Autistic Functioning and Language Development

This thesis is a retrospective qualitative study based on psychotherapy sessions with children presenting autistic features who use language in atypical ways. The aim was to understand, through the transferential relationship, what psychological context in terms of anxieties and defences prevents the child from using language efficiently. Hypotheses concerning children‘s use of language in the context of their emotional oscillation and evolution during the course of treatment were noted and checked against subsequent developments. They were also triangulated with the outcome of a grounded theory analysis. The grounded theory analysis led to the emergence of higher-level themes that were compared within and across cases and allowed factors surrounding the children‘s use of language to be conceptualized. The grounded theory method was used in parallel with the usual process of evaluation of the dynamics of each session and patient used by psychoanalysts a posteriori and which is part of the researcher‘s background. This procedure was enhanced by the use of Bion‘s Grid, here in a version adapted to the aims of the research. This approach is discussed in detail in the Methodology chapter. The psychoanalytic theoretical background that supported the research was mainly based on the tradition of Object-Relations Theory, particularly the evolution of Kleinian thinking represented by Bion‘s works, and as far as autism is concerned, by Frances Tustin and Donald Meltzer‘s formulations. Concerning the subject of language development, Meltzer‘s explorations on the necessary conditions for its development and the philosopher Wittgenstein‘s investigations on the social function of language were the main influences of this work. The evolution of the children‘s use of language in parallel with their emotional development in the context of their psychotherapies was analyzed and some hypotheses about the oscillations in their emotional and mental functioning were made. The oscillation in the children‘s emotional state, language use and thinking processes was also studied in terms of a general fluctuation between different mental states that was considered to be present in different degrees and quality in mental life and more strongly when there are limitations in communication skills and social interaction. A few excerpts from notes on adolescent and adult cases with autistic features were included in the Discussion Chapters to briefly illustrate this aspect.

The Role of HBD-2 and HBD-3 in Human T Cell Development

Human β-defensins (hBDs) are a family of cationic peptides able to directly kill a wide range of microorganisms including bacteria, fungi and viruses. In addition to their antimicrobial activities, defensins also contribute to the modulation of both the host innate and adaptive immunity. In this project, we demonstrate that the αCD3/28 co-stimulation of human CD4+ T cells in the presence of 10μg/ml hBD-2 or hBD-3 together causes an up-regulation in numbers of CD4+CD69+CD25+ and CD4+CD69-CD25+ T cell subsets, indicating that the treatment of hBD-2 and 3 enhances CD4+ T cell activation. Consistent with this finding, proliferation assay using CFSE suggests that hBD-2 and hBD-3 treatment in vitro induces the proliferation of CD4+ T cells following by 96hrs culture. Analysis of expression of the regulatory T cells (Tregs) specific marker, FoxP3, reveals a shift in the CD4+CD127-CD25+ Treg subset at 18hrs. However, at the later time point, we found that the percentage of FoxP3+cells decreased in the CD4+CD127-CD25+ Treg population, whereas the presence of the FoxP3+CTLA-4+ Treg subset increased. These data indicate that Treg suppressive function may be potentially defective following the co-incubation of purified T cells with either hBD-2 or hBD-3 for 42hrs in vitro due to the apparent loss of FoxP3 expression. We further characterise the role of hBD-2 and hBD-3 in driving human CD4+ T cells polarisation. Our in vitro data suggests that treatment with hBD-2 and hBD-3 can not only induces effector T cell (Teff) differentiation into RORγt+T-bet+ (Th17/Th1) cells, but can also trigger the differentiation of Treg expressing RORγt and T-bet rather than the master controller of Treg function, FoxP3. This apparent plasticity of T cell phenotype allows them to convert from Treg to Th1/17-like effector T cell phenotype following 18hrs in culture. By 42hrs in culture, treatment with hBD-2 and hBD-3 induced both Teff cell and Treg cell differentiation towards the Th17-like phenotype. Compared with the treatment with hBD-2, treatment with hBD-3 induced a more pronounced effect to increase levels of RORγt in CD4+ T cells. This elevated expression may, in turn, be responsible for the induction of higher IL-17A secretion. Consistent with this idea, it was found that treatment with hBD-3 but not hBD-2 was capable of inducing the higher level of secretion of IL-17A. Additionally, treatment with hBD-3 induced an increased expression of IL-6, which is capable of driving the differentiation of naïve T cells towards IL-17-producing Th17 cells. Functionally, using the Treg suppression assay, the data suggested that hBD-2 may dampen down Treg cell ability to induce suppression of Teff cell activity. Interestingly, co-culture with hBD-2 would also appear to increase Teff cell resistance to Treg immunoregulation in vitro. Further investigation using microarray gene analysis revealed chemokine C-C motif ligand 1 (CCL1) as potential genes responding to hBD-2 treatment. The blockade of CCL1 has been reported to inhibit Treg suppressive function. Thus, this study explored the function of these antimicrobial candidates in regulating CD4+ T cell plasticity which could result in hBD-2 and hBD-3 being able to regulate its own production, but also may regulate Treg and Teff cell development and function, thus strengthening the link between innate and adaptive immunity