Chronic parvovirus B19 infection and systemic necrotising vasculitis: opportunistic infection or aetiological agent?

Polyarteritis Nodosa: Old Disease, New Etiologies

Polyarteritis nodosa (PAN), also known as panarteritis nodosa, represents a form of necrotizing vasculitis that predominantly affects medium-sized vessels, although it is not restricted to them and can also involve smaller vessels. The clinical presentation is heterogeneous and characterized by a significant number of patients exhibiting general symptoms, including asthenia, fever, and unintended weight loss. Although PAN can involve virtually any organ, it preferentially affects the skin, nervous system, and the gastrointestinal tract. Orchitis is a rare but specific manifestation of PAN. The absence of granulomas, glomerulonephritis, and anti-neutrophil cytoplasmic antibodies serves to distinguish PAN from other types of vasculitis. Major complications consist of hemorrhagic and thrombotic events occurring in mesenteric, cardiac, cerebral, and renal systems. Historically, PAN was frequently linked to hepatitis B virus (HBV) infection, but this association has dramatically changed in recent years due to declining HBV prevalence. Current epidemiological research often identifies a connection between PAN and genetic syndromes as well as neoplasia. This article provides a comprehensive review of PAN, specifically focusing on the progression of its clinical manifestations over time.

Clinical Reasoning: A 39-Year-Old Man With Asymmetric Distal Weakness and Loss of Sensitivity

A 39-year-old man presented with an asymmetric distal weakness and loss of sensitivity sequentially affecting both lower extremities and the left upper limb. Nerve conduction studies showed a multifocal sensory and motor axonal neuropathy, and a pseudo-conduction block of the right fibular nerve, the whole being consistent with a mononeuropathy multiplex. An uncommon etiology was found after an extensive workup. Axonal loss was severe, with only partial response to treatment with corticosteroids and IV immunoglobulins.

[Parvovirus B19 infections in adults]

Acute Parvovirus B19 (PVB19) infection is responsible for erythema infectiosum in children and non-specific polyarthralgias in immunocompetent adults associated with skin lesions and rarer manifestations (hepatic, neurological, cardiac or nephrological). In immunocompromised patients, cytopenias are more frequent and in some cases, viremia persists and is responsible for PVB19 chronic infection. PVB19 is responsible for pure red cell aplasia during chronic hemolytic diseases. Acute PVB19 infection is a differential diagnosis of some autoimmune diseases and has been suspected to be a trigger for some autoimmune diseases because of its ability to promote the emergence of autoimmune markers. Mechanisms of molecular mimicry, induction of apoptosis and activation of enzymes have been demonstrated, explaining in part the production of autoantibodies during infection. However, the demonstration of a causal relationship in the triggering of autoimmune disease remains to be done. This review provides a synthesis of the PVB19 infection clinical data in adults with a particular focus on these links with autoimmunity.

COVID-19 and New Onset IgA Vasculitis: A Systematic Review of Case Reports

INTRODUCTION

Immunoglobulin A vasculitis is historically more commonly found in children after certain viral infections such as Epstein-Barr, varicella virus, and parvovirus B19. COVID-19 has not been formally established in literature as a trigger for immunoglobulin A vasculitis. However, a main pathogenetic mechanism of COVID-19 is vascular damage, which makes it likely that vasculitis associated with COVID-19 (ie, COVID-19-mediated immunoglobulin A vasculitis) could be biologically plausible, with serious implications, especially for adults. The purpose of this review is to assist emergency nurses in gaining knowledge on the pathophysiology, symptoms, and treatment of COVID-19-mediated immunoglobulin A vasculitis.

METHODS

A systematic search for case reports of COVID-19-associated immunoglobulin A vasculitis was conducted in the PubMed and Scopus electronic databases. The search terms used were COVID-19, coronavirus 2019, SARS COVID-19, and IgA vasculitis, case reports. The following were the inclusion criteria: publication dates between December 1, 2019, and December 1, 2021; full-text article, clinical case studies, and letters to the editor available electronically in English. The following were exclusion criteria: a summary of reports and newspaper publications.

RESULTS

Only 13 clinical cases met the inclusion criteria. The median age of patients described in the case reports were 38.1 years. Of them, 3 children were less than 5 years old. Twelve patients were male. In 7 of 13 cases of immunoglobulin A vasculitis, renal involvement was found.

DISCUSSION

The analysis of published clinical cases showed that COVID-19-associated immunoglobulin A vasculitis affected mostly adults and was characterized by a more severe course because of renal involvement. COVID-19 may be a possible trigger for immunoglobulin A-related disorders. More research is needed to better understand the relationship between immunoglobulin A vasculitis and COVID-19.

Polyarteritis Nodosa with Cytomegalovirus Enteritis and Jejunoileal Perforation: Report of a Case with a Literature Review

Polyarteritis nodosa (PAN) is a rare systemic necrotizing vasculitis affecting small- to medium-sized arteries. The most common gastrointestinal manifestation of PAN is postprandial abdominal pain from mesenteric arteritis causing bowel ischemia. When transmural ischemia develops, there may be ischemic necrosis and perforation of the bowel wall, which are life-threatening. Severe, life-threatening gastrointestinal involvement is relatively rare in pediatric PAN and may require different management in adult patients. We report a pediatric PAN case in a patient who presented with acute abdominal pain and superimposed cytomegalovirus enteritis with jejunoileal perforation. The patient improved with emergency small intestinal resection followed by conventional immunosuppressive drugs of a corticosteroid and cyclophosphamide, and anti-viral drugs. Before increasing the immunosuppressive drug dosage, initial screening of infectious cytomegalovirus and comprehensive evaluation for surgical conditions are essential in pediatric PAN with severe gastrointestinal involvement. Early aggressive treatment for acute abdomen is useful in reducing morbidity and mortality in pediatric PAN.

