Muscle power development during the first year of life predicts neuromotor behaviour at 7 years in preterm born high-risk infants

The aim of the study was to find if neurological function during the first year of life could predict neuromotor behaviour at 7 years of age in children born preterm with a high risk. A follow-up study of neuromotor behaviour in 52 children at a mean age of 3, 6, 12 months (corrected age) and 7 years was performed. All children were born with a gestational age less than 32 weeks and/or a birthweight under 1500 g and the infants were categorised according to their medical history in the three highest categories of the 'Neonatal Medical Index' (NMI, from category I to V, from few to serious complications). In addition, neonatal cerebral ultrasound abnormalities were used to divide the infants further into the different NMI categories. At 3 and 6 months, the relationship between active and passive muscle power was measured in shoulders, trunk and legs and (a)symmetry between right and left was noted. The results at 3 and 6 months were ranged from 1 for optimal to 5 for poor muscle power regulation. At 12 months of age, a neurological examination was done with special emphasis on the assessment of postural control, spontaneous motility, hand function and elicited infantile reactions with special attention to (a)symmetry. Outcome at 12 months was expressed as percentage of the optimal score on each subcategory. At 7 years, the motor behaviour study based on Touwen's examination for minor neurological dysfunction was performed. This investigation focuses on different functions, such as hand function, quality of walking, posture, passive muscle tone, coordination and diadochokinesis. The outcome was expressed as percentage of the optimal score on the combined subcategories. The best prediction of neuromotor behaviour at 7 years was assessed with stepwise linear multiple regression, using as potential predictors perinatal factors and outcome of motor behaviour at the corrected age of 3, 6 and 12 months. At 7 years none of the children scored 100% on the combined subcategories, 15 children (29%) scored between 75% and 99%, whereas 15 children scored less than 50%. Neuromotor behaviour at 7 years could be predicted by the NMI categorisation and gender with a sensitivity of 92% (specificity 47%; positive and negative predictive value 81% and 70%). No direct relation was found between neuromotor behaviour and cerebral ultrasound classification only, days on the ventilator and/or continuous positive airway pressure, birthweight, gestational age and dysmaturity. The best predictor of neuromotor behaviour at 7 years was the combination of outcome of muscle power in shoulders and legs at 3 months and postural control at 12 months, taking into account the gender of the child (sensitivity 95%; specificity 40%; positive predictive value 80%; negative predictive value 75%).     

Adaptive T-cell responses regulating oral tolerance to protein antigen

The term oral (or mucosal) tolerance has been classically defined as the suppression of T- and B-cell responses to an antigen by prior administration of the antigen by the oral route. In recent years, it has become clear that both innate and acquired regulatory immune responses are essential for the development of oral tolerance. As such, mucosal microenvironmental factors such as transforming growth factor- β, prostaglandins but also dietary vitamin A create conditioning of an adaptive regulatory T-cell response that suppresses subsequent antigen-specific responses. Particular resident subsets of antigen presenting dendritic cells are pivotal to convey conditioning signals next to the presentation of antigen. This review discusses the primary mechanisms of adaptive regulatory T-cell induction to ingested soluble protein antigen. However, we also discuss the limitations of our knowledge with respect to understanding the very common food hypersensitivity Celiac disease caused by an aberrant adaptive immune response to the food protein gluten.     

The production of secretory leukocyte protease inhibitor by dendritic cells

Secretory leukocyte protease inhibitor (SLPI) is produced at mucosal sites where it plays an important role in the homeostatic control of local inflammation. In addition to its anti-protease activity SLPI is able to reduce LPS activity by interfering with the transfer of LPS to CD14. In addition SLPI can be taken up by cells where it can prevent signaling via the NF-κB route.It is preferentially expressed in dendritic cells from mucosal sites, suggesting a role in the maintenance of a tolerogenic environment, but it is unclear how this differential expression is regulated.Here we analyzed the regulation of SLPI expression in dendritic cells and found that activation by TLR ligands but not via antiCD40 leads to its expression, which is predominantly dependent on p38 activation. This induced expression is late compared to the induction of cytokines and co-stimulatory molecules, is not dependent on factors that are secreted by the cell itself and may be related to cellular feedback mechanisms involved in inflammation and immunity. In correlation with the differential expression by TLR ligands and antiCD40, SLPI deficient mice show enhanced specific immunity when antigen is co-injected with LPS, but not with antiCD40. The results underscore the importance of SLPI as a modulator of specific immunity that can also function at peripheral sites under pathogenic pressure.     

