Inhibition of PRMT5/MEP50 Arginine Methyltransferase Activity Causes Cancer Vulnerability in NDRG2low Adult T-Cell Leukemia/Lymphoma

N-myc downstream-regulated gene 2 (NDRG2), which is a tumour suppressor, is frequently lost in many types of tumours, including adult T-cell leukaemia/lymphoma (ATL). The downregulation of NDRG2 expression is involved in tumour progression through the aberrant phosphorylation of several important signalling molecules. We observed that the downregulation of NDRG2 induced the translocation of protein arginine methyltransferase 5 (PRMT5) from the nucleus to the cytoplasm via the increased phosphorylation of PRMT5 at Serine 335. In NDRG2low ATL, cytoplasmic PRMT5 enhanced HSP90A chaperone activity via arginine methylation, leading to tumour progression and the maintenance of oncogenic client proteins. Therefore, we examined whether the inhibition of PRMT5 activity is a drug target in NDRG2low tumours. The knockdown of PRMT5 and binding partner methylsome protein 50 (MEP50) expression significantly demonstrated the suppression of cell proliferation via the degradation of AKT and NEMO in NDRG2low ATL cells, whereas NDRG2-expressing cells did not impair the stability of client proteins. We suggest that the relationship between PRMT5/MEP50 and the downregulation of NDRG2 may exhibit a novel vulnerability and a therapeutic target. Treatment with the PRMT5-specific inhibitors CMP5 and HLCL61 was more sensitive in NDRG2low cancer cells than in NDRG2-expressing cells via the inhibition of HSP90 arginine methylation, along with the degradation of client proteins. Thus, interference with PRMT5 activity has become a feasible and effective strategy for promoting cancer vulnerability in NDRG2low ATL.

The 'ABC' of respiratory disorders among adult Indigenous people: asthma, bronchiectasis and COPD among Aboriginal Australians - a systematic review

BACKGROUND

Aboriginal Australians are reported to have higher presence of chronic respiratory diseases. However, comprehensive evidence surrounding this is sparse. Hence, a systematic review was undertaken to appraise the current state of knowledge on respiratory health in the adult Aboriginal Australians, in particular among the three most common respiratory disorders: asthma, bronchiectasis and chronic obstructive pulmonary disease (COPD).

METHODS

A systematic review of primary literature published between January 2012 and October 2022, using the databases PubMed and Scopus, was conducted. Studies were included if they reported adult Aboriginal Australian prevalence's or outcomes related to asthma, bronchiectasis or COPD, and excluded if adult data were not reported separately, if Aboriginal Australian data were not reported separately or if respiratory disorders were combined into a single group. Risk of bias was assessed by both Joanne Briggs Institute checklists and Hoys' bias assessment. Summary data pertaining to prevalence, lung function, symptoms, sputum cultures and mortality for each of asthma, bronchiectasis and COPD were extracted from the included studies.

RESULTS

Thirty-seven studies were included, involving approximately 33 364 participants (71% female). Eighteen studies reported on asthma, 21 on bronchiectasis and 30 on COPD. The majority of studies (94%) involved patients from hospitals or respiratory clinics and were retrospective in nature. Across studies, the estimated prevalence of asthma was 15.4%, bronchiectasis was 9.4% and COPD was 13.7%, although there was significant geographical variation. Only a minority of studies reported on clinical manifestations (n=7) or symptoms (n=4), and studies reporting on lung function parameters (n=17) showed significant impairment, in particular among those with concurrent bronchiectasis and COPD. Airway exacerbation frequency and hospital admission rates including mortality are high.

DISCUSSION

Although risk of bias globally was assessed as low, and study quality as high, there was limited diversity of studies with most reporting on referred populations, and the majority originating from two centres in the Northern Territory. The states with the greatest Aboriginal Australian population (Victoria and New South Wales) reported the lowest number of studies and patients. This limits the generalisability of results to the wider Aboriginal Australian population due to significant environmental, cultural and socioeconomic variation across the population. Regardless, Aboriginal Australians appear to display a high prevalence, alongside quite advanced and complex chronic respiratory diseases. There is however significant heterogeneity of prevalence, risk factors and outcomes geographically and by patient population. Further collaborative efforts are required to address specific diagnostic and management pathways in order to close the health gap secondary to respiratory disorders in this population.

