Marijke Van Ghelue

BK and JC Viruses in Patients with Systemic Lupus Erythematosus: Prevalent and Persistent BK Viruria, Sequence Stability of the Viral Regulatory Regions, and Nondetectable Viremia

A role for polyomaviruses in the pathogenesis of systemic lupus erythematosus (SLE) has been suggested. BK virus (BKV) and JC virus (JCV) were demonstrated in single urine specimens from 7 (16%) of 44 and 5 (11%) of 44 patients with SLE and 0/88 and 18 (21%) of 88 matched healthy controls, respectively. During a 1-year follow-up study, episodes of polyomaviruria were detected in 16 (80%) of 20 patients, BKV in 13, and JCV in 3 patients. A group of 12 (60%) of 20 patients demonstrated persistent or recurrent polyomaviruria, BKV viruria (n=9), or JCV viruria (n=3) in 180 (70%) of 256 specimens. Polyomaviruria was not significantly associated with immunosuppressive therapy. The BKV and JCV isolates revealed predominantly stable archetypal regulatory regions over 3 years, indicating viral persistence rather than reinfection as a cause for urinary shedding. The demonstration of nondetectable viremia and stable archetypal BKV and JCV noncoding control regions during persistent viruria argue against the urinary tract as a focus for the creation of rearranged regulatory region variants.

Genome analysis of the new human polyomaviruses

Polyomaviridae is a growing family of naked, double‐stranded DNA viruses that infect birds and mammals. The last few years, several new members infecting birds or primates have been discovered, including seven human polyomaviruses: KI, WU, Merkel cell polyomavirus, HPyV6, HPyV7, trichodysplasia spinulosa‐associated polyomavirus, and HPyV9. In addition, DNA and antibodies against the monkey lymphotropic polyomavirus have been detected in humans, indicating that this virus can also infect man. However, little is known about the route of infection, transmission, cell tropism, and, with the exception of Merkel cell polyomavirus and trichodysplasia spinulosa‐associated polyomavirus, the pathogenicity of these viruses. This review compares the genomes of these emerging human polyomaviruses with previously known polyomaviruses detected in man, reports mutations in different isolates, and predicts structural and functional properties of their viral proteins. Copyright

Human Polyomaviruses in Skin Diseases

Polyomaviruses are a family of small, nonenveloped viruses with a circular double-stranded DNA genome of ∼5,000 base pairs protected by an icosahedral protein structure. So far, members of this family have been identified in birds and mammals. Until 2006, BK virus (BKV), JC virus (JCV), and simian virus 40 (SV40) were the only polyomaviruses known to circulate in the human population. Their occurrence in individuals was mainly confirmed by PCR and the presence of virus-specific antibodies. Using the same methods, lymphotropic polyomavirus, originally isolated in monkeys, was recently shown to be present in healthy individuals although with much lower incidence than BKV, JCV, and SV40. The use of advanced high-throughput sequencing and improved rolling circle amplification techniques have identified the novel human polyomaviruses KI, WU, Merkel cell polyomavirus, HPyV6, HPyV7, trichodysplasia spinulosa-associated polyomavirus, and HPyV9. The skin tropism of human polyomaviruses and their dermatopathologic potentials are the focus of this paper.

Autoimmunity to nucleosomes related to viral infection: a focus on hapten-carrier complex formation

Systemic lupus erythematosus (SLE) is an autoimmune disorder with unknown aetiology. The major hallmark of this disease is the presence of antibodies against nuclear components, including double-stranded (ds)DNA and histones. The disease affects different organs, particularly the skin, kidneys and the nervous system. Although the exact molecular mechanisms underlying the pathophysiological processes in SLE remain unknown, several inherent and environmental factors seem to be involved in the ethiopathogenesis of this disorder. Viruses may be one of the factors that induce the production of autoreactive antibodies although the involved mechanisms are still incompletely understood. One proposed mechanism for virus-induced production of autoantibodies is molecular mimicry. Another mechanism derives from studies with the human polyomavirus BK. In these studies, in vivo binding of the polyomaviruses large T-antigen to chromatin of infected cells may render chromatin immunogenic. The large T-antigen-chromatin complex may thus function as a hapten-carrier model with subsequent production of anti-chromatin antibodies, including anti-dsDNA and anti-histones antibodies. This review focuses on the recent findings suggesting that this model may be applicable for other human viruses associated with SLE.

