Endocrine and metabolic disorders in HTLV-1 infected patients

HTLV-I and Strongyloides in Australia: The worm lurking beneath

Strongyloidiasis and HTLV-I (human T-lymphotropic virus-1) are important infections that are endemic in many countries around the world with an estimated 370 million infected with Strongyloides stercoralis alone, and 5-10 million with HTVL-I. Co-infections with these pathogens are associated with significant morbidity and can be fatal. HTLV-I infects T-cells thus causing dysregulation of the immune system which has been linked to dissemination and hyperinfection of S. stercoralis leading to bacterial sepsis which can result in death. Both of these pathogens are endemic in Australia primarily in remote communities in Queensland, the Northern Territory, and Western Australia. Other cases in Australia have occurred in immigrants and refugees, returned travellers, and Australian Defence Force personnel. HTLV-I infection is lifelong with no known cure. Strongyloidiasis is a long-term chronic disease that can remain latent for decades, as shown by infections diagnosed in prisoners of war from World War II and the Vietnam War testing positive decades after they returned from these conflicts. This review aims to shed light on concomitant infections of HTLV-I with S. stercoralis primarily in Australia but in the global context as well.

Regulation of Expression and Latency in BLV and HTLV

Human T-lymphotrophic virus type 1 (HTLV-1) and Bovine leukemia virus (BLV) belong to the Deltaretrovirus genus. HTLV-1 is the etiologic agent of the highly aggressive and currently incurable cancer adult T-cell leukemia (ATL) and a neurological disease HTLV-1-associated myelopathy (HAM)/tropical spastic paraparesis (TSP). BLV causes neoplastic proliferation of B cells in cattle: enzootic bovine leucosis (EBL). Despite the severity of these conditions, infection by HTLV-1 and BLV appear in most cases clinically asymptomatic. These viruses can undergo latency in their hosts. The silencing of proviral gene expression and maintenance of latency are central for the establishment of persistent infection, as well as for pathogenesis in vivo. In this review, we will present the mechanisms that control proviral activation and retroviral latency in deltaretroviruses, in comparison with other exogenous retroviruses. The 5′ long terminal repeats (5′-LTRs) play a main role in controlling viral gene expression. While the regulation of transcription initiation is a major mechanism of silencing, we discuss topics that include (i) the epigenetic control of the provirus, (ii) the cis-elements present in the LTR, (iii) enhancers with cell-type specific regulatory functions, (iv) the role of virally-encoded transactivator proteins, (v) the role of repressors in transcription and silencing, (vi) the effect of hormonal signaling, (vii) implications of LTR variability on transcription and latency, and (viii) the regulatory role of non-coding RNAs. Finally, we discuss how a better understanding of these mechanisms may allow for the development of more effective treatments against Deltaretroviruses.

Pathways involved in viral oncogenesis: New perspectives from virus-host protein interactomics

Oncogenic viruses are among the apparent causes of cancer-associated mortality. It was estimated that 12% to 15% of human malignancies are linked to oncoviruses. Although modernist strategies and traditional genetic studies have defined host-pathogen interactions of the oncoviruses, their host functions which are critical for the establishment of infection still remain mysterious. However, over the last few years, it has become clear that infections hijack and modify cellular pathways for their benefit. In this context, we constructed the virus-host protein interaction networks of seven oncoviruses (EBV, HBV, HCV, HTLV-1, HHV8, HPV16, and HPV18), and revealed cellular pathways hijacking as a result of oncogenic virus infection. Several signaling pathways/processes such as TGF-β signaling, cell cycle, retinoblastoma tumor suppressor protein, and androgen receptor signaling were mutually targeted by viruses to induce oncogenesis. Besides, cellular pathways specific to a certain virus were detected. By this study, we believe that we improve the understanding of the molecular pathogenesis of viral oncogenesis and provide information in setting new targets for treatment, prognosis, and diagnosis.