High Human T-Cell Leukemia Virus Type 1c Proviral Loads Are Associated With Diabetes and Chronic Kidney Disease: Results of a Cross-Sectional Community Survey in Central Australia

BACKGROUND

A link between chronic inflammation and several noncommunicable diseases (NCDs) has been established. Although chronic infection with the human T-cell leukemia virus type 1 (HTLV-1) is the recognized cause of several inflammatory diseases and these are associated with a high number of HTLV-1-infected cells in peripheral blood (proviral load [PVL]), possible interactions between PVL and NCDs have not been studied at a community level.

METHODS

Adult Aboriginal residents of 7 remote communities were invited to complete a health survey between 25 August 2014 and 30 June 2018. Blood was drawn for HTLV-1 serology and PVL, and relevant medical conditions were obtained from health records. Associations between HTLV-1 PVL and diabetes, chronic kidney disease (CKD), and coronary artery disease (CAD) were determined using logistic regression, adjusting for available confounders.

RESULTS

Among 510 participants (56% of the estimated adult resident population, 922), 197 (38.6%) were HTLV-1-infected. A high HTLV-1 PVL was associated with a 2-fold increase in the odds of diabetes and CKD (diabetes, adjusted odds ratio [aOR], 1.95; 95% confidence interval [CI], 1.06-3.61; P = .033 and CKD: aOR, 2.00; 95% CI, 1.03-3.8; P = .041). A nonsignificant association between high PVL and CAD (aOR, 7.08; 95% CI, 1.00-50.18; P = .05) was found for participants aged <50 years at the time of angiography.

CONCLUSIONS

In a community-based study in central Australia, people with HTLV-1 who had high HTLV-1 PVL were more likely to have diabetes and CKD. These findings have potential clinical implications.

HTLV-I associated bronchioloalveolar disorder (HABA): disease concept and differential diagnosis of an unsolved disease entity

INTRODUCTION

Human T-cell leukemia virus type 1 (HTLV-I) associated bronchioloalveolar disorder (HABA) is a chronic and progressive bronchiolar/alveolar disorder related to HTLV-1 infection. Clinical knowledge and guidance are lacking for the diagnosis and management of this condition.

AREAS COVERED

This work aimed to review the latest information and challenges regarding HABA diagnosis and treatment.

EXPERT OPINION

HABA is an immune-mediated state induced by HTLV-1. For diagnosis of HABA, other infectious diseases and pulmonary infiltration of adult T-cell leukemia should be excluded by investigations such as computed tomography (CT), transbronchial biopsy, and bronchoalveolar lavage fluid (BALF) analysis. Typical CT findings in HABA include diffuse panbronchiolitis-like or bronchiectasis patterns, whereas cases with other abnormalities, including interstitial pneumonia, have also been reported. A high rate of polyclonal CD4+ and CD25+ lymphocytes is detected in BALF of patients with HABA, reflecting the infiltration of HTLV-1 infected T-cells in the lung. Current treatment options are not HABA specific, and include corticosteroids, macrolide antibiotics, and pirfenidone. Mitigation of the adverse effects of HTLV-1 infection requires the establishment of diagnostic criteria for the disease, screening programs for HABA in HTLV-1 infected individuals, and the development of effective disease treatment strategies.

