Involvement of Cbl-b-mediated macrophage inactivation in insulin resistance

Aging and overnutrition cause obesity in rodents and humans. It is well-known that obesity causes various diseases by producing insulin resistance(IR). Macrophages infiltrate the adipose tissue(AT) of obese individuals and cause chronic low-level inflammation associated with IR. Macrophage infiltration is regulated by the chemokines that are released from hypertrophied adipocytes and the immune cells in AT. Saturated fatty acids are recognized by toll-like receptor 4(TLR4) and induce inflammatory responses in AT macrophages(ATMs). The inflammatory cytokines that are released from activated ATMs promote IR in peripheral organs, such as the liver, skeletal muscle and AT. Therefore, ATM activation is a therapeutic target for IR in obesity. The ubiquitin ligase Casitas b-lineage lymphoma-b(Cbl-b) appears to potently suppress macrophage migration and activation. Cbl-b is highly expressed in leukocytes and negatively regulates signals associated with migration and activation. Cbl-b deficiency enhances ATM accumulation and IR in aging- and diet-induced obese mice. Cbl-b inhibits migration-related signals and SFA-induced TLR4 signaling in ATMs. Thus, targeting Cbl-b may be a potential therapeutic strategy to reduce the IR induced by ATM activation. In this review, we summarize the regulatory functions of Cbl-b in ATMs.

Evaluation of Terpenes’Degradation Rates by Rumen Fluid of Adapted and Non-adapted Animals

The aim of the present study was to evaluate terpenes degradation rate in the rumen fluid from adapted and non-adapted animals.Four castrated healthy animals,two rams and two bucks,were used.Animals were daily orally dosed for 2 weeks with 1 g of each of the following terpenes,α-pinene,limonene andβ-caryophyllene.At the end of each week,rumen fluid(RF)samples were assayed in vitro for their potential to degrade terpenes over time.For each animal,a 10 mL reaction medium(RM)at a ratio 1:9(v/v)was prepared and a terpenes solution at a concentration of 100μg/ml each,was added in each RM tube.Tubes were incubated at 39℃ under anaerobic conditions and their contents sampled at 0,2,4,8,21 and 24 h.RF could degrade terpenes as it was shown by the significantly(P<0.05)higher overall degradation rates.Individual terpene degradation rates,were significantly(P<0.05)higher in week 5 for limonene and marginally(P=0.083)higher also in week 5 forα-pinene.In conclusion,the findings of the present preliminary study suggest that terpenes can be degraded in the rumen fluid.

Distinct Gene Expression Profile Distinguishes Increased Metabolic Activity in Spontaneously Hyperactive Rats While Sedentary from That Induced by Exercise

The Spontaneously-Running Tokushima Shikoku (SPORTS) strain is an original line derived from Wistar rats, which spontaneously runs >6 km/day on wheels, and has better glucose tolerance and less fat than Wistar rats. However, the molecular mechanism that contributes to the increased metabolic activity in SPORTS rats is unknown. The present study aimed to characterize the gene expression profiles of skeletal muscles in SPORTS rats housed under sedentary (SED) conditions. We found that the expression levels of genes encoding mitochondrial respiratory chain enzymes such as ATP synthase 6 (mt-Atp6) and cytochrome c oxidase subunit 6c (Cox6c), were higher in the soleus (SOL) muscles of SED SPORTS than in SED Wistar rats. The ratio of type IIa myofibers was higher and glucose tolerance was better in SED SPORTS than in Wistar rats that were sedentary and trained daily on treadmills, respectively. We then investigated candidate genes that might contribute to the better glucose tolerance of SED SPORTS rats using DNA microarray analysis. Among 116 upregulated genes in the SOL muscles of SED SPORTS rats, only 19 were also increased in trained Wistar rats. We focused on v-erb-b2 erythroblastic leukemia viral oncogene homolog 3 (Erbb3), which was associated with glucose transport in myocytes, and found higher expression levels in the SOL muscles of SED SPORTS than in SED Wistar rats. The SOL muscles of SED SPORTS rats also contained more activity of β-hydroxyacylCoA dehydrogenase, a key enzyme of β-oxidation, indicating enhanced lipid oxidation. These findings suggest that increased metabolic activity in skeletal muscle (especially the SOL muscle) of SPORTS rats is congenital and that gene expression profiles of SPORTS rats and Trained Wistar rats are different.

