Rumen-protected l-carnitine supplementation during mating period altered metabolic status and reproductive performance of ewes.

Current study hypothesized that dietary l-carnitine (LC) inclusion during the mating period ameliorates both metabolic status and reproductive performance of ewes. Seventy Baluchi ewes (52 ± 4.2 kg of bodyweight and 18 ± 6 months old of age) were enrolled in this study. Animals were randomly allocated into two dietary treatments, control (only basal diet) or basal diet plus supplementation with a rumen-protected LC (Carneon 20 Rumin-pro; 20% LC; Kaesler Nutrition GmbH) at the rate of 10 g/head/day from 21 days before until 35 days after introducing rams to the ewes (MP). Feed intake was monitored by subtracting the ort from feed offered. Blood sample collection was conducted on Days -10, +10 and +20 relative to MP. Pregnancy was confirmed on Day 30 post-MP. Feed intake of the ewes in the LC group was higher than the control (p < 0.05). LC supplementation increased the cholesterol concentration in the ewes (p < 0.05). Blood urea concentration of animals in the LC group was significantly lower than the control (p < 0.05). The mRNA expression of toll-like receptor 4 was evidently lower in animals supplemented with LC than the control (p < 0.05). Both lambing and fecundity rates in the LC group tended to be higher compared with the control. LC supplementation showed potential to alter certain metabolites in the ewes. A tendency for higher lambing rate may partly be driven by dams efficient energy partitioning to support foetal growth and maintaining pregnancy.

Regulation of oxidative stress by methylation-controlled J protein controls macrophage responses to inflammatory insults.

Mitochondria contribute to macrophage immune function through the generation of reactive oxygen species, a byproduct of the mitochondrial respiratory chain. MCJ (also known as DnaJC15) is a mitochondrial inner membrane protein identified as an endogenous inhibitor of respiratory chain complex I. Here we show that MCJ is essential for the production of tumor necrosis factor by macrophages in response to a variety of Toll-like receptor ligands and bacteria, without affecting their phagocytic activity. Loss of MCJ in macrophages results in increased mitochondrial respiration and elevated basal levels of reactive oxygen species that cause activation of the JNK/c-Jun pathway, lead to the upregulation of the TACE (also known as ADAM17) inhibitor TIMP-3, and lead to the inhibition of tumor necrosis factor shedding from the plasma membrane. Consequently, MCJ-deficient mice are resistant to the development of fulminant liver injury upon lipopolysaccharide administration. Thus, attenuation of the mitochondrial respiratory chain by MCJ in macrophages exquisitely regulates the response of macrophages to infectious insults.

CD14 cooperates with complement receptor 3 to mediate MyD88-independent phagocytosis of Borrelia burgdorferi.

Phagocytosis of Borrelia burgdorferi, the causative agent of Lyme disease, is a poorly understood process, despite its importance during the host immune response to infection. B. burgdorferi has been shown to bind to different receptors on the surface of phagocytic cells, including the ß(2) integrin, complement receptor 3 (CR3). However, whether these receptors mediate the phagocytosis of the spirochete remains unknown. We now demonstrate that CR3 mediates the phagocytosis of the spirochete by murine macrophages and human monocytes. Interaction of B. burgdorferi with the integrin is not sufficient, however, to internalize the spirochete; phagocytosis requires the interaction of CR3 with the GPI-anchored protein, CD14, independently of TLR/MyD88-induced or inside-out signals. Interestingly, the absence of CR3 leads to marked increases in the production of TNF in vitro and in vivo, despite reduced spirochetal uptake. Furthermore, the absence of CR3 during infection with B. burgdorferi results in the inefficient control of bacterial burdens in the heart and increased Lyme carditis. Overall, our data identify CR3 as a MyD88-independent phagocytic receptor for B. burgdorferi that also participates in the modulation of the proinflammatory output of macrophages. These data also establish a unique mechanism of CR3-mediated phagocytosis that requires the direct cooperation of GPI-anchored proteins.

Local production of IFN-gamma by invariant NKT cells modulates acute Lyme carditis.

The Lyme disease spirochete Borrelia burgdorferi is the only known human pathogen that directly activates invariant NKT (iNKT) cells. The number and activation kinetics of iNKT cells vary greatly among different strains of mice. We now report the role of the iNKT cell response in the pathogenesis of Lyme disease using C57BL/6 mice, a strain with optimal iNKT cell activation that is resistant to the development of spirochetal-induced inflammation. During experimental infection of B6 mice with B. burgdorferi, iNKT cells localize to the inflamed heart where they are activated by CD1d-expressing macrophages. Activation of iNKT cells in vivo results in the production of IFN-gamma, which we demonstrate ameliorates the severity of murine Lyme carditis by at least two mechanisms. First, IFN-gamma enhances the recognition of B. burgdorferi by macrophages, leading to increased phagocytosis of the spirochete. Second, IFN-gamma activation of macrophages increases the surface expression of CD1d, thereby facilitating further iNKT activation. Collectively, our data demonstrate that in the resistant background, B6, iNKT cells modulate the severity of murine Lyme carditis through the action of IFN-gamma, which appears to self-renew through a positive feedback loop during infection.

Borrelia burgdorferi lipoprotein BmpA activates pro-inflammatory responses in human synovial cells through a protein moiety.