Polyarteritis Nodosa: State of the art

Polyarteritis nodosa (PAN) is a systemic necrotizing vasculitis that preferentially affects medium-sized vessels. The idiopathic form has become rare. Its treatment relies on corticosteroid therapy and is combined with cyclophosphamide infusions for severe forms. Secondary PANs were mainly associated with hepatitis B virus infection; they were treated with plasma exchange and antivirals in combination with short-term corticosteroid therapy. Other secondary forms of PAN are now becoming more common, such as those due to blood disorders. More recently, a monogenic form linked to adenosine deaminase-2 mutations has been identified. It requires treatment with TNF inhibitors to decrease the occurrence of ischemic central nervous system complications, which make it serious. Once remission is obtained, relapses are typically rare during PAN and affect 28% of idiopathic PANs, within an average of 26 months from the diagnosis. The prognosis has improved considerably, with 5- and 10-year survival rates of 83% and 74%.

Association of Parvovirus B19 with Rheumatic Diseases

Human parvovirus B19 infections are well reported to be associated with different autoimmune disorders. They can either mimic or trigger autoimmune diseases, such as systemic lupus erythematous (SLE), rheumatoid arthritis (RA), and vasculitis. A lack of awareness about this infection can result in delays in diagnosis and poor care. In this review, the basic biology and clinical aspects of the parvovirus, human immune response, and the pathogenesis in the rheumatic diseases are discussed.

Neurological Manifestations Associated with Parvovirus B19 Infection in Immunocompetent Children: Case Series and Systematic Review

An increasing number of reports have described human parvovirus B19 infection in association with a variety of neurological manifestations, especially in children. This study assessed the clinical and laboratory outcomes found in a case series of immunocompetent children who tested positive for parvovirus B19 by qualitative polymerase chain reaction assays of cerebrospinal fluid, in a tertiary referral center in the western Brazilian Amazon. We screened 178 children with clinically diagnosed central nervous system infections (meningoencephalitis). Of these, five (2.8%) were positive for parvovirus B19. A literature review also presented herein identified a further 50 cases of parvovirus B19 with neurological manifestations. Thus, even if the classic signs of parvovirus B19 infection are absent, such as the well-known rash, children with signs of neurological infection should also be evaluated for parvovirus B19 infection.

Infection, Infectious Agents and Vascular Disease

BACKGROUND

Infectious agents may be involved in the pathogenesis of vascular disease and related complications. The aim of this review is to analyze the most relevant information on the common infections related to vascular disease, discussing the main pathophysiological mechanisms.

METHODS

In the current review, the most important evidence on the issue of infections and vascular disease is searched on Medline, Scopus, and ScienceDirect database.

RESULTS

Among infectious agents, herpesviruses, parvovirus B19, hepatitis viruses, human immunodeficiency virus, severe acute respiratory syndrome coronavirus 2, treponema pallidum, mycobacterium tuberculosis, pseudomonas aeruginosa, staphylococcus aureus, and candida albicans seem to particularly related to vascular disease.

CONCLUSION

Infectious agents may affect vessel's homeostasis and functionality, both on the arterial and venous side, by means of several pathophysiological mechanisms such as dysregulation in vasomotor function, thromboembolic complications, initiation and progression of atherosclerosis, alteration of perivascular adipose tissue, recruiting inflammatory cells and molecules.

Treatment of parvovirus B19 viremia to facilitate kidney transplantation in a patient with collapsing glomerulopathy

Collapsing glomerulopathy (CG) is a severe form of glomerulopathy which results in nephrotic syndrome and often ensues in rapid progression to end-stage kidney disease (ESKD). Although most commonly a result of HIV infection, other conditions such as parvovirus B19 (PB19) infection have been associated with CG. We present a case of an 18-year-old male with CG associated with PB19 infection who was heterozygous for APOL1 G1 and G2 genetic variants. In an attempt to treat, he was started on intravenous immunoglobulin (IVIg), however rapidly progressed to ESKD. During workup for a living donor kidney transplant he was found to have persistent low-grade PB19 viremia. Despite having no major immunodeficiency and given subsequent courses of IVIg, viremia continued to persist. In a final attempt to eradicate the PB19 we began treatment with cidofovir, an antiviral agent with in vitro efficacy against PB19. Subsequent to initiation of cidofovir, PB19 viremia slowly cleared after which he received a living unrelated kidney transplant. The patient had an early cellular rejection treated with rabbit antithymocyte globulin after which he recovered kidney function without signs of recurrent CG. Our case report suggests efficacy of IVIg and cidofovir for persistent PB19 infection in ESKD to allow subsequent transplantation, while minimizing the risk of recurrent CG.

A Case of Adult-onset Henoch-Schönlein Purpura Triggered by Fire Ants

Adult-onset IgA vasculitis, also known as Henoch-Schönlein purpura (HSP), is a rare disease that often presents with a non-blanchable, purpuric rash and can simultaneously affect the gastrointestinal, renal and musculoskeletal systems. The etiology of HSP is unknown. It can be triggered by any entity that creates an immunological insult, including medications, infections and vaccines. We describe a unique case of an adult woman who presented with HSP after experiencing multiple insect bites from fire ants and mosquitos while traveling overseas.

