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

Correlation of Impaired NF-kB Activation in Sepsis-Induced Acute Lung Injury (ALI) in Diabetic Rats

Background

The allergic lung inflammation is reduced in the diabetic rats which can be restored by treating it with insulin. As observed in multiple studies, the diabetic patients are more vulnerable to infections and their inflammatory reactions. There are confirmations on insulin and its effects control the inflammatory reactions.

Objective

This study was performed to understand the correlation of impaired NF-kB activation in sepsis-induced acute lung injury (ALI) in diabetic rats. Material and Methods. Streptozotocin was used for induction of diabetes and sepsis was induced by colon ligation puncture surgery. Post 6 hours of CLP, the lungs in the groups were analyzed for cell infiltration using broncho-alveolar lavage. The lungs were removed for histopathological analysis at the end of study where the bronchioles, alveoli, and edema were analyzed and compared. Cell expressions quantified by the help of antibodies and inflammatory events were analyzed.

Results

Diabetic rats developed mild acute lung injury due to the suppression of activation of NF-kB in alveolar macrophages.

Conclusion

Even the diabetic rats were more susceptible to sepsis in comparison to the nondiabetic rats, but the NF-kB suppression has a major role to play in the faint symptoms of ALI.

Streptozotocin-Induced Diabetes Mellitus in Neonatal Rats: An Insight into its Applications to Induce Diabetic Complications

BACKGROUND

Diabetic complications are the major contributor in the mortality of diabetic patients despite controlling blood glucose level. In the journey of new drug discovery, animal models have to play a major role. A large number of chemical-induced and genetically modified animal models have been investigated to induce diabetic complications but none of them was found to be mimicking the pathophysiology of the human. Therefore, the search and identification of the appropriate animal model become essential.

OBJECTIVE

In the present review, we have made an attempt to understand the pathophysiology of diabetic complication in the neonatal streptozotocin-diabetic rat model and tried to identify the targets for therapeutic agents. The review will help the researchers to explore the animal model to induce diabetic complications, to identify targets and further to find lead molecules for treatment or prevention of diabetic complications.

METHODS

We have compiled the available research work from 1974 by using prominent databases, organized the available information and analyzed the data to improve the understanding of the pathophysiology of streptozotocin-induced diabetic complications in neonates of rats.

RESULTS

The neonatal streptozotocin-diabetic rat model is frequently used and well-established animal model for type 2 diabetes mellitus. We have found that this model has been used to study the pathogenesis of various micro and macrovascular diabetic complications and also investigated for its effects on the liver, thymus gland, and brain. The underlying pathophysiology for complications had a resemblance to the human.

CONCLUSION

The neonatal streptozotocin-diabetic rat model may demonstrate symptomatic diabetic complications due to persistent hyperglycemia at the age of approximately 18-24 weeks. Critical interpretations of available research work showed that the researcher can explore split dose STZ (90- 100mg/kg b.w) model to induce Type 2 DM in neonates of rats at 2nd or 3rd postnatal day.

Transcriptional and Functional Plasticity Induced by Chronic Insulin Exposure in a Mast Cell-Like Basophilic Leukemia Cell Model

Objective

Secretory granules (SG) and lipid bodies (LB) are the primary organelles that mediate functional responses in mast cells. SG contains histamine and matrix-active proteases, while LB are reservoirs of arachidonic acid and its metabolites, precursors for rapid synthesis of eicosanoids such as LTC₄. Both of these compartments can be dynamically or ontologically regulated, with metabolic and immunological stimuli altering lipid body content and granule numbers responding to contextual signals from tissue. We previously described that chronic in vitro or in vivo hyperinsulinemia expands the LB compartment with a concomitant loss of SG capacity, suggesting that this ratio is dynamically regulated. The objective of the current study is to determine if chronic insulin exposure initiates a transcriptional program that biases model mast cells towards a lipogenic state with accompanying loss of secretory granule biogenesis.