Borrelia burgdorferi invasion of mammalian joints results in genesis of Lyme arthritis. Other than spirochete lipids, existence of protein antigens, which are abundant in joints and participate in B. burgdorferi-induced host inflammatory response, is unknown. Here, we report that major products of the B. burgdorferi basic membrane protein (bmp) A/B operon that are induced in murine and human joints, possess inflammatory properties. Compared to the wild type B. burgdorferi, an isogenic bmpA/B mutant induced significantly lower levels of pro-inflammatory cytokines TNF-alpha and IL-1beta in cultured human synovial cells, which could be restored using bmpA/B-complemented mutants, and more directly, upon addition of recombinant BmpA, but not BmpB or control spirochete proteins. Non-lipidated and lipidated versions of BmpA induced similar levels of cytokines, and remained unaffected by treatment with lipopolysaccharide inhibitor, polymyxin B. The bmpA/B mutant was also impaired in the induction of NF-kappaB and p38 MAP kinase signaling pathways in synovial cells, which were activated by non-lipidated BmpA. These results show that a protein moiety of BmpA can induce cytokine responses in synovial cells via activation of the NF-kappaB and p38 MAP kinase pathways and thus, could potentially contribute to the genesis of Lyme arthritis.

Ikaros mediates the DNA methylation-independent silencing of MCJ/DNAJC15 gene expression in macrophages.

MCJ (DNAJC15) is a mitochondrial protein that regulates the mitochondrial metabolic status of macrophages and their response to inflammatory stimuli. CpG island methylation in cancer cells constitutes the only mechanism identified for the regulation of MCJ gene expression. However, whether DNA methylation or transcriptional regulation mechanisms are involved in the physiological control of this gene expression in non-tumor cells remains unknown. We now demonstrate a mechanism of regulation of MCJ expression that is independent of DNA methylation. IFNγ, a protective cytokine against cardiac inflammation during Lyme borreliosis, represses MCJ transcription in macrophages. The transcriptional regulator, Ikaros, binds to the MCJ promoter in a Casein kinase II-dependent manner, and mediates the repression of MCJ expression. These results identify the MCJ gene as a transcriptional target of IFNγ and provide evidence of the dynamic adaptation of normal tissues to changes in the environment as a way to adapt metabolically to new conditions.

p38 mitogen-activated protein kinase controls NF-kappaB transcriptional activation and tumor necrosis factor alpha production through RelA phosphorylation mediated by mitogen- and stress-activated protein kinase 1 in response to Borrelia burgdorferi antigens.

The interaction of Borrelia burgdorferi, the causative agent of Lyme borreliosis, with phagocytic cells induces the activation of NF-kappaB and the expression of proinflammatory cytokines including tumor necrosis factor alpha (TNF-alpha). B. burgdorferi-induced TNF-alpha production is also dependent on the activation of p38 mitogen-activated protein (MAP) kinase. The specific contribution of these signaling pathways to the response of phagocytic cells to the spirochete and the molecular mechanisms underlying this response remain unresolved. We now show that p38 MAP kinase activity regulates the transcriptional activation of NF-kappaB in response to spirochetal lysate stimulation of phagocytic cells. The regulation occurs at the nuclear level and is independent of the translocation of the transcription factor to the nucleus or its capacity to bind to specific DNA target sequences. In RAW264.7 cells, p38alpha MAP kinase regulates the phosphorylation of NF-kappaB RelA. p38 MAP kinase phosphorylates the nuclear kinase mitogen- and stress-activated protein kinase 1 (MSK1). MSK1 in turn phosphorylates the transcriptionally active subunit of NF-kappaB, RelA. The repression of MSK1 expression with small interfering RNA results in reduced RelA phosphorylation and a significant decrease in the production of TNF-alpha in response to B. burgdorferi lysates. Overall, these results clarify the contribution of the signaling pathways that are activated in response to the interaction of spirochetes with phagocytic cells to TNF-alpha production. Our results situate p38 MAP kinase activity as a central regulator of the phagocytic proinflammatory response through MSK1-mediated transcriptional activation of the transcription factor NF-kappaB.

c-Jun N-terminal kinase 1 is required for Toll-like receptor 1 gene expression in macrophages.

The regulation of innate immune responses to pathogens occurs through the interaction of Toll-like receptors (TLRs) with pathogen-associated molecular patterns and the activation of several signaling pathways whose contribution to the overall innate immune response to pathogens is poorly understood. We demonstrate a mechanism of control of murine macrophage responses mediated by TLR1/2 heterodimers through c-Jun N-terminal kinase 1 (JNK1) activity. JNK controls tumor necrosis factor alpha production and TLR-mediated macrophage responses to Borrelia burgdorferi, the causative agent of Lyme disease, and the TLR1/TLR2-specific agonist PAM(3)CSK(4). JNK1, but not JNK2, activity regulates the expression of the tlr1 gene in the macrophage cell line RAW264.7, as well as in primary CD11b(+) cells. We also show that the proximal promoter region of the human tlr1 gene contains an AP-1 binding site that is subjected to regulation by the kinase and binds two complexes that involve the JNK substrates c-Jun, JunD, and ATF-2. These results demonstrate that JNK1 regulates the response to TLR1/2 ligands and suggest a positive feedback loop that may serve to increase the innate immune response to the spirochete.