Carnitine Palmitoyl Transferase Deficiency in a University Immunology Practice

PURPOSE

This report describes the clinical manifestations of 35 patients sent to a University Immunology clinic with a diagnosis of fatigue and exercise intolerance who were identified to have low carnitine palmitoyl transferase activity on muscle biopsies.

RECENT FINDINGS

All of the patients presented with fatigue and exercise intolerance and many had been diagnosed with fibromyalgia. Their symptoms responded to treatment of the metabolic disease. Associated symptoms included bloating, diarrhea, constipation, gastrointestinal reflux symptoms, recurrent infections, arthritis, dyspnea, dry eye, visual loss, and hearing loss. Associated medical conditions included Hashimoto thyroiditis, Sjogren's syndrome, seronegative arthritis, food hypersensitivities, asthma, sleep apnea, and vasculitis. This study identifies clinical features that should alert physicians to the possibility of an underlying metabolic disease. Treatment of the metabolic disease leads to symptomatic improvement.

Clinical impact & pathogenic mechanisms of human parvovirus B19: A multiorgan disease inflictor incognito

Human parvovirus B19 (B19V) causes myriads of clinical diseases; however, owing to lack of awareness and undetermined clinical impact, it has failed to become a virus pathogen of global concern. Cryptically, B19V causes significant morbidity and mortality. Half of the world population and 60 per cent of Indians are known to be serologically naive and are at risk of acquiring B19V infections. Cumulatively, our data showed 21.3 per cent B19V-infected patients with juvenile chronic arthropathy, recurrent abortions, multi-transfused thalassaemia and leukaemia. In addition, B19V-infected cases that ended fatally included patients with pure red cell aplasia, fulminant hepatitis and haemophagocytic syndrome. Novel clinical associations of B19V observed were amegakaryocytic thrombocytopaenia, myositis and non-occlusive ischaemic gangrene of bowel. B19V possesses multiple receptors which are distributed widely in human tissues. Vascular endothelial cell infection by B19V causes endothelialitis and vasculitic injuries besides antibody-dependent enhancement which empowered B19V to cause multiorgan diseases. Owing to lack of suitable animal model for B19V, true causal role remains to be determined, but numerous reports on B19V infections substantiate a causal role in multiorgan diseases. Hence, B19V infections need to be recognized, investigated and treated besides making efforts on vaccine developments.

Kidney Diseases Associated With Parvovirus B19, Hanta, Ebola, and Dengue Virus Infection: A Brief Review

Viral infection-associated kidney diseases are an emerging public health issue in both developing and developed countries. Many new viruses have emerged with new paradigms of kidney injury, either directly through their cytopathic effect or indirectly through immune-mediated glomerulopathy, tubulointerstitial disease, and acute kidney injury as part of multiorgan failure. Herein, we will discuss Parvovirus, which causes glomerulopathy, and Hanta, Ebola, and Dengue viruses, which cause viral hemorrhagic fever and acute kidney injury. Clinical manifestations also depend on extrarenal organ systems involved. Diagnosis of these viral infections is mainly based on a high index of suspicion, serologic testing, and isolation of viral DNA/RNA. Management is largely conservative, as specific antiviral agents are unavailable.

Genetic Associations and Environmental Exposures in the Aetiopathogenesis of Anti-Neutrophil Cytoplasmic Antibody- Associated Vasculitis: An Updated Review

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) represents a heterogeneous group of rare diseases characterised by necrotising inflammation of the small blood vessels and the presence of ANCA with specificity for proteinase-3 or myeloperoxidase. Genetic susceptibility along with malignancy, drug exposure, and environmental exposures to infectious agents and silica are involved in disease progression. To date, growing evidence has revealed that ANCA specificity defines homogeneous groups of patients more effectively than clinical diagnosis, since proteinase-3 ANCA and myeloperoxidase-ANCA are linked with different genetic backgrounds and epidemiologies. This review presents current and updated knowledge on the central aetiopathogenic role of genetic associations and environmental exposures in AAV; discusses the main mechanisms of ANCA immunogenesis; and highlights the value of ANCA specificity for future classification criteria.

Recent Advances in Replication and Infection of Human Parvovirus B19

Parvovirus B19 (B19V) is pathogenic to humans and causes bone marrow failure diseases and various other inflammatory disorders. B19V infection exhibits high tropism for human erythroid progenitor cells (EPCs) in the bone marrow and fetal liver. The exclusive restriction of B19V replication to erythroid lineage cells is partly due to the expression of receptor and co-receptor(s) on the cell surface of human EPCs and partly depends on the intracellular factors essential for virus replication. We first summarize the latest developments in the viral entry process and the host cellular factors or pathways critical for B19V replication. We discuss the role of hypoxia, erythropoietin signaling and STAT5 activation in the virus replication. The B19V infection-induced DNA damage response (DDR) and cell cycle arrest at late S-phase are two key events that promote B19V replication. Lately, the virus infection causes G2 arrest, followed by the extensive cell death of EPCs that leads to anemia. We provide the current understanding of how B19V exploits the cellular resources and manipulate pathways for efficient virus replication. B19V encodes a single precursor mRNA (pre-mRNA), which undergoes alternate splicing and alternative polyadenylation to generate at least 12 different species of mRNA transcripts. The post-transcriptional processing of B19V pre-mRNA is tightly regulated through cis-acting elements and trans-acting factors flanking the splice donor or acceptor sites. Overall, in this review, we focus on the recent advances in the molecular virology and pathogenesis of B19V infection.

