Resistance to infection in the alloxan-diabetic rabbit

Immune response modulation in acutely ethanol-intoxicated, acutely diabetic male and female rats

We examined how acute diabetes mellitus and acute ethanol intoxication modulate factors that mediate immune responses as a basis for explaining the increased susceptibility to infection in these two conditions. Our working hypothesis is that ethanol intoxication in diabetes compromises host defense mechanisms to a greater extent than observed in each condition alone. Male and female rats were made diabetic with streptozotocin (65 mg/kg, i.p.). Forty-eight hours after administration of streptozotocin, rats either received no treatment (control group) or were treated with (1) ethanol (bolus injection of 1.75 g/kg, followed by a 3-h infusion at the rate of 300 mg/kg/h), (2) lipopolysaccharide [(LPS); 0.9 mg/kg], or (3) a combination of LPS+ethanol. At the end of 3 h, rats were killed, and the livers were digested by perfusion with collagenase-containing Hanks' balanced salt solution to isolate hepatocytes and Kupffer cells. To measure chemokine generation, hepatocytes (2.5x10(5) cells per well) and Kupffer cells (1x10(6) cells per well) were cultured for 20 h, and the supernatant was used to measure cytokine-induced neutrophil chemoattractant (CINC) and regulated on activation, normal T-cell expressed and secreted (RANTES) chemokines. Phagocytosis by Kupffer cells was measured by flow cytometry and expressed as mean channel fluorescence intensity (MCF). Induction of diabetes as well as treatment of nondiabetic rats with LPS, ethanol, or LPS+ethanol caused depression of MCF values of Kupffer cells. However, treatment of the diabetic male and female rats with LPS and LPS+ethanol increased the MCF values relative to those of Kupffer cells obtained from untreated diabetic rats, but administration of ethanol to diabetic rats did not have a similar effect. The induction of diabetes caused an increase in CINC generation by Kupffer cells obtained from male rats, but not from female rats. This diabetes-induced elevation of chemoattractant factor was decreased when diabetic animals were treated with LPS, ethanol, or LPS+ethanol, and the sex difference was obliterated. Thus, the induction of diabetes as well as treatment with LPS, ethanol, or LPS+ethanol in nondiabetic rats depressed the phagocytic capability of Kupffer cells, whereas the presence of endotoxemia (administration of the endotoxin LPS) or administration of LPS+ethanol reversed the diabetic effect, but ethanol intoxication did not. These findings seem to indicate a persistence of depression of host defense capacity in the ethanol-intoxicated diabetic condition. This is further reinforced by the depression of the diabetes-induced enhancement of chemotaxis when the diabetic rats became intoxicated.

The development of the acute inflammatory response to experimental cutaneous mucormycosis in normal and diabetic rabbits

The histologic changes associated with the development of the acute inflammatory response to experimental cutaneous mucormycosis were studied at various times from 5 minutes to 24 hours after inoculation into normal rabbits and in rabbits with acute alloxan diabetes and acidosis. In normal animals the response by polymorphonuclear leukocytes began within a few minutes after inoculation, increased rapidly in extent and intensity and reached its peak within 6 to 12 hours. By that time there was also early proliferation of fibroblasts and of large mononuclear cells and these cellular reactions, together with the accumulated granulocytes, began to produce a demarcation of the lesions. Beginning 4 to 6 hours after inoculation the fungus showed some growth but this remained confined to the necrotic center of the lesions. In the diabetic rabbits the onset of the response by polymorphonuclear leukocytes was delayed by several hours, reduced in intensity and was apparently less effective. There was no proliferation of fibroblasts and the lesions were spreading rather than circumscribed. Fungus growth in the tissues began shortly after inoculation, was marked, progressed rapidly, and soon extended beyond the site of inoculation. The large mononuclear cells, however, appeared at about the same time and in equal number in the lesions of both diabetic and non-diabetic animals and showed no morphologic changes. It is concluded that a significant delay and impaired effectiveness of the response by polymorphonuclear leukocytes, a lack of fibroblastic proliferation and an enhanced growth of the fungus lower host resistance to infection with it and are directly consequent on severe alterations in host metabolism.

Bacterial translocation from the gastrointestinal tract in various mouse models for human diabetes

Bacterial translocation from the gastrointestinal (GI) tract to other internal organs was examined in multiple low-dose streptozotocin-injected (M-STZ), single large-dose streptozotocin-injected (S-STZ), alloxan-injected (Alloxan), and non-obese diabetic (NOD) mice. The incidence of bacterial translocation from the GI tract to the tested organs among diabetic mice was in the order of M-STZ mice greater than S-STZ mice greater than NOD, Alloxan, and control mice. The injections of insulin to M-STZ mice did not decrease the incidence of translocation. These results suggest that bacterial translocation from the GI tract in diabetic mice is not induced by diabetes.

