Interleukin-12 (-1188) A/C and interferon-γ (+874) A/T gene polymorphisms in subacute sclerosing panencephalitis patients

Subacute sclerosing panencephalitis

Subacute sclerosing panencephalitis (SSPE) is a slowly progressive brain disorder caused by mutant measles virus. SSPE affects younger age groups. SSPE incidence is proportional to that of measles. High-income countries have seen substantial decline in SSPE incidence following universal vaccination against measles. SSPE virus differs from wild measles virus. Measles virus genome recovered from the autopsied brain tissues demonstrates clustered mutations in virus genome particularly in the M gene. These mutations destroy the structure and functioning of the encoded proteins. Complete infectious virus particle has rarely been recovered from the brain. Human neurons lack required receptor for entry of measles virus inside the neurons. Recent in vitro studies suggest that mutations in F protein confer hyperfusogenic properties to measles virus facilitating transneuronal viral spread. The inflammatory response in the brain leads to extensive tissue damage. Clinically, SSPE is characterized by florid panencephalitis. Clinically, SSPE is characterized by cognitive decline, periodic myoclonus, gait abnormalities, vision loss, and ultimately to a vegetative state. Chorioretinitis is a common ocular abnormality. Electroencephalography (EEG) shows characteristic periodic discharges. Neuroimaging demonstrates periventricular white matter signal abnormalities. In advanced stages, there is marked cerebral atrophy. Definitive diagnosis requires demonstration of elevated measles antibody titers in cerebrospinal fluid (CSF). Many drugs have been used to stabilize the course of the disease but without evidence from randomized clinical trials. Six percent of patients may experience prolonged spontaneous remission. Fusion inhibitor peptide may, in the future, be exploited to treat SSPE. A universal vaccination against measles is the only proven way to tackle this menace currently.

Genetic modifications of cytokine genes and Toxoplasma gondii infections in pregnant women

PURPOSE

Toxoplasma gondii causes one of the most common intrauterine infections worldwide, thus being a severe threat during pregnancy. IL1, IL6, IL10, IL12, and TNF-α cytokines were reported to be involved in immune responses to infections with T. gondii. The research was aimed to reveal relationships between genetic changes within the polymorphisms of these cytokine genes and the incidence of T. gondii infection among pregnant women, as well as congenital transmission of the parasite to the foetuses of their infected mothers.

METHODS

The primary study was performed in 148 Polish pregnant women, including 74 T. gondii-infected patients and 74 age-matched uninfected individuals; and further analysis - among the additional 142 pregnant women. Genotypes within IL1A -889 C>T, IL1B +3954 C>T, IL6 -174 G>C, IL10 -1082 G>A, IL12B -1188 A>C and TNFA -308 G>A single nucleotide polymorphisms (SNPs) were determined, using self-designed nested PCR-RFLP assays. Randomly selected PCR products, representing distinct genotypes in the analyzed polymorphisms, were confirmed by sequencing, using the Sanger method. A statistical analysis was carried out of relationships between genetic alterations within studied SNPs and the occurrence of T. gondii infection, using the following tools: cross-tabulation, Pearson's Chi-square test and the logistic regression model to estimate genetic models of inheritance. A power analysis of statistically significant outcomes was performed by Cramér's V test.

RESULTS

A multiple-SNP analysis showed TC haplotype for IL1A and IL1B SNPs to be significantly associated with a decreased risk of the parasitic infection (OR 0.41, P≤0.050). The association remained important after power analysis (Cramér's V = 0.39, χ² = 7.73, P≤0.050), and the additional analysis with larger groups of patients (OR 0.47, P≤0.050). Moreover, the CCCAGA complex variants were for all the studied polymorphisms at an increased risk of T. gondii infection (OR 8.14, P≤0.050), although this strong relationship was not significant in the further analysis (Cramér's V = 0.76, χ² = 26.81, P = 0.310). Regarding the susceptibility to congenital transmission of T. gondii from mothers to their foetuses among the infected pregnant women, the presence of GA heterozygotic status within IL10 polymorphism significantly increased the risk of parasitic transmission (OR 5.73 in the codominant model and OR 5.18 in the overdominant model; P≤0.050). The correlation stayed important in the power analysis (Cramér's V = 0.29, χ² = 6.03, P≤0.050), although it was non-significant in larger groups of patients. Important relationships specific for the first study cohort remained non-significant in the second group of studied pregnant women.

CONCLUSIONS

Within the analyzed cohort of Polish pregnant women, the genetic modifications from SNPs of genes, encoding both the proinflammatory IL1α, IL1β, IL6, IL12 and TNF-α, and anti-inflammatory IL10 cytokines, may have been associated with susceptibility to T. gondii infection. It is the first study on the contribution of cytokine genes polymorphisms to the occurrence of T. gondii infection during pregnancy. Further studies for other populations of pregnant women would be justified to reveal a detailed role of the analyzed polymorphisms for the occurrence of T. gondii infections during pregnancy.

Subacute sclerosing panencephalitis and immune thrombocytopenia: More than a coincidence?

Subacute sclerosing panencephalitis (SSPE) is a progressive disease caused by persistent measles virus (MV). It has an incidence of 0.4-2.0/million in Turkey. Immune thrombocytopenia (ITP) is a bleeding disorder whose estimated incidence is 4.2/100.000 person/years in the pediatric age group. We observed three cases with ITP in our cohort of 315 pediatric SSPE cases, an incidence higher than coincidentally expected in the general population. We hypothesize an association between SSPE and ITP. Our three cases had measles 1-2 years before the onset of ITP and 8-10 years before first symptoms of SSPE. A common immunogenetic background creating susceptibility to infection and autoimmunity might play a role. Alternatively, chronic antigenic stimulation by the MV leading to synthesis of cross-reacting antibodies against platelets, or treatment of ITP with immunoglobulins or steroids might affect or alter the development and manifestation of SSPE. The co-occurrence of these two disorders of viral and immune pathogenesis may draw attention to similar observations and provide clues for their mechanisms.