Adult-Onset Henoch-Schonlein Purpura Duodenitis

Henoch-Schonlein purpura (HSP) is an immune-mediated vasculitis. HSP presents with purple spots on the skin (purpura), arthralgia, digestive problems, and kidney injury. HSP is most commonly seen in children, and rarely presents in adults. The pathogenesis involves the deposition of immune complexes in small to medium size blood vessels which leads to necrosis and inflammation. Most patients recover after symptomatic treatment, while more severe cases are treated with steroids. We report a 28-year-old female patient who presented with two episodes of hematemesis, worsening abdominal pain, and bloody diarrhea. Physical examination showed erythematous, palpable, purpuric rashes on her thighs and lower legs. Contrast-enhanced computed tomography (CT) scan showed thickening of the duodenal wall, and upper endoscopy revealed mild gastric erythema and diffuse erythematous, hemorrhagic, friable mucosa with superficial, thick, adherent white exudate seen in the second portion of the duodenum, consistent with the diagnosis of HSP. We report on the clinical presentation of our patient, and review adult-onset HSP.

Human Parvoviruses

Parvovirus B19 (B19V) and human bocavirus 1 (HBoV1), members of the large Parvoviridae family, are human pathogens responsible for a variety of diseases. For B19V in particular, host features determine disease manifestations. These viruses are prevalent worldwide and are culturable in vitro, and serological and molecular assays are available but require careful interpretation of results. Additional human parvoviruses, including HBoV2 to -4, human parvovirus 4 (PARV4), and human bufavirus (BuV) are also reviewed. The full spectrum of parvovirus disease in humans has yet to be established. Candidate recombinant B19V vaccines have been developed but may not be commercially feasible. We review relevant features of the molecular and cellular biology of these viruses, and the human immune response that they elicit, which have allowed a deep understanding of pathophysiology.

Human parvovirus B19 antibodies induce altered membrane protein expression and apoptosis of BeWo trophoblasts

Human parvovirus B19 (B19) is harmful during pregnancy since it can be vertically transmitted to the developing fetus. In addition, the anti‑B19 antibodies induced by B19 infection are believed to have a cytopathic role in B19 transmission; however, knowledge regarding the effects of anti‑B19 antibodies during pregnancy is limited. To investigate the possible roles of anti‑B19 antibodies during pregnancy, the present study examined the effects of anti‑B19‑VP1 unique region (VP1u), anti‑B19‑VP2 and anti‑B19‑nonstructural protein 1 (NS1) immunoglobulin G (IgG) antibodies on BeWo trophoblasts. Briefly, BeWo trophoblasts were incubated with purified IgG against B19‑VP1u, B19‑VP2 and B19‑NS1. Subsequently, the expression of surface proteins and apoptotic molecules were assessed in BeWo trophoblasts using flow cytometry, ELISA and western blotting. The expression levels of human leukocyte antigen (HLA)‑G were significantly increased on BeWo trophoblasts treated with rabbit anti‑B19‑VP1u IgG, and were unchanged in those treated with rabbit anti‑B19‑NS1 and anti‑B19‑VP2 IgG, as compared with the control group. Furthermore, the expression levels of globoside (P blood group antigen) and cluster of differentiation (CD)29 (β1 integrin) were significantly increased in BeWo trophoblasts treated with rabbit anti‑B19‑NS1 and anti‑B19‑VP2 IgG, whereas only CD29 was also significantly increased in cells treated with anti‑B19‑VP1u IgG. In addition, the number of cells at sub‑G1 phase; caspase‑3 activity; and the expression of intrinsic and extrinsic apoptotic molecules, including Fas‑associated death domain protein, activated caspase‑8, activated caspase‑3, B‑cell lymphoma 2‑associated X protein, cytochrome c, apoptotic peptidase activating factor 1 and activated caspase‑9, were significantly increased in BeWo trophoblasts treated with anti‑B19‑VP1u and anti‑B19‑NS1 IgG. In conclusion, the present study demonstrated that antibodies against B19 may have a crucial role in pathological processes during pregnancy. These findings may help to elucidate the mechanisms underlying transmission of the B19 virus during pregnancy.

Granulomatosis with polyangiitis (Wegener's disease): An updated review of ocular disease manifestations

Granulomatosis with polyangiitis (GPA) is a potentially lethal systemic disorder that is characterized by necrotizing vasculitis of small arteries and veins. The respiratory system is most commonly affected in limited forms of the disease, however upper and lower respiratory system, systemic vasculitis, and necrotizing glomerulonephritis are the characteristic components of the disease triad. The peak incidence is observed at 64-75 years of age, with a prevalence of 8-10 per million depending on geographic location. In this review we focus on the ocular manifestations of the disease which occur in nearly in one third of the patients. In addition we describe the neuro-ophthalmic complications which occur in up to half of cases. We also discuss the current systemic treatment options including corticosteroids, cyclophosphamide, azathioprine, and the available biologic response modifiers including rituximab. The disease remains difficult to diagnose due to the generalized symptomatic presentation of patients with GPA. As a result, several sets of diagnostic criteria have been developed which include clinical, serological, and histopathological findings to varying extents. Early diagnosis and multi-specialty collaboration among physicians is necessary to adequately manage the disease and the potential complications that may result from drugs used in the treatment of the disease. Despite recent advances, more research is necessary to prevent the high rates of mortality from the disease itself and from therapeutic side effects.

Skin Rash and Microscopic Hematuria in a 10-Year-Old Caucasian Male

OBJECTIVE

Henoch-Schonlein purpura (HSP) is an acute, systemic, vasculitis with IgA-dominant immune deposits. With the emphasis on educational value of HSP, which is the most common form of vasculitis in children, we report an actual case from a 10-year-old boy.