Methods

We used a basophilic leukemic cell line with mucosal mast cell-like features as a model system. We tested the hypothesis that chronic insulin exposure initiates a transcriptional program that biases these model mast cells towards a lipogenic state with accompanying loss of secretory granule biogenesis. Transcriptional arrays were used to map gene expression patterns. Biochemical, immunocytochemical and mediator release assays were used to evaluate organelle numbers and functional responses.

Results

In a mucosal mast cell model, the rat basophilic leukemia line RBL2H3, mast cell granularity and SG numbers are inversely correlated with LB numbers. Chronic insulin exposure appears to modulate gene networks involved in both lipid body biogenesis and secretory granule formation. Western blot analysis confirms upregulation of protein levels for LB proteins, and decreases in proteins that are markers for SG cargo.

Conclusions

The levels of insulin in the extracellular milieu may modify the phenotype of mast cell-like cells in vitro.

Immunomodulatory effects of black seeds and garlic on alloxan-induced Diabetes in albino rat

BACKGROUND

Alteration in the proliferation capacity of leukocytes and in the level of some cytokines, such as TNF-α, IL-4 and IL-8 have been suggested to associate with Diabetes mellitus in alloxan-induced diabetic rats given the potential immunomodulatory effects of black seeds and garlic.

AIM OF THE WORK

The aim of this study was to test the effects of these agents on the immune cells in alloxan-induced diabetic rats.

METHODS

To this end, Diabetes was induced in albino rats by a single intraperitoneal injection of alloxan monohydrate (120mg/kg of body weight). Diabetic rats were then fed normal diet or diet with black seeds or garlic for 28 days.

RESULTS

The results showed significant increase in the numbers of monocytes and granulocytes, but with significant decreases in lymphocyte proliferation and the TNF-α, interleukin (IL)-4 and IL-8 levels in the diabetic group. Treatment of diabetic rats with black seeds or garlic induced significant amelioration in the numbers of monocytes and granulocytes, with significant increase in lymphocytes numbers and the TNF-α, IL-4 and IL-8 levels.

CONCLUSIONS

These results indicate the potential beneficial effects of black seeds and garlic as adjuvant treatment during treatment of Diabetes.

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.

Insulin modulates cytokine release and selectin expression in the early phase of allergic airway inflammation in diabetic rats

BACKGROUND

Clinical and experimental data suggest that the inflammatory response is impaired in diabetics and can be modulated by insulin. The present study was undertaken to investigate the role of insulin on the early phase of allergic airway inflammation.

METHODS

Diabetic male Wistar rats (alloxan, 42 mg/Kg, i.v., 10 days) and controls were sensitized by s.c. injection of ovalbumin (OA) in aluminium hydroxide 14 days before OA (1 mg/0.4 mL) or saline intratracheal challenge. The following analyses were performed 6 hours thereafter: a) quantification of interleukin (IL)-1beta, tumor necrosis factor (TNF)-alpha and cytokine-induced neutrophil chemoattractant (CINC)-1 in the bronchoalveolar lavage fluid (BALF) by Enzyme-Linked Immunosorbent Assay, b) expression of E- and P- selectins on lung vessels by immunohistochemistry, and c) inflammatory cell infiltration into the airways and lung parenchyma. NPH insulin (4 IU, s.c.) was given i.v. 2 hours before antigen challenge.

RESULTS

Diabetic rats exhibited significant reduction in the BALF concentrations of IL-1beta (30%) and TNF-alpha (45%), and in the lung expression of P-selectin (30%) compared to non-diabetic animals. This was accompanied by reduced number of neutrophils into the airways and around bronchi and blood vessels. There were no differences in the CINC-1 levels in BALF, and E-selectin expression. Treatment of diabetic rats with NPH insulin, 2 hours before antigen challenge, restored the reduced levels of IL-1beta, TNF-alpha and P-selectin, and neutrophil migration.

CONCLUSION

Data presented suggest that insulin modulates the production/release of TNF-alpha and IL-1beta, the expression of P- and E-selectin, and the associated neutrophil migration into the lungs during the early phase of the allergic inflammatory reaction.