Interstitial Migration of CD8αβ T Cells in the Small Intestine Is Dynamic and Is Dictated by Environmental Cues

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Associations between Apolipoprotein E Genotype, Diet, Body Mass Index, and Serum Lipids in Lithuanian Adult Population

Background

Apolipoprotein E (APOE) polymorphism is associated with lipid levels. Some studies have reported that blood lipid response to diet or obesity varies depending on APOE genotypes. The aim of this study was to assess the effect of APOE genotypes, the intake of saturated fatty acids (SFA), and obesity on serum lipid levels in Lithuanian adult population.

Methodology/Principal Findings

A cross-sectional health survey was carried out in five municipalities of Lithuania. The random sample was obtained from lists of 25–64 year-old inhabitants registered at primary health care centres. The data from 996 subjects (416 men and 580 women) were analysed in this study. Two single-nucleotide polymorphisms (rs429358 and rs7412) were assessed using a real-time polymerase chain reaction. 24-hour recall and food frequency questionnaire were used for evaluation of dietary habits. Serum lipids were determined using enzymatic methods.Men and women with the APOE2 genotype had the lowest level of total cholesterol (TC) (p = 0.002 for men, and p = 0.02 for women) and low-density lipoprotein cholesterol (LDL-C) (p<0.001). Multivariate linear regression analysis showed that age, genotype APOE2, SFA intake, and body mass index (BMI) were significant determinants of TC and LDL-C level (with p values ranging from 0.043 to 0.001). Our data did not reveal any statistically significant interactions between APOE genotype and SFA intake or between APOE genotype and BMI regarding TC and LDL-C level (all p>0.05). However, the predictive power of the regression model for LDL-C improved when gene-BMI interaction and gene-BMI interaction plus gene-nutrient interaction were added (p = 0.04 and p = 0.032 for R² change, respectively).

Conclusions/Significance

APOE genotypes, SFA intake, and obesity were found to be associated with blood lipid levels in Lithuanian adult population. Analysis of gene-diet and gene-obesity interactions did not confirm that the effects of diet and obesity on TC and LDL-C level significantly depended on APOE genotype.     

Blood Plasma TGF- β1 Concentration in Sporadic Dilatative Pathology of Ascending Aorta: More Questions than Answers

Transforming growth factor β1 (TGF- β1) is a cytokine that participates in a broad range of cellular regulatory processes and is associated with various diseases including aortic aneurysm. Increased TGF- β1 levels are associated with Marfan syndrome (MFS) caused by FBN1 mutations and subsequent defects in signaling system. We studied TGF- β1 levels in 62 patients with sporadic, non syndromic, dilatative pathology of ascending aorta (DPAA) and in reference group subjects (n = 212). An initial screening of 212 reference individuals identified TGF- β1 gender discrepancies and age-dependent cytokine increase in women. Patients with DPAA had increased levels of TGF- β1 in comparison to reference group subjects (median 7.7 ng/ml, range 2.1–25.3, and median 6.2 ng/ml, range 1.0–33.1, respectively). There is a significant association between TGF-β1 concentration and DPAA (OR 1.084, CI 1.027–1.144, p = 0.004) but the mechanisms of cause and effect have not been established yet. Slightly increased TGF-β1 concentrations in patients with sporadic DPAA in comparison to the reference subjects show a potential use of TGF-β1 as a biomarker for the disease. However, cytokine dependence on age, gender, and other unknown factors among individuals with no cardiovascular complains reduces its specificity for DPAA. We would also like to raise awareness regarding the choice of methods when measuring TGF-β1 levels with an emphasis on preanalytical phase and the choice of sample.     

Inherited phenotype instability of inflorescence and floral organ development in homeotic barley double mutants and its specific modification by auxin inhibitors and 2,4-D