METHOD

The patient presented with the chief complaint of a skin rash. His illness history, family medical history, physical examination, and relevant laboratory findings were summarized, followed by a question and possible answer format discussion.

RESULTS AND CONCLUSION

With the significant elevation of red blood cells in his urine and moderate to severe deposition of IgA in kidney biopsy, the patient was diagnosed with HSP nephritis. Renal symptoms, such as proteinuria and hematuria, are mostly the last to develop and determine the long-term prognosis in HSP patients. The patient is currently undergoing steroid treatment, which is the primary intervention for HSP as it spontaneously resolves in most of affected children.

Up-regulation of epithelial Na(+) channel ENaC by human parvovirus B19 capsid protein VP1

BACKGROUND

Clinical disorders caused by parvovirus B19 (B19V) infection include endothelial dysfunction with cardiac ischemia. The virus is effective in part by lysophosphatidylcholine-producing phospholipase A2 (PLA2) activity of B19V capsid protein VP1. Mechanisms compromising endothelial function include up-regulation of amiloride sensitive epithelial Na(+)-channel ENaC leading to endothelial cell stiffness. Regulators of ENaC include ubiquitin-ligase Nedd4-2. The present study explored whether VP1 modifies ENaC-activity.

METHODS

cRNA encoding ENaC was injected into Xenopus oocytes without or with cRNA encoding VP1. Experiments were made with or without coexpression of Nedd4-2. ENaC activity was estimated from amiloride (50 μM) sensitive current.

RESULTS

Injection of cRNA encoding ENaC into Xenopus oocytes was followed by appearance of amiloride sensitive current, which was significantly enhanced by additional injection of cRNA encoding VP1, but not by additional injection of cRNA encoding PLA2-negative VP1 mutant (H153A). The effect of VP1 on ENaC was mimicked by treatment of ENaC expressing oocytes with lysophosphatidylcholine (1 μg/ml). The effect of VP1 and lysophosphatidylcholine was not additive. ENaC activity was downregulated by Nedd4-2, an effect not reversed by VP1.

CONCLUSIONS

The B19V capsid protein VP1 up-regulates ENaC, an effect at least partially due to phospholipase A2 (PLA) dependent formation of lysophosphatidylcholine.

Vasculitis related to viral and other microbial agents

Vasculitis due to infection may occur as a consequence of the inflammation of vessel walls due to direct or contiguous infection, type II or immune complex-mediated reaction, cell-mediated hypersensitivity, or inflammation due to immune dysregulation triggered by bacterial toxin and/or superantigen production. As immunosuppressive therapy administered in the absence of antimicrobial therapy may increase morbidity and fail to effect the resolution of infection-associated vascular inflammation, it is important to consider infectious entities as potential inciting factors in vasculitis syndromes. The causality between infection and vasculitis has been established in hepatitis B-associated polyarteritis nodosa (HBV-PAN) and hepatitis C-associated (cryoglobulinemic) vasculitis (HCV-CV). The review summarizes the recent literature on the pathophysiological mechanisms and the approaches to the management of HBV-PAN and HCV-CV. Roles of other viral and microbial infections, which either manifest as vasculitic syndromes or are implicated in the pathogenesis of primary vasculitides, are also discussed.

Down-regulation of inwardly rectifying Kir2.1 K+ channels by human parvovirus B19 capsid protein VP1

Parvovirus B19 (B19V) has previously been shown to cause endothelial dysfunction. B19V capsid protein VP1 harbors a lysophosphatidylcholine producing phospholipase A2 (PLA2). Lysophosphatidylcholine inhibits Na(+)/K(+) ATPase, which in turn may impact on the activity of inwardly rectifying K(+) channels. The present study explored whether VP1 modifies the activity of Kir2.1 K(+) channels. cRNA encoding Kir2.1 was injected into Xenopus oocytes without or with cRNA encoding VP1 isolated from a patient suffering from fatal B19V-induced inflammatory cardiomyopathy or the VP1 mutant (H153A)VP1 lacking a functional PLA2 activity. K(+) channel activity was determined by dual electrode voltage clamp. In addition, Na(+)/K(+)-ATPase activity was estimated from K(+)-induced pump current (I(pump)) and ouabain-inhibited current (I(ouabain)). Injection of cRNA encoding Kir2.1 into Xenopus oocytes was followed by appearance of inwardly rectifying K(+) channel activity (I(K)), which was significantly decreased by additional injection of cRNA encoding VP1, but not by additional injection of cRNA encoding (H153A)VP1. The effect of VP1 on I K was mimicked by lysophosphatidylcholine (1 μg/ml) and by inhibition of Na(+)/K(+)-ATPase with 0.1 mM ouabain. In the presence of lysophosphatidylcholine, I K was not further decreased by additional treatment with ouabain. The B19V capsid protein VP1 thus inhibits Kir2.1 channels, an effect at least partially due to PLA2-dependent formation of lysophosphatidylcholine with subsequent inhibition of Na(+)/K(+)-ATPase activity.

