Valproic acid inhibits interferon-γ production by NK cells and increases susceptibility to Listeria monocytogenes infection.

Valproic acid (VPA) is a drug commonly used for epileptic seizure control. Recently, it has been shown that VPA alters the activation of several immune cells, including Natural Killer (NK) cells, which play an important role in the containment of viruses and intracellular bacteria. Although VPA can increase susceptibility to extracellular pathogens, it is unknown whether the suppressor effect of VPA could affect the course of intracellular bacterial infection. This study aimed to evaluate the role of VPA during Listeria monocytogenes (L.m) infection, and whether NK cell activation was affected. We found that VPA significantly augmented mortality in L.m infected mice. This effect was associated with increased bacterial load in the spleen, liver, and blood. Concurrently, decreased levels of IFN-γ in serum and lower splenic indexes were observed. Moreover, in vitro analysis showed that VPA treatment decreased the frequency of IFN-γ-producing NK cells within L.m infected splenocytes. Similarly, VPA inhibited the production of IFN-γ by NK cells stimulated with IL-12 and IL-18, which is a crucial system for early IFN-γ production in listeriosis. Finally, VPA decreased the phosphorylation of STAT4, p65, and p38, without affecting the expression of IL-12 and IL-18 receptors. Altogether, our results indicate that VPA increases the susceptibility to Listeria monocytogenes infection and suggest that NK cell is one of the main targets of VPA, but further work is needed to ascertain this effect.

The Frequency and Clinical Features of Hypersensitivity Reactions to Antiepileptic Drugs in Children: A Prospective Study.

BACKGROUND: Antiepileptic drugs (AEDs) can cause hypersensitivity reactions during childhood. Studies report a wide clinical spectrum of reactions with AED use, ranging from a mild rash to severe cutaneous reactions. OBJECTIVE: To determine the prevalence and clinical features of AED hypersensitivity reactions during childhood. METHODS: Patients in our pediatric neurology clinic who were prescribed an AED for the first time between November 2015 and November 2016 were monitored and those who developed skin rash during this period were evaluated. RESULTS: A total of 570 patients were evaluated. The median age of the patients was 8.86 (interquartile range, 4.2-13.7) years, and 55.8% (318) of patients were male. The most frequently used AEDs were valproic acid (42%, n = 285) and carbamazepine (20.4%, n = 116). Hypersensitivity reactions to AEDs developed in 5.4% of patients. Of these patients, 71% (29) had cutaneous drug reactions and 29% (9) had severe cutaneous drug reactions; 61.3% (19) were using aromatic AEDs, and the leading suspected AED was carbamazepine (45.2%). Comparison of patients who did and did not develop AED hypersensitivity showed that hypersensitivity was more frequent among patients who were younger than 12 years, who used aromatic AEDs, or who used multiple AEDs. In addition, according to regression analysis results, aromatic AED use significantly increased the risk of AED hypersensitivity (P < .001). CONCLUSIONS: Although allergic reactions to AEDs are rare, they are of significance because they can cause life-threatening severe cutaneous drug reactions. Therefore, patients receiving AEDs, especially aromatic AEDs, must be monitored closely.

Secretion of MIP-1ß and MIP-1α by CD8(+) T-lymphocytes correlates with HIV-1 inhibition independent of coreceptor usage.

CD8(+) T-lymphocytes can utilize noncytolytic mechanisms to suppress HIV-1 replication through the secretion of soluble factors. The secretion of MIP-1ß, MIP-1α, IP-10, MIG, IL-1α, and interferon gamma correlated most strongly with soluble noncytolytic suppression (p<0.0001). Since the noncytolytic response is impaired by histone hyperacetylation, we examined the ability of histone hyperacetylation to alter the expression of immune-related genes. MIP-1α and IP-10 were also among the genes that were down-regulated by histone hyperacetylation. We define a multifactorial cytokine profile of CD8(+) T-lymphocytes capable of mediating noncytolytic suppression of CXCR4-tropic HIV-1 replication.

Genetic basis for idiosyncratic reactions to antiepileptic drugs.

