Mette Nielsen

Independent Introduction of Two Lactase-Persistence Alleles into Human Populations Reflects Different History of Adaptation to Milk Culture

The T(-13910) variant located in the enhancer element of the lactase (LCT) gene correlates perfectly with lactase persistence (LP) in Eurasian populations whereas the variant is almost nonexistent among Sub-Saharan African populations, showing high prevalence of LP. Here, we report identification of two new mutations among Saudis, also known for the high prevalence of LP. We confirmed the absence of the European T(-13910) and established two new mutations found as a compound allele: T/G(-13915) within the -13910 enhancer region and a synonymous SNP in the exon 17 of the MCM6 gene T/C(-3712), -3712 bp from the LCT gene. The compound allele is driven to a high prevalence among Middle East population(s). Our functional analyses in vitro showed that both SNPs of the compound allele, located 10 kb apart, are required for the enhancer effect, most probably mediated through the binding of the hepatic nuclear factor 1 alpha (HNF1 alpha). High selection coefficient (s) approximately 0.04 for LP phenotype was found for both T(-13910) and the compound allele. The European T(-13910) and the earlier identified East African G(-13907) LP allele share the same ancestral background and most likely the same history, probably related to the same cattle domestication event. In contrast, the compound Arab allele shows a different, highly divergent ancestral haplotype, suggesting that these two major global LP alleles have arisen independently, the latter perhaps in response to camel milk consumption. These results support the convergent evolution of the LP in diverse populations, most probably reflecting different histories of adaptation to milk culture.

Interferon-alpha induces transient suppressors of cytokine signalling expression in human T cells.

The suppressors of cytokine signalling (SOCS) proteins comprise a newly identified family of negative feedback regulators of cytokine signalling. SOCS expression is differentially induced upon cytokine stimulation in different cell types. Here we show that interferon-α (IFNα) is a potent inducer of SOCS expression in human T cells, as high expression of CIS, SOCS-1, SOCS-2, and SOCS-3 was detectable after IFNα stimulation. After 4 h of stimulation, CIS, SOCS-1, and SOCS-3 expression had returned to baseline levels, whereas SOCS-2 expression had not declined. In contrast, after IL-2 induction neither CIS, SOCS-1, nor SOCS-2 expression levels declined after 6 h. In conclusion, we provide the first evidence that IFNα induces SOCS expression in human T cells. Moreover, we show that IFNα and IL-2 induce distinct patterns of expression kinetics, suggesting that dynamic changes in cytokine sensitivity might be mediated via induction of SOCS expression with different kinetics in T cells.

MHC class II ligation induces CD58 (LFA-3)-mediated adhesion in human T cells

MHC class II positive T cells found in areas of inflammation are believed to play an important pathogenetic role in autoimmunity. In experimental models , class II molecules have been shown to regulate adhesion between human T cells. It is, however, not known in detail how class II molecules are functionally linked to adhesion molecules. Some data suggest that β2 integrin (CD11a/CD18) molecules play a role in class-II-induced homotypic adhesion in B cells, monocytes, and virus-transformed or neoplastic cell lines. We have previously obtained evidence that adhesion molecules other than β2 integrins might play a role in class-II-mediated adhesion in T cells. To study further class-II-mediated adhesion in T cells, we have taken advantage of (allo)antigen-specific β2-integrin-negative, CD4-positive T cell lines obtained from a leukocyte adhesion deficiency patient. We show that class II ligation induces homotypic adhesion in both β2-integrin-positive and negative, CD4-positive T cell lines. Anti-CD18 monoclonal antibody (mAb) weakly inhibited the adhesion response in β2-integrin-positive T cells and had no effect on β2-integrin-negative T cells. In contrast, an anti-CD58 (LFA-3) mAb almost completely inhibited the adhesion response in β2-integrin-negative T cells. Antibodies against the CD58 ligand, CD2, partly inhibited the adhesion response in β2-integrin-negative T cells whereas antibodies against other adhesion molecules did not. The adhesion response in β2-integrin-positive T cells was partly inhibited by antibodies against CD58 and CD2. Taken together, these data provide the first evidence that CD58 molecules are involved in class-II-induced homotypic adhesion between T cells.