Down-regulation of K⁺ channels by human parvovirus B19 capsid protein VP1

Parvovirus B19 (B19V) can cause inflammatory cardiomyopathy and endothelial dysfunction. Pathophysiological mechanisms involved include lysophosphatidylcholine producing phospholipase A2 (PLA2) activity of the B19V capsid protein VP1. Most recently, VP1 and lysophosphatidylcholine have been shown to inhibit Na(+)/K(+) ATPase. The present study explored whether VP1 modifies the activity of Kv1.3 and Kv1.5 K(+) channels. cRNA encoding Kv1.3 or Kv1.5 was injected into Xenopus oocytes without or with cRNA encoding VP1 isolated from a patient suffering from fatal B19V-induced myocarditis. K(+) channel activity was determined by dual electrode voltage clamp. Injection of cRNA encoding Kv1.3 or Kv1.5 into Xenopus oocytes was followed by appearance of Kv K(+) channel activity, which was significantly decreased by additional injection of cRNA encoding VP1, but not by additional injection of cRNA encoding PLA2-negative VP1 mutant (H153A). The effect of VP1 on Kv current was not significantly modified by transcription inhibitor actinomycin (10 μM for 36 h) but was mimicked by lysophosphatidylcholine (1 μg/ml). The B19V capsid protein VP1 inhibits host cell Kv channels, an effect at least partially due to phospholipase A2 (PLA) dependent formation of lysophosphatidylcholine.

Antibody-mediated enhancement of parvovirus B19 uptake into endothelial cells mediated by a receptor for complement factor C1q

Despite its strong host tropism for erythroid progenitor cells, human parvovirus B19 (B19V) can also infect a variety of additional cell types. Acute and chronic inflammatory cardiomyopathies have been associated with a high prevalence of B19V DNA in endothelial cells of the myocardium. To elucidate the mechanisms of B19V uptake into endothelium, we first analyzed the surface expression of the well-characterized primary B19V receptor P antigen and the putative coreceptors α5β1 integrins and Ku80 antigen on primary and permanent endothelial cells. The receptor expression pattern and also the primary attachment levels were similar to those in the UT7/Epo-S1 cell line regarded as functional for B19V entry, but internalization of the virus was strongly reduced. As an alternative B19V uptake mechanism in endothelial cells, we demonstrated antibody-dependent enhancement (ADE), with up to a 4,000-fold increase in B19V uptake in the presence of B19V-specific human antibodies. ADE was mediated almost exclusively at the level of virus internalization, with efficient B19V translocation to the nucleus. In contrast to monocytes, where ADE of B19V has been described previously, enhancement does not rely on interaction of the virus-antibody complexes with Fc receptors (FcRs), but rather, involves an alternative mechanism mediated by the heat-sensitive complement factor C1q and its receptor, CD93. Our results suggest that ADE represents the predominant mechanism of endothelial B19V infection, and it is tempting to speculate that it may play a role in the pathogenicity of cardiac B19V infection. Importance: Both efficient entry and productive infection of human parvovirus B19 (B19V) seem to be limited to erythroid progenitor cells. However, in vivo, the viral DNA can also be detected in additional cell types, such as endothelial cells of the myocardium, where its presence has been associated with acute and chronic inflammatory cardiomyopathies. In this study, we demonstrated that uptake of B19V into endothelial cells most probably does not rely on the classical receptor-mediated route via the primary B19V receptor P antigen and coreceptors, such as α5β1 integrins, but rather on antibody-dependent mechanisms. Since the strong antibody-dependent enhancement (ADE) of B19V entry requires the CD93 surface protein, it very likely involves bridging of the B19V-antibody complexes to this receptor by the complement factor C1q, leading to enhanced endocytosis of the virus.

[Wegener's granulomatosis]

Wegener's granulomatosis is a necrotizing inflammation of small and medium size vessels with granuloma formation. It is a very heterogeneous disease in respect of severity and clinical manifestation. While it can be a rapidly progressive disease with fatal ending, there are forms limited only to one organ. Diagnosis is supported by the positivity of anti-neutrophil cytoplasmatic antibody and the presence of the typical histological findings. Unfortunately, these examinations cannot confirm clinical suspicion relatively frequently. In addition, there may be only symptoms related to one single organ for a long time at the beginning of the disease and, therefore, one have to be aware of the clinical signs and symptoms of the different organ systems. This may allow us to make an early diagnosis and start treatment in time.

Parvovirus b19 associated hepatitis

Parvovirus B19 infection can present with myriads of clinical diseases and syndromes; liver manifestations and hepatitis are examples of them. Parvovirus B19 hepatitis associated aplastic anemia and its coinfection with other hepatotropic viruses are relatively underrecognized, and there is sufficient evidence in the literature suggesting that B19 infections can cause a spectrum of liver diseases from elevation of transaminases to acute hepatitis to fulminant liver failure and even chronic hepatitis. It can also cause fatal macrophage activation syndrome and fibrosing cholestatic hepatitis. Parvovirus B19 is an erythrovirus that can only be replicate in pronormoblasts and hepatocytes, and other cells which have globosides and glycosphingolipids in their membrane can also be affected by direct virus injury due to nonstructural protein 1 persistence and indirectly by immune mediated injury. The virus infection is suspected in bone marrow aspiration in cases with sudden drop of hemoglobin and onset of transient aplastic anemia in immunosuppressed or immunocompetent patients and is confirmed either by IgM and IgG positive serology, PCR analysis, and in situ hybridization in biopsy specimens or by application of both. There is no specific treatment for parvovirus B19 related liver diseases, but triple therapy regimen may be effective consisting of immunoglobulin, dehydrohydrocortisone, and cyclosporine.

The association between silica exposure and development of ANCA-associated vasculitis: systematic review and meta-analysis

BACKGROUND

Crystalline silica is among the environmental exposures associated with increased risk of autoimmune diseases, including rheumatoid arthritis, systemic sclerosis and systemic lupus erythematosus. Silica exposure has also been related to the development of ANCA-associated vasculitides (AAV), but past studies appear to conflict as to the presence and magnitude of the associated risks of disease. We aimed to conduct a systematic review of the existing studies and meta-analysis of their results.

