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Coexistence of Autoantibodies and Other Autoimmune Diseases with Multiple Sclerosis and Related Disorders – Experience from the Mangalore Demyelinating Disease Registry (MANDDIR)

Background: Co-occurrence of other autoimmune disorders (AID) and autoantibodies in patients with autoimmune demyelinating CNS disorders have not been studied previously in patients of Indian origin. Objective: To determine the frequency of concomitant autoimmune disorders, anti-nuclear antibody (ANA) and antithyroid antibody (ATAb) and to evaluate the impact on clinical course of disease. Materials and Methods: A total of 111 patients with MS and 152 patients with non-MS demyelinating disorders were included. Demographics, clinical course and disability were recorded. History of other autoimmune disorders (AIDs) in patients and first degree relatives was noted. Serum ANA and ATAb were tested. Results: Concomitant AIDs were seen in 21% of MS and 19% of non-MS patients. Autoimmune thyroid disease was most frequent and seen in 10.8% of MS and 6.6% of non-MS disorders. Frequency of ATAb was significantly higher among MS group (MS 25.5% vs non-MS 13.2% P = 0.04) but that of ANA was similar between the 2 groups (MS 19.8% vs non-MS 26.9% P = 0.17). A positive family history of autoimmune disorders was noted in 20% of MS and 15.1% of non-MS disorders. Clinical course was unaffected by presence of concomitant AID and autoantibodies. Conclusion: Cooccurrence of autoantibodies and AID are seen in a significant number of patients with MS and non-MS disorders and influences clinical management.

diseases may impact treatment strategies and management. [9] In this background, the current study aimed to determine the frequency of concomitant autoimmune disorders, anti-nuclear antibody (ANA), and antithyroid antibody (ATAb) and to evaluate the impact on clinical course of disease.

Patient selection
Hundred and eleven patients with MS diagnosed by McDonald's 2017 criteria [10] and 152 patients with non-MS demyelinating disorders who were prospectively enrolled in the Mangalore demyelinating disease registry [11] were selected. Among 111 MS patients there were 93 with relapsing remitting (RR), 15 with secondary progressive (SP), and 3 with primary progressive (PP) MS [ Table 1]. The non-MS demyelinating disorders included 40 aquaporin-4 antibody positive (AQP4-IgG +) NMOSD, [12] 41 myelin oligodendrocyte glycoprotein antibody positive (MOG-IgG+), and 71 seronegative patients [ Table 1]. Blood samples from 46 age and gender matched healthy controls were included for analysis of antibody frequency for ANA and ATAb.

Data collection
Demographic details including gender, age at onset of disease, disease duration, and expanded disability status scale (EDSS) was obtained. A detailed history of other disorders of possible autoimmune origin were queried (using a previously validated questionnaire) [13] and confirmed (from medical records & prescriptions). Treatment history was recorded. Family history of AID in first degree relatives was also obtained.

Autoantibody testing
Patient sera in 1:100 dilution was tested for anti-nuclear antibody (blood collected prior to treatment with steroids) using indirect immunofluorescence (Euroimmun, Lubeck Germany) technique as per manufacturer's instructions. Anti-thyroid antibody including both thyroid peroxidase (TPO Ab) and thyroglobulin (TG Ab) were tested (1:10 serum dilution) in 102 MS, 136 non-MS (40 AQP4 IgG+, 41 MOG IgG+, 55 seronegative) patients and all healthy controls, using a commercial kit (Euroimmun, Lubeck, Germany). Tests were done by first author (CM) and results were independently verified by 2 nd & 3 rd coauthors (LP & AD). Presence of one or both ATAb was taken to be a positive test result. In addition thyroid functions including serum triiodothyronine (T3), thyroxine (T4), and thyroid stimulating hormone (TSH) levels were checked. Diagnosis of autoimmune disorders was made by other concerned specialists as per relevant criteria and patients were jointly managed with treating neurologist (LP). This study was approved by the institutional ethics committee and informed consent was obtained from all patients and healthy volunteers.

Statistical analysis
Statistical analyses were done using the IBM SPSS for Windows Version 21.0 (IBM Corp. Armonk, NY, USA) statistical package. Continuous variables between the groups was analyzed with the non-parametric Mann-Whitney U test. Analysis of categorical variables between the two groups was