An Overview of Human T-Lymphotropic Virus Type 1 Lung Injury

Previous studies have demonstrated the development of pulmonary impairment in individuals infected with human T-lymphotropic virus type 1 (HTLV-1). Complications, such as alveolitis and bronchiectasis, were found in individuals who developed tropical spastic paraparesis/HTLV-1-associated myelopathy (TSP-HAM) due to chronic inflammation. These patients exhibited increased levels of lymphocytes (CD4+ and CD25+), cytokines (IL-2, IL-12, and IFN-γ), inflammatory chemokines (MIP-1α and IP-10), and cell adhesion molecules (ICAM-1) in the bronchoalveolar lavage fluid, with the result of chronic inflammation and lung injury. The main lesions observed at Chest high-resolution computed tomography were centrilobular nodules, parenchymal bands, lung cysts, bronchiectasis, ground-glass opacity, mosaic attenuation, and pleural thickening. It can lead to progressive changes in pulmonary function with the development of restrictive and obstructive diseases. Recent studies suggest a causal relationship between HTLV-1 and pulmonary diseases, with intensification of lesions and progressive decrease in pulmonary function. This summary updates a previous publication and addresses the general lack of knowledge regarding the relationship between TSP-HAM and pulmonary disease, providing direction for future work and the management of these individuals.

A Qualitative Study Exploring Perceptions to the Human T Cell Leukaemia Virus Type 1 in Central Australia: Barriers to Preventing Transmission in a Remote Aboriginal Population

Background

Central Australia has the highest recorded prevalence of infection with the human T cell leukaemia virus type 1 (HTLV-1) worldwide. Each of the clinical diseases associated with HTLV-1 have been reported in this region, including deaths due to adult T cell leukaemia, which is causally linked to HTLV-1. Nevertheless, no public health response has been implemented to reduce HTLV-1 transmission among the affected Aboriginal population. In the first study to explore the perceptions of healthcare professionals along with those of Aboriginal people whose communities are actually impacted by HTLV-1, we sought to understand the barriers to preventing HTLV-1 transmission in this remote area.

Methodology/Principal Findings

Semi and un-structured interviews were conducted with 30 Australian Aboriginal people, 26 non-Aboriginal healthcare professionals and 3 non-Aboriginal community workers. The purpose of the interviews was to explore perceptions towards HTLV-1 in a health context with a focus on sexual and reproductive rights. Deductive and inductive analyses were applied to the data and a decolonizing lens brought peripheral stories to the fore. A major finding was the contrast between views expressed by Aboriginal participants and healthcare professionals regarding the provision of knowledge to those affected. Aboriginal participants consistently articulated that they and their communities should be informed of, and can hold, knowledges pertaining to HTLV-1. This finding controverted the perceptions of healthcare professionals that the complexities of the virus would not be well-understood by their Aboriginal patients and that sharing HTLV-1 knowledges might overwhelm Aboriginal people. Further analyses revealed a spectrum of understanding and clinical practice, while also delineating signs of an imagined public health response.

Conclusions/Significance

HTLV-1 remains a neglected infection in Australia. Knowledge of HTLV-1 is held by a privileged medical elite and does not flow to marginalised Aboriginal people living in affected communities. We demonstrate that differences in the perspectives of stakeholders presents a significant barrier to the development of cohesive, culturally safe prevention programs that foster a shared knowledge of HTLV-1. The interview data suggests that a successful public health program is likely to require a dual approach that includes clinical care and community-driven health promotion. Aspects of this approach, which would raise awareness and potentially reduce transmission and lower HTLV-1 prevalence in Central Australia, may be applicable to other endemic settings with similar conditions of social disadvantage, geographic remoteness, resource limitations and cross-cultural challenges.

Clinical and Public Health Implications of Human T-Lymphotropic Virus Type 1 Infection

Human T-lymphotropic virus type 1 (HTLV-1) is estimated to affect 5 to 10 million people globally and can cause severe and potentially fatal disease, including adult T-cell leukemia/lymphoma (ATL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). The burden of HTLV-1 infection appears to be geographically concentrated, with high prevalence in discrete regions and populations. While most high-income countries have introduced HTLV-1 screening of blood donations, few other public health measures have been implemented to prevent infection or its consequences. Recent advocacy from concerned researchers, clinicians, and community members has emphasized the potential for improved prevention and management of HTLV-1 infection. Despite all that has been learned in the 4 decades following the discovery of HTLV-1, gaps in knowledge across clinical and public health aspects persist, impeding optimal control and prevention, as well as the development of policies and guidelines. Awareness of HTLV-1 among health care providers, communities, and affected individuals remains limited, even in countries of endemicity. This review provides a comprehensive overview on HTLV-1 epidemiology and on clinical and public health and highlights key areas for further research and collaboration to advance the health of people with and at risk of HTLV-1 infection.