Effects of partial (Belsey Mark IV) and complete (Nissen) fundoplication on proximal gastric function and esophagogastric junction dynamics

OBJECTIVES: This study aimed to assess the effects of Belsey Mark IV 270 degrees (partial) and Nissen 360 degrees (complete) fundoplication on proximal stomach function, transient lower esophageal sphincter relaxation (TLESR) elicitation and the esophagogastric junction (EGJ) pressure profile during TLESR to further elucidate the mechanism of action of fundoplication. METHODS: Ten patients after partial and 10 patients after complete fundoplication were studied. High-resolution EGJ manometry and pH recording were performed for 1 h at baseline and 2 h following meal ingestion (500 mL/300 kcal). Three dimensional (3D) ultrasonographic images of the stomach were acquired every 15 min after meal ingestion. From the 3D ultrasonographic images, proximal gastric volumes were computed. RESULTS: Postprandial proximal to complete gastric volume distribution ratios were larger among patients after partial (0.42 +/- 0.028) compared with patients after complete fundoplication (0.37 +/- 0.035; p < 0.05). Partial fundoplication patients had a markedly greater postprandial rate of TLESR (1.7 +/- 0.3/h) than patients after complete fundoplication (0.8 +/- 0.2/h; p < 0.05). The axial EGJ pressure profile was minimally affected by partial fundoplication but instead markedly changed after complete fundoplication. CONCLUSIONS: Patients after partial fundoplication exhibit a larger meal-induced increase in proximal stomach volume, a higher TLESR rate, and a minimally affected axial EGJ pressure profile compared to patients after complete fundoplication.     

Long-term follow up of children exposed in utero to nifedipine or ritodrine for the management of preterm labour

OBJECTIVE: To compare the long-term psychosocial and motor effects on children exposed in utero to nifedipine or ritodrine for the management of preterm labour. DESIGN: Randomised controlled trial. SETTING: Multicentre study in two university and one primary hospital in the Netherlands. POPULATION: In the original trial, 185 women were randomised to either nifedipine (n = 95) or ritodrine (n = 90). Of the 185 liveborn children, 171 survived (92%), and of these 102 (61%) were followed up at age 9-12 years. METHODS: Age-specific questionnaires were administered to the parent and teacher. Additional data were obtained from medical records. MAIN OUTCOME MEASURES: Questionnaires were used to assess the child's behavioural-emotional problems, quality of life (QoL), motor functioning, parenting distress and the child's education. RESULTS: Of the 171 eligible families, 102 (61%) agreed to participate and completed the questionnaires. Response was equal in the ritodrine group (n = 54 of 83 surviving children, 65%) compared with the nifedipine group (n= 48 of 88 surviving children, 55%). After controlling for differing perinatal characteristics at birth, no significant differences between the groups were detected with respect to long-term behaviour-emotional outcome, QoL, education, motor functioning or parenting distress. Psychosocial outcome was slightly better in the nifedipine group. CONCLUSIONS: The results do not support any differential postnatal effect of the tocolytic agents ritodrine or nifedipine on the child's long-term psychosocial and motor functioning. The slightly better outcome of children randomised in the nifedipine group is most likely due to more favourable perinatal outcomes in this group. These results merit further investigation in a larger group of survivors.     