Background and Aims Barley (Hordeum vulgare) double mutants Hv-Hd/tw₂, formed by hybridization, are characterized by inherited phenotypic instability and by several new features, such as bract/leaf-like structures, long naked gaps in the spike, and a wide spectrum of variations in the basic and ectopic flowers, which are absent in single mutants. Several of these features resemble those of mutations in auxin distribution, and thus the aim of this study was to determine whether auxin imbalances are related to phenotypic variations and instability. The effects of auxin inhibitors and 2,4-D (2,4-dichlorophenoxyacetic acid) on variation in basic and ectopic flowers were therefore examined, together with the effects of 2,4-D on spike structure.Methods The character of phenotypic instability and the effects of auxin inhibitors and 2,4-D were compared in callus cultures and intact plants of single homeotic Hv-tw₂ and Hv-Hooded/Kap (in the BKn3 gene) mutants and alternative double mutant lines: offspring from individual plants in distal hybrid generations (F₉–F₁₀) that all had the same BKn3 allele as determined by DNA sequencing. For intact plants, two auxin inhibitors, 9-hydroxyfluorene-9-carboxylic acid (HFCA) and p-chlorophenoxyisobutyric acid (PCIB), were used.Key Results Callus growth and flower/spike structures of the Hv-tw₂ mutant differed in their responses to HFCA and PCIB. An increase in normal basic flowers after exposure to auxin inhibitors and a decrease in their frequencies caused by 2,4-D were observed, and there were also modifications in the spectra of ectopic flowers, especially those with sexual organs, but the effects depended on the genotype. Exposure to 2,4-D decreased the frequency of short gaps and lodicule transformations in Hv-tw₂ and of long naked gaps in double mutants.Conclusions The effects of auxin inhibitors and 2,4-D suggest that ectopic auxin maxima or deficiencies arise in various regions of the inflorescence/flower primordia. Based on the phenotypic instability observed, definite trends in the development of ectopic flower structures may be detected, from insignificant outgrowths on awns to flowers with sterile organs. Phenotypically unstable barley double mutants provide a highly promising genetic system for the investigation of gene expression modules and trend orders.     

Cutting edge: inflammatory signals drive organ-specific autoimmunity to normally cross-tolerizing endogenous antigen

Links have been observed between infections and the development of autoimmunity. Proposed explanations include activation of self-Ag-bearing APC. Using a model system in which transgenic OVA is expressed in enterocytes, we showed that CD8 T cell recognition of cross-presented Ag in gut-associated lymph nodes was tolerogenic. However, concomitant infection with vesicular stomatitis virus encoding OVA abrogated tolerance and induced disease. We now show that following transfer of naive OT-I T cells, the addition of wild-type vesicular stomatitis virus, oral cholera toxin, or CD40 triggering can induce intestinal disease in transgenic mice. Tissue damage accompanied dramatic increases in cytokine release by activated OT-I cells in the intestine. The data indicated that products of antigenically unrelated infections can combine with cross-presented self-Ags on APC to prime autoaggressiveness, independent of additional Ag release. These results help explain how diverse pathogens, lacking any homology to self-proteins, could be causative agents in induction of organ-specific autoimmunity.     

Tissue-level regulation of Th1 and Th2 primary and memory CD4 T cells in response to Listeria infection

Ag-specific Th1 and Th2 cytokine-producing CD4 T cells were quantitated in secondary lymphoid and tertiary tissues following oral Listeria monocytogenes infection. Although the response to Listeria was previously believed to be predominantly Th1 like, CD4 T cells producing IL-4 or IL-5 comprised a substantial proportion of the overall primary and memory response. The frequency of IFN-gamma-, IL-4-, or IL-5-producing primary effector or memory CD4 T cells was significantly higher in lung, liver, and intestinal lamina propria (LP) as compared with spleen and lymph node. However, maximum numbers of IL-4- and IL-5-producing cells were detected in the LP several days after the peak of the Th1 response, and IL-5 production was skewed toward the mucosal tissues. Remarkably, the recall response resulted in sustained Th1 and Th2 responses in tertiary, but not lymphoid tissues and long-term retention of Th1 and Th2 memory cells in equal proportions in the LP. Finally, CD40 ligand was essential for induction of IFN-gamma in the spleen and LP, but not in the liver and lung, while the IL-4 response required CD40 ligand only in the spleen. Therefore, the rules governing the effector phenotype, and the overall magnitude of the CD4 response, are regulated at the level of individual tissues.     