Reflections on Some of the Exceptional Features of HTLV-1 and HTLV-1 Research: A Perspective

The report is not a review or a summary. In a manner, it is a perspective but an unusual one. It looks back to the years my colleagues and I (RG) began preparing for human retroviruses (beginning in 1970), how they evolved, and attempts to bring to light or simply to emphasize many exceptional characteristics of a retrovirus known as HTLV-1 and some fortuitous coincidences, with emphasis on the needs of the field. These events cover over one half a century. We have had many reviews on HTLV-1 disease, epidemiology, and basic aspects of its replication, genome, gene functions, structure, and pathogenesis, though continued updates are needed. However, some of its truly exceptional features have not been highlighted, or at least not in a comprehensive manner. This article attempts to do so.

The Association between Diabetes and Human T-Cell Leukaemia Virus Type-1 (HTLV-1) with Strongyloides stercoralis: Results of a Community-Based, Cross-Sectional Survey in Central Australia

In central Australia, an area that is endemic for the human T-cell leukaemia virus type-1 (HTLV-1), the prevalence of Strongyloides stercoralis and its association with other health conditions are unknown. A cross-sectional community-based survey was conducted in seven remote Aboriginal communities in central Australia, from 2014 to 2018. All residents aged ≥10 years were invited to complete a health survey and to provide blood for Strongyloides serology, HTLV-1 serology and HTLV-1 proviral load (PVL). Risk factors for Strongyloides seropositivity and associations with specific health conditions including diabetes and HTLV-1 were determined using logistic regression. Overall Strongyloides seroprevalence was 27% (156/576) (children, 22% (9/40); adults (≥15 years), 27% (147/536), varied widely between communities (5–42%) and was not associated with an increased risk of gastrointestinal, respiratory or dermatological symptoms. Increasing age, lower HTLV-1 PVL (<1000 copies per 105 peripheral blood leucocytes) compared to the HTLV-1 uninfected group and community of residence were significant risk factors for Strongyloides seropositivity in an adjusted model. A modest reduction in the odds of diabetes among Strongyloides seropositive participants was found (aOR 0.58, 95% CI 0.35, 1.00; p = 0.049); however, this was lost when body mass index was included in the adjusted model (aOR 0.48, 95% CI 0.48, 1.47; p = 0.542). Strongyloides seropositivity had no relationship with anaemia. Exploring social and environmental practices in communities with low Strongyloides seroprevalence may provide useful lessons for similar settings.

Computed tomography with 6-year follow-up demonstrates the evolution of HTLV-1 related lung injuries: A cohort study

Previous observational studies have demonstrated the development of pulmonary impairments in human T-lymphotropic virus type 1 (HTLV-1) infected individuals. The main observed lesions due to chronic inflammation of viral infection in situ are bronchiectasis and lung-scarring injuries. This lung inflammation may be the causal agent of restrictive and obstructive lung diseases, primarily in tropical spastic paraparesis/HTLV-1-associated myelopathy (TSP-HAM) patients. We conducted a prospective cohort study to compare spirometry and high-resolution computed tomography (HRCT) findings among 28 HTLV-1-carrier patients over the course of 6 years (2014–2019) (male/female: 7/21; mean age: 54.7 ± 9.5, range: 41–68 years). Chest HRCT exams revealed the development and evolution of lung lesions related to TSP-HAM: including centrilobular nodules, parenchymal bands, lung cysts, bronchiectasis, ground-glass opacity, mosaic attenuation, and pleural thickening. Spirometry exams showed maintenance of respiratory function, with few alterations in parameters suggestive of obstructive and restrictive disorders primarily in individuals with lung lesions and TSP-HAM. The findings of the present study indicate that pulmonary disease related to HTLV-1 is a progressive disease, with development of new lung lesions, mainly in individuals with TSP-HAM. To improve clinical management of these individuals, we recommend that individuals diagnosed with PET-MAH undergo pulmonary evaluation.

