In rheumatoid arthritis, increased expression of TNF-alpha and IL-6 in synovial tissue is most likely due to which epigenetic mechanism?

1. A

   Activation of DNA methylation

2. B

   Inhibition of DNA methylation

3. C

   Activation of histone deacetylation

4. D

   Inhibition of histone acetylation

Appeared in: INI-CET EXAM -2025

Explanation

• The question describes increased expression of pro-inflammatory genes (TNF-alpha, IL-6) in rheumatoid arthritis.
• Epigenetic mechanisms control whether genes are switched on or off. DNA methylation is a primary mechanism for switching genes off (silencing).
• Inhibition of DNA methylation, also known as hypomethylation, removes these 'off-switches' from the gene's promoter region.
• This removal allows transcription factors to access the DNA, leading to increased gene expression and overproduction of the associated proteins (in this case, TNF-alpha and IL-6).
• This process is a key factor in the chronic inflammatory state of synovial tissue in RA.

Why Other Options Were Wrong

• Option A: Activation of DNA methylation (hypermethylation) is a repressive mechanism that silences genes. This would lead to decreased, not increased, expression of TNF-alpha and IL-6.
• Option C: Activation of histone deacetylation removes acetyl groups from histones, causing the chromatin to become more compact and inaccessible for transcription. This silences gene expression, which is the opposite of what is described in the question.
• Option D: Histone acetylation is an activating mark. Therefore, inhibiting this process would lead to gene silencing or reduced expression, which is contrary to the increased expression of TNF-alpha and IL-6 in RA.

Related Visual

• Visual 1: Diagram - A flowchart illustrating the difference between DNA methylation and hypomethylation. Show a methylated gene as 'OFF' (condensed chromatin, no transcription) and a hypomethylated gene as 'ON' (open chromatin, transcription of TNF-alpha/IL-6 occurs).

Clinical Relevance

• Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Epigenetic regulation of gene expression in the pathophysiology of Rheumatoid Arthritis (RA) as background academic context rather than a clinical decision trigger.
• Understanding the epigenetic basis of RA opens doors for novel therapeutic strategies. Drugs that target epigenetic enzymes, such as DNA methyltransferase (DNMT) inhibitors, are being explored to modify the disease course.
• This knowledge helps explain why individuals with the same genetic predisposition may have different disease severities, as environmental factors can influence epigenetic marks over time.
• What if? If a patient's RA was primarily driven by histone modification rather than DNA methylation, drugs targeting histone deacetylases (HDAC inhibitors) might be more effective than DNMT inhibitors. This highlights the future potential for personalized medicine in rheumatology based on a patient's specific epigenetic profile.

How to Approach the Question

• First, identify the core observation in the question: 'increased expression' of specific genes (TNF-alpha, IL-6) in a disease context (RA).
• Next, analyze the four options, which are all epigenetic mechanisms. For each option, determine its fundamental effect on gene expression: does it activate (switch on) or silence (switch off) a gene?
• Activation of DNA methylation and histone deacetylation are silencing mechanisms. Inhibition of histone acetylation is also a silencing mechanism.
• Inhibition of DNA methylation is an activating mechanism.
• Match the mechanism's effect with the observation in the question. Since the question states 'increased expression,' the correct answer must be a mechanism that causes gene activation.
• Only 'Inhibition of DNA methylation' fits this criterion, making it the most likely correct answer.

Concept Tested & Keywords

• Concept Tested: Epigenetic regulation of gene expression in the pathophysiology of Rheumatoid Arthritis (RA).
• Stem keywords: rheumatoid arthritis, TNF-alpha, IL-6, synovial tissue, epigenetic mechanism
• Lead-in keywords: most likely due to

Question ID

Q-Rv0elF9gqD2P37AmZGfA

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