A cytokine promoter/yellow fluorescent protein reporter transgene serves as an early activation marker of lymphocyte subsets

A mouse containing an IL-4 promoter linked to the yellow fluorescent protein (YFP) reporter transgene was created to follow aspects of lymphocyte development and function. Following stimulation with phorbol 12-myristate 13-acetate and ionomycin, anti-CD3/CD28, antigen-specific peptide, or allogeneic cells, both CD4 and CD8 T cells expressed the transgene within 24h in a manner that was consistent with cellular activation markers. Transgene induction was inhibited by cyclosporine and FK506, suggesting that its activation occurs in an NFAT-dependent manner. B lymphocytes were also able to express the transgene when stimulated with LPS. This induction was inhibited in part by rapamycin. The results suggest that this transgene can function as an indicator of lymphocyte activation. Because YFP is not toxic and requires no preparation of the cells to view the reporter gene, this system provides a unique tool to follow lymphocyte activation in a number of model systems, such as those involving transplantation, allergy, and vaccine development.     

Activated primary and memory CD8 T cells migrate to nonlymphoid tissues regardless of site of activation or tissue of origin

Following activation within secondary lymphoid tissue, CD8 T cells must migrate to targets, such as infected self tissue, allografts, and tumors, to mediate contact-dependent effector functions. To test whether the pattern of migration of activated CD8 T cells was dependent on the site of Ag encounter, we examined the distribution of mouse Ag-specific CD8 T cells following local challenges. Our findings indicated that activated CD8 T cells migrated pervasively to all nonlymphoid organs irrespective of the site of initial Ag engagement. Using an adoptive transfer system, migration of nonlymphoid memory cells was also examined. Although some limited preference for the tissue of origin was noted, transferred CD8 memory T cells from various nonlymphoid tissues migrated promiscuously, except to the intestinal mucosa, supporting the concept that distinct memory pools may exist. However, regardless of the tissue of origin, reactivation of transferred memory cells resulted in widespread dissemination of new effector cells. These data indicated that recently activated primary or memory CD8 T cells were transiently endowed with the ability to traffic to all nonlymphoid organs, while memory cell trafficking was more restricted. These observations will help refine our understanding of effector and memory CD8 T cell migration patterns.     

Cytochrome <Emphasis Type="Italic">c</Emphasis>-induced lymphocyte death from the outside in: inhibition by serum leucine-rich alpha-2-glycoprotein-1

Previously we reported that serum leucine-rich alpha-2-glycoprotein-1 (LRG) binds cytochrome c (Cyt c; Cummings et al., Apoptosis 11:1121–1129, 2009). Here we show that LRG binding to Cyt c is similar to that of Apaf-1. LRG and Apaf-1 share partial amino acid sequences, compete for binding Cyt c, and are inhibited by modification at lysine 72 in Cyt c. However, in contrast to Apaf-1, LRG acts as a survival factor in vitro rather than a pro-apoptotic factor. By depleting LRG from culture medium we found that LRG protects against a toxic effect of exogenous Cyt c on lymphocytes that would otherwise result in an apoptotic phenotype. LRG, as well as antibodies specific for Cyt c, increased cell viability in the absence of added Cyt c indicating that Cyt c released by dying cells in the cultures is itself toxic. Protection from extracellular Cyt c-induced lymphotoxicity appears to involve an active mechanism rather than steric hindrance of Cyt c. Thus, serum LRG when bound to extracellular Cyt c that is released from apoptotic cells acts as a survival factor for lymphocytes and possibly other cells that are susceptible to the toxic effect of extracellular Cyt c.     

Fully functional memory CD8 T cells in the absence of CD4 T cells

The role of CD4 T cells in providing help to CD8 T cells in primary and secondary responses to infection remains controversial. Using recombinant strains of virus and bacteria expressing the same Ag, we determined the requirement for CD4 T cells in endogenous CD8 T cell responses to infection with vesicular stomatitis virus and Listeria monocytogenes (LM). Depletion of CD4 T cells had no effect on the frequency of primary or secondary vesicular stomatitis virus-specific CD8 T cells in either lymphoid or nonlymphoid tissues. In contrast, the primary LM-specific CD8 T cell response was CD4 T cell dependent. Surprisingly, the LM-specific CD8 T cell recall response was also CD4 T cell dependent, which correlated with a requirement for CD40/CD40L interactions. However, concomitant inhibition of CD40L and CD4 T cell removal revealed that these pathways may be operating independently. Importantly, despite the absence of CD4 T cells during the recall response or throughout the entire response, CD8 memory T cells were functional effectors and proliferated equivalently to their "helped" counterparts. These data call into question the contention that CD4 T cells condition memory CD8 T cells during the primary response and indicate that the principal role of CD4 T cells in generating CD8 memory cells after infection is augmentation of proliferation or survival through costimulatory signals.