Development of lupus nephritis in a patient with human T-cell lymphotropic virus type I-associated myelopathy

Viral Infections and Systemic Lupus Erythematosus: New Players in an Old Story

A causal link between viral infections and autoimmunity has been studied for a long time and the role of some viruses in the induction or exacerbation of systemic lupus erythematosus (SLE) in genetically predisposed patients has been proved. The strength of the association between different viral agents and SLE is variable. Epstein-Barr virus (EBV), parvovirus B19 (B19V), and human endogenous retroviruses (HERVs) are involved in SLE pathogenesis, whereas other viruses such as Cytomegalovirus (CMV) probably play a less prominent role. However, the mechanisms of viral-host interactions and the impact of viruses on disease course have yet to be elucidated. In addition to classical mechanisms of viral-triggered autoimmunity, such as molecular mimicry and epitope spreading, there has been a growing appreciation of the role of direct activation of innate response by viral nucleic acids and epigenetic modulation of interferon-related immune response. The latter is especially important for HERVs, which may represent the molecular link between environmental triggers and critical immune genes. Virus-specific proteins modulating interaction with the host immune system have been characterized especially for Epstein-Barr virus and explain immune evasion, persistent infection and self-reactive B-cell "immortalization". Knowledge has also been expanding on key viral proteins of B19-V and CMV and their possible association with specific phenotypes such as antiphospholipid syndrome. This progress may pave the way to new therapeutic perspectives, including the use of known or new antiviral drugs, postviral immune response modulation and innate immunity inhibition. We herein describe the state-of-the-art knowledge on the role of viral infections in SLE, with a focus on their mechanisms of action and potential therapeutic targets.

Lupus nephritis class I accompanied by tubulointerstitial nephritis with marked T-lymphocyte infiltration in an HTLV-1 positive patient

We herein describe the case of a 40-year-old Japanese male who was admitted to our hospital because of a continuous remittent fever lasting 1 month. He fulfilled the items of the classification criteria for the diagnosis of systemic lupus erythematosus (SLE). The administration of 20 mg per day of oral prednisolone completely diminished his clinical symptoms. However, his renal biopsy performed 1 day after the admission showed marked pathognomonic characteristics. Not only did his glomeruli show class I lupus nephritis with mesangial depositions of IgG, IgA, C3, and C1q, but also tubulointerstitial nephritis with marked T-lymphocyte infiltration. These infiltrated T cells partly had nuclear atypia. The patient was positive for human T cell leukemia virus type 1 (HTLV-1) antibodies. Furthermore, clonal rearrangements of T cell receptor-gamma chain gene was detected in the DNA extracted from his kidney sections by the polymerase chain reaction (PCR) method. A second renal biopsy 6 months after the prednisolone treatment showed that the infiltrating T lymphocytes had markedly diminished. This is the first case report of lupus nephritis class I with tubulointerstitial nephritis, which might include oncogenic T lymphocytes, in an HTLV-1 positive patient.