Tuberculosis in Myasthenia Gravis patients on immunosuppressive therapy in a high-risk area: Implications for preventative therapy

Latent tuberculosis infection in myasthenia gravis patients on immunosuppressive therapy: high incidence yet moderate reactivation rate

BACKGROUND

Immunosuppressive therapies (ISTs) are mainstays for management of myasthenia gravis (MG). Meanwhile, latent tuberculosis infection (LTBI) is common in the setting of high-burden countries. However, the prevalence of LTBI among MG patients and whether receiving ISTs for MG would aggravate LTBI reactivation remain unknown.

METHODS

We retrospectively analyzed the frequency of LTBI via interferon-gamma release assay (IGRA) positivity among hospitalized MG patients from both rural and urban areas in a tertiary hospital, and those receiving ISTs were followed up to investigate the reactivation risk of LTBI.

RESULTS

A total of 300 MG patients with determinate IGRA results were enrolled, where the frequency of LTBI was 35.0%. Male (OR = 1.910, 95% CI: 1.181-3.089, p = .008) and elderly (OR = 1.044, 95% CI: 1.027-1.061, p < .001) patients were prone to LTBI. Of those with LTBI, 78 individuals on ISTs were successfully followed up for a median duration of 18.3 (8.5-24.0) months, of which 25 (32.1%) received anti-tuberculosis (TB) treatments. The rate of various degrees of adverse events was 82.1% over the course of the follow-up, but was not different between individuals with and without therapies against TB (χ2 < 0.001, p > .999). Only 1 patient eventually reported lymph node and intestinal TB, with the incidence rate of LTBI reactivation preliminarily estimated to be 0.81 per 100 person years.

CONCLUSION

The frequency of LTBI is high in our MG cohort, especially among those with advanced age and males. However, receiving immunosuppressives seems not to increase the risk of LTBI reactivation. LTBI screening is strongly recommended for all MG patients ready to receive ISTs, while preventive anti-TB chemotherapy should be prescribed after weighing potential benefits against the risk of side effects in those with LTBI. In-depth investigation is still entailed to further verify these findings due to the limitation of the retrospective single-center design of our study.

Post-Infectious Autoimmunity in the Central (CNS) and Peripheral (PNS) Nervous Systems: An African Perspective

The direct impact and sequelae of infections in children and adults result in significant morbidity and mortality especially when they involve the central (CNS) or peripheral nervous system (PNS). The historical understanding of the pathophysiology has been mostly focused on the direct impact of the various pathogens through neural tissue invasion. However, with the better understanding of neuroimmunology, there is a rapidly growing realization of the contribution of the innate and adaptive host immune responses in the pathogenesis of many CNS and PNS diseases. The balance between the protective and pathologic sequelae of immunity is fragile and can easily be tipped towards harm for the host. The matter of immune privilege and surveillance of the CNS/PNS compartments and the role of the blood-brain barrier (BBB) and blood nerve barrier (BNB) makes this even more complex. Our understanding of the pathogenesis of many post-infectious manifestations of various microbial agents remains elusive, especially in the diverse African setting. Our exploration and better understanding of the neuroimmunology of some of the infectious diseases that we encounter in the continent will go a long way into helping us to improve their management and therefore lessen the burden. Africa is diverse and uniquely poised because of the mix of the classic, well described, autoimmune disease entities and the specifically "tropical" conditions. This review explores the current understanding of some of the para- and post-infectious autoimmune manifestations of CNS and PNS diseases in the African context. We highlight the clinical presentations, diagnosis and treatment of these neurological disorders and underscore the knowledge gaps and perspectives for future research using disease models of conditions that we see in the continent, some of which are not uniquely African and, where relevant, include discussion of the proposed mechanisms underlying pathogen-induced autoimmunity. This review covers the following conditions as models and highlight those in which a relationship with COVID-19 infection has been reported: a) Acute Necrotizing Encephalopathy; b) Measles-associated encephalopathies; c) Human Immunodeficiency Virus (HIV) neuroimmune disorders, and particularly the difficulties associated with classical post-infectious autoimmune disorders such as the Guillain-Barré syndrome in the context of HIV and other infections. Finally, we describe NMDA-R encephalitis, which can be post-HSV encephalitis, summarise other antibody-mediated CNS diseases and describe myasthenia gravis as the classic antibody-mediated disease but with special features in Africa.