Experimental Candida albicans, Staphylococcus aureus, and Streptococcus faecalis pyelonephritis in diabetic rats

Pyelonephritis was studied after an intravenous injection of Candida albicans, Staphylococcus aureus, or enterococcus in alloxan-diabetic rats and in water-diuresing or non-diuresing nondiabetic rats. The renal microbial populations of C. albicans or S. aureus were found to be greater than 10(5) colony-forming units per g for up to 42 days in diabetic rats, whereas the kidneys tended to become sterile in nondiabetic rats. No significant difference was found in the course of enterococcal pyelonephritis in diabetic versus control rats. The difference in the 50% infective dose for each microorganism between diabetic and control rats was less than or equal to log10. Neither duration of diabetes nor weight loss contributed to the greater and more sustained renal populations of C. albicans and S. aureus in diabetic rats. The inflammatory reaction in kidneys infected with S. aureus or C. albicans was greater in diabetic rats. Fungus balls associated with ureteral obstruction and gross multiple renal abscesses occurred in diabetic, but not in nondiabetic, rats infected with Candida. Growth of C. albicans and S. aureus in vitro in urine from diabetic rats was significantly greater than it was in urine from control rats. Addition of water or glucose to the urine of non-diuresing, nondiabetic rats significantly increased in vitro growth of S. aureus and C. albicans. These studies demonstrate greater severity of infection in the diabetic kidney due to S. aureus and C. albicans, which can be partially explained by decreased inhibitory activity of urine for these organisms in diabetic rats.

Impaired wound healing in streptozotocin diabetes. Prevention by supplemental vitamin A

Goodson and Hunt showed that wound healing is impaired in streptozotocin (Sz) diabetic rats; we speculated that this impairment results from defective early inflammatory responses to wounding. Because we had shown that supplemental vitamin A stimulates the early inflammatory response to wounding in nondiabetic rats, we studied the effect of supplemental vitamin A on wound healing in rats with Sz-induced diabetes. Male Sprague-Dawley rats were fed a commercial rat chow containing twice the amount of vitamin A recommended by the NRC for healthy rats. The rats ate and drank (tap water) ad libitum. Two-thirds of the rats were injected (intravenously) with Sz 60 mg/kg body weight. All of these rats became diabetic (hyperglycemia greater than 350 mg/dl, hyperphagic, polydipsic, polyuric, glycosuric greater than 2%). Seven days later, half of the Sz-injected rats were continued on the chow (Group 2) while the other half (Group 3) were switched to the chow supplemented with 150,000 units of vitamin A/kg chow. The next day, all were wounded (7 cm skin incisions and s.c. polyvinyl alcohol sponge implants). Similarly wounded saline injected nondiabetic rats ingesting the unsupplemented chow served as controls (Group 1). The wounds of Group 2 rats healed poorly compared to Group 1 (breaking strength of skin incisions, 308 +/- 19 g vs 584 +/- 23 g, p less than 0.001; hydroxyproline of the sponge reparative tissue, 0.87 mg vs 2.40 mg/100 mg sponge p less than 0.001). Supplemental vitamin A (Group 3) did not affect the hyperglycemia, hyperphagia, polydipsia or glycosuria, but increased the breaking strengths of the incisions of the diabetic rats (468 +/- 40 g, p less than 0.001), and the sponge hydroxyproline (2.38 mg/100 mg sponge, p less than 0.001). In another experiment, in which the wounding and start of supplemental vitamin A were delayed until 28 days after streptozotocin administration (50 mg/kg body weight), similar results were obtained. Streptozotocin diabetes also caused a decrease in the cross-linking of reparative collagen as judged by the ratio of breaking strengths of skin incisions before and after formalin fixation. Supplemental vitamin A did not influence this defect. Sz also caused peripheral lymphocytopenia, adrenal hypertrophy and thymic involution which responded to the supplemental vitamin A. Based upon experimental data and theoretical considerations we conclude Sz diabetes causes two defects in wound healing: a) quantitatively (reduction in reparative collagen accumulation) and b) qualitative reduction in the degree of cross-linking of reparative wound collagen. The action of supplemental vitamin A in correcting the impaired wound healing, adrenal enlargement, thymic involution and lymphocytopenia of Sz-diabetic rats is independent of an effect on their disturbed carbohydrate metabolism.

Phagocytosis of inert particles in the reticuloendothelial system in rats with experimental insulinopenic diabetes

Phagocytosis of inert, radioactive gold particles in the reticuloendothelial system in rats in the case of experimental insulinopenic diabetes was studied. In the spleen, phagocytosis was seen to have fallen to a relatively low level after four weeks from the induction of diabetes. In the liver, there was noted a reduction of phagocytosis per gram of organ, though it remained the same for the total organ which in the case of diabetes mellitus increases in weight relative to body weight. This difference in reaction of the reticuloendothelial system in the liver and spleen has also been observed in mice with tumors. The importance of the findings of the present study for increased sensitivity to infections of poorly controlled diabetic patients is discussed in greater detail.

Studies on the pathogenesis of acute inflammation. IX. The influence of hyperosomolality secondary to hyperglycemia upon the acute inflammatory response induced by thermal injury to ear chambers of rabbits

The inflammatory reaction induced in ear chambers of rabbits by heat injury was studied in nondiabetic animals made hyperglycemic with continuous infusions of glucose. Hypertonic solutions of glucose administered intravenously to rabbits induced the following triad: hyperglycemia, hyperosmolality, and metabolic lactic acidosis. It was found that relatively short periods of this metabolic abnormality were associated with a significant reduction in the intensity of the inflammatory reaction. There was no evidence microscopically of circulatory impairment within ear chambers; and since neither arterial hypotension nor oxygen deficit was recorded during experiments, it appeared most likely that decreased leucocytic margination per se best explained the inhibited exudative response. Hyperglycemia seemed the dominant factor responsible for this anti-inflammatory effect. It was found subsequently that hyperglycemia and hyperosmolality without metabolic acidosis impaired cellular exudation just as well.