Diet supplementation with an organic acids-based formulation affects gut microbiota and expression of gut barrier genes in broilers

This study was designed to study the effect of diet supplementation with an organic acids-based formulation(OABF) on luminal-and mucosa-associated bacteria, concentration of volatile fatty acids(VFA), microbial glycolytic enzyme activity and expression of mucin 2(MUC2), immunoglobulin A(IgA)and tight junction protein, i.e., zonula occludens-1(ZO1), zonula occludens-2(ZO2), claudin-1(CLDN1),claudin-5(CLDN5) and occludin(OCLN), genes at the ileal and cecal level. A 2 × 2 factorial design was used having OABF inclusion and avilamycin as main factors. Subsequently, 544 day-old male Cobb broilers were allocated in the following 4 treatments, each with 8 replicates: no additions(CON), 1 g OABF/kg diet(OA),2.5 mg avilamycin/kg diet(AV) and combination of OA and AV(OAAV). The trial lasted for 42 days. In the ileum, OAAV resulted in lower mucosa-associated total bacteria levels(PO × A= 0.028) compared with AV.In addition, ileal digesta levels of Clostridium perfringens subgroup were decreased by avilamycin(PA= 0.045). Inclusion of OABF stimulated the activity of microbial glycolytic enzymes, whereas avilamycin resulted in lower acetate(PA= 0.021) and higher butyrate(PA= 0.010) molar ratios. Expression of ZO1 and CLDN5 was down-regulated by both OABF(PO= 0.016 and PO= 0.003, respectively) and avilamycin(PA= 0.016 and PA= 0.001, respectively). In addition, CLDN1 was down-regulated in AV compared with CON(PO × A= 0.012). Furthermore, OABF down-regulated MUC2(PO= 0.027), whereas avilamycin down-regulated nuclear factor kappa B subunit 1(NFKB1)(PA= 0.024), toll-like receptor 2 family member B(TLR2B)(PA= 0.011) and toll-like receptor 4(TLR4)(PA= 0.014) expression. In the ceca, OABF inclusion increased digesta levels of Clostridium coccoides(PO= 0.018) and Clostridium leptum(PO= 0.040) subgroups, while it up-regulated MUC2 expression(PO= 0.014). Avilamycin(PA= 0.044) and interaction(PO × A< 0.001) effects for IgA expression were noted, with CON having higher IgA expression compared with AV. In conclusion, new findings regarding OABF inclusion effects on an array of relevant biomarkers for broiler gut ecology have been reported and discussed in parallel with avilamycin effects used as a positive control. This new knowledge is expected to provide a response baseline for follow up trials under various stress and challenge conditions.

Broiler gut microbiota and expressions of gut barrier genes affected by cereal type and phytogenic inclusion

The present study assessed the effects of cereal type and the inclusion level of a phytogenic feed additive(PFA) on broiler ileal and cecal gut microbiota composition, volatile fatty acids(VFA) and gene expression of toll like receptors(TLR), tight junction proteins, mucin 2(MUC2) and secretory immunoglobulin A(sIgA). Depending on cereal type(i.e. maize or wheat) and PFA inclusion level(i.e. 0, 100 and 150 mg/kg diet), 450 one-day-old male broilers were allocated in 6 treatments according to a 2 × 3 factorial arrangement with 5 replicates of 15 broilers each, for 42 d. Significant interactions(P 0.05) between cereal type and PFA were shown for cecal digesta Bacteroides and Clostridium cluster XIVa, ileal digesta propionic and branched VFA, ileal s IgA gene expression, as well as cecal digesta branched and other VFA molar ratios. Cereal type affected the cecal microbiota composition. In particular, wheat-fed broilers had higher levels of mucosa-associated Lactobacillus(P_(CT)= 0.007) and digesta Bifidobacterium(P_(CT)< 0.001),as well as lower levels of total bacteria(P_(CT)= 0.004) and Clostridia clusters I, IV and XIVa(P_(CT) 0.05),compared with maize-fed ones. In addition, cereal type gave differences in fermentation intensity(P_(CT)= 0.021) and in certain individual VFA molar ratios. Wheat-fed broilers had higher(P 0.05) ileal zonula occluden 2(ZO-2) and lower ileal and cecal TLR2 and sIgA levels, compared with maize-fed broilers. On the other hand, PFA inclusion at 150 mg/kg had a stimulating effect on microbial fermentation at ileum and a retarding effect in ceca with additional variable VFA molar patterns. In addition, PFA inclusion at 100 mg/kg increased the ileal mucosa expression of claudin 5(CLDN5)(PPFA= 0.023) and MUC2(PPFA= 0.001) genes, and at 150 mg/kg decreased cecal TLR2(PPFA= 0.022) gene expression compared with the un-supplemented controls. In conclusion, cereal type and PFA affected in combination and independently broiler gut microbiota composition and metabolic activity as well as the expression of critical gut barrier genes including TLR2. Further exploitation of these properties in cases of stressor challenges is warranted.