Agrin mutations lead to a congenital myasthenic syndrome with distal muscle weakness and atrophy

Congenital myasthenic syndromes are a clinically and genetically heterogeneous group of rare diseases resulting from impaired neuromuscular transmission. Their clinical hallmark is fatigable muscle weakness associated with a decremental muscle response to repetitive nerve stimulation and frequently related to postsynaptic defects. Distal myopathies form another clinically and genetically heterogeneous group of primary muscle disorders where weakness and atrophy are restricted to distal muscles, at least initially. In both congenital myasthenic syndromes and distal myopathies, a significant number of patients remain genetically undiagnosed. Here, we report five patients from three unrelated families with a strikingly homogenous clinical entity combining congenital myasthenia with distal muscle weakness and atrophy reminiscent of a distal myopathy. MRI and neurophysiological studies were compatible with mild myopathy restricted to distal limb muscles, but decrement (up to 72%) in response to 3 Hz repetitive nerve stimulation pointed towards a neuromuscular transmission defect. Post-exercise increment (up to 285%) was observed in the distal limb muscles in all cases suggesting presynaptic congenital myasthenic syndrome. Immunofluorescence and ultrastructural analyses of muscle end-plate regions showed synaptic remodelling with denervation-reinnervation events. We performed whole-exome sequencing in two kinships and Sanger sequencing in one isolated case and identified five new recessive mutations in the gene encoding agrin. This synaptic proteoglycan with critical function at the neuromuscular junction was previously found mutated in more typical forms of congenital myasthenic syndrome. In our patients, we found two missense mutations residing in the N-terminal agrin domain, which reduced acetylcholine receptors clustering activity of agrin in vitro. Our findings expand the spectrum of congenital myasthenic syndromes due to agrin mutations and show an unexpected correlation between the mutated gene and the associated phenotype. This provides a good rationale for examining patients with apparent distal myopathy for a neuromuscular transmission disorder and agrin mutations.

Increased levels of BAFF in patients with systemic lupus erythematosus are associated with acute-phase reactants, independent of BAFF genetics: a case–control study

OBJECTIVES To determine whether increased levels of B-cell activating factor (BAFF) in patients with SLE are due to disease activity or genetic variations in the promoter region of the BAFF gene and BAFF gene expression. METHODS The case-control study included 101 SLE patients and 111 healthy controls. Five single nucleotide polymorphisms (SNPs) in the BAFF promoter region were investigated by melting point analysis: c.-2841 (T > C), c.-2704 (T > C), c.-2701 (A > T), c.-871 (C > T) and c.-514 (A > G). BAFF mRNA levels were determined by real-time PCR (BAFF-RQ) and serum BAFF (s-BAFF) levels were measured by ELISA. Independent predictors that might be correlated with increased s-BAFF in SLE patients were analysed by multivariate regression methods. RESULTS; Although s-BAFF levels were increased in SLE patients (1.73 vs 0.98 ng/μl, P < 0.001), no specific BAFF genotype was found to associate with SLE. The different genotypes defined by the investigated SNPs were identified both in SLE patients and healthy controls with similar frequencies. No association was found between BAFF genotype and BAFF-RQ. s-BAFF was independent of other factors, correlated with CRP (β = 0.40, P < 0.001) and physicians visual analogue score (R = 0.21, P = 0.046) and inversely with haemoglobin (β = -0.32, P < 0.001) and IgA (β = -0.33, P = 0.001). CONCLUSIONS Increased s-BAFF levels in SLE patients are associated with the acute-phase responses, CRP and haemoglobin, but probably not dependent on BAFF genotype or expression. This indicates that s-BAFF production occurs at sites of inflammation.

Human T Cell Activation by Costimulatory Signal-Deficient Allogeneic Cells Induces Inducible Costimulator-Expressing Anergic T Cells with Regulatory Cell Activity

Although immunoregulation by several types of regulatory T cells is now clearly established in mice, the demonstration of such regulatory T cells in humans has been proven more difficult. In this study we demonstrate the induction of anergic regulatory T cells during an MLR performed in the presence of blocking mAb to the costimulatory molecules CD40, CD80, and CD86. Despite this costimulation blockade, which totally blocks T cell proliferation and cytokine production, a nonproliferating T cell subpopulation was activated to express inducible costimulator (ICOS). These ICOS+ cells were anergic when restimulated with unmanipulated allogeneic stimulator cells at the level of proliferation and Th1 and Th2 cytokine production, but they did produce IL-10. These ICOS-expressing cells also blocked the capacity of reciprocal ICOS-negative cells to proliferate and to produce cytokines. ICOS+ anergic cells could suppress allogenic responses of either primed or naive T cells through inhibition of IL-2 gene transcription. Suppression was not mediated by IL-10 and did not require ICOS-ICOS ligand interaction, but depended on cell-cell contact. Thus, a subtype of regulatory T cells in human blood can be activated in the absence of costimulatory signals from CD40, CD80, and CD86, and they can be identified by expression of ICOS after activation.

