Immune Response Activated by RNA Splicing Opens Targeted Therapies

In a new study published in Nature Communications titled, “Native long-read RNA sequencing of human monocytes reveals activation-induced alternative splicing toward functional isoforms,” researchers at University Medical Center (UMC) Utrecht have uncovered a previously underappreciated mechanism that helps immune cells respond rapidly to infections. The team showed that alternative RNA splicing plays a central role in shaping immune responses. The results provide new insights into immune-mediated diseases, such as infections, rheumatoid arthritis and lupus, and open the door to more targeted therapies. 

The study focused on monocytes, a type of innate immune cell that acts as a first responder to pathogens. Using long-read RNA sequencing, the authors generated a comprehensive map of full-length RNA transcripts in human monocytes before and after activation. They identified more than 24,000 isoforms, the majority of which have never been described, revealing a previously hidden layer of molecular complexity. 

Notably, immune activation triggers widespread ‘isoform switching.’ Rather than simply turning genes on or off, monocytes shift toward producing longer, fully functional RNA variants that are more likely to be translated into proteins. These isoforms contain complete coding sequences, fewer non-coding interruptions, and greater structural complexity, all features associated with more effective protein production. 

“In our study we also confirmed that these RNA changes have real functional consequences,” said Jorg van Loosdregt, PhD, associate professor at UMC Utrecht and corresponding author of the study. “By integrating data on protein synthesis and ribosome activity, we demonstrated that the observed isoform shifts are linked to increased production of immune effector proteins. This shows that alternative splicing directly enhances the cell’s ability to respond to infection or inflammation.” 

While previous studies have linked conditions, such as rheumatoid arthritis and lupus, to genetic variation affecting RNA splicing, the study demonstrates that disease mechanisms may also depend on which isoforms are produced and how efficiently they are translated into proteins. 

“Our study underscores the importance of studying gene regulation at the isoform level. Traditional methods may overlook critical changes that only become visible with full-length RNA analysis,” said van Loosdregt. “The adoption of long-read sequencing technologies could therefore transform research into immune function and disease mechanisms.” 

Emerging approaches, such as antisense oligonucleotides or drugs that influence splicing factors, may enable more precise modulation of the immune system and the development of targeted treatments for immune-mediated diseases.