Priming of intestinal cytoprotective genes and antioxidant capacity by dietary phytogenic inclusion in broilers

The potential of a phytogenic premix(PP)based on ginger,lemon balm,oregano and thyme to stimulate the expression of cytoprotective genes at the broiler gut level was evaluated in this study.In particular,the effects of PP inclusion levels on a selection of genes related to host protection against oxidation(catalase[GAT],superoxide dismutase 1[SOD1],glutathione peroxidase 2[GPX2],heme oxygenase 1[HMOX1],NAD(P)H quinone dehydrogenase 1[NQO1],nuclear factor(erythroid-derived 2)-like 2[Nrf2]and kelch like ECH associated protein 1[Keap1]),stress(heat shock 70 kDa protein 2[HSP70]and heat shock protein 90 alpha family class A member 1[HSP90])and inflammation(nuclear factor kappa B subunit 1[NF-κB1],Toll-like receptor 2 family member B(TLR2 B)and Toll-like receptor 4[TLR4])were profiled along the broiler intestine.In addition,broiler intestinal segments were assayed for their total antioxidant capacity(TAC).Depending on PP inclusion level(i.e.0,750,1,000 and 2,000 mg/kg diet)in the basal diets,1-d-old Cobb broiler chickens(n=500)were assigned into the following 4 treatments:CON,PP-750,PP-1000 and PP-2000.Each treatment had 5 replicates of 25 chickens with ad libitum access to feed and water.Data were analyzed by ANOVA and means compared using Tukey’s honest significant difference(HSD)test.Polynomial contrasts tested the linear and quadratic effect of PP inclusion levels.Inclusion of PP increased(P≤0.05)the expression of cytoprotective genes against oxidation,except CAT.In particular,the cytoprotective against oxidation genes were up-regulated primarily in the duodenum and the ceca and secondarily in the jejunum.Most of the genes were upregulated in a quadratic manner with increasing PP inclusion level with the highest expression levels noted in treatments PP-750 and PP-1000 compared to CON.Similarly,intestinal TAC was higher in PP-1000 in the duodenum(P=0.011)and the ceca(P=0.050)compared to CON.Finally,increasing PP inclusion level resulted in linearly reduced(P<0.05)expression of NF-κB1,TLR4 and HSP70,the former in the duodenum and the latter 2 in the ceca.Overall,PP inclusion consistently up-regulated cytoprotective genes and down-regulated stress and inflammation related ones.The effect is dependent on PP inclusion level and the intestinal site.The potential of PP to beneficially prime bird cytoprotective responses merit further investigation under stress-challenge conditions.

Growth performance, nutrient digestibility, antioxidant capacity,blood biochemical biomarkers and cytokines expression in broiler chickens fed different phytogenic levels

The effects of inclusion levels of a phytogenic feed additive(PFA), characterized by menthol anethol and eugenol, on broiler growth performance, nutrient digestibility, biochemical biomarkers and total antioxidant capacity(TAC) of plasma and meat, as well as on the relative expression of selected cytokines,were studied in a 42-d experiment. A total of 225 one-day-old male Cobb broiler chickens were assigned into 3 treatments, with 5 replicates of 15 chickens each. Chickens were fed maize-soybean meal basal diets following a 3 phase(i.e., starter, grower and finisher) feeding program. Depending on PFA inclusion level, treatments were: no PFA(PFA-0), PFA at 100 mg/kg(PFA-100) and PFA at 150 mg/kg(PFA-150).Feed and water were available ad libitum. Feed conversion ratio(FCR) during finisher phase was improved quadratically(P < 0.05) with increasing PFA level. Overall, increasing PFA level increased body weight gain(BWG) in a linear(P < 0.05) and quadratic(P < 0.05) manner with treatments PFA-100 and PFA-150 being greater(P < 0.05) compared with PFA-0. Total tract apparent digestibility of dry matter increased linearly(P < 0.05) and quadratically(P < 0.05) with increasing PFA level. The apparent metabolizable energy corrected for nitrogen(AMEn) also increased linearly(P < 0.05). Increasing PFA level resulted in a linear(P < 0.05) increase in blood plasma TAC. Expression of pro-inflammatory cytokine interleukin-18(IL-18) was reduced linearly(P < 0.05) in spleen with increasing PFA level. In conclusion, PFA inclusion at 100 mg/kg diet positively influenced performance, whereas PFA inclusion at150 mg/kg resulted in a stronger improvement in AMEn and plasma TAC. Finally, PFA inclusion resulted in a pattern of reduced pro-inflammatory biomarker IL-18 at spleen. Overall, this study provides evidence for the beneficial role of PFA as a natural growth and health promoter in broiler chickens that needs to be further confirmed in field studies.