Serological cross-reactivity between human polyomaviruses

Until 2006, BKPyV and JCPyV were the only known human polyomaviruses. A third polyomavirus, simian virus 40 whose natural host is the macaque was accidently introduced into man because of contaminated poliovirus vaccines, although there is epidemiological evidence that SV40 may be transmitted between man independently from contaminated vaccines. Since 2007, 10 new human polyomaviruses have been identified: KIPyV, WUPyV, Merkel cell polyomavirus, trichodysplasia spinulosa‐associated polyomavirus, and human polyomaviruses 6, 7, 9, 10, STL, and 12. Moreover, the DNA of the monkey lymphotropic polyomavirus has been amplified from human peripheral blood. Seroepidemiological studies frequently based on the presence of antibodies against the major capsid protein VP1 or virus‐like particles indicate that most human adults have been exposed to many, if not all, human polyomaviruses. However, because of the high amino acid sequence identity between VP1 of some human polyomaviruses, cross‐reactivity of antibodies is occasionally observed. In addition, human sera possess reactivity against VP1 of polyomaviruses from other species, suggesting serological cross‐reaction with known or closely related, yet unidentified human polyomaviruses and/or the possibility of zoonotic transmission. Thus, current serological results should be interpreted with caution, and controls excluding cross‐reactivity with other polyomaviruses are required. Copyright

A longitudinal study of human cytomegalovirus serology and viruria fails to detect active viral infection in 20 systemic lupus erythematosus patients

In this study, we investigated whether active human cytomegalovirus infection could be detected in 20 systemic lupus erythematosus (SLE) patients over a one-year observation period by polymerase chain reaction on serial urine specimens and by monitoring of IgG and IgM HCMV-specific antibody profiles in serial serum samples. Of 788 urine samples analysed for the presence of human cytomegalovirus DNA, only 2 specimens (0.25%) collected from two different patients contained genuine human cytomegalovirus sequences as determined by polymerase chain reaction and subsequent sequencing of the PCR products. These two patients had one positive sample out of 36 samples or 40 samples, respectively. Nineteen of the patients (95%) possessed IgG antibodies against human cytomegalovirus, while 9 (45%) produced IgM antibodies. However, none of the patients showed signs of an active virus infection as judged by the stable anti-HCMV IgG or IgM antibody levels during the observation period, nor was any correlation between disease activity and HCMV serology/viruria observed. Of single serum samples of 26 age-and sex-matched blood donors, 21 (81%) were HCMV IgG positive and 1 (3.8%) was IgM seropositive. In conclusion, our data fail to establish an active human cytomegalovirus infection in SLE patients.

VP1 DNA sequences of JC and BK viruses detected in urine of systemic lupus erythematosus patients reveal no differences from strains expressed in normal individuals.

The ubiquitous human polyomaviruses BK (BKV) and JC (JCV) persist with no adverse effects in immunocompetent individuals. Virus-induced pathogenesis has been linked to virus reactivation during impaired immune conditions. Previous studies have shown a significant difference between the VP1 DNA sequences of JCV obtained from control urine samples and those in progressive multifocal leukoencephalopathy brain samples. This difference could not be detected when comparing normal control urinary JCV DNA with DNA sequences from chronic progressive multiple sclerosis patients. Since BKV and JCV are readily activated in systemic lupus erythematosus (SLE) patients, the presence of specific strains, related to VP1 DNA sequences, was investigated in these patients. VP1 DNA sequences in 100 urine samples from 21 SLE patients and 75 urine samples from 75 healthy pregnant women were analysed and compared to previously reported sequences. The results show that the VP1 sequence profiles of JCV and BKV excreted by SLE patients do not differ significantly from those excreted by immunocompetent individuals. The European JCV subtypes 1A or 1B were represented among all JCV-positive urine specimens, while BKV VP1 sequences showed complete, or almost complete, identity with the MM or JL strains. Different urine samples from the same patient collected over a 1 year period were predominantly stable. BKV VP1 DNA in urine specimens from healthy pregnant women was only detected during the third trimester of their pregnancy. These results argue against SLE-specific JCV and BKV strains and suggest reactivation of the viruses rather than recurrent re-infections of patients with SLE.