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Gene & Protein in Disease Autoimmune thyroid disease in narcolepsy

Table 2. Laboratory studies at an increased risk of developing another autoimmune
disease . HLA-DRB1*0803 and DQB1*0601 haplotypes
[8]
Variables Baseline value Normal range have been found to be strongly linked with AITD . We
[29]
T 1.36 ng/mL 0.91–2.18 ng/mL
3 suspect that HLA-related homologous genes could make
T 7.02 μg/dL 5.91–13.2 μg/dL it easier for specific autoantigens to be presented to self-
4
FT 6.11 pmol/L 3.93–7.7 pmol/L reactive T cells, leading to defects in peripheral autoimmune
3
FT 4 14.24 pmol/L 12.6–21 pmol/L responses and resulting in autoimmune diseases. All in all,
TSH 2.38 uIU/mL 0.51–4.3 uIU/mL narcolepsy and AITD may share common susceptibility
genes, thus supporting the hypothesis that common genetic
TgAb 12.1 IU/mL 0–4 IU/mL variants lead to immune dysregulation and autoimmune
TPOAb 243.53 IU/mL 0–9 IU/mL susceptibility. However, the specific susceptibility loci and
T : Triiodothyronine; T : Thyroxine; FT : Free triiodothyronine; genes shared by narcolepsy and AITD remain unknown,
3
3
4
FT : Free thyroxine; TGAb: Thyroglobulin antibody; TPOAb: Thyroid thereby requiring further research in this area.
4
peroxidase antibody; TSH: Thyroid stimulating hormone
Vitamin D has been shown to be an immunomodulatory
In this case, the patient’s thyroid function was normal on hormone . Although the patient was measured for
[30]
admission but she tested positive for thyroid antibodies. Vitamin D deficiency in our case, we were unable to infer
The previous studies have suggested that abnormal with certainty the cause of the deficiency. At present,
thyroid function may be preceded by prolonged thyroid the relationship between Vitamin D and narcolepsy is
autoimmune abnormalities and that most thyroid function understudied, and the findings are inconsistent [31,32] .
abnormalities are predominantly hypothyroid . In this Interestingly, the previous studies have found that
[19]
case, despite the short follow-up period, abnormal thyroid Vitamin D deficiency contributes to the development of
[33]
[34]
function was observed after a year, thus suggesting that AITD . T cells have immunomodulatory properties .
annual screening of thyroid function is necessary for Maintaining the T helper 17 cell/regulatory T cell
narcolepsy patients with positive thyroid antibodies. (Th17/Treg) balance that occurs during chronic inflammation
It is noteworthy that although the exact mechanisms is an important key point in the treatment of autoimmune
leading to neuronal destruction in narcolepsy remain diseases . A growing body of evidence has demonstrated
[35]
unclear , environmental trigger, genetic factors, viral that Vitamin D is associated with the inhibition of Th17 cell
[20]
infections, and autoimmunity have been found to be differentiation and the upregulation of Tregs .
[36]
associated with the pathogenesis of narcolepsy [21,22] . In addition, the previous studies have demonstrated
Epidemiological studies have reported a significant six to that pro-inflammatory cytokines interleukin 6 (IL-6) is
nine times increase in incidence of narcolepsy in 2010 , upregulated in narcolepsy patients . This finding supports
[23]
[37]
and analyses have suggested that the cause of the increased the hypothesis that inflammation is associated with the
incidence in 2010 may be closely related to H1N1 influenza pathophysiology of narcolepsy . Cytokines are involved
[38]
infection in the winter of 2009 and the AS03-adjuvanted in the pathogenesis of thyroid disease; they play a role in
influenza A vaccine [23-25] . Studies have also found an the immune system and directly target thyroid follicular
association between upper respiratory tract Streptococcus cells . Cytokines also have certain roles in promoting and
[39]
pyogenes infection and narcolepsy . In addition, the suppressing the development of autoimmune diseases .
[26]
[40]
association of narcolepsy with human leukocyte antigen We hypothesize that appetitive-regulating cell-associated
(HLA) has been extensively investigated, in which the antigens may be expressed in thyroid tissue; thus,
frequency of HLA-DQB1*06:02 and HLA-DQA1*01:02 when Th17/Treg ratio imbalance and immune balance
motifs has been found to be associated with the onset disruption occur, the corresponding antibodies produced
of the disease . However, there is a growing body of against hypocretin neuron-associated antigens will act on
[27]
evidence supporting the hypothesis that narcoleopsy is a T the thyroid tissue and promote the development of AITD.
cell-mediated autoimmune disease that attacks hypocretin
neurons [21,28] . 4. Conclusion
There are different mechanisms to explain the causal Given that both narcolepsy and AITD have a basic
relationship between narcolepsy and autoimmune diseases. defect in immune regulation as a shared, similar
One explanation for the observed association between disease mechanism, thyroid autoantibodies and thyroid
narcolepsy and AITD is the common immunological function should be checked regularly to facilitate early
pathogenetic pathway. The previous studies have shown detection and treatment of abnormal thyroid function
that patients with one autoimmune disease are usually and to prevent complications. Nevertheless, we lack

Volume 2 Issue 1 (2023) 3 https://doi.org/10.36922/gpd.v2i1.235