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Ex vivo cytokine mRNA levels correlate with changing clinical status of ethiopian TB patients and their contacts over time.

Wassie L, Demissie A, Aseffa A, Abebe M, Yamuah L, Tilahun H, Petros B, Rook G, Zumla A, Andersen P, Doherty TM, VACSEL Study Gro - PLoS ONE (2008)

Bottom Line: This correlated with a decrease in the relative amount of IL-4 expressed.IL-4 expression was disproportionately increased in this group.However, the data also suggest that there are no clear-cut differences between groups: the immune response over time appears to include changes in the expression of IFN-gamma, IL-4 and IL-4delta2, and it is the relative, not absolute levels of cytokine expression that are characteristic of clinical status.

View Article: PubMed Central - PubMed

Affiliation: Armauer Hansen Research Institute, Addis Ababa, Ethiopia.

ABSTRACT
There is an increasing body of evidence which suggests that IL-4 plays a role in the pathogenesis of TB, but a general consensus on its role remains elusive. We have previously published data from a cohort of Ethiopian TB patients, their contacts, and community controls suggesting that enhanced IL-4 production is associated with infection with M. tuberculosis, rather than overt disease and that long-term protection in infected community controls is associated with co-production of the IL-4 antagonist IL-4d2, alongside elevated IL-4. Here, for the first time, we compare data on expression of IFN-gamma, IL-4 and IL-4delta2 over time in TB patients and their household contacts. During the follow-up period, the TB patients completed therapy and ceased to display TB-like symptoms. This correlated with a decrease in the relative amount of IL-4 expressed. Over the same period, the clinical status of some of their contacts also changed, with a number developing TB-like symptoms or clinically apparent TB. IL-4 expression was disproportionately increased in this group. The findings support the hypothesis that elevated IL-4 production is generally associated with infection, but that TB disease is associated with a relatively increased expression of IL-4 compared to IFN-gamma and IL-4delta2. However, the data also suggest that there are no clear-cut differences between groups: the immune response over time appears to include changes in the expression of IFN-gamma, IL-4 and IL-4delta2, and it is the relative, not absolute levels of cytokine expression that are characteristic of clinical status.

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Comparison of relative levels of IL-4, IL-4δ2 and IFN-γ mRNA from unstimulated leukocytes of healthy household contacts (HHC, n = 104) and TB patients (TB, n = 76).Results are presented as medians and ranges of either (A) cytokine message, assessed by RT-PCR, and normalized against β-actin as a housekeeping gene or (B) the ratio of the normalized values of IL-4δ2 and IFN-γ divided by the normalized IL-4 value, as a proxy for the Th1/Th2 balance. Levels of gene expression which were significantly different between groups are indicated, as are the associated p values. Analysis of differences between the groups was performed by Kruskal-Wallis.
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pone-0001522-g001: Comparison of relative levels of IL-4, IL-4δ2 and IFN-γ mRNA from unstimulated leukocytes of healthy household contacts (HHC, n = 104) and TB patients (TB, n = 76).Results are presented as medians and ranges of either (A) cytokine message, assessed by RT-PCR, and normalized against β-actin as a housekeeping gene or (B) the ratio of the normalized values of IL-4δ2 and IFN-γ divided by the normalized IL-4 value, as a proxy for the Th1/Th2 balance. Levels of gene expression which were significantly different between groups are indicated, as are the associated p values. Analysis of differences between the groups was performed by Kruskal-Wallis.

Mentions: Participants were recruited first when sputum-positive TB patients presented at the local TB clinic. Once TB was diagnosed, the index case was asked to return with their household members so that they could also be examined-this is standard practice. If, after counselling and explanation of the study' aims, they were prepared to enter into the study, the adult members of the household were enrolled. At entry to the study, all participants received a clinical examination and a blood draw. Cells from the peripheral blood of each group were lysed (without in vitro culture) and mRNA extracted and reverse transcribed into cDNA to analyse the ex vivo responses. This cDNA was used for all subsequent analyses. We compared the expression of IL-4, IFN-γ, and IL-4δ2 mRNA in healthy household contacts (designated HHC, n = 104) and index cases (designated TB, n = 76). As seen in Figure 1A, there were no significant differences between these groups when individual cytokines were compared. This is consistent with earlier results (author's unpublished data and [14], [15]). However, there was a weak trend towards higher expression of IL-4 in TB patients and