|  Hashimoto's
Thyroiditis is an autoimmune thyroid disease in which
the immune system attacks and destroys the thyroid
gland. The thyroid helps set the rate of metabolism
- the rate at which the body uses energy.
Hashimoto’s
prevents the gland from producing enough thyroid hormones
for the body to work correctly. It is the most common
form of Hypothyroidism (underactive thyroid), 30 times
more common among humans with IDDM than in the general
population.
Lymphocytic
infiltration of the thyroid has been also described
in both diabetic and non-diabetic BB/Wor animals, but
the lesion does not progress to frank hypothyroidism
in the absence of dietary or other manipulation.
In
early reports, thyroiditis was observed in about 59%
of diabetic and 11% of non-diabetic BB/Wor rats. It
is MHC-associated. The prevalence of lymphocytic thyroiditis
varies among different diabetes prone sublines in the
Worcester colony. At 110 days of age, for example, the
prevalence was 100% in NB line rats but only 4.9% in
BE line animals.
This observation, together with the low rate of concordance
of diabetes and thyroiditis, suggests that these two
hereditary autoimmune diseases are not tightly linked
genetically.
Pathologically,
thyroiditis is associated with infiltration of both
dendritic cells and lymphocytes. RT-PCR analyses of
cytokine mRNA in the thyroid glands of RT6-depleted
BB/Wor rats revealed a Th1-type cytokine profile similar
to that observed in inflamed islets.
Thyroiditis can also be adoptively transferred from
BB rats to MHC compatible naive recipients using splenocytes,
and it can be prevented by the transfusion of normal
MHC-compatible lymphocytes.
Lines
of thyroid-reactive cells have also been derived from
diabetes prone animals.
In
early reports, thyroiditis was observed in about 59%
of diabetic and 11% of non-diabetic DP-BB/Wor rats.
It is MHC-associated.
The
prevalence of lymphocytic thyroiditis varies among different
diabetes prone sublines in the Worcester colony. At
110 days of age, for example, the prevalence was 100%
in NB line rats but only 4.9% in BE line animals.
This observation,
together with the low rate of concordance
of diabetes and thyroiditis, suggests
that these two hereditary autoimmune
diseases are not tightly linked genetically. |
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