PURPOSE OF REVIEW: In recent years, there has been an explosion of genetic research in epilepsy, including a search for genetic markers of adverse reactions to antiepileptic drugs. This article will focus on recent findings concerning genetic factors affecting susceptibility to idiosyncratic reactions to antiepileptic drugs. RECENT FINDINGS: Recent studies have investigated the role of genetic factors in the development of antiepileptic drug-induced cutaneous reactions, carbamazepine and valproate-induced liver toxicity, vigabatrin-induced visual field defects, and antiepileptic drug-induced teratogenicity. The greatest progress has been an improved definition of the role of human leukocyte antigen-related genes as predictors of the risk of serious antiepileptic drug-induced cutaneous reactions. This has led to the recommendation that patients of Asian ancestry be tested for the HLA-B*1502 allele, in order to identify those at high risk of developing Stevens-Johnson syndrome and toxic epidermal necrolysis after administration of carbamazepine and, possibly, phenytoin and other antiepileptic drugs. SUMMARY: Future research will probably lead to discovery of additional genetic predictors of susceptibility to adverse reactions to antiepileptic drugs. Identification of genetic markers should, in turn, allow unravelling of the molecular mechanisms underlying these reactions. Ultimately, these advances should lead not only to improved personalization of therapy but also to development of safer drugs.

[Acute reversible liver necrosis after valproate therapy (immunologic hypersensitivity)]. / Akute Reversible Lebernekrose nach Valproat-Behandlung (immunologisch bedingte Idiosynkrasie).

We describe a case of a 9-year-old boy with the severe acute liver injury caused by idiosyncrasy after the administration of valproate. The liver biopsy performed during the first days after the onset of the disease revealed the necrosis of more than 50% of hepatocytes but the injury was almost fully reversible which was well demonstrated by the second biopsy five months later. After five years an evidence for the immunologic idiosyncrasy caused by valproate was still present, which was demonstrated in vitro by blastic transformation of lymphocytes from the patient. The boy is quite healthy and epilepsy is under control of suximide. The family was informed that the boy could be treated with valproate never more.

Studies on the reactivity of acyl glucuronides--III. Glucuronide-derived adducts of valproic acid and plasma protein and anti-adduct antibodies in humans.

The major metabolite of the anti-epileptic agent valproic acid (VPA) is its acyl glucuronide conjugate (VPA-G), which undergoes non-enzymic, pH-dependent rearrangement via acyl migration to a mixture of beta-glucuronidase-resistant forms (collectively VPA-G-R). We have compared the reactivity of VPA-G and VPA-G-R towards covalent VPA-protein adduct formation by incubation in buffer, human serum albumin (HSA) and fresh human plasma at pH 7.4 and 37 degrees. In all three media, the predominant reaction of VPA-G over 30 hr was rearrangement to VPA-G-R (ca. 24%). Hydrolysis was quite minor (ca. 2%) and covalent adduct formation negligible (when protein was present). On the other hand, both hydrolysis (ca. 27%) and adduct formation (ca. 7%) were extensive when VPA-G-R was incubated with HSA or plasma. These data do not support a transacylation mechanism for VPA-protein adduct formation, since this pathway should be much more highly favoured by VPA-G (an acyl-substituted acetal) than VPA-G-R (simple esters). VPA-protein adducts were found in the plasma of epileptic patients taking VPA chronically (mean 0.77 +/- SD 0.63 microgram VPA equivalents/mL, N = 17). An enzyme linked immunosorbent assay was developed, using HSA modified by incubation with VPA-G-R, to test the immunoreactivity of the patients' plasma. Of 57 patients tested, nine showed measurable levels of antibodies to these adducts, but the titres were very low, with no difference in response to modified and unmodified protein detectable at plasma dilutions of 1:16 or greater. These results suggest that the VPA-protein adducts have little immunogenicity, and are in agreement with clinical observations that drug hypersensitivity responses have not been associated with VPA therapy. Thus, although the in vitro data show that VPA-G is an example of a relatively unreactive acyl glucuronide, covalent VPA-plasma protein adducts and anti-adduct antibodies are nonetheless formed in vivo, at least in some patients on chronic therapy with the drug.