Effect of prophylactic supplementation with grape polyphenolics on endotoxin-induced serum secretory phospholipase A2 activity in rats.

This study investigated whether dietary supplementation of polyphenolics-rich grape extract (GE) could attenuate endotoxin-induced serum secretory phospholipase A(2) (sPLA(2)) activity, a modulator of inflammation. Male Sprague-Dawley rats were fed a control diet or the diet supplemented with polyphenolic-rich GE (100 or 300 mg/kg daily) for 3 wk prior to intraperitoneal injection of 3 or 15 mg/kg LPS. A fluorometric assay was used to measure serum sPLA(2) activity during a 5-d period before and after LPS injection. Body weight, hematocrit, and serum C-reactive protein level were also measured. Administration of LPS induced a rapid increase in sPLA(2) activity, which peaked 1 to 2 d after LPS injection and resolved to near-baseline values on days 4 to 5. Marked declines in body weight and hematocrit, increases in C-reactive protein levels, and effects on health status also occurred. GE supplementation significantly attenuated the LPS-induced increase in sPLA(2) activity and decline in hematocrit, but its effects on the loss of body weight and C-reactive protein levels were not significant. Among the measurements, serum sPLA(2) was the only marker that showed a dose-dependent response to both LPS and GE supplementation. The current findings show that oral consumption of polyphenolic-rich GE suppresses endotoxin-induced sPLA(2) activity.

Perturbations in cytokine gene expression after inoculation of C57BL/6 mice with Pasteurella pneumotropica.

Pasteurella pneumotropica can cause inflammation and abscess formation in a variety of tissues. Most commonly, P. pneumotropica produces clinical disease in immunodeficient mice or those concurrently infected with other pathogens. Because clinical disease is infrequent in immunocompetent mice harboring P. pneumotropica, some scientists consider it an opportunistic pathogen with little clinical relevance to biomedical research. However, other infectious agents, including mouse parvoviruses, mouse rotavirus, and Helicobacter spp. alter physiologic or biologic responses without causing clinical signs of illness. We investigated the potential for P. pneumotropica to modulate the transcription of cytokine genes in immunocompetent mice. In C57BL/6 mice inoculated oronasally with a minimal colonizing dose of P. pneumotropica, modest but statistically significant elevations of IL1beta, TNFalpha, CCL3, CXCL1, and CXCL2 mRNA were detected in mandibular and superficial cervical lymph nodes at 7 d after inoculation, and upregulation of IL1beta mRNA was detected 28 d after inoculation. These perturbations were not present in C57/BL6 mice inoculated with heat killed-P. pneumotropica or the related bacterium Actinobacillus muris. Nasal mucosal cytokine transcription did not vary significantly in C57BL/6 mice given a high dose of P. pneumotropica. These data indicate that slight and transient experimental perturbations are possible in immunocompetent mice colonized with P. pneumotropica. Knowing the full health status of experimental mice is paramount to avoid unwanted experimental variables, especially when using exquisitely sensitive testing methodologies such as those for quantification of gene expression.

Macrophage killing of Leishmania amazonensis amastigotes requires both nitric oxide and superoxide.

The requirements for effective and efficient intracellular killing of Leishmania amazonensis by activated macrophages are unknown. Despite resistance to the arginase inhibitor LOHA by intracellular L. amazonensis amastigotes, enhanced replication did not account for the relative resistance of this parasite to macrophage activation. Herein we report that the presence of both superoxide and nitric oxide is necessary for efficient killing of L. amazonensis amastigotes within LPS/IFN-gamma-activated bone marrow-derived macrophages generated from C3H mice. Addition of an extracellular signal-regulated kinase (ERK) inhibitor to L. amazonensis-infected macrophages increased the ability of these activated macrophages to kill L. amazonensis amastigotes. This enhanced macrophage killing through addition of ERK inhibitor was abrogated by inhibition of superoxide or iNOS, whereas inhibiting superoxide had no effect on the killing of L. major. These results suggest that ERK activation may modulate effective macrophage killing, leading to the ability of L. amazonensis to resist elimination within activated macrophages.

Strategies for refinement of abdominal device implantation in mice: strain, carboxymethylcellulose, thermal support, and atipamezole.

A widely used in vivo technique in mice and other species is the surgical implantation of transmitters for telemetric monitoring of core body temperature, locomotor activity, and other variables. However, these devices are quite large relative to the size of the mouse abdomen. We report here on the results of several related studies that we conducted to evaluate refinement strategies relevant to implantation of abdominal devices in mice. First, we evaluated survival from surgery as a function of strain and body weight and found that both parameters influence the proportion of mice that survive. Second, we assessed the effect of several interventions on postsurgical recovery of food and water intakes, core temperature, and locomotor activity. Some of the interventions were associated with increased mortality (atipamezole) or were otherwise detrimental (the abdominal lubricant carboxymethylcellulose), whereas others had little or no effect on recovery (thermal support). These findings indicate that interventions presumed to promote recovery from surgery that are based on data from other species may not always have the anticipated positive effect in mice. This study therefore underscores the need to carefully assess the effect of modifications in experimental procedures to avoid causing unexpected complications in mice.