Plasma carnitine ester profile in homozygous and heterozygous OCTN2 deficiency.

The carnitine ester spectrum was studied using ESI tandem mass spectrometry in a 2.5-year-old male Roma child with homozygous deletion of 844C of the SLC22A5 gene, presenting with hepatopathy and cardiomyopathy. Besides the dramatic decrease of plasma free carnitine (1.38 vs 32.7 mumol/L in controls) all plasma carnitine esters were severely decreased in the proband: the total esters were 31.4% of the controls. In three heterozygous siblings the free carnitine level was 62.3% of the normal controls, while the levels of the individual carnitine esters ranged between 15.5% and 163% (average 70.9%). The heterozygous parents exhibited the same pattern. The proband was supplemented with 50 mg/kg per day of L-carnitine oral solution. After 2 months of treatment, his hepatomegaly, elevated transaminases and the pathological cardiac ultrasound parameters normalized. The plasma free carnitine rose to 12.8 mumol/L (39% of the controls). All of the carnitine esters also increased; however, the individual esters were still 8.5-169.7% of the controls (average 55.5%). After 13 months of treatment there was a further increase in free carnitine (15.9 mumol/L) as well as in the level of the individual esters, ranging between 16.1% and 140.3% of the controls (average 66.9%). The data presented here show that, besides the dramatic decrease of free carnitine, the carnitine ester metabolism is also affected in OCTN2 deficiency; the replenishment of the pools under treatment is slow. Despite an impressive clinical improvement, the carnitine metabolism can be still seriously affected.

No influence of SLC22A4 C6607T and RUNX1 G24658C genotypic variants on the circulating carnitine ester profile in patients with rheumatoid arthritis.

OBJECTIVE: In a Japanese study, the C6607T SNP mapping to intron 1 of the SLC22A4 gene encoding the OCTN1 protein was found to be associated with rheumatoid arthritis. Similarly, a G24658C transversion in intron 6 of the gene encoding the RUNX1 transcription factor that regulates OCTN1 and also likely OCTN2 expression was also found to confer susceptibility to the disease. METHODS: We investigated the prevalence of these two SNPs by RFLP analysis in a cohort of 209 Hungarian rheumatoid arthritis patients, and 217 healthy controls. Since both the OCTN1 and OCTN2 play a central role in the transmembrane transport of carnitine, we also determined the quantitative serum carnitine ester profile by ESI tandem mass spectrometry. RESULTS: No statistically significant differences were found comparing the genotype prevalence rates between the patients and the controls for either the SLC22A4 genotypes or for the RUNX1 SNPs. There was no significant difference in the serum carnitine ester profile when the rheumatoid arthritis patients were compared with the controls; furthermore, no significant difference in the carnitine esters could be detected when genotype specific subgroups of the patients and the controls were studied. CONCLUSION: Data of the current study do not confirm the universal and population independent susceptibility role of the SLC22A4 C6607T and RUNX1 G24658C variants for rheumatoid arthritis; furthermore, the data presented here show, that there are no significant carnitine-metabolism associated functional consequences of the different genotypes evidenced by the lack of detectable differences in the carnitine ester profiles.

Prevalence of functional haplotypes of the peptidylarginine deiminase citrullinating enzyme gene in patients with rheumatoid arthritis: no influence of the presence of anti-citrullinated peptide antibodies.

OBJECTIVE: Citrullinated peptides produced by enzymatic deimination of arginine residues in proteins by peptidylarginine deiminases are of particular interest in the pathogenesis of rheumatoid arthritis (RA). One type of citrullinated protein - the cyclic citrullinated peptide - is the target of the anti-cyclic citrullinated peptide antibody, the most sensitive and specific autoantibody in RA. The peptidylarginine deiminase type 4 (PADI4) gene, which codes one of the PADI enzyme isotypes, has genetic variants that confer susceptibility to RA in Asian, but not in European populations. METHODS: Genetic associations were examined in 214 Hungarian RA patients characterized for the presence of anti-CCP and rheumatoid factor. The patients were characterized for the existing haplotypes of the PADI4 gene (defined by the combinations of 4 exonic padi4_89: 163G/A, padi4_90: 245T/C, padi4_92: 335C/G, padi4_104: 349T/C and 2 intronic padi4_94: 17535226C/T and padi4_102: 17546809C/T variants) by the PCR-RFLP method. RESULTS: None of the PADI4 haplotypes was accumulated in RA patients. One new finding was that we also did not detect the accumulation of any haplotypes either in the anti-CCP or in the RF-positive subgroups of patients. CONCLUSION: The data presented here show that none of the naturally occurring haplotypes of the PADI4 gene conferred susceptibility to RA in an average group of Hungarian patients; this is in agreement with findings for other European populations. In addition, none of the functional PADI4 haplotypes were associated with the pathologic immune response, which was evidenced by the absence of accumulation of anti-CCP-positive subjects in the specific PADI4 haplotypes.

Insect cuticle, an in vivo model of protein trafficking.

In the course of this study more than 20 proteins have been isolated from the larval cuticle of Manduca sexta. Synthesis, secretion, transport and accumulation of four particular proteins, representative members of four characteristic groups, were followed during metamorphosis by immunoblot and immuncytochemical methods and are described in detail in this paper. We established that only some of the proteins of the soft cuticle of Lepidopteran larvae are synthesized in epidermal cells at the beginning of the larval stages and are digested during the moulting period (MsCP29). Other proteins (MsCP30/11) are secreted into the cuticle by the epidermal cells in different forms during various developmental stages. Some proteins are secreted apically during the feeding period, but before ecdysis they are then taken up by epidermal cells and transported in a basolateral direction back into the hemolymph and saved in an immunologically intact form by the fat body cells (MsCP12.3). Some cuticle proteins have a non-epidermal origin. They are transported from the hemolymph into the cuticle. Before and during ecdysis these molecules reappear in the hemolymph and are detectable again in the pupal cuticle (MsCP78). Our data prove that the cuticle is not a non-living part of the insect body: it is not only an inert, protective armor, but maintains a continuous and dynamic metabolic connection with the other organs of the organism.