Lymphocyte subsets, TNFα and interleukin-4 levels in treated and untreated subacute sclerosing panencephalitis patients

Cardiac Rhythm Aberrations in Subacute Sclerosing Panencephalitis: Insights From Heart Rate Variability Analysis

PURPOSE

Subacute sclerosing panencephalitis (SSPE) is a fatal neurological disorder resulting from persistent measles virus infection within the brain. Although neurological manifestations have been well-documented, the impact of SSPE on cardiac autonomic function, assessed through heart rate variability (HRV), remains understudied.

METHODS

In this prospective single-center study conducted from January 2022 to March 2023 in Southern India, 30 consecutive SSPE patients and age- and sex-matched controls underwent electrocardiogram recordings for HRV analysis. Various HRV parameters were assessed, including time-domain metrics (SD of normal-to-normal intervals, root mean square of successive differences between normal heartbeats, percentage of successive normal interbeat intervals greater than 50 msec), SD1 and SD2 for Poincaré plot analysis, and frequency-domain metrics (low frequency %, high frequency %, low frequency:high frequency ratio).

RESULTS

In the study, SSPE patients exhibited markedly reduced HRV. Specifically, SD of normal-to-normal intervals ( P = 0.003), percentage of successive normal interbeat intervals greater than 50 msec ( P = 0.03), and SD2 ( P = 0.0016) were significantly lower compared with controls. Frequency-domain analysis did not reveal significant distinctions. Correlation analysis demonstrated a negative relationship between percentage of successive normal interbeat intervals greater than 50 msec and SSPE severity ( r = -0.37, P = 0.042). Heart rate variability did not significantly differ between SSPE stages or with clinical variables. The interbeat interval range showed a narrower distribution in SSPE subjects.

CONCLUSIONS

Our study highlights the clinical relevance of HRV analysis in SSPE and autonomic dysfunction throughout the disease course underscoring its importance in SSPE. This investigation provides valuable insights into cardiac autonomic dysfunction probably because of affliction of the central autonomic networks caused by the disease process and may be a contributing factor to mortality in SSPE.

Immune-dysregulation in subacute sclerosing panencephalitis: An exploratory case-control study

Subacute sclerosing panencephalitis (SSPE) is a chronic progressive neurological condition caused by a defective measles virus. It is postulated that immune-dysregulation might result in persistent infection (immune evasion) as well as initiation of autoimmune phenomenon (via natural killer cells) leading to panencephalitis. The primary objective of this case-control study was to analyse the pattern of immune dysregulation in cases with SSPE. The secondary objective was to assess the correlation between the measured immunological variables and disability/death at 6 months. This was an exploratory case-control study conducted at a tertiary-care referral-facility from January 2020 to September 2021. Thirty consecutive patients fulfilling the Dyken's criteria for SSPE and 30 age-and-sex-matched healthy controls were enrolled. Immunological profile constituted by lymphocyte subset analysis, immunoglobulin levels and complement levels were done in all cases and controls. Cases were staged as per Jabbour's system; disability was assessed using the modified Rankin Scale (mRS). Patients with SSPE had a mean age of 14.76 years (±6.9 years). There were 25 males and 5 females; 6.7% cases belonged to Jabbour's first stage, 40% to second stage and 53.3% to third stage. At least 1/4th had evidence of measles vaccination. Levels of absolute lymphocyte count, B-cells, T cells, helper T-cells, and cytotoxic T-cells were significantly higher in cases. IgG, IgM, and IgE levels were significantly higher while IgD levels were significantly lower in cases. At baseline, 13.3% of cases had a mRS score of 0-2 and 86.7% had a score of 3-6; at 6 months 10% had a mRS score 0-2 (favorable outcome) while 90% had a mRS score 3-6 (poor outcome). Higher IgE levels were found to correlate significantly with favorable outcome. Immune-dysregulation may play a significant role in shaping one's response to measles infection as well as in determining vaccine-efficacy.

Serum and cerebrospinal fluid cytokine concentrations in subacute sclerosing panencephalitis

Subacute sclerosing panencephalitis (SSPE) is a neurodegenerative disease due to persistent measles virus infection. Its immunopathogenesis is unknown. Tumor necrosis factor (TNF)-alpha, interleukin (IL)-2, IL-6, IL-10 and IL-4 concentrations were measured in cerebrospinal fluid (CSF) and serum samples from 30 SSPE patients and 19 control subjects by cytometric bead array. CSF and serum IFN-gamma, IL-12 and IL-18 levels were measured in 18 SSPE patients by ELISA. Serum IL-4 and IL-10 (p<0.001), CSF IL-4 (p<0.001) and IL-6 (p=0.049) concentrations were lower, and serum IL-2 concentrations, higher (p=0.001) in SSPE patients. Serum TNF-alpha and IL-6, CSF TNF-alpha, IL-10, and IL-2 concentrations were not different between SSPE and control groups. Serum IFN-gamma levels were higher in stage I and II than stage III patients (p<0.05), whereas there was no difference between stages in terms of other cytokines. The levels of Th2-type cytokines: IL-4, IL-6 and IL-10 were suppressed in our SSPE cases. This finding, along with relatively elevated IFN-gamma and IL-2 levels, may suggest more active effector T cells compared to regulatory T cells (Treg), especially induced Treg, in early disease. High serum IL-2 concentrations might indicate peripheral Th1 activation. Discrepancies between various reports in the literature should be examined in view of the ages, stage and treatments of the patients studied. The interplay of various cytokines or cellular systems which may vary over time and between patients. Studies of treatment measures favoring the preservation of the early inflammatory response may be of interest in SSPE.

Signaling lymphocyte activating molecule (SLAM) expression in subacute sclerosing panencephalitis

Signaling lymphocyte activating molecule (SLAM) is a receptor for measles virus which also has immunomodulatory activity. We analyzed SLAM expression in mononuclear cells (MNC) of patients with SSPE (n=7) and control subjects (n=7) from the same population. Native 10% PAGE analysis in cell and brain tissue extracts followed by Western blotting using monoclonal anti-human SLAM showed four types of bands. Differences in the type and amount of SLAM expression were observed between SSPE and control cases. Lymphocytes of SSPE patients showed two types of SLAM bands in comparison to only one in control lymphocytes. Stimulation of cells with lipopolysaccharide (80 u/ml) and concanavalin A (1 microg/ml) in vitro led to the appearance of a second isoform in both groups. Brain homogenates of SSPE patients (n=2) displayed all four types of SLAM isoforms at significantly higher levels than those of control brains (n=2). Our results show native PAGE enables the detection of all SLAM isotypes. The expression of SLAM is increased in lymphocytes, monocytes, and brain tissues of SSPE patients.

Rituximab in subacute sclerosing panencephalitis

Subacute sclerosing panencephalitis (SSPE) is a progressive, fatal neurological disorder of childhood and early adolescence. It is caused by a persistent measles virus infection of the brain without any available treatment to date. The physiopathology of the disease is largely unknown. Considering the potential role of humoral immunity in the pathogenesis of SSPE, one patient was given compassionate anti-CD20 antibodies. However, disease progression under treatment led to reconsider B cell involvement in this pathology. Nevertheless, we observed that carbamazepine was useful in improving life quality in our patient, and should be considered as a first-line drug. To date, measles vaccination remains the only solution to SSPE.