Immune and biochemical responses in skin differ between bovine hosts genetically susceptible and resistant to the cattle tick Rhipicephalus microplus.

BACKGROUND: Ticks attach to and penetrate their hosts' skin and inactivate multiple components of host responses in order to acquire a blood meal. Infestation loads with the cattle tick, Rhipicephalus microplus, are heritable: some breeds carry high loads of reproductively successful ticks, whereas in others, few ticks feed and reproduce efficiently. METHODS: In order to elucidate the mechanisms that result in the different outcomes of infestations with cattle ticks, we examined global gene expression and inflammation induced by tick bites in skins from one resistant and one susceptible breed of cattle that underwent primary infestations with larvae and nymphs of R. microplus. We also examined the expression profiles of genes encoding secreted tick proteins that mediate parasitism in larvae and nymphs feeding on these breeds. RESULTS: Functional analyses of differentially expressed genes in the skin suggest that allergic contact-like dermatitis develops with ensuing production of IL-6, CXCL-8 and CCL-2 and is sustained by HMGB1, ISG15 and PKR, leading to expression of pro-inflammatory chemokines and cytokines that recruit granulocytes and T lymphocytes. Importantly, this response is delayed in susceptible hosts. Histopathological analyses of infested skins showed inflammatory reactions surrounding tick cement cones that enable attachment in both breeds, but in genetically tick-resistant bovines they destabilized the cone. The transcription data provided insights into tick-mediated activation of basophils, which have previously been shown to be a key to host resistance in model systems. Skin from tick-susceptible bovines expressed more transcripts encoding enzymes that detoxify tissues. Interestingly, these enzymes also produce volatile odoriferous compounds and, accordingly, skin rubbings from tick-susceptible bovines attracted significantly more tick larvae than rubbings from resistant hosts. Moreover, transcripts encoding secreted modulatory molecules by the tick were significantly more abundant in larval and in nymphal salivary glands from ticks feeding on susceptible bovines. CONCLUSIONS: Compared with tick-susceptible hosts, genes encoding enzymes producing volatile compounds exhibit significantly lower expression in resistant hosts, which may render them less attractive to larvae; resistant hosts expose ticks to an earlier inflammatory response, which in ticks is associated with significantly lower expression of genes encoding salivary proteins that suppress host immunity, inflammation and coagulation.

Length and density of filiform tongue papillae: differences between tick-susceptible and resistant cattle may affect tick loads.

BACKGROUND: Indicine breeds of bovines are highly resistant and taurine breeds are susceptible to the cattle tick, Rhipicephalus microplus, a species which causes great damage to livestock. Animals use their tongues for self-grooming, an important behavior for ridding themselves of ectoparasites. However, the role of tongue morphology, notably the filiform papillae, in this process is not known. FINDINGS: This study compared features of the filiform papillae of tongues in eight Nelores (indicine breed) and eight Holsteins and two Brown Swiss (taurine breeds) and verified how they associate with tick loads. Biopsies were taken from identical positions of tongues and measured by scanning electron microscopy. One-way analysis of variance detected significant differences between morphological features of tongues from indicine and taurine breeds: Nelores had longer papillae (mean of 2.3 mm ± 0.029 SD; P < 0.001), and more papillae per cm(2) (mean of 25.2 papillae ± 1.92 SD; P < 0.05) than European bovines (means of, respectively, 1.8 mm ± 0.027 SD and 20.9 ± 0.74 SD papillae per cm(2)). After infestations with equal numbers of larvae, loads of adult ticks were inversely correlated with length of papillae and directly correlated with distances between the apices of papillae (P = 0.014; r = -0.566 and P = 0.018; r = 0.567, Pearson product momentum correlation, respectively). CONCLUSIONS: Spacing between papillae is smaller in Nelores, thus their tongues may be rougher and, consequently, more effective in removing tick larvae during self-grooming, explaining the greater resistance to ticks among Zebu breeds of cattle.

Effect of Zinc Supplementation on Serological Response to Vaccination Against Streptococcus Pneumoniae in Patients Undergoing Chemotherapy for Colorectal Cancer.

The aim of the study was to evaluate the effect of zinc supplementation on the antibody titer and the 23-valent pneumococcal seroconversion after vaccination in patients undergoing chemotherapy for colorectal cancer. The study included 25 patients undergoing postsurgery chemotherapy for colorectal adenocarcinoma (chemo group). Subjects were assessed in the perioperative period (prevaccination), before chemotherapy (4th wk) and after 3 cycles of chemotherapy (16th wk). Thirty-two healthy volunteers (control group) were included in the study. Participants received the 23-valent pneumococcal conjugate vaccine, and capsules containing zinc (Zn) sulfate (70 mg daily) or identical placebo capsules (containing wheat starch with no added Zn) for 16 wk and were randomly allocated on one of the following groups: chemo-Zn (n = 10), chemo-placebo (n = 15), control-Zn (n = 21), and control-placebo (n = 11). The antipneumococcal antibody titer against 6 polysaccharides was analyzed by ELISA and compared using linear mixed models. The seroconversion rate was compared using Fisher's exact test. An immune response to the vaccination against pneumococcus was observed in all participants. In the 16th wk, the polysaccharide 6 concentration was lower in the chemo-Zn group [2.96 (1.74-5.03) µg/mL] compared with the Chemo-Placebo group [10.75 (5.37-21.54) µg/mL] and the seroconversion rate was lower in the chemo-placebo (36%) compared with the control-placebo (85%) (P = 0.027). Zinc supplementation did not change the antibody titer after vaccination. However, the lower seroconversion rate observed in the chemo-placebo suggests an influence of zinc in the vaccinal protection.