Helicobacter pylori induces in-vivo expansion of human regulatory T cells through stimulating interleukin-1ß production by dendritic cells.

Helicobacter pylori is one of the most common infections in the world. Despite inciting inflammation, immunological clearance of the pathogen is often incomplete. CD4(+) CD25(hi) forkhead box protein 3 (FoxP3(+)) regulatory T cells (T(regs)) are potent suppressors of different types of immune responses and have been implicated in limiting inflammatory responses to H. pylori. Investigating the influence of H. pylori on T(reg) function and proliferation, we found that H. pylori-stimulated dendritic cells (DCs) induced proliferation in T(regs) and impaired their suppressive capability. This effect was mediated by interleukin (IL)-1ß produced by H. pylori-stimulated DCs. These data correlated with in-vivo observations in which H. pylori(+) gastric mucosa contained more T(regs) in active cell division than uninfected stomachs. Inciting local proliferation of T(regs) and inhibiting their suppressive function may represent a mechanism for the chronic gastritis and carcinogenesis attributable to H. pylori.

Placenta-derived MSCs are partially immunogenic and less immunomodulatory than bone marrow-derived MSCs.

Over the past few years, mesenchymal stem cells (MSCs) have become of increasing interest for use in the field of regenerative medicine. To date, bone marrow (BM) has been the main source of MSCs (BM-MSCs) for both experimental and clinical studies. However, the use of MSCs derived from BM can be problematic, due to the low number of MSCs found in bone marrow aspirates and the invasive procedure associated with obtaining them. We aimed to develop a method of obtaining high numbers of purified MSCs from placental tissue with minimal expansion and to characterize their phenotype and function relative to BM-MSCs. We show here that placenta-derived MSCs (PD-MSCs) can be isolated with high numbers from whole placental tissue. However, PD-MSCs isolated from whole tissue were often found to be a mixed population of both maternal and neonatal cells. The immunological properties of PD-MSCs and BM-MSCs were compared. PD-MSCs were found to express lower levels of HLA class I and higher levels of PDL-1 and CD1a, compared to BM-MSCs. HLA-DR became upregulated in PD-MSCs following treatment with IFNγ, whereas BM-MSCs expressed constitutively low levels of HLA-DR. Whilst untreated or IFNγ-treated BM-MSCs were incapable of stimulating T cells, we observed a small T cell proliferation in response to the highest concentration of PD-MSCs when treated with IFNγ. It was noted that BM-MSCs were more immunomodulatory than PD-MSCs in this study. We therefore suggest that BM-MSCs may be better candidates for use in commercial regenerative or transplantation medicine.

Relative resistance of human CD4(+) memory T cells to suppression by CD4(+) CD25(+) regulatory T cells.

Successful expansion of functional CD4(+) CD25(+) regulatory T cells (T(reg)) ex vivo under good manufacturing practice conditions has made T(reg) -cell therapy in clinical transplant tolerance induction a feasible possibility. In animals, T(reg) cells home to both transplanted tissues and local lymph nodes and are optimally suppressive if active at both sites. Therefore, they have the opportunity to suppress both naïve and memory CD4(+) CD25(-) T cells (Tresp). Clinical transplantation commonly involves depleting therapy at induction (e.g. anti-CD25), which favors homeostatic expansion of memory T cells. Animal models suggest that T(reg) cells are less suppressive on memory, compared with naïve Tresp that mediate allograft rejection. As a result, in the context of human T(reg) -cell therapy, it is important to define the effectiveness of T(reg) cells in regulating naïve and memory Tresp. Therefore, we compared suppression of peripheral blood naïve and memory Tresp by fresh and ex vivo expanded T(reg) cells using proliferation, cytokine production and activation marker expression (CD154) as readouts. With all readouts, naïve human Tresp were more suppressible by approximately 30% than their memory counterparts. This suggests that T(reg) cells may be more efficacious if administered before or at the time of transplantation and that depleting therapy should be avoided in clinical trials of T(reg) cells.

Aspirin-treated human DCs up-regulate ILT-3 and induce hyporesponsiveness and regulatory activity in responder T cells.