Endogenous secretory leukocyte protease inhibitor inhibits microbial-induced monocyte activation

In the intestine, epithelial factors condition incoming immune cells including monocytes to adapt their threshold of activation and prevent undesired inflammation. Colonic epithelial cells express Secretory Leukocyte Protease Inhibitor (SLPI), an inhibitor of NF kappa light chain enhancer of activated B cells (NF-κB) that mediates epithelial hyporesponsiveness to microbial stimuli. Uptake of extracellular SLPI by monocytes has been proposed to inhibit monocyte activation. We questioned whether monocytes can produce SLPI and whether endogenous SLPI can inhibit monocyte activation. We demonstrate that human THP-1 monocytic cells produce SLPI and that CD68⁺ SLPI-producing cells can be detected in human intestinal lamina propria. Knockdown of SLPI in human THP-1 cells significantly increased NF-κB activation and subsequent C-X-C motif chemokine ligand 8 (CXCL8) and TNF-α production in response to microbial stimulation. Reconstitution of SLPI-deficient cells with either full-length SLPI or SLPI lacking its signal peptide rescued inhibition of NF-κB activation and cytokine production, demonstrating that endogenous SLPI inhibits monocytic cell activation. Unexpectedly, exogenous SLPI did not inhibit CXCL8 or TNF-α production, despite efficient uptake. Our data argue that endogenous SLPI can regulate the threshold of activation in monocytes, thereby preventing activation by commensal bacteria in mucosal tissues.     

Endogenous Interleukin-4 Does Not Suppress the Resistance Against a Primary or a Secondary Listeria monocytogenes Infection in Mice

Interleukin-4 (IL-4), a cytokine produced by T-helper 2 (Th2) cells, can inhibit the development of T-helper 1 (Th1) cells, which results in a decreased release of cytokines by the latter. As interferon-γ (IFN-γ), produced by Th1 cells, is involved in the resistance against a Listeria monocytogenes infection, the role of endogenously formed IL-4 during a Listeria infection in mice was investigated. Neutralization of endogenously formed cytokines by subcutaneously injected alginate-encapsulated monoclonal antibody (MoAb)-forming cells results in high antibody titres in the circulation over a long time period. The aim of the present study was to re-evaluate the effect of neutralization of IL-4 during a primary Listeria infection and to investigate the role of IL-4 during a secondary infection in mice using encapsulated MoAb-forming cells. During the course of a primary infection in mice given anti-IL-4 antibody-forming cells (anti-IL-4-FC), the number of Listeria found in the liver and spleen was comparable to that found in control mice given anti-β-galactosidase antibody-forming cells (anti-β-gal-FC). Activation of macrophages measured by inhibition of Toxoplasma gondii proliferation and the release of reactive nitrogen intermediates (RNI) was not affected by anti-IL-4-FC treatment during infection. Furthermore, during a secondary L. monocytogenes infection the number of bacteria in the liver and spleen of anti-IL-4-treated immune mice was comparable to anti-β-gal-FC-treated, control, immune mice. The concentration of IFN-γ in plasma of anti-IL-4-treated immune mice was similar to that of control immune mice. Taken together, these findings demonstrate that neutralization of endogenously formed IL-4 does not affect resistance to a primary or a secondary L. monocytogenes infection in mice.     

Sialic acid-modified antigens impose tolerance via inhibition of T-cell proliferation and de novo induction of regulatory T cells

