Fabricio F. Melo

The levels of IL-17A and of the cytokines involved in Th17 cell commitment are increased in patients with chronic immune thrombocytopenia

Th17 cells have been associated with immune-mediated diseases in humans but it has still not been determined whether they play a role in immune thrombocytopenia. We evaluated representative cytokines of the Th17, Th1, Th2 and Treg cell commitment in the serum of patients with chronic immune thrombocytopenia, as well as the cell source of IL-17A. Higher levels of IL-17A and Th17-related cytokines, and an increased percentage of IL-17A producing CD4+ and neutrophils were observed in patients. The levels of cytokines involved in Th1 cell commitment IFN-γ, IL-2, IL12-p70 and the percentages of Th1 cells were also increased, but IL-4 was not detected. Although the concentrations of IL-10 were higher, the levels of TGF-β were similar in both groups. In conclusion, our results point to a putative role for Th-17 cells/IL-17A cytokine in the pathogenesis of chronic immune thrombocytopenia.

A regulatory instead of an IL-17 T response predominates in Helicobacter pylori-associated gastritis in children

Th17 cells seem to have an important role in the efficacy of vaccines against Helicobacter pylori. Because children are a target group for human vaccination and Th17/T(reg) cells have intrinsically linked and antagonic commitments, we compared the gastric levels of Th17- and T(reg)-associated cytokines of children and adults. IL-6, IL-10 and TGF-β1 levels and Foxp3(+) cell numbers were higher, but IL-1β, IL-17A and IL-23 were lower in infected children than in infected adults. In conclusion T(reg) instead of Th17 cell response to H. pylori-infection predominates in children.

dupA polymorphisms and risk of Helicobacter pylori-associated diseases

The dupA of Helicobacter pylori has been suggested as a virulence marker associated with the development of duodenal ulcer disease. However, the studies performed in different geographical areas have shown that there are variations in the prevalence of dupA and its association with H. pylori clinical outcomes. Our group did not observe associations between the presence of dupA and H. pylori clinical outcomes in Brazil. On the other hand, we observed 2 mutations in the sequence of dupA that lead to stop codons: a deletion of an adenine at position 1311 and an insertion of an adenine at position 1426 of the gene. Our aim was to evaluate associations of the presence of dupA with duodenal ulcer and gastric cancer, considering dupA-positive only those H. pylori strains that do not have the mutations in the gene sequence. We also evaluated the effect of infection with a strain carrying an intact dupA on the gastric mucosa histology and IL-8 gastric levels. Colonization with strains that had the intact dupA was negatively associated with gastric carcinoma (p=0.001, OR=0.32, 95% CI=0.16-0.66). The presence of dupA was also associated with an increased degree of antral mucosa inflammation (p=0.01) and with decreased corpus atrophy (p<0.01) as well as with increased gastric mucosa IL-8 levels (p=0.04). In conclusion, the infection with a H. pylori strain containing the dupA without the stop codon polymorphisms is associated with a lower risk of development of gastric carcinoma in Brazilian subjects.

Toll-like receptor (TLR2, TLR4 and TLR5) gene polymorphisms and Helicobacter pylori infection in children with and without duodenal ulcer

Helicobacter pylori infection is mainly acquired in childhood, and polymorphisms in the host genes coding for Toll-like receptors (TLRs) may influence the innate and adaptive immune response to the infection, affecting the susceptibility to H. pylori or the disease outcomes. Our aim was to investigate whether TLR4, TLR2, and TLR5 polymorphisms were associated with H. pylori susceptibility and risk for duodenal ulcer in children. Gastric biopsy specimens were obtained at endoscopy for evaluation of H. pylori status, TLR4, TLR2 and TLR5 polymorphisms from 486 children (254 H. pylori-negative and 232 H. pylori-positive: 72 with and 160 without duodenal ulcer). cagA status of H. pylori infection was investigated by PCR. The levels of gastric cytokines were detected by ELISA. H. pylori-positivity or duodenal ulcer were not associated with TLR2, TLR4 or TLR5 polymorphisms. Otherwise, the presence of TLR4 polymorphic allele was associated with infection by cagA-positive strains and with increased gastric levels of interleukin-8 and interleukin-10. TLR4 polymorphism might ultimately contribute to more severe consequences of the infection in adulthood since it was associated with susceptibility to cagA-positive H. pylori infection early in life.