C-terminal Modification of Osteopontin Inhibits Interaction with the αVβ3-Integrin

Osteopontin (OPN) is a multifunctional phosphorylated protein containing the integrin binding sequence Arg-Gly-Asp through which it interacts with several integrin receptors, such as the αVβ3-integrin. OPN exists in many different isoforms differing in phosphorylation status that are likely to interact differently with integrins. The C-terminal region of OPN is particularly well conserved among mammalian species, which suggests an important functional role of this region. In this study, we show that modification of the extreme C terminus of OPN plays an important regulatory role for the interaction with the αVβ3-integrin. It is demonstrated that highly phosphorylated OPN has a much reduced capability to promote cell adhesion via the αVβ3-integrin compared with lesser phosphorylated forms. The cell attachment promoted by highly phosphorylated OPN could be greatly increased by both dephosphorylation and proteolytic removal of the C terminus. Using recombinantly expressed OPN containing a tag in the N or C terminus, it is shown that a modification in the C-terminal part significantly reduces the adhesion of cells to OPN via the αVβ3-integrin, whereas modification of the N terminus does not influence the binding. The inhibited binding of the αVβ3-integrin to OPN could be restored by proteolytic removal of the C terminus by thrombin and plasmin. These data illustrate a novel mechanism regulating the interaction of OPN and the αVβ3-integrin by modification of the highly conserved C-terminal region of the protein.

Protein phosphatase 2A (PP2A) regulates interleukin-4-mediated STAT6 signaling.

Interleukin-4 (IL-4) plays a pivotal role in the induction and maintenance of allergy by promoting Th2 differentiation and B cell isotype switching to IgE. Studies on STAT6-deficient mice have demonstrated the essential role of STAT6 in mediating the biological functions of IL-4. IL-4 induces tyrosine phosphorylation of STAT6, which in turn leads to transcription of IL-4-specific genes. In addition, serine phosphorylation of STAT6 has recently been reported. Here we study the functional role of STAT6 serine phosphorylation and the kinases and phosphatases involved. We show that inhibition of protein phosphatase 2A (PP2A) induces serine phosphorylation of STAT6 and severely inhibits DNA binding of STAT6. In contrast, IL-4-induced tyrosine phosphorylation of Janus kinase-1 and STAT6 is not affected, suggesting that PP2A acts downstream of Janus kinases in IL-4 signaling. In conclusion, we provide the first evidence that PP2A plays a crucial role in the regulation of STAT6 function.

Radically altered T cell receptor signaling in glycopeptide‐specific T cell hybridoma induced by antigen with minimal differences in the glycan group

A T cell hybridoma raised against the synthetic glycopeptide T72(Tn) was used to study whether the initial TCR signaling events are markedly different when the hybridoma is stimulatedwith glycopeptides closely related to the cognate glycopeptide antigen. T72(Tn) has an α‐D‐GalNAc group O‐linked to the central threonine in the decapeptide VITAFTEGLK, and the hybridoma is known to be highly specific for this carbohydrate group. T72(Tn)‐pulsed APC induced tyrosine phosphorylation of the TCR‐ζ 21‐ and 23‐kDa proteins and the downstream p42/44 MAP kinase and strong IL‐2 secretion. APC pulsed with T72(α‐D‐GlcNAc), which differs from T72(Tn) solely by the orientation of a hydroxy group in the carbohydrate structure, completely failed to induce detectable tyrosine phosphorylation and IL‐2 secretion. APC pulsed with S72(Tn), which differs from T72(Tn) by not having a methyl group in theserine amino acid side chain to which the glycan is attached, induced partial tyrosine phosphorylation of the TCR‐ζ 21‐kDa protein, no tyrosine phosphorylation of the MAP kinases and no IL‐2 production. Molecular modeling of the MHC/glycopeptide complex revealed that the dramatic difference between the stimulatory power of T72(Tn) and T72(α‐D‐GlcNAc) is mainly due to very small differences in the TCR exposed carbohydrate structure.

Hedonic Changes in Food Choices Following Roux-en-Y Gastric Bypass

It has been suggested that a shift in food choices leading to a diet with a lower energy density plays an important role in successful weight loss after Roux-en-Y gastric bypass (RYGB) surgery. A decreased hedonic drive to consume highly palatable foods may explain these changes in eating behavior. Here, we review the literature examining postoperative changes in mechanisms contributing to hedonic drive (food preferences, reinforcing value of food, dopamine signaling, and activity reward-related brain regions). The majority of studies reviewed support that RYGB decrease the hedonic drive to consume highly palatable foods. Still, in order to fully understand the complexity of these changes, we need studies combining sociological and psychological approaches with objective measures of actual food choices examining different measures of hedonic drive.