METHODS

We searched EMBASE, MEDLINE and international scientific conference abstract databases for studies examining the association of silica exposure with AAV. Studies in English, French, or Spanish were included and those examining the association of silica with ANCA-positivity alone were excluded. We assessed study quality using the Newcastle-Ottawa Scale. We meta-analyzed the results using random effects models and tested for heterogeneity. We performed sensitivity and subgroup analyses, examining studies that adjusted for smoking and occupational risk factors as well as studies that analyzed by subtypes of AAV.

RESULTS

We identified 158 potential manuscripts and 3 abstracts related to silica exposure and risk of AAV. 147 were excluded after abstract review and 14 underwent detailed evaluation of full manuscript/abstract. After further application of exclusion criteria, 6 studies (all cases-controls) remained. The studies had moderate heterogeneity in selection of cases and controls, exposure assessment, disease definition and controlling for potential confounders. We found an overall significant summary effect estimate of silica "ever exposure" with development of AAV (summary OR 2.56, 95% CI 1.51-4.36), with moderate heterogeneity (I(2)=48.40%). ORs were similar for studies examining only MPA (OR 3.95, CI 95% 1.89-8.24), compared to those only studying GPA (OR 3.56, CI 95% 1.85-6.82).

CONCLUSION

Despite moderate heterogeneity among studies, the totality of the evidence after meta-analysis points to an association between silica exposure and risk for developing AAV.

Intravenous immunoglobulin therapy in vasculitic ulcers: a case of polyarteritis nodosa

Introduction

Polyarteritis nodosa (PAN) is a systemic necrotizing medium-size-vessel vasculitis with variable clinical manifestations. Diagnosis is confirmed by histology or angiography. The mainstay of treatment is corticosteroids alone or combined with cyclophosphamide (CYF).

Case report

Seventy-one-year-old female, follow-up started in 1997 at the age of 56 for suspected relapsing febrile viral exanthema. Skin biopsy was performed and the diagnosis of lymphomatoid papulosis was made, with complete response to treatment with dapsone. In 2005, she presented with arthralgia, lower limb (LL) edema, livedo reticularis and elevated erythrocyte sedimentation rate (ESR). PAN was confirmed on histology and visceral angiography; antineutrophil cytoplasmic antibodies (ANCA) were negative. She responded to prednisolone but relapsed in 2006. Twelve cycles of CYF were administered, with clinical, angiographic and analytical improvement. In 2008, a new relapse occured with LL neuropathic pain and ESR elevation. Electromyogram (EMG) confirmed axonal sensory polyneuropathy (PNP). Azathioprine was started with a poor response. A second EMG, 12 months later in 2009 still evidenced PNP, and nerve biopsy confirmed vasculitic neuropathy. In 2010, she had ulcers in LL and iron-deficient anemia. She started intravenous immunoglobulin (IVIG) for six cycles, achieving ulcer healing, absence of pain, no anemia and ESR normalization.

Discussion

IVIG therapy has proven benefit in Kawasaki disease, also showing efficacy in refractory ANCA-associated vasculitis. In PAN, only very few case reports show benefit. In this case, IVIG therapy induced total remission of LL ulcers and PNP, suggesting that it may be useful in selected cases of refractory PAN.

Complete remission of human parvovirus b19 associated symptoms by loxoprofen in patients with atopic predispositions

Two cases of women in their thirties with past histories of atopic dermatitis and allergic rhinitis developed a low grade fever, followed by a butterfly-shaped erythema, swelling of their fingers, and polyarthralgia. Despite such symptoms that overlap with those of systemic lupus erythematosus (SLE), the diagnostic criteria for SLE were not fulfilled. Due to positive results for human parvovirus B19 (HPV-B19) IgM antibodies in the serum, diagnoses of HPV-B19 infection were made in both cases. Although acetaminophen failed to improve their deteriorating symptoms, a nonsteroidal anti-inflammatory drug (NSAID), loxoprofen, completely removed the symptoms immediately after the administration. In those cases, since the patients were predisposed to atopic disorders, an increased immunological response based on the lymphocyte hypersensitivity was likely to be involved in the pathogenesis. The immunomodulatory property of NSAID was thought to repress such lymphocyte activity and thus provided a rapid and sustained remission of the disease.

The Molecular Biology and Treatment of Systemic Vasculitis in Children

Primary systemic vasculitides are rare in childhood but are associated with significant morbidity and mortality. The cause of the majority of vasculitides is unknown, although it is likely that a complex interaction between environmental factors, such as infections and inherited host responses, triggers the disease and determines the vasculitis phenotype. Several genetic polymorphisms in vasculitides have now been described, which may be relevant in terms of disease predisposition or development of disease complications. Treatment regimens continue to improve with the use of different immunosuppressive medications and newer therapeutic approaches such as biologic agents. This chapter reviews recent studies shedding light on the pathogenesis of vasculitis with emphasis on molecular biology where known, and summarizes current treatment strategies. We discuss new emerging challenges particularly with respect to the long-term cardiovascular morbidity for children with systemic vasculitis and emphasize the importance of future international multicenter collaborative studies to further increase and standardize the scientific base investigating and treating childhood vasculitis.