Mature dendritic cells (mDCs) are potent antigen presenting cells, but immature DCs (iDCs) have been shown to have reduced antigen stimulatory capacity. Different strategies have been investigated to augment the tolerogenic capacity of dendritic cells (DCs). We demonstrate that in aspirin-treated human DCs, there is reduced expression of CD1a, HLA-DR and CD86, up-regulation of ILT-3 expression and marginal increases in PDL-1. Aspirin-treated DCs are partially resistant to phenotypic changes following maturational stimuli, such as lipopolysaccharide (LPS) or TNFalpha, IL-1alpha and PGE2. Aspirin-treated DCs demonstrate normal endocytic function, but have a reduced ability to stimulate allogeneic T cells, which is comparable to iDCs. Furthermore, they induce hyporesponsiveness and regulatory activity in responder naïve and memory T cells; for naïve T cells this is achieved more quickly and efficiently than with iDCs. We investigated the mechanism of this regulatory activity and found that both cell-cell contact and inhibitory cytokine activity are involved, although no one cytokine predominates in importance. Blocking ILT-3 or IL-12 does not diminish the capacity of these DCs to induce regulation or Foxp3 expression on the regulatory T cells. Results demonstrate that aspirin-treated DCs display tolerogenic potential, which is of interest in their therapeutic potential in reducing chronic allograft rejection.

HLA class II allele frequencies in type 1A diabetes mellitus Slovak patients.

BACKGROUND: Diabetes mellitus type 1A (DM-1A) is an autoimmune disease in which the immune response is directed to pancreatic islet cells. DM-1A occurs in genetically predisposed individuals. Among type 1A diabetes associated genes, those of the HLA region have the greatest effect. OBJECTIVES: The aim of our study was to obtain a comprehensive survey of the HLA-DRB1 and HLA-DQB1 allele frequencies in Slovak patients suffering from DM-1A. METHODS: HLA class II genotyping was performed on genomic DNA by the PCR-SSP method according to the 12th Workshop protocol. RESULTS: Our report gives the first presentation of the distribution of HLA-DRB1 alleles (including complete DRB1*04 subtypes) and that of HLA-DQB1 alleles in the Slovak diabetic patients diagnosed at 0-18 years of age. Susceptibility is significantly associated with the alleles DQB1*0302 (OR = 7.8), DRB1*04 (OR = 4.9), DRB1*0301 (OR = 4.2) and DQB1*02 (OR = 2.2), whereas the alleles DQB*0602 (OR = 0.05), DRB1*11 (OR = 0.2), DRB1*15 (OR = 0.2) and DQB1*0301 (OR = 0.3) were found to be protective. CONCLUSIONS: Our results, consistent with other studies, show increased frequencies of known positively associated HLA class II alleles in our type 1A diabetes mellitus patients compared to the general (nondiabetic) population. The protective effect of previously reported alleles was confirmed as well. Results of our population-based study serve in clinical practice for the identification of subjects at risk of developing DM-1A among the first-degree relatives (Tab. 2, Ref. 12).

HLA alleles and susceptibility to dermatological disorders associated with Helicobacter pylori infection: a significant association to HLA-Cw*06.

The occurrence rate of HLA class I and class II alleles was established in 24 patients suffering from dermatological disorders associated with the Helicobacter pylori infection. The increased frequency of HLA-C*0602, 4 was found to be 0.1875 compared to 0.0733 in the control group (odds ratio: 2.913; two-sided P value: P = 0.0251). Our data suggest that the HLA-Cw6 molecule play a role in the susceptibility to the Helicobacter pylori infection.

[Selection of donor-recipient pairs in families for allogenic bone marrow transplantation]. / Výber párov darca-príjemca v rodinách pre alogénnu transplantáciu kostnej drene.

In the years 1985-1999 452 were families investigated with the aim to find up an HLA-identical sibling for a patient suffering from a disease, the treatment of which requires bone marrow transplantation. Total number of investigated siblings (including patients) was 1334. HLA typing was done by serological methods, mixed lymphocyte culture test (MLC), and in the last three years also by DNA-typing (PCR-SSP). 188 HLA identical donor-recipient sib-pairs were found. At the same time the number shows that a potential donor could be found in 41.5% of investigated families.

[Association of type I diabetes mellitus with HLA alleles]. / Asociácia diabetes mellitus I. typu s HLA-alelami.

Insulin-dependent diabetes mellitus is a chronic autoimmune disease characterised by a loss of tolerance towards own antigene structures beta-pancreatic cells. The destruction of cells subsequently leads to the loss of insulin production. There are more factors which trigger the autoimmune response in susceptible individuals, however, they are only partially known so far. One of the predisposing factors is the genotype, while the main role is ascribed to genes of the main histocompatible complex (HLA). Out of extensive genetic and epidemiological studies, the Caucasoid population is known to have a significant association of insulin-dependent diabetes mellitus with the increased frequencies of haplotypes HLA-DRB1*04-DQA1*0301-DQB1*0302 and DRB1*0301-DQA1*0501-DQB1*0201.

Occurrence rates of HLA-DRB1, HLA-DQB1, and HLA-DPB1 alleles in patients suffering from vitiligo.

