| 1. |
- Andresen, Louise C., et al.
(författare)
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Seasonal changes in nitrogen availability, and root and microbial uptake of (15)N(13)C(9)-phenylalanine and (15)N-ammonium in situ at a temperate heath
- 2011
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Ingår i: Applied Soil Ecology. - : Elsevier BV. - 0929-1393. ; 51, s. 94-101
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Tidskriftsartikel (refereegranskat)abstract
- In the plant biosynthesis of secondary compounds, phenylalanine is a precursor of condensed tannins. Tannins are deposited into the soil in plant root exudates and dead plant material and have been suggested to precipitate some soil nutrients and hence reduce nutrient availability for plants. Free amino acid, inorganic and microbial N concentration during the growing season was investigated in an ecosystem with a natural tannin chemosphere. The influence of tannins on the uptake of nitrogen in plants and microbes was followed by injecting tannic acid (TA), ammonium-(15)N and phenylalanine-(15)N/(13)C(9). Plants preferred ammonium over phenylalanine, while microbes had no preference. Soil microbes had a 77% uptake of intact phenylalanine. Phenylalanine was acquired intact by both grasses and Calluna, with 63% and 38% uptake of intact phenylalanine in grass fine roots and Calluna roots, respectively. Inorganic N and amino acid concentrations were lowest in the period with highest plant activity and grass root biomass but were unaffected by TA addition. (C) 2011 Elsevier B.V. All rights reserved.
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| 2. |
- Backteman, Karin, et al.
(författare)
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Cytomegalovirus seropositivity is a major determinant of CD28null T cell expansion in patients with coronary artery disease
- 2014
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Objective: Accumulation of CD4+28null cells, with a proinflammatory and senescent phenotype, has been associated with unstable conditions of coronary artery disease (CAD). Human cytomegalovirus (HCMV) is known to exert profound effects on T cells, including loss of CD28. Here, we longitudinally assessed the proportions of CD28null and CD28nullCD57+ cells in CD4+ and CD8+ T cell populations of patients with CAD and related the findings to HCMV seropositivity.Methods: HCMV antibody levels and expression of CD28 and CD57 on CD4+ and CD8+ T cells were analysed in 31 patients with acute coronary syndrome (ACS), 34 patients with stable angina (SA) and 37 healthy controls. Samples were taken prior to 34 coronary angiography and after 3 and 12 months. In a subsample, HCMV-specific IFN-γ and TNF production was assessed ex vivo.Results: Increased proportions of CD4+CD28null, but not CD8+CD28null cells, were significantly associated with presence of CAD. Significant increases in CD28null 37 and CD28nullCD57+ cells occurred within CD4+ and CD8+ T cell compartments in both ACS and SA patients during 12-month follow-up. HCMV was the major determinant of CD28null and CD28nullCD57+ T cell levels in both patients and controls (p <0.001). There were no obvious signs of CMV reactivation in patients.Conclusion: HCMV was a major determinant of the presence of CD28null and CD28nullCD57+ T cells in patients with CAD, independent of clinical stage. Findings also indicate that HCMV might have a large impact on the T cell aging process that occurred in patients after a cardiac event.
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| 3. |
- Backteman, Karin, et al.