Recent aspects of vasculitis and future direction

Vasculitis is pathologically identified as specific cellular inflammation, vessel destruction, and tissue necrosis. Current classifications of vasculitis such as the Chapel Hill Classification (CHCC) and American College of Rheumatology (ACR) guidelines are not sufficiently adequate for clinicians to diagnose vasculitis. The biomarkers that are currently in clinical use such as PR3-ANCA and MPO-ANCA, only help in diagnosing small vessel vasculitis and their sensitivity and specificity are not sufficient. However, recent developments related to the pathogenesis and etiopathogenesis of vasculitis have the potential to contribute to new and improved biomarkers. The determination of diverse roles of ANCA and synergistic effects of infection, genetic, environmental factors and drugs on pathogenesis is quite important. The demonstration of a new autoantibody directed to hLAMP-2 and the resemblance to some microbial structures, in addition to the determination of the possible roles of hepatitis B and C on vasculitis are important findings. These hints may lead to new biomarker developments, providing a better method to diagnose vasculitis. The evidence on T cell immunity as circulatory and lesional will likely contribute to the development of new drugs for vasculitis.

Cutaneous polyarteritis nodosa in childhood: a case report and review of the literature

Polyarteritis nodosa is a rare vasculitis of childhood. Cutaneous PAN (cPAN) is limited to the skin, muscles, joints, and peripheral nerves. We describe a 7.5-year-old girl with cPAN presenting initially as massive cervical edema who later went on to develop subcutaneous nodules, livedo reticularis, myositis, arthritis, and mononeuritis multiplex. The use of corticosteroids resulted in initial clinical improvement, but symptom recurrence necessitated disease modifying antirheumatic drugs and biologic therapy. We review a further 119 reports of biopsy proven cPAN in the literature. A majority of patients (96.6%) had cutaneous involvement; musculoskeletal involvement was common and included both articular (58.0%) and muscular (42.9%) symptoms, and nervous system involvement was least common (18.5%). Corticosteroids were used in the majority of patients (85.7%), followed by use of disease modifying antirheumatic drugs (33.0%), nonsteroidal anti-inflammatory drugs (10.7%), and intravenous immunoglobulin (9.8%). Therapy of cPAN with biologics has only been reported in 2 patients, and we report the first patient treated with Rituximab. A diagnosis of cPAN should be considered in a child with fever, vasculitic rash, and musculoskeletal symptoms. Most children respond to corticosteroids and have a benign course, but some require disease modifying antirheumatic drugs and biologic therapies.

Do infections facilitate the emergence of systemic sclerosis?

Systemic sclerosis (SSc) is an autoimmune disease characterized by vascular obliteration, excessive extracellular matrix deposition, and fibrosis of the connective tissues of the skin, lungs, gastrointestinal tract, heart, and kidneys. Infections are believed to play a role in the immunopathogenesis of SSc. A number of infectious agents have been proposed as possible triggering factors in SSc. Homology between viruses and autoantibody targets suggests that molecular mimicry may play a role in the initiation of antibody response in disorders characterized by diffuse vascular disease, mainly SSc. Four pathogenic hypotheses have been proposed: molecular mimicry, endothelial cell damage, super-antigens, and microchimerism. Although several studies have provided important information linking infectious agents to SSc, a clear, direct association is still missing. It is very likely that the infectious agents are cofactors in a specific hormonal and environmental setting that mounts an immune reaction, which leads to the emergence of the disorder.

Medium-size-vessel vasculitis

Medium-size-artery vasculitides do occur in childhood and manifest, in the main, as polyarteritis nodosa (PAN), cutaneous PAN and Kawasaki disease. Of these, PAN is the most serious, with high morbidity and not inconsequential mortality rates. New classification criteria for PAN have been validated that will have value in epidemiological studies and clinical trials. Renal involvement is common and recent therapeutic advances may result in improved treatment options. Cutaneous PAN is a milder disease characterised by periodic exacerbations and often associated with streptococcal infection. There is controversy as to whether this is a separate entity or part of the systemic PAN spectrum. Kawasaki disease is an acute self-limiting systemic vasculitis, the second commonest vasculitis in childhood and the commonest cause of childhood-acquired heart disease. Renal manifestations occur and include tubulointerstitial nephritis and renal failure. An infectious trigger and a genetic predisposition seem likely. Intravenous immunoglobulin (IV-Ig) and aspirin are effective therapeutically, but in resistant cases, either steroid or infliximab have a role. Greater understanding of the pathogenetic mechanisms involved in these three types of vasculitis and better long-term follow-up data will lead to improved therapy and prediction of prognosis.

Human parvovirus b19 infection in patients with coronary atherosclerosis

BACKGROUND AND AIMS

The identification of possible pathogens for an infectious etiology of atherosclerotic coronary artery disease (CAD) is an expanding field. The present study was undertaken to explore the role of parvovirus B19, a potent infectious agent.

METHODS

A total of 565 patients were analyzed (90 patients with CAD, and 475 controls). Serologic analysis for human paravovirus B19 (B19) specific IgM and IgG was carried out in all patients. In addition, tissue specimens were obtained from five patients who received heart transplants. Direct in situ polymerase chain reaction (PCR) and immunocytochemistry were performed in the samples to localize B19 DNA.

RESULTS

Enzyme immunoassay showed that the seropositive rate of anti-B19 IgG in patients with CAD was 1.5- to 2.7-fold more frequent than in healthy controls. Clinical characteristics did not affect the prevalence of seropositivity for B19. However, anti-B19 IgM and B19-specific DNA were not detected in healthy or individuals with CAD. Furthermore, nonradioactive in situ PCR found that the majority of B19-specific DNA was located in the endothelial cells of the thickened intima.

CONCLUSIONS

Our results first demonstrate a seroepidemiological and histopathological association between chronic B19 infection and CAD, suggesting that B19 infection may have a potential role in the pathogenesis of coronary atherosclerosis.