The occurrence of systemic lupus erythematosus in an asymptomatic carrier of human T-cell lymphotropic virus type I

The role of viral infections in the development of autoimmune diseases

The exact aetiology of most autoimmune diseases remains unknown, nonetheless, several factors contributing to the induction or exacerbation of autoimmune reactions have been suggested. These include the genetic profile and lifestyle of the affected individual in addition to environmental triggers such as bacterial, parasitic, fungal and viral infections. Infections caused by viruses usually trigger a potent immune response that is necessary for the containment of the infection; however, in some cases, a failure in the regulation of this immune response may lead to harmful immune reactions directed against the host's antigens. The autoimmune attack can be carried out by different arms and components of the immune system and through different possible mechanisms including molecular mimicry, bystander activation, and epitope spreading among others. In this review, we examine the data available for the involvement of viral infections in triggering or exacerbating autoimmune diseases in addition to discussing the mechanisms by which these viral infections and the immune pathways they trigger possibly contribute to the development of autoimmunity.

Rate of positive autoimmune markers in Human T lymphotropic virus type 1 carriers: a case-control study from Iran

AIM

Human T lymphotropic virus type 1 (HTLV-1) infection with high prevalence in the north-east of Iran, particularly in Mashhad, can lead to adult T-cell leukemia (ATL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) and a variety of autoimmune diseases. The aim of the study was to examine the presence of autoimmune markers in HTLV carries.

METHODS

Serum samples were obtained from blood donors in Mashhad, northeastern Iran. One hundred and five HTLV-1 positive (cases) and 104 age- and sex-matched HTLV-1 negative donors (controls) were assessed for presence of serum autoimmune markers by enzyme-linked immunosorbent assay.

RESULTS

The mean ages of cases and controls were 40.8 ± 9.4 and 41.5 ± 9.3 years, respectively (P = 0.5). In the case group, 81.9% and in the control group 83.7% were male (P = 0.74). The frequency of positive antinuclear antibodies and anticyclic citrullinated peptide antibodies in the serum of the two groups were not significantly different (P = 0.68 and P = 0.62, respectively). Only one antineutrophil cytoplasmic antibody-positive case (1%) was observed in the group and no anti-phospholipid immunoglobulin G positivity was observed. The frequency of rheumatoid factor (RF) was greater in case group than in the control group, although the difference was not significant (P = 0.08). The amount of RF in all 12 RF positive sera were higher than normal levels (33-37 IU/mL).

CONCLUSION

Because we failed to detect any significant relation between serum autoimmune markers and HTLV-1 infection, and because of the relatively low prevalence of autoimmune diseases, it could be concluded that healthy HTLV-1 carriers do not produce rheumatologic-related auto-antibodies more than the healthy population.

HTLV-1, Immune Response and Autoimmunity

Human T-lymphotropic virus type-1 (HTLV-1) infection is associated with adult T-cell leukemia/lymphoma (ATL). Tropical spastic paraparesis/HTLV-1-associated myelopathy (PET/HAM) is involved in the development of autoimmune diseases including Rheumatoid Arthritis (RA), Systemic Lupus Erythematosus (SLE), and Sjögren's Syndrome (SS). The development of HTLV-1-driven autoimmunity is hypothesized to rely on molecular mimicry, because virus-like particles can trigger an inflammatory response. However, HTLV-1 modifies the behavior of CD4⁺ T cells on infection and alters their cytokine production. A previous study showed that in patients infected with HTLV-1, the activity of regulatory CD4⁺ T cells and their consequent expression of inflammatory and anti-inflammatory cytokines are altered. In this review, we discuss the mechanisms underlying changes in cytokine release leading to the loss of tolerance and development of autoimmunity.

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.