High-yield production in E. coli and characterization of full-length functional p13II protein from human T-cell leukemia virus type 1

Human T-cell leukemia virus type 1 is an oncovirus that causes aggressive adult T-cell leukemia but is also responsible for severe neurodegenerative and endocrine disorders. Combatting HTLV-1 infections requires a detailed understanding of the viral mechanisms in the host. Therefore, in vitro studies of important virus-encoded proteins would be critical. Our focus herein is on the HTLV-1-encoded regulatory protein p13^II, which interacts with the inner mitochondrial membrane, increasing its permeability to cations (predominantly potassium, K⁺). Thereby, this protein affects mitochondrial homeostasis. We report on our progress in developing specific protocols for heterologous expression of p13^II in E. coli, and methods for its purification and characterization. We succeeded in producing large quantities of highly-pure full-length p13^II, deemed to be its fully functional form. Importantly, our particular approach based on the fusion of ubiquitin to the p13^II C-terminus was instrumental in increasing the persistently low expression of soluble p13^II in its native form. We subsequently developed approaches for protein spin labeling and a conformation study using double electron-electron resonance (DEER) spectroscopy and a fluorescence-based cation uptake assay for p13^II in liposomes. Our DEER results point to large protein conformation changes occurring upon transition from the soluble to the membrane-bound state. The functional assay on p13^II-assisted transport of thallium (Tl⁺) through the membrane, wherein Tl⁺ substituted for K⁺, suggests transmembrane potential involvement in p13^II function. Our study lays the foundation for expansion of in vitro functional and structural investigations on p13^II and would aid in the development of structure-based protein inhibitors and markers.

Uncommon Association Between Diabetic Ketoacidosis, Thyrotoxicosis, Cutaneous Abscess and Acute Pericarditis in an Immunocompetent Patient: A Single Case Report and Literature Review

INTRODUCTION

The typical factors precipitating diabetic ketoacidosis (DKA) include infections (30%), cessation of antidiabetic medication (20%), and a new diagnosis of diabetes (25%). The etiology remains unknown in 25% of cases. Less frequent causes cited in the literature include severe thyrotoxicosis and, infrequently, pericarditis. Few publications have described the role of human T lymphotropic virus type 1 (HTLV-1) in endocrine and metabolic disorders. Based on a clinical case associated with several endocrine and metabolic disorders, we suggest a potential role for HTLV-1, an endemic virus in the Amazonian area, and review the literature concerning the role of this virus in thyroiditis, pericarditis and diabetes mellitus.

CASE REPORT

A fifty-year-old Surinamese woman without any medical history was admitted for diabetic ketoacidosis. No specific anti-pancreatic autoimmunity was observed, and the C-peptide level was low, indicating atypical type-1 diabetes mellitus. DKA was associated with thyrotoxicosis in the context of thyroiditis and complicated by nonbacterial pericarditis and a Staphylococcus aureus subcutaneous abscess. The patient was infected with HTLV-1.

CONCLUSION

To our knowledge, this uncommon association is described for the first time. Few studies have analyzed the implications of HTLV-1 infection in thyroiditis and diabetes mellitus. We did not find any reports describing the association of pericarditis with HTLV-1 infection. Additional studies are necessary to understand the role of HTLV-1 in endocrine and cardiac disorders.

Non-Structural Proteins from Human T-cell Leukemia Virus Type 1 in Cellular Membranes-Mechanisms for Viral Survivability and Proliferation

Human T-cell leukemia virus type 1 (HTLV-1) is the causative agent of illnesses, such as adult T-cell leukemia/lymphoma, myelopathy/tropical spastic paraparesis (a neurodegenerative disorder), and other diseases. Therefore, HTLV-1 infection is a serious public health concern. Currently, diseases caused by HTLV-1 cannot be prevented or cured. Hence, there is a pressing need to comprehensively understand the mechanisms of HTLV-1 infection and intervention in host cell physiology. HTLV-1-encoded non-structural proteins that reside and function in the cellular membranes are of particular interest, because they alter cellular components, signaling pathways, and transcriptional mechanisms. Summarized herein is the current knowledge about the functions of the membrane-associated p8^I, p12^I, and p13^II regulatory non-structural proteins. p12^I resides in endomembranes and interacts with host proteins on the pathways of signal transduction, thus preventing immune responses to the virus. p8^I is a proteolytic product of p12^I residing in the plasma membrane, where it contributes to T-cell deactivation and participates in cellular conduits, enhancing virus transmission. p13^II associates with the inner mitochondrial membrane, where it is proposed to function as a potassium channel. Potassium influx through p13^II in the matrix causes membrane depolarization and triggers processes that lead to either T-cell activation or cell death through apoptosis.

Fatal cardiovascular instability secondary to hypercalcaemia and intracellular calcium deposition complicating T-cell leukaemia-lymphoma

Adult T-cell leukaemia-lymphoma is a rare haematological malignancy, which can cause severe hypercalcaemia and metastatic calcification resulting in life-threatening arrhythmias.