IL2-330G polymorphic allele is associated with decreased risk of Helicobacter pylori infection in adulthood

We evaluated whether polymorphisms in genes coding molecules linked to the innate and adaptive immune response are associated with susceptibility to Helicobacter pylori infection. IL1B-511C-->T, IL1B-31T-->C, IL1RN allele 2, IL2-330T-->G, TNFA-307G-->A, TLR2Arg677Trp, TLR2Arg753Gln, TLR4Asp299Gly, and TLR5(392STOP) polymorphisms were determined in 541 blood donors. IL2-330T-->G allele carriers had a decreased H. pylori infection risk (OR=0.63, 95% CI=0.43-0.93) after adjustment for demographic and environmental factors. Hence, we investigated whether the polymorphism is functional by evaluating IL-2 serum concentration in 150 blood donors and 100 children. IL-2 pro-inflammatory and anti-inflammatory properties were indirectly investigated by determining serum IFN-gamma and IL-10/TGF-beta levels. The polymorphism was associated with increased mean IL-2 levels in H. pylori-positive adults (2.65 pg/mL vs. 7.78 pg/mL) and children (4.19 pg/mL vs. 8.03 pg/mL). Increased IL-2 was associated with pro-inflammatory activity in adults (IFN-gamma=18.61 pg/mL vs. 25.71 pg/mL), and with anti-inflammatory activity in children (IL-10=6.99 vs. 14.17 pg/mL, TGF-beta=45.88 vs. 93.44 pg/mL) (p<10(-3) for all). In conclusion, in the context of H. pylori infection, IL2-330 T-->G polymorphism is functional and is associated with decreased risk of infection in adults.

Helicobacter pylori Infection in Infants and Toddlers in South America: Concordance between [13C]Urea Breath Test and Monoclonal H. pylori Stool Antigen Test

ABSTRACT Accurate noninvasive tests for diagnosing Helicobacter pylori infection in very young children are strongly required. We investigated the agreement between the [13C]urea breath test ([13C]UBT) and a monoclonal ELISA (HpSA) for detection of H. pylori antigen in stool. From October 2007 to July 2011, we enrolled 414 infants (123 from Brazil and 291 from Peru) of ages 6 to 30 months. Breath and stool samples were obtained at intervals of at least 3 months from Brazilian (n = 415) and Peruvian (n = 908) infants. [13C]UBT and stool test results concurred with each other in 1,255 (94.86%) cases (kappa coefficient = 0.90; 95% confidence interval [CI] = 0.87 to 0.92). In the H. pylori-positive group, delta-over-baseline (DOB) and optical density (OD) values were positively correlated (r = 0.62; P < 0.001). The positivity of the tests was higher (P < 0.001; odds ratio [OR] = 6.01; 95% CI = 4.50 to 8.04) in Peru (546/878; 62.2%) than in Brazil (81/377; 21.5%) and increased with increasing age in Brazil (P = 0.02), whereas in Peru it decreased with increasing age (P < 0.001). The disagreement between the test results was associated with birth in Brazil and female gender but not with age and diarrhea. Our results suggest that both [13C]UBT and the stool monoclonal test are reliable for diagnosing H. pylori infection in very young children, which will facilitate robust epidemiological studies in infants and toddlers.

research paper: IL1RN VNTR and IL2−330 polymorphic genes are independently associated with chronic immune thrombocytopenia

Chronic Immune Thrombocytopenia (cITP) is an acquired immune‐mediated disease associated with a T‐helper cell type 1 (Th1) immune polarization, whose genetic risk factors, however, are largely unknown. We investigated polymorphisms in promoter regions of genes that code molecules involved in proinflammatory immune response [IL1B−31T/C, IL1RN variable number tandem repeats (VNTR), IL2−330T/G, and TNF−307G/A] as well as in genes that code Toll like receptors (TLR) (TLR2 Arg753Gln, TLR4 Asp299Gly and TLR5 Arg392stop) in 122 patients with cITP and 541 blood donors. The frequencies of the IL1RN polymorphic allele 2 (P = 0·001) and of the IL2−330 polymorphic allele G (P = 0·004) were significantly higher in cITP patients than in blood donors. In logistic analysis adjusting for age and gender, the polymorphisms remained independently associated with cITP. Enhanced serum concentrations of interleukin (IL)‐1α and IL‐1β were observed in cITP (P < 10−3) and blood donor (P = 0·04) carriers of the IL1RN*2. Also, the serum levels of IL‐2 and γ‐interferon (IFN‐γ) were increased in cITP patients (P < 10−3 and P = 0·04 respectively) and blood donors (P < 10−3 and P = 0·03 respectively) harbouring the IL2−330G allele. Here we demonstrated that IL2−330G and IL1RN*2 are independently associated with cITP and are functional in vivo, which strongly suggests that they contribute to the pathogenesis of cITP.