(författare)
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Lymphocyte Subpopulations in Lymph Nodes and Peripheral Blood: A Comparison between Patients with Stable Angina and Acute Coronary Syndrome
- 2012
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Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 7:3
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Atherosclerosis is characterized by a chronic inflammatory response involving activated T cells and impairment of natural killer (NK) cells. An increased T cell activity has been associated with plaque instability and risk of acute cardiac events. Lymphocyte analyses in blood are widely used to evaluate the immune status. However, peripheral blood contains only a minor proportion of lymphocytes. In this study, we hypothesized that thoracic lymph nodes from patients with stable angina (SA) and acute coronary syndrome (ACS) might add information to peripheral blood analyses. less thanbrgreater than less thanbrgreater thanMethods: Peripheral blood and lymph nodes were collected during coronary by-pass surgery in 13 patients with SA and 13 patients with ACS. Lymphocyte subpopulations were assessed by flow cytometry using antibodies against CD3, CD4, CD8, CD19, CD16/56, CD25, Foxp3, CD69, HLA-DR, IL-18 receptor (R) and CCR4. less thanbrgreater than less thanbrgreater thanResults: Lymph nodes revealed a lymphocyte subpopulation profile substantially differing from that in blood including a higher proportion of B cells, lower proportions of CD8(+) T cells and NK cells and a 2-fold higher CD4/CD8 ratio. CD4(+)CD69(+) cells as well as Foxp3(+) regulatory T cells were markedly enriched in lymph nodes (p andlt; 0.001) while T helper 1-like (CD4(+)IL-18R(+)) cells were more frequent in blood (p andlt; 0.001). The only significant differences between ACS and SA patients involved NK cells that were reduced in the ACS group. However, despite being reduced, the NK cell fraction in ACS patients contained a significantly higher proportion of IL-18R(+) cells compared with SA patients (p andlt; 0.05). less thanbrgreater than less thanbrgreater thanConclusion: There were several differences in lymphocyte subpopulations between blood and lymph nodes. However, the lymphocyte perturbations in peripheral blood of ACS patients compared with SA patients were not mirrored in lymph nodes. The findings indicate that lymph node analyses in multivessel coronary artery disease may not reveal any major changes in the immune response that are not detectable in blood.
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| 4. |
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| 5. |
- Backteman, Karin, et al.
(författare)
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Natural killer (NK) cell deficit in coronary artery disease: no aberrations in phenotype but sustained reduction of NK cells is associated with low-grade inflammation
- 2014
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Ingår i: Clinical and Experimental Immunology. - : Wiley-Blackwell. - 0009-9104 .- 1365-2249. ; 175:1, s. 104-112
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Tidskriftsartikel (refereegranskat)abstract
- Although reduced natural killer (NK) cell levels have been reported consistently in patients with coronary artery disease (CAD), the clinical significance and persistence of this immune perturbation is not clarified. In this study we characterized the NK cell deficit further by determining (i) differentiation surface markers and cytokine profile of NK cell subsets and (ii) ability to reconstitute NK cell levels over time. Flow cytometry was used to analyse NK cell subsets and the intracellular cytokine profile in 31 patients with non-ST elevation myocardial infarction (non-STEMI), 34 patients with stable angina (SA) and 37 healthy controls. In blood collected prior to coronary angiography, the proportions of NK cells were reduced significantly in non-STEMI and SA patients compared with controls, whereas NK cell subset analyses or cytokine profile measurements did not reveal any differences across groups. During a 12-month follow-up, the proportions of NK cells increased, although not in all patients. Failure to reconstitute NK cell levels was associated with several components of metabolic syndrome. Moreover, interleukin (IL)-6 levels remained high in patients with sustained NK cell deficit, whereas a decline in IL-6 (P < 0·001) was seen in patients with a pronounced increase in NK cells. In conclusion, we found no evidence that reduction of NK cells in CAD patients was associated with aberrations in NK cell phenotype at any clinical stage of the disease. Conversely, failure to reconstitute NK cell levels was associated with a persistent low-grade inflammation, suggesting a protective role of NK cells in CAD.