Very high prevalence of infection with the human T cell leukaemia virus type 1c in remote Australian Aboriginal communities: Results of a large cross-sectional community survey

Infection with the human T cell leukaemia virus type 1 (HTLV-1) subtype C is endemic among Aboriginal people in central Australia. To provide insights into the risk factors for transmission, we conducted the first large-scale, community-based prevalence study in seven remote Aboriginal communities. Residents >2 years old were invited to participate in the study between August 2014 and June 2018. HTLV-1 infection was defined as a positive western blot (WB) test or a positive HTLV-1 PCR. 720 community residents participated in the study (children <15 years, 142; adults, 578). Prevalences for children and adults were 3.5% (5/142) and 36.8% (213/578), respectively, reaching 49.3% (106/215) for those older than 45 years. A wide range of proviral loads were measured for both asymptomatic and symptomatic participants with no difference within groups according to age or gender; however, median PVL was 1.34 log10 higher for symptomatic participants. The adult prevalence of HTLV-1 infection in central Australia is the highest reported worldwide. Sexual contact is likely to be the predominant mode of transmission.

Risk factors for HTLV-1, acute kidney injury, and urinary tract infection among aboriginal adults with end stage kidney disease in central Australia

Central Australia is a human T-cell leukemia virus type 1c (HTLV-1c) endemic region and has the highest incidence of chronic kidney disease (CKD) in Australia. The factors associated with HTLV-1 seropositivity among Aboriginal Australian adults with CKD receiving hemodialysis (HD) were determined. A retrospective observational study of Aboriginal adults (≥ 18 years) who were receiving regular HD at the two main dialysis units in Alice Springs, December 1, 2010 to December 31, 2015. Demographic and clinical data before commencing HD were extracted from hospital records from the first presentation to Alice Springs Hospital (ASH) to HD commencement and associations were determined using logistic regression. Among 373 patients receiving HD, 133 (35.9%) were HTLV-1 infected. Identifiable factors associated with HTLV-1 status included increasing age, male gender, and diabetes before HD. The odds of diabetes mellitus were significantly higher among patients with HTLV-1 (adjusted odds ratio [aOR]: 2.76, 95% confidence interval [CI]: 1.19, 6.39; p = 0.017). More than one-fifth of participants had an acute kidney injury, the risk of which was increased among those with a previous blood stream infection (aOR: 3.02, 95% CI: 1.71, 5.34, p < 0.001). Men with a high HTLV-1 proviral load (≥500 copies per 105 peripheral blood leukocytes) had an increased risk of urinary tract infection (UTI) before HD (aOR: 5.15, 95% CI: 1.62, 16.40; p = 0.006). A strong association between HTLV-1 and diabetes, and an increased risk of UTI among men with a high HTLV-1 PVL, suggest that interactions between HTLV-1 infection and conventional risk factors may increase the risk for CKD in this population.

Human T-cell leukaemia virus type 1 associated pulmonary disease: clinical and pathological features of an under-recognised complication of HTLV-1 infection

The lung is one of several organs that can be affected by HTLV-1 mediated inflammation. Pulmonary inflammation associated with HTLV-1 infection involves the interstitium, airways and alveoli, resulting in several clinical entities including interstitial pneumonias, bronchiolitis and alveolitis, depending on which structures are most affected. Augmentation of the inflammatory effects of HTLV-1 infected lymphocytes by recruitment of other inflammatory cells in a positive feedback loop is likely to underlie the pathogenesis of HTLV-1 associated pulmonary disease, as has been proposed for HTLV-1 associated myelopathy. In contrast to the conclusions of early case series, HTLV-1 associated pulmonary disease can be associated with significant parenchymal damage, which may progress to bronchiectasis where this involves the airways. Based on our current understanding of HTLV-1 associated pulmonary disease, diagnostic criteria are proposed.