs stimulated with LPS and suggest that the protective effect of insulin in sepsis could be through modulation of signal transduction pathways elicited by LPS in lung macrophages.

Inhibition of tumor necrosis factor-alpha-induced intercellular adhesion molecule-1 expression in diabetic rats: role of insulin

OBJECTIVE

The effects of insulin on intercellular adhesion molecule (ICAM)-1-mediated leukocyte adhesion and migration were investigated.

METHODS

Diabetic rats (alloxan, 42 mg/kg, i. v., 42 days), matching controls, and insulin (NPH, 2 IU/day for 12 days) treated diabetic rats were used. The internal spermatic fascia of the animals was used for direct vital microscopy of the microcirculation, and for quantitation of ICAM-1 expression by immunohistochemistry and reverse transcriptase-polymerase chain reaction (RT-PCR). Experiments were performed 2 h after the local injection of recombinant rat tumor necrosis factor-alpha (5 ng).

RESULTS

Relative to controls (C), diabetic (D) rats exhibited a reduced number of adhered (D: 2.2 +/- 0.4 and C: 14.1 +/- 0.6 cells/100 microm venule length, P < 0.001) and migrated leukocytes (D: 1.1 +/- 0.3 and C: 6.3 +/- 0.6 cells/1,000 microm (2), P < 0.001) accompanied by low expression of ICAM-1 in postcapillary venules (D: 18 +/- 4 and C: 51 +/- 7 arbitrary units, P < 0.001). There were no differences in ICAM-1 mRNA levels (D: 1.01 +/- 0.05 and C: 1.18 +/- 0.09 ICAM-1/GAPDH ratio, P > 0.05). Treatment of diabetic rats with insulin restored the number of adhered (10.9 +/- 1.2 cells/100 microm venule length), and migrated leukocytes (4.0 +/- 0.3 cells/1,000 microm (2)) as well as ICAM-1 expression (45 +/- 3 arbitrary units). Levels of mRNA for ICAM-1 remained unchanged after treatment (1.15 +/- 0.04 ICAM-1/GAPDH ratio).

CONCLUSION

Insulin modulates TNF-alpha-induced ICAM-1 expression on microvascular endothelium controlling, therefore, leukocyte adhesion and migration.