Th1 immune response to H. pylori infection varies according to the age of the patients and influences the gastric inflammatory patterns

To compare children and adults in respect to the effect of H. pylori infection on the gastric concentrations of cytokines linked to innate and Th1 immune response, as well as to investigate the changes in the gastric concentrations of the studied cytokines according to the age. We studied 245 children (142 H. pylori-negative and 103 H. pylori-positive) and 140 adults (40 H. pylori-negative and 100 H. pylori-positive). The gastric concentrations of cytokines representative of the innate and Th1 response were higher in the H. pylori-positive than in the -negative children and adults. The gastric concentrations of IL-1α and TNF-α were significantly higher, while those of IL-2, IL-12p70 and IFN-γ were lower in the infected children than in the infected adults. In the infected children, the gastric concentration of IL-1α, IL-2, IL-12p70 and IFN-γ increased, whereas in adults, the gastric concentrations of IFN-γ and IL-12p70 decreased with the aging. Increased gastric concentration of Th1 associated cytokines correlated with increased degree of gastritis that is the background lesion for the development of the H. pylori associated severe diseases. Concluding, Th1 response to H. pylori infection varies according to the age and seems to have determinant implication in the H. pylori infection outcomes.

The presence of Helicobacter pylori in the liver depends on the Th1, Th17 and Treg cytokine profile of the patient

The hypothesis that Helicobactermight be a risk factor for human liver diseases has arisen after the detection of Helicobacter DNA in hepatic tissue of patients with hepatobiliary diseases. Nevertheless, no explanation that justifies the presence of the bacterium in the human liver has been proposed. We evaluated the presence of Helicobacterin the liver of patients with hepatic diseases of different aetiologies. We prospectively evaluated 147 patients (106 with primary hepatic diseases and 41 with hepatic metastatic tumours) and 20 liver donors as controls. Helicobacter species were investigated in the liver by culture and specific 16S rDNA nested-polymerase chain reaction followed by sequencing. Serum and hepatic levels of representative cytokines of T regulatory cell, T helper (Th)1 and Th17 cell lineages were determined using enzyme linked immunosorbent assay. The data were evaluated using logistic models. Detection of Helicobacter pylori DNA in the liver was independently associated with hepatitis B virus/hepatitis C virus, pancreatic carcinoma and a cytokine pattern characterised by high interleukin (IL)-10, low/absent interferon-γ and decreased IL-17A concentrations (p < 10(-3)). The bacterial DNA was never detected in the liver of patients with alcoholic cirrhosis and autoimmune hepatitis that are associated with Th1/Th17 polarisation. H. pylori may be observed in the liver of patients with certain hepatic and pancreatic diseases, but this might depend on the patient cytokine profile.

Cytokine profile of patients with chronic immune thrombocytopenia affects platelet count recovery after Helicobacter pylori eradication

Helicobacter pylori eradication induces platelet recovery in a subgroup of patients with chronic immune thrombocytopenia (cITP), but the mechanisms involved are still not understood. We aimed to evaluate the effect of H. pylori eradication on platelet response and to identify the associated serum cytokine profile in 95 patients with cITP. Serum cytokine concentrations were determined by enzyme‐linked immunosorbent assay prior to and 6 months after H. pylori eradication. Remission of cITP was observed in 17 (28·8%) of 59 patients in whom the bacterium was eradicated. Six months after treatment, a significant reduction in the concentrations of T‐helper (Th) 1 and Th17 cells and an increase in T regulatory (Treg) and Th2‐cell commitment cytokines were observed in patients who recovered, but not in those whose platelet count did not recover. Patients who had a platelet response to eradication of the bacteria had higher pre‐treatment serum levels of γ‐interferon (IFNG, IFN‐γ), transforming growth factor‐β (TGFB1, TGF‐β) and interleukin 17 (IL17A, IL‐17) than patients who did not respond, but only higher pre‐treatment TGFB1 levels was independently associated with platelet response. In conclusion, amelioration of cITP after eradication of H. pylori was linked to a more efficient suppression of Th1 and Th17 response and a more pronounced Treg cell response.