Non-MS disorders AQP4 IgG associated NMOSD
Twenty percent (8/40) had ATAb associated with AQP4 IgG + NMOSD. Among them 2 had accompanying thyroid dysfunction, one with GD that developed during the course of NMOSD and another with HT [ Table 2, Figure 1]. Fifteen percent (6/40) had hypothyroidism unaccompanied by ATAb and 15% had ATAb without thyroid dysfunction. Among AQP4 IgG + patients 42% (17/40) tested positive for ANA. Other AID included two patients each with AD (5%) and atopic BA (5%). Four (10%) patients had first degree relatives with a diagnosis of HT and one relative (2.5%) had atopic BA.
We reviewed the treatments received by patients at the time they were tested for autoantibodies. None had received   oral or parenteral steroids in the 6 months preceding blood testing. There was no significant difference in type of therapy given between patients with thyroid dysfunction/ autoantibodies and those without, among MS and non-MS disorders [Supplementary Table 1]. We have compared the demographics, age at disease onset, duration, and disability (as measured by EDSS) among MS and non-MS groups based on the presence/absence of autoantibodies and found no statistical difference [ Supplementary Tables 2 and 3].
Frequency of ATAb was significantly higher among MS group (MS 25.5% vs non-MS 13.2% P = 0.04). Frequency of ANA was similar between the 2 groups (MS 19.8% vs non-MS 26.9% P = 0.17). Among non-MS disorders, frequency of ANA positivity among patients was significantly higher among AQP4IgG + NMOSD (AQP4 IgG + 42.5% vs MOG IgG + 22% P = 0.04; AQP4 IgG + 42.5% vs seronegative 21% P = 0.017). Five percent of MS patients and 8.5% of non-MS patients had both ANA and ATAb (MS 5% vs non-MS 8.5% P = 0.36). Speckled pattern was the most common ANA pattern seen in 50% of MS and 44% of non-MS disorders who were positive for the test and there was no gender or age bias detected for the same (data not shown).

Healthy controls
Among 46 healthy controls there were 12 patients who tested positive for ATAb (26%). Among them 4 had concomitant (asymptomatic) hypothyroidism. Antinuclear antibody testing revealed that 2 (4.3%) were positive among healthy controls.

dIscussIon
Autoimmune CNS demyelinating disorders are heterogeneous conditions with a varied clinical course, associated biomarkers and treatment modalities. The shared genetic susceptibility with other autoimmune disorders raises the possibility of cooccurrence of these disorders in MS and related disorders.
While several studies outside the country have addressed the coexistence of other AID and the impact on disease course, we are for the first time reporting the same based on data from our registry from India.
In our study concomitant AIDs were seen in 21% of MS and 19% of non-MS disorders. Among the MS cohort autoimmune thyroid disease was most commonly seen followed by atopic BA (4.5%) and AD (2.7%). Our study like others [14] showed that a number of patients had ATAb without concomitant thyroid dysfunction. Among MS patients 3% (3/102) had hypothyroidism unaccompanied by ATAb which we have labelled as non immune thyroid disease. It may be argued that in some of the latter, treatment for thyroid dysfunction and or disease modifying therapy may have influenced antibody detection. Non-immune thyroid disease has however been reported in approximately 9% of patients with MS. [15] Among non-MS disorders, AQP4 IgG and MOG IgG disorders have been previously studied for the associated AID and auto-antibodies. [6,8] In our study AD was most frequent (9.2%) followed by autoimmune thyroid disorder (6.6%) and atopic BA (2.6%). Frequency of ATAb was significantly increased among MS patients when compared to non-MS disorders (p = 0.01). Frequency of ANA was similar between the 2 groups, though ANA frequency among non-MS disorders was significantly higher in AQP4 IgG + NMOSD. Presence of autoimmune disorders and or autoantibodies did not influence the clinical course of the disease as mentioned in some other studies. [16] A positive family history of autoimmune disorders was noted in both MS (20%) and non-MS (15.1%) patients. Familial autoimmune disorders are not uncommon and have been reported for most autoimmune disorders including MS. [17,18] We found subclinical hypothyroidism among some healthy controls accompanied by ATAb among them. Previous studies in coastal south western India have shown asymptomatic hypothyrodism and high prevalence of ATAb among healthy and predominantly women volunteers. [19] In our study there were many similarities between MS and non-MS disorders including the co-occurrence of autoimmune disorders that targeted thyroid gland, auto-antibodies being detected in the absence of clinical disease and a positive family history of autoimmunity. Presence of concomitant AID did not influence the clinical course of underlying demyelinating disorder.
It is important to investigate for other AID from the point of mitigation of comorbidities such as underlying thyroid dysfunction in the case of autoimmune thyroid disease. Further the presence of autoantibodies, other AID and a positive family history of AID lends support to the presumed autoimmune nature of the neurological illness This is particularly true for seronegative non-MS disorders. The detection of ANA in our patient cohort was not associated with any collagen vascular disorder throughout the course of observation in the study and probably reflects a shared genetic susceptibility.
There were several limitations to our study. Our patient numbers were small in each subgroup. We have tested only two auto-antibodies among patients and relied on clinical and treatment history for co-existence of other autoimmune disorders. Recall bias may have influenced details about history of AID among family members. A larger population study is also warranted to understand whether concomitant autoimmune disorders exceeded expectation for the general population.

Financial support and sponsorship
Nil.

Conflicts of interest
There are no conflicts of interest.