Research on Blood as a Diagnostic Tool for Cystic Fibrosis

Overview of Cystic Fibrosis

Cystic fibrosis is a genetic disorder that primarily affects the lungs and digestive system. Individuals with this condition often face significant respiratory challenges, frequent lung infections, and a gradual decline in lung function. Some patients may also experience diminished pancreatic function. Although there is currently no cure, available treatments enable many patients to live into early-to-mid adulthood.

Genetic Basis of Cystic Fibrosis

This disease results from mutations in the CFTR gene. To develop cystic fibrosis, a person must inherit two mutated copies of this gene, one from each parent. Various mutations exist, some causing moderate reductions in CFTR protein production or function, while others lead to minimal or no production.

Variability in Symptoms

Patients with cystic fibrosis display a wide range of symptoms, severity levels, and rates of symptom progression. This variability complicates the application of standardized treatment protocols. While genetic mutations account for some differences in symptoms, they do not explain all the variability observed among patients.

Research Focus on Gene Expression

Recent studies have investigated whether variations in gene expression levels could contribute to the differences in symptoms. Some research suggests a link between airway infections and gene expression related to immune responses. However, the underlying mechanisms and dynamics of this relationship remain largely unexplored.

Study Findings on Gene Expression Patterns

A recent study published in *Physiological Genomics* by researchers at the Stanley Manne Children’s Research Institute and the Ann & Robert H. Lurie Children’s Hospital of Chicago examined gene expression differences in the white blood cells of cystic fibrosis patients. The study involved 103 cystic fibrosis patients aged 2 to 53 (median age 14) and 31 healthy controls aged 6 to 38 (median age 16).

To explore the causes of gene expression differences, the researchers cultured white blood cells from healthy individuals in plasma derived from cystic fibrosis patients, as plasma components can influence cellular signaling.

Key Findings

The results indicated that airway infections and subsequent inflammation may alter gene expression patterns in cystic fibrosis patients through the release of immune response molecules. This conclusion is supported by two major findings:
1. Cultured white blood cells from healthy individuals in cystic fibrosis plasma exhibited gene expression patterns similar to those found in cystic fibrosis patients.
2. A correlation was identified between immune response molecules in the blood of cystic fibrosis patients and specific gene expression patterns in their white blood cells.

Among the 1,094 differentially expressed genes in cystic fibrosis patients, 51 were associated with pancreatic function, and 224 were linked to specific bacterial infections. The study also highlighted a connection between the expression of certain genes and pancreatic function.

Implications for Cystic Fibrosis Treatment

The study suggests that distinct gene expression patterns in white blood cells may serve as early indicators of airway infections or pancreatic issues in cystic fibrosis patients. This advancement could allow healthcare providers to conduct regular, non-invasive blood tests to monitor gene expression changes, facilitating timely interventions.

Study Limitations and Future Research

The authors of the study recognize certain limitations, including a small participant pool for specific groups and the absence of control patients with other lung diseases, which raises questions about the specificity of observed changes in gene expression.

Future research aims to identify specific genes or gene sets that correlate with symptom presence, severity, and progression in cystic fibrosis. The researchers also plan to investigate how antibiotics and other medications influence gene expression levels, potentially allowing for tailored treatments that target specific gene expression changes, leading to improved lifespans and quality of life for individuals with cystic fibrosis.

Conclusion

This research represents a significant step toward understanding the complexities of cystic fibrosis and enhancing treatment strategies through targeted gene expression monitoring.

Written by Melissa H. Wong, MSc
Reference: Levy H, Jia S, Pan A, et al. Identification of molecular signatures of cystic fibrosis disease status using plasma-based functional genomics. 2018. Physiol Genomics DOI:10.1152/physiolgenomics.00109.2018