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| 6. |
- Backteman, Karin, 1960-
(författare)
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T Cells and NK Cells in Coronary Artery Disease : Longitudinal and methodological studies in humans
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Coronary artery disease (CAD) is the leading cause of death worldwide and most often due to atherosclerosis. Atherosclerosis is a chronic inflammatory process that involves the arteries, inclouding those that supply blood to the heart muscle. Although inflammation is an important contributing factor to atherosclerosis, the mechanisms are not fully understood. One mechanism contributing to atherogenesis may involve some infectious microorganisms such as cytomegalovirus (CMV). In atherosclerosis, the arterial wall becomes infiltrated with lipids followed by different types of leukocytes and inflammatory mediators (atherogenesis). Leukocytes recirculate continuously between the blood and lymphoid organs, such as lymph nodes, where the adaptive immune response is started and regulated.The general aim of this thesis was to increase the understanding of associations between lymphocyte populations and different conditions of CAD (unstable and stable). To assess changes over time, a longitudinal follow up design was mostly used. Therefore, also perspectives of longitudinal variation were included in the thesis.Paper I showed that flow cytometric evaluation of lymphocyte populations is a robust technique that can be used in longitudinal studies, both in clinical and research settings. It was also shown that the time of sampling over the year did not have a major impact on the findings.In paper II, thoracic lymph nodes were investigated to assess whether CAD-associated changes were more prominent in comparison with blood. As expected, there were several major differences in lymphocyte composition between lymph nodes and blood. However, the analysis of thoracic lymph nodes did not reveal any further changes that were not detected in blood. Thus, blood is still the most reliable compartment for studies of lymphocyte populations in CAD since it is not possible to examine the local findings in the artery wall.Natural killer (NK) cells are innate lymphocytes with both regulatory and effector functions. In paper II and III we confirmed previous findings that CAD patients have lower proportions of NK cells in blood. However, the NK subtype and cytokine profile (paper III, measured by subtype markers and intra-cellular cytokine staining) did not differ between patients and controls. During a 12-month follow-up, the proportions of NK cells increased, although not in all patients. Failure to reconstitute NK cell levels was associated with several components of the metabolic syndrome and with a persistent low-grade inflammation as measured by plasma IL-6 levels. The findings support the notion of a protective role for NK cells in inflammation.CD4+ but not CD8+ T cells were significantly increased in patients with both unstable and stable conditions compared with healthy individuals (paper IV). Subpopulations of CD4+ T cells (CD4+CD28null) have previously been associated with CAD. However, we show that CD28null and CD28null57+ cells within the CD4+ and CD8+ T cell populations were similar in CAD patients and healthy controls. Instead, CMV seropositivity was the major determinant of expanded CD28null and CD57+ T cell fractions in both patients and healthy individuals. During the 1 year follow up the proportion of CD4+CD28null and CD8+CD28null cells increased in patients, which may reflect an accelerated immunological ageing occurring after the cardiac event.
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| 7. |
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| 8. |
- Bergström, Ida, et al.
(författare)
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Annexin A1 expression in blood mononuclear cells : a potential marker of glucocorticoid activity in patients with coronary artery disease
- 2014
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- An imbalance between pro- and anti-inflammatory actions is believed to drive progression of atherosclerosis. Annexin A1 (AnxA1) is a key player in resolution of inflammation and a mediator of anti-inflammatory effects of glucocorticoids. Here, we investigated whether expression of AnxA1 in peripheral blood mononuclear cells (PBMCs) was altered in patients with coronary artery disease (CAD) and also related findings to glucocorticoid sensitivity ex vivo.We included 57 patients 6-12 months after acute coronary syndrome (ACS), 10 patients with ACS, and healthy controls. AnxA1 mRNA was measured in PBMCs and AnxA1 protein was assessed in monocytes and lymphocyte subsets by flow cytometry. In post-ACS patients and controls, glucocorticoid sensitivity was determined by measuring inhibitory effects of dexamethasone on LPS46 induced cytokine secretion.AnxA1 mRNA levels in PBMCs were higher in patients compared with controls, although most pronounced in ACS patients. AnxA1 protein was most abundant in the monocyte fraction. ACS patients exhibited the highest levels of cell surface-associated AnxA1 protein while levels in post-ACS patients and controls were similar. Ex vivo assays showed that PBMCs from post-ACS patients were more prone to release IL-6. Glucocorticoid sensitivity correlated with cell surface-associated AnxA1 protein in peripheral monocytes. Dexamethasone also induced upregulation of AnxA1 mRNA.AnxA1 expression in PBMCs is closely associated with glucocorticoid actions and cell surface associated AnxA1 appears to be a marker of glucocorticoid sensitivity. Although still speculative, a “normal” expression of cell surface-associated AnxA1 in post-ACS patients may suggest that glucocorticoid actions in vivo are insufficient to provide adequate anti-inflammatory effects in these patients.
