Analysis of T cell receptor (TCR) BV-gene clonotypes in NC/Nga mice developing dermatitis resembling human atopic dermatitis

Perturbation of the T cell receptor repertoire occurs with increasing age in dogs

Immunosenescence is the gradual deterioration in immune system function associated with ageing. This decline is partly due to involution of the thymus, which leads to a reduction in the output of naive T cells into the circulating lymphocyte pool. Expansion of existing naive and memory T cell populations, to compensate for the reduction in thymic output, can lead to reduced diversity in the T cell repertoire with increasing age, resulting in impairment of immune responses to novel antigenic challenges, such as during infection and vaccination. Since associations between T cell repertoire and age have only been examined in a limited number of species, to gain further insights into this relationship, we have investigated age-related changes in the canine T cell receptor (TCR) repertoire. Blood samples were obtained from Labrador retriever dogs of varying ages and variation in the complementary determining region 3 (CDR3) of the T cell receptor beta (TCRB) chain was investigated. CDR3 size spectratyping was employed to evaluate clonal expansion/deletion in the T cell repertoire, allowing identification of profiles within individual variable (V) region families that skewed away from a Gaussian distribution. Older dogs (10-13 years) were found to have an increased number of TCRB V gene spectratypes that demonstrated a skewed distribution, compared with young dogs (≤3 years). Additionally, there was a reduction in the number of clonal peaks present in the spectratypes of old dogs, compared with those of young dogs. The study findings suggest that there is an age-associated disturbance in the diversity of the T cell receptor repertoire in dogs.

Lessons from murine models of atopic dermatitis

Atopic dermatitis (AD) is a complex disease that manifests immunologic abnormalities in the skin. The immunologic changes of AD are characterized by a T helper cell type 2 (Th2)-dominated immune response in its acute phase and a Th1/Th2 mixed immune response in its chronic phase. Although the clinical presentation and pathologic changes are initially in the skin, AD may be, in part, a systemic disorder. In fact, AD is often considered to be the initial manifestation of the "atopic march" that progresses from AD to allergic rhinitis and asthma. In the past several years, a number of murine models of AD have been developed or discovered, and studies on these models have contributed greatly to our understanding of the immunopathogenesis of this disease. This review is focused on these recent, illuminating advances in animal models of AD.