Non-cancerous complications in HTLV-1 carriers

ABSTRACT

Introduction

Human T-cell leukemia virus type 1 (HTLV-1) carriers may develop adult T-cell leukemia (ATL), or HTLV-1-associated myelopathy (HAM)/tropical spastic paraparesis (TSP). The evidence is limited regarding other diseases potentially associated with HTLV-1, such as HTLV-1-associated autoimmune diseases.

Area covered

We summarized the available information on complications associated with HTLV-1 infection.

Expert opinion

Previous studies showed that HTLV-1 carriers have an increased incidence of collagen diseases including Sjögren’s syndrome, as well as dysthyroidism, diabetes mellitus, and atherosclerosis. Furthermore, cognitive deficits are observed in asymptomatic carriers and in symptomatic carriers who develop HAM/TSP. It is hypothesized that altered immunoregulation occurs as a result of persistent HTLV-1 infection. A systematic review and meta-analysis demonstrated that HTLV-1 infection itself has an adverse impact on overall survival. ATL alone cannot entirely explain the adverse impact of HTLV-1 infection on overall mortality, because the incidence is low, and therefore HTLV-1-associated diseases as a whole may contribute to the inferior clinical outcome. However, there are insufficient data to determine the causal relationship between HTLV-1 infection and each complication. While non-cancerous events linked to HTLV-1 infection are not fatal, they are likely to reduce quality of life. Large prospective studies should be conducted by international collaborators.

KEYWORDS:

• HTLV-1
• non-cancerous complications
• collagen disease
• dysthyroidism
• cognitive deficits

Article highlights

• HTLV-1 carriers may develop various non-cancerous comorbidities, although the strength of the causal relationship varies.

• These comorbidities extend beyond HTLV-1-associated myelopathy (HAM) / tropical spastic paraparesis (TSP), and may include diabetes mellitus and atherosclerosis, which have traditionally been recognized as lifestyle diseases.

• There are currently no established treatments for HTLV-1-associated complications, and patients usually receive general management that is not specific to HTLV-1.

• In the future, large, prospective cohort studies should be conducted by international collaborators in endemic areas.

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Acknowledgments

The authors would like to thank ZENIS CO., LTD. for English language editing.

Additional information

Funding

This study was supported by AMED under Grant Numbers JP23fk0108672.