T helper 17 (Th17) cells belong to a group of T cells with essential functions in autoimmune diseases and inflammation. Regulatory T cells (iTregs) are T cells with a suppressive function to maintain self-tolerance and prevent autoimmune responses.

Researchers from Turku Centre for Biotechnology and Aalto University together utilized the advanced technology called label-free quantitative proteomics to identify the proteomes of Th17 and iTreg cells.

Proteins are one of the major biomolecules that form the functional and structural entity of a living cell. Mass spectrometry-based quantitative proteomics can be used to determine the set of proteins expressed by a cell, tissue, or organism at a certain time.

The immune system defends the body against harmful pathogens and tumors, and also provides self-tolerance. T helper cells are major components of the adaptive system, and they play critical roles in controlling immune reactions.

Role of helper T cells

During her postdoctoral study at the National Institutes of Health (NIH), USA, Dr. Zhi Chen started working on Th17 cells, a subset of helper T cells with an important role in autoimmune inflammation. The label-free quantitative proteomics technology has been established at the Turku Centre for Biotechnology.

Using this technology, Chen's research team in collaboration with computational scientists from Aalto University and scientists from the University of Turku, Åbo Akademi University and the University of Maryland generated a resource that was used to identify over 4000 proteins expressed in Th17 and iTreg cells.

"We also combined analysis of proteome and gene expression data and discovered protein expression changes that were not associated with changes at the transcriptional level," said Chen. "These identified proteins can potentially be targeted in immunotherapy, especially in disease conditions like cancer and autoimmunity."

The transcriptional network and protein regulators that govern T helper 17 (Th17) cell differentiation have been studied extensively using advanced genomic approaches. For a better understanding of these biological processes, the researchers have moved a step forward, from gene- to protein-level characterization of Th17 cells. 

Mass spectrometry-based label-free quantitative (LFQ) proteomics analysis was made of in vitro differentiated murine Th17 and induced regulatory T (iTreg) cells. More than 4,000 proteins, covering almost all subcellular compartments, were detected. 

Quantitative comparison of the protein expression profiles resulted in the identification of proteins specifically expressed in the Th17 and iTreg cells. The combined analysis of proteome and gene expression data revealed protein expression changes that were not associated with changes at the transcriptional level.