Analysis of viral infection in patients with IgA nephropathy

Infection-Related Focal Segmental Glomerulosclerosis in Children

Focal segmental glomerulosclerosis (FSGS) is the most common cause of steroid resistant nephrotic syndrome in children. It describes a unique histological picture of glomerular damage resulting from several causes. In the majority of patients the causing agent is still unknown, but in some cases viral association is evident. In adults, the most established FSGS causing virus is the human immune-deficiency virus, which is related to a collapsing variant of FSGS. Nevertheless, other viruses are also suspected for causing a collapsing or noncollapsing variant, for example, hepatitis B virus, parvovirus B19, and Cytomegalovirus. Although the systemic infection mechanism is different for these viruses, there are similarities in the pathomechanism for the induction of FSGS. As the podocyte is the key structure in the pathogenesis of FSGS, a direct infection of these cells or immediate damage through the virus or viral components has to be considered. Although viral infections are a very rare cause for FSGS in children, the treating pediatric nephrologist has to be aware of a possible underlying infection, as this has a relevant impact on therapy and prognosis.

Viruses and collapsing glomerulopathy: a brief critical review

BACKGROUND

Collapsing glomerulopathy may occur in an idiopathic (primary) form and in association with a wide spectrum of infectious and inflammatory conditions and medications. The association of collapsing glomerulopathy with human immunodeficiency virus (HIV)-1 infection is well established; less certain is the association with other viral infections.

METHODS

We searched PubMed for articles in all languages that addressed glomerulopathies associated with parvovirus B19, cytomegalovirus (CMV), Epstein-Barr virus (EBV), hepatitis C virus (HCV) and simian virus 40 (SV40).

RESULTS

Case reports and small-case series link infection with these common viruses and glomerular injury. The evidence for a pathogenic role is generally stronger for glomerulonephritis than for collapsing glomerulopathy.

CONCLUSIONS

The evidence linking collapsing glomerulopathy with CMV is relatively strong but not yet conclusive, while the evidence for a pathogenic role for EBV and parvovirus B19 is weaker.

Relationship between tonsils and IgA nephropathy as well as indications of tonsillectomy

Although there are many papers about IgA nephropathy (IgAN) and tonsils, respectively, reviews about the relationship between tonsils, tonsillitis, tonsillectomy, and IgAN are limited. In this review, we introduced the structure, development, and function of tonsils, difference of tonsils with and without IgAN, consistency of both tonsillar IgA and glomerular IgA, the effect of tonsil stimulation, tonsil infection, and tonsillectomy on IgAN showed some evidences in which tonsils were closely related to IgAN and polymeric IgA1 deposited in glomerular mesangium were at least in part of tonsillar origin. Tonsillectomy can improve the urinary findings, keep stable renal function, improve mesangial proliferation and IgA deposit, have a favorable effect on long-tern renal survival in some IgAN patients, and do not cause significant immune deficiency and do not increase incidence of the upper respiratory tract infections, and can be used as a potentially effective treatment. The indications of tonsillectomy in patients with IgAN include mainly the deterioration of urinary findings after tonsillar infection, mild or moderate renal damage. However, tonsillectomy may not be enough and may not change the prognosis in IgAN patients with marked renal damage.

Detection of Epstein-Barr virus in tonsillar tissue of children and the relationship with recurrent tonsillitis

Recurrent tonsillitis has been the subject of much investigation. Events considered to predispose to or cause recurrent tonsillitis (RT) include the misuse of antibiotic therapy in acute bouts, alterations in the microflora, structural changes in crypt epithelium and certain viral infections. Epstein-Barr Virus (EBV) infection usually occurs in early childhood and can persist in palatine tonsil lymphocytes to induce tonsillitis at a later date. We have examined the presence of EBV in palatine tonsils in order to assess the relationship between this virus and recurrent acute tonsillitis. Tonsils were obtained from 85 patients, 2--14 years old (mean 5.6 years old) who underwent tonsils and adenoid (T&A) removal because of recurrent tonsillitis (RT) or T&A hypertrophy (TH). Tissues specimens were processed for non-isotopic in situ hybridization (ISH) using EBER 1/2 oligonucleotides (EBER RNA). The indications for surgery were RT in 42 patients and TH in 43 patients. In 25 out of 85 cases (29.4%) a positive EBER RNA reaction (15 RT and 33 TH) was found. The chi(2)-test showed no statistically significant difference in frequency of positive results between RT and TH group. We conclude that tonsils of children can be colonized by EBV and that the virus may be implicated in RT and TH.