4.1 Study design and Population
This is a pilot case-control research that was performed on (54 subjects) diagnosed with multiple sclerosis at different stages and 20 age- and sex-matched healthy controls. All subjects were recruited during the period from (January 2021) to (May 2021) from Multiple Sclerosis Research Unit, Kasr Al-Ainy, Neurology department, Cairo University hospitals, Cairo, Egypt. Written informed consent was obtained from all patients and controls. The study was approved by the ethical committee board of neurology department, Kasr Al-Ainy hospital, Cairo University.
4.2 Subjects
All subjects were diagnosed according to the International Panel on Diagnosis of Multiple Sclerosis “McDonald's criteria” 2010 (Polman et al. 2011). The study consisted of total (74 subjects), divided into (31 RRMS) group, (13 SPMS) group, (10 PPMS) group and (20 healthy control) group. Both RRMS group and SPMS group were subdivided into (16 Relapse RRMS), (15 Remitting RRMS), (8 Relapse SPMS) and (5 Remitting SPMS). The clinical disability was assessed using the Kurtzke Expanded Disability Status Scale (EDSS). Relapse was defined by the appearance of new neurological symptoms or worsening of pre-existing neurological symptoms lasting at least 24 hours in a patient who had been neurologically stable or improving for the previous 30 days accompanied by objective changes on neurological examination (worsening on the expanded disability status scale “EDSS” of 0.5 point or a worsening by 1.0 point on the pyramidal, cerebellar, brainstem or visual functional system scores) (Kurtzke 1983).
4.3 Exclusion criteria
Subjects were excluded from the study if they have a history of other associated autoimmune disease, malignancy, liver disease, diabetes mellitus, hypertension, cerebrovascular disease, pregnant females, or any inflammatory or infectious diseases in the previous month. Smoking or alcoholic subjects were also considered non-eligible for the study.
4.4 Demographics and disease characteristics in MS subjects
The following clinical data were collected from all participants in this study:
- Age & Sex. (Statistical analysis was carried out on the data to ensure non-significant difference i.e., Age- and sex-matched groups)
- Clinical picture of the patient regarding any existing or past disease.
- Family History of MS or any other autoimmune disease.
- History and duration of MS.
- Status of the current examination (Relapse/Remitting) at the time of sampling.
- Number of relapses within the last 3 years.
- EDSS
4.5 Specimen collection
Five milliliters of whole blood were drawn from patients and controls. Each blood sample was left at 37 °C for 30 minutes before being centrifuged at 3000 rpm for 10 minutes. Sera were divided into two aliquots and frozen at -80 °C until use.
4.6 RNA extraction
Total RNA was extracted from 200 µl of pre-isolated serum using miRNeasy Serum/Plasma Kit (QIAGEN, Catalog no. 217184) according to the manufacturer protocol. An aliquot of ~ 14 µl was eluted and analyzed for concentration and purity using (NanoDrop One spectrophotometerTM, ThermoFisher) and then stored at −80 °C till use.
4.7 Complementary DNA (cDNA) synthesis
Complementary DNA (cDNA) was synthesized using 2.5 mg total RNA using RT² First Strand Kit (QIAGEN, Catalog no.330404) according to the manufacturer's protocol. Reverse transcription was performed at 42°C for 5 minutes, 37°C for 60 minutes, and 95°C for 5 minutes, and the cDNA obtained was stored at - 20°C till use. The reverse transcription was carried out using (SimpliAmpTM Thermal Cycler-Applied Biosystems).
4.8 Real-time PCR
Using cDNA obtained from the previous steps, relative gene expression for (BDNF-AS) and a reference gene (GAPDH) were quantified using the following primer kits: RT² lncRNA qPCR Assay (QIAGEN, Catalog no.330701) with the following IDs: (BDNF-AS) (ID: LPH15814A-200) and (GAPDH) (ID: LPH15126A-200). All of the PCR reaction were performed using the Mastermix kit: RT² SYBR Green ROX qPCR Mastermix (QIAGEN, Catalog no.330520). The Real-time PCR conditions were 95°C for 10 minutes and 40X (95°C for 15 seconds, 60°C for 1 minute) followed by a melt curve analysis. All Real-time PCR reactions and the melt curve analysis were carried out using (QuantStudioTM 1 Real-Time PCR- Applied Biosystems).
4.9 Relative Gene Expression
The relative expression of (BDNF-AS) was calculated for each sample by analyzing the results of RT-PCR using double-delta Ct analysis. The Ct values for all samples were normalized against (GAPDH). Fold Change (FC) was calculated for each sample then compared between patients and normal controls for the determination if (BDNF-AS) is relatively differentiated in MS.
4.10 Statistical analysis
SPSS version 26 (Chicago, IL, USA) was used for statistical analyses. Normality testing was done on all data to determine parametric from non-parametric data. For the analysis of difference between groups, One-way ANOVA, or the related non-parametric test, Kruskal-Wallis test, was used depending on the type of data being analyzed (Parametric Vs. Non-Parametric). To investigate the source of any differences between the groups, multiple comparisons tests were performed. Similarly, Pearson or Spearman test of correlation was used for parametric or non-parametric data, respectively. ROC curve analysis was also used to draw a conclusion about the usefulness of the diagnostic ability of (BDNF-AS). P-value of < 0.05 was considered statistically significant. All figures and tables