Sialic acids are negatively charged nine-carbon carboxylated monosaccharides that often cap glycans on glycosylated proteins and lipids. Because of their strategic location at the cell surface, sialic acids contribute to interactions that are critical for immune homeostasis via interactions with sialic acid-binding Ig-type lectins (siglecs). In particular, these interactions may be of importance in cases where sialic acids may be overexpressed, such as on certain pathogens and tumors. We now demonstrate that modification of antigens with sialic acids (Sia-antigens) regulates the generation of antigen-specific regulatory T (Treg) cells via dendritic cells (DCs). Additionally, DCs that take up Sia-antigen prevent formation of effector CD4⁺ and CD8⁺ T cells. Importantly, the regulatory properties endowed on DCs upon Sia-antigen uptake are antigen-specific: only T cells responsive to the sialylated antigen become tolerized. In vivo, injection of Sia-antigen–loaded DCs increased de novo Treg-cell numbers and dampened effector T-cell expansion and IFN-γ production. The dual tolerogenic features that Sia-antigen imposed on DCs are Siglec-E–mediated and maintained under inflammatory conditions. Moreover, loading DCs with Sia-antigens not only inhibited the function of in vitro–established Th1 and Th17 effector T cells but also significantly dampened ex vivo myelin-reactive T cells, present in the circulation of mice with experimental autoimmune encephalomyelitis. These data indicate that sialic acid-modified antigens instruct DCs in an antigen-specific tolerogenic programming, enhancing Treg cells and reducing the generation and propagation of inflammatory T cells. Our data suggest that sialylation of antigens provides an attractive way to induce antigen-specific immune tolerance.Antigen-presenting cells (APCs), and predominantly dendritic cells (DCs), are crucial to maintain immune homeostasis, because these cells determine whether or not an immune reaction is mounted against pathogens or self or innocuous foreign antigens. In healthy individuals, encounter with innocuous (self-)antigens will lead to induction of regulatory T (Treg) cells, which in turn dampen excessive immune responses, a process that fails in autoimmune patients (1).Ways to promote this immune-inhibitory signature of DCs may therefore provide new therapeutic strategies to fight autoimmune disorders. Although different methods are described to push DCs into an immune-inhibitory mode, none of these methods is antigen-specific and may therefore exert off-target effects. Additional evidence suggests that merely generating a large pool of Treg cells is not sufficient to control aberrant immunity: the inflammatory milieu in the affected areas promotes a strong APC-mediated activation of antigen-specific autoreactive T cells, which makes these autoreactive T cells refractory to suppression by Treg cells (2–5). These findings suggest that strategies that aim at controlling autoimmunity should not only involve inducing Treg-cell populations but also dampening autoreactive T cells, thereby creating a milieu that allows Treg cells to exert their suppressive function. Certain pathogenic infections and tumors are marked by the presence of tolerogenic DCs and T cells (6–9). An often overlooked feature shared by these pathological conditions is the presence of aberrant glycosylation patterns (7, 10–12). In particular, increased levels of sialic acids have been demonstrated in these situations. On tumors, enhanced sialylation driven by enhanced expression and activity of β-galactoside α2,6-sialyltransferase 1 (ST6Gal-1) and/or α-N-acetylgalactosaminide α2,6-sialyltransferase 1 (ST6GalNAc-I) often correlates with tumor invasion and poor prognosis (13–15). Additionally, the hypersialylated pathogens Campylobacter jejuni and Neisseria meningitides were shown to negatively affect human APC function and consequently subvert immune responses (7, 16–19).Sialic acids are the outermost monosaccharides on glycan chains of glycoproteins and glycolipids, attached to the underlying glycans with α2,3, α2,6, or α2,8 linkage (14) and as such form the recognition elements for sialic acid-binding Ig-like lectins (siglecs) (14, 20). Siglecs are predominantly expressed by innate immune cells, such as DCs, macrophages, and B cells (20). On these cells, siglecs function as endocytic receptors as well as can regulate activation status and cytokine secretion. Most siglecs are characterized by the presence of one or more immunoreceptor tyrosine-based inhibitory motifs (ITIMs) in their intracellular domain (21) and, thus, siglec triggering often counteracts activatory signals elicited by receptors containing immunoreceptor tyrosine-based activatory motifs (ITAMs) (20). Although engagement of the hCD33rSiglecs on innate cells by sialylated antigens has been shown to negatively modulate the proinflammatory functions of APCs, effects on T-cell responses have not yet been investigated in detail.Because the immune-inhibitory effects induced by sialylated pathogens and tumors may be attributed to different configurations of sialic acid-containing glycoproteins or glycolipids, we set out to characterize the effects of sialic acids on DCs and T-cell responses using a well-characterized neoglycoconjugate approach based on the model antigens ovalbumin (OVA) or the encephalitogenic peptide derived from myelin oligodendrocyte glycoprotein (MOG_35–55) that we modified with either α2,3- or α2,6-linked sialyl-lactose (hereafter named Sia-antigens). Our data reveal that internalization of Sia-antigen by DCs endows them with the ability to promote the differentiation of naive CD4⁺ T cells into Treg cells at the expense of functional CD4⁺ and CD8⁺ effector T cells, both in vitro and in vivo. We provide evidence that this feature is antigen-specific and even effective under inflammatory conditions. Moreover, our findings demonstrate that Sia-antigen–loaded DCs also dampen the function of established effector T cells, suggesting that sialylation of antigens provides a means to dampen excessive T-cell pathologies.