Deoxynivalenol suppresses circulating and splenic leukocyte subpopulations in BALB/c mice: dose response, time course and sex differences.

It was hypothesized that suppression of peripheral blood leukocyte subsets were markers of exposure to dietary deoxynivalenol (DON), a Fusarium graminearum mycotoxin in grain, at 1.0 mg kg(-1) but not at lesser doses in BALB/c mice. Groups of 10 female and 10 male BALB/c mice were fed 0, 0.25, 0.5, 1.0, and 2.0 mg kg(-1) DON for 14 and 28 days. Using flow cytometry with staining for leukocyte surface markers, the percentage of CD19(+) leukocytes (B cells) in peripheral blood was decreased in both sexes of BALB/c mice after 14 days of exposure to 1.0 or 2.0 mg kg(-1) DON, whereas exposure to DON over 28 days did not inhibit B cells compared to the control diet. The percentage of mononuclear cells in peripheral blood was decreased in female BALB/c mice fed 1 and 2 mg kg(-1) DON after 14 days compared with control diet. The percentage of CD11b(+) leukocytes (monocytes) in peripheral blood and total CD11b(+) splenic leukocytes were decreased only in female mice fed 1.0 and 2.0 mg kg(-1) DON after 28 days compared with control diet, which shows the greater sensitivity to DON in females compared to males. It was concluded that BALB/c mice adapted to DON exposure because peripheral blood cellular effects of DON at 14 days disappeared by 28 days with the exception of monocyte changes in females. This suggests that female sex hormones potentiate one potential marker of DON immunotoxicity in BALB/c mice.

Surfactant protein D expression in normal and pneumonic ovine lung.

Surfactant protein D (SP-D) is a collagenous calcium-dependent lectin constitutively expressed by alveolar type II pneumocytes and non-ciliated bronchiolar epithelial (Clara) cells. It binds to surface glycoconjugates expressed by a wide variety of microorganisms such as Gram-negative bacteria, influenza A virus, and various fungi, leading to pathogen inactivation or enhanced neutrophil and macrophage activity. Since a hallmark of bronchopneumonia is the initiation of inflammation in the bronchi and bronchoalveolar junction, we chose a classic ruminant model of bronchopneumonia caused by Mannheimia haemolytica to study the expression of SP-D within the bronchioles of infected lambs. Healthy weaned lambs were inoculated with either pyrogen-free saline (controls) or M. haemolytica intrabronchially using a fiber-optic bronchoscope. SP-D protein and mRNA expression in lung was detected by immunohistochemistry (IHC) and fluorogenic real-time relative quantitative reverse transcriptase polymerase chain reaction (real-time RT-PCR), respectively, during acute (1 day), subacute (15 days), and chronic (45 days) bronchopneumonia. At 15 and 45 days post-inoculation, areas of lung had peribronchiolar inflammatory cell infiltrate, epithelial cell hyperplasia, tortuosity of the airway lumens, and decreased intensity of SP-D protein staining and number of positive cells. The levels of SP-D mRNA were not increased or significantly altered by M. haemolytica infection when compared to control animals. In conclusion, cell-associated SP-D protein expression significantly decreases within hyperplastic epithelium of lungs from infected animals during chronic bronchopneumonia. Exhaustion of SP-D protein reserves and absence of SP-D gene upregulation during the progression of bacterial pneumonia into chronicity may result in failure to clear the pathogen from the lung and/or cause animals to be more susceptible to re-infection.

Distribution of substance P receptor (neurokinin-1 receptor) in normal ovine lung and during the progression of bronchopneumonia in sheep.

Substance P contributes to the physiological homeostasis of pulmonary airways and vasculature. During pneumonia, alterations in substance P production and receptor expression can influence bronchoconstriction and vascular perfusion. The distribution of substance P receptor [neurokinin-1 receptor (NK-1R)] in lungs of normal sheep and sheep with acute (1 day), subacute (15 days), and chronic (45 days) bronchopneumonia caused by Mannheimia haemolytica was determined by immunohistochemistry (IHC). Three rabbit polyclonal antibodies generated to the same cytosolic C-terminal portion of NK-1R (residues 393-407) were tested. NK-1R immunoreactivity was traced in digital images and quantified with IPLAB software. There were no significant differences in NK-1R protein density between normal and infected lambs. Antibody 1 had the broadest distribution and intensity, and stained alveolar septae, smooth muscle cells of airways and vessels, epithelial cells of airways and alveoli, and submucosal glands. When all animals from the study were included, there was a trend towards decreased NK-1R immunoreactivity over time. The work suggests that (a) the density of NK-1R does not change during progression of bacterial (M. haemolytica) bronchopneumonia, (b) NK-1R is widely distributed in ovine lung and decreases with age, and (c) antibodies to the same NK-1R cytosolic region can vary in specificity and affinity.