Efficacy of a liquid low-energy formula diet in achieving preoperative target weight loss before bariatric surgery

A preoperative weight loss of 8 % is a prerequisite to undergo bariatric surgery (BS) in Denmark. The aim of the present study was to evaluate the efficacy of a 7- or an 11-week low-energy diet (LCD) for achieving preoperative target weight before BS. A total of thirty obese patients (BMI 46·0 (sd 4·4) kg/m2) followed an LCD (Cambridge Weight Plan®, 4184 kJ/d (1000 kcal/d)) for 7 or 11 weeks as preparation for BS. Anthropometric measurements including body composition (dual-energy X-ray absorptiometry), blood parameters and blood pressure were assessed at weeks 0, 7 and 11. At week 7, the majority of patients (77 %) had reached their target weight, and this was achieved after 5·4 (sem 0·3) weeks. Mean weight loss was 9·3 (sem 0·5) % (P < 0·01) and consisted of 41·6 % fat-free mass (FFM) and 58·4 % fat mass. The weight loss was accompanied by a decrease in systolic and diastolic blood pressure (7·1 (sem 2·3) and 7·3 (sem 1·8) mmHg, respectively, all P < 0·01) as well as an improved metabolic profile (8·2 (sem 1·8) % decrease in fasting glucose (P < 0·01), 28·6 (sem 6·4) % decrease in fasting insulin (P < 0·01), 23·1 (sem 2·2) % decrease in LDL (P < 0·01), and 9·7 (sem 4·7) % decrease in TAG (P < 0·05)). Weight, FFM and fat mass continued to decrease from week 7 to 11 (all P < 0·01), whereas no additional improvements was observed in the metabolic parameters. Severely obese patients can safely achieve preoperative target weight on an LCD within 7 weeks as part of preparation for BS. However, the considerable reduction in FFM in severely obese subjects needs further investigation.

Maternal fish oil supplementation during lactation is associated with reduced height at 13 years of age and higher blood pressure in boys only

Dietary long-chain n-3 PUFA (n-3 LCPUFA) in infancy may have long-term effects on lifestyle disease risk. The present follow-up study investigated whether maternal fish oil (FO) supplementation during lactation affected growth and blood pressure in adolescents and whether the effects differed between boys and girls. Mother-infant pairs (n 103) completed a randomised controlled trial with FO (1·5 g/d n-3 LCPUFA) or olive oil (OO) supplements during the first 4 months of lactation; forty-seven mother-infant pairs with high fish intake were followed-up for 4 months as the reference group. We also followed-up 100 children with assessment of growth, blood pressure, diet by FFQ and physical activity by 7-d accelerometry at 13·5 (sd 0·4) years of age. Dried whole-blood fatty acid composition was analysed in a subgroup (n 49). At 13 years of age, whole-blood n-3 LCPUFA, diet, physical activity and body composition did not differ between the three groups. The children from the FO group were 3·4 (95 % CI 0·2, 6·6) cm shorter (P=0·035) than those from the OO group, and tended to have less advanced puberty (P=0·068), which explained the difference in height. There was a sex-specific effect on diastolic blood pressure (P sex×group=0·020), which was driven by a 3·9 (95 % CI 0·2, 7·5) mmHg higher diastolic blood pressure in the FO compared with the OO group among boys only (P=0·041). Our results indicate that early n-3 LCPUFA intake may reduce height in early adolescence due to a delay in pubertal maturation and increase blood pressure specifically in boys, thereby tending to counteract existing sex differences.

Patient profiling for success after weight loss surgery (GO Bypass study): An interdisciplinary study protocol

Despite substantial research efforts, the mechanisms proposed to explain weight loss after gastric bypass (RYGB) and sleeve gastrectomy (SL) do not explain the large individual variation seen after these treatments. A complex set of factors are involved in the onset and development of obesity and these may also be relevant for the understanding of why success with treatments vary considerably between individuals. This calls for explanatory models that take into account not only biological determinants but also behavioral, affective and contextual factors. In this prospective study, we recruited 47 women and 8 men, aged 25–56 years old, with a BMI of 45.8 ± 7.1 kg/m2 from the waiting list for RYGB and SL at Køge hospital, Denmark. Pre-surgery and 1.5, 6 and 18 months after surgery we assessed various endpoints spanning multiple domains. Endpoints were selected on basis of previous studies and include: physiological measures: anthropometrics, vital signs, biochemical measures and appetite hormones, genetics, gut microbiota, appetite sensation, food and taste preferences, neural sensitivity, sensory perception and movement behaviors; psychological measures: general psychiatric symptom-load, depression, eating disorders, ADHD, personality disorder, impulsivity, emotion regulation, attachment pattern, general self-efficacy, alexithymia, internalization of weight bias, addiction, quality of life and trauma; and sociological and anthropological measures: sociodemographic measures, eating behavior, weight control practices and psycho-social factors. Joining these many endpoints and methodologies from different scientific disciplines and creating a multi-dimensional predictive model has not previously been attempted. Data on the primary endpoint are expected to be published in 2018. Trial registration Clinicaltrials. gov ID NCT02070081.