By investigating a group of 39 unrelated adults suffering from vitiligo it was found that alleles HLA-DRB1*0701, -DQB1*0201, and -DPB1*1601 differed in their frequencies in comparison to those observed in the healthy population. The allele HLA-DRB1*0701 was found in 26.5% of patients compared to 14.2% in the healthy group (p < 0,01, RR = 2.17). The allele HLA-DQB1*0201 was present in 33.8% of patients compared to 21.2% (p < 0,025, RR = 1.89). The allele HLA-DPB1*1601 was found in 6.41% of patients compared to 2.05% in the healthy group (p < 0.05, RR = 3.3). No other significant deviations in the frequencies of investigated alleles were observed.

HLA-DRB1, -DQB1 and -DPB1 polymorphism in the Slovak population.

HLA-DRB1, -DQB1 and -DPB1 allele frequencies were investigated in a sample of the Slovak population by PCR-SSP and PCR-RFLP methods. The most frequent DRB1 alleles were DRB1*1101-5 (0.2038), DRB1*0701-2 (0.1423), and DRB1*1501-2 (0.1231). The most rare alleles found were DRB1*0901 (0.0038), and DRB1*1201 (0.015). The most common DQB1 alleles were DQB1*0301 (0.2448), DQB1*0201 (0.2098), and DQB1*0501 (0.1119), respectively. The alleles with the least occurrence rate were DQB1*0601 (0.0035) and DQB1*0401 (0.007). The most common DPB1 alleles found were DPB1*0401 (0.4329), DPB1*0402 (0.2089), and DPB1*0201 (0.1438), respectively. The least frequent alleles were DPB1*0601, *1101, and *1501 (0.0034). Allele frequencies found in our study were compared to those in Czech, Austrian, and German populations. No statistically significant differences were observed.

[Frequency of the HLA-DPB1 allele in the Slovak population]. / Frekvencia HLA-DPB1 alel v Slovenskej populácii.

The polymorphism at the HLA-DPB1 locus was established in 146 unrelated persons. The polymerase chain reaction (PCR) in combination with restriction fragment length polymorphism (RFLP) technique was used. After PCR amplification of the second exon of the HLA-DPB1 locus, the PCR products were digested with seven allele specific endonucleases. The alleles DPB1*0401 (43.29%), DPB1*0402 (20.89%), DPB1*0201 (14.39%) and DPB1*0301 (9.25%) were the most common among 15 DPB1 alleles detected in the tested group. The least frequent alleles were DPB1 *0202, *0601, *1101 and *1501 (0.34%). The comparison with allele frequencies in Austrian and German populations showed no statistically significant differences. (Tab. 2, Ref. 18.)

[DNA typing of class I HLA alleles]. / DNA-typizácia HLA-alel triedy I.

The major histocompatibility complex (MHC) in man, the HLA-complex, is for its marked significance in the regulation of immune system reactions and for its important role in clinical medicine the object of incessant interest for further studies. There is also a constant search for new methods of HLA typing. HLA antigens have been traditionally detected by serological and cellular methods. Recently HLA typing methods based on DNA typing utilising polymerase chain reaction (PCR) are being introduced. PCR-SSO (sequence-specific oligonucleotide) and PCR-SSP (sequence-specific primers) methods are most frequently used for routine typing of HLA class I alleles. We present technical details of the PCR-SSP method, recently introduced at our department and a short review of other techniques. (Fig. 1, Ref. 34.)

[Frequency of loci of HLA-DRB1* and -DQB1* alleles in the Slovak population]. / Frekvencia alel lokusov HLA-DRB1* a -DQB1* v Slovenskej populácii.

Results on HLA-DRB1* and HLA-DQB1* allele frequencies in the Slovak population by PCR-SSP method are presented. HLA-DRB1* alleles were determined in 130 and HLA-DQB1* alleles in 143 healthy unrelated individuals. The highest frequency was observed for the alleles HLA-DRB1*1101-13 (0.203), HLA-DRB1*0701 (0.142), HLA-DQB1*0301 (0.244), and HLA-DQB1*0201 (0.209). The least frequent alleles were HLA-DRB1*1402-6-9, HLA-DRB1*0901 (both 0.0038), HLA-DQB1*0401 (0.007), and HLA-DQB1*0601 (0.0035). The results obtained by DNA-typing were compared with those calculated from the serological study. No statistically significant differencies were found. The allele frequencies obtained in our study were also compared with those of the Czech and Austrian populations. No statistically significant differencies were observed. (Fig. 2, Tab. 3, Ref. 13.)