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| 9. |
- Bergström, Ida, et al.
(författare)
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Higher expression of annexin A1 in 1 CD56+ than in CD56-T cells : Potential implications for coronary artery disease
- 2014
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Background: Increased proportions of circulating proinflammatory CD56+ T cells have been reported in patients with coronary artery disease (CAD). Yet, little is known about regulation of these cells. In the present study, we investigated the expression and potential role of the glucocorticoid-mediated protein annexin A1 (AnxA1) in CD56+ and CD56-T cell subsets, with focus on CAD.Methods and Results: We included totally 52 healthy individuals, 28 patients with acute coronary syndrome (ACS) and 57 patients with a history of ACS. AnxA1 mRNA expression was assessed in peripheral blood mononuclear cells. AnxA1 protein expression (total and cell surface-associated) was measured by whole blood flow cytometry in circulating CD56+ and CD56- T cell subsets. Furthermore, inhibitory effects of dexamethasone and/or recombinant AnxA1 on cytokine secretion by CD56+ and CD56- T cells were explored in vitro. We found that CD56+ T cells (the majority CD8+), expressed higher levels of AnxA1 mRNA and protein than did CD56- T cells. When comparing CAD patients with healthy controls, significantly higher levels of cell surface-associated AnxA1 expression were seen in patients, most pronounced in ACS patients. In vitro, dexamethasone reduced cytokine secretion by CD56+ T cells, whereas AnxA1 alone had no effect, and AnxA1 combined with dexamethasone abolished the dexamethasone-induced suppressive effects.Conclusion: AnxA1 was expressed more abundantly in proinflammatory CD56+ T cells. Patients with ACS exhibited increased levels of cell surface-associated AnxA1, thus indicating increased activation of the AnxA1 pathway. Our data further suggested that AnxA1 might counteract glucocorticoid mediated anti-inflammatory effects in T cells.
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| 10. |
- Bergström, Ida, et al.
(författare)
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Persistent accumulation of interferon-gamma-producing CD8(+)CD56(+) T cells in blood from patients with coronary artery disease
- 2012
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Ingår i: Atherosclerosis. - : Elsevier. - 0021-9150 .- 1879-1484. ; 224:2, s. 515-520
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Tidskriftsartikel (refereegranskat)abstract
- Objective: There is emerging evidence for CD8(+) T cell alterations in blood from patients with coronary artery disease (CAD). We examined whether the distribution and phenotype of CD8(+)CD56(+) T cells differed according to the clinical manifestation of CAD. less thanbrgreater than less thanbrgreater thanMethods: Patients with acute coronary syndrome (ACS, n = 30), stable angina (SA, n = 34) and controls (n = 36) were included. Blood was collected before and up to 12 months after referral for coronary investigation. CD8(+)CD56(+) T cells were assessed by flow cytometry for expression of surface markers, apoptosis, and intracellular expression of cytokines. less thanbrgreater than less thanbrgreater thanResults: The proportions of CD8(+)CD56(+) T cells were significantly higher in both ACS and SA patients compared with controls, and remained so after 3 and 12 months. This was independent of age, sex, systemic inflammation and cytomegalovirus seropositivity. CD8(+)CD56(+) T cells differed from CD8(+)CD56(-) T cells in terms of lower CD28 expression and fewer apoptotic cells. Both CD8(+) T cell subsets were positive for interferon (IFN)-gamma and tumor necrosis factor, although IFN-gamma was significantly more confined to the CD8(+)CD56(+) T cells. less thanbrgreater than less thanbrgreater thanConclusion: The persistent accumulation of CD8(+)CD56(+) T cells in ACS and SA patients share several features with immunological aging. It also contributes to a larger IFN-gamma(+) pool in blood, and may thereby hypothetically drive the atherosclerotic process in a less favorable direction.
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