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Distinctive gene signature may signal new way to diagnose Lyme disease
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Researchers who identified a distinctive gene signature in patients infected with Lyme disease think the discovery may signal a new way to diagnose the tick-borne infection.
More than 30,000 cases of Lyme disease are reported in the United States annually, according to the CDC, but the number could be at least 10 times higher because of underreporting and an overreliance on insensitive diagnostic tests in the acute phase of the infection, the researchers wrote in mBio.
“Improved diagnostics are urgently needed for Lyme disease,” investigator Charles Y. Chiu, MD, PhD, associate professor of laboratory medicine at University of California, San Francisco, said in a news release. “The tick that transmits Lyme also harbors many other pathogens, and early diagnosis is critical in guiding appropriate treatment and preventing later complications of the illness.”
The study included 29 patients with Lyme disease who enrolled at an outpatient clinic in Maryland from May 1 to Nov. 23, 2009. The researchers examined the patients before and after they underwent 3 weeks of doxycycline therapy, and also 6 months later.
Transcriptome analysis of the Borrelia burgdorferi bacterium using unbiased RNA-sequencing showed the patients had a gene signature that persisted for at least 3 weeks after the acute phase of infection and had fewer than 44% differently expressed genes (DEGs) in common with other infectious or noninfectious syndromes.
The researchers noted a marked upregulation in multiple toll-like receptors during the period of acute Lyme disease before initiating antibiotic therapy, and immediately after 3 weeks of doxycycline treatment. They wrote that B-cell development and downregulation of calcium-induced T-cell apoptosis — prominent in other acute infectious syndromes — were not found to be significant pathways in acute Lyme disease.
Patients in the acute phase of influenza had 35% of their DEGs in common with Lyme disease patients, the researchers noted. Six months after completion of therapy, Lyme disease patients had 31% to 60% of their pathways in common with three different immune-mediated chronic diseases: chronic fatigue syndrome, lupus and rheumatoid arthritis.
Among patients who completed the study, no differences in gene expression were observed between patients with resolved illness (n = 15) and those with persistent symptoms 6 months after treatment (n = 13). The researchers said larger cohort studies are needed to confirm this finding.
“The identification of a distinct and sustained transcriptome signature in early Lyme disease may facilitate the development and validation of human gene expression biomarker panels to improve diagnostic testing in the future, in parallel with other published studies investigating cytokine or metabolic biosignatures,” Chiu and colleagues concluded. – by Gerard Gallagher
Disclosure: The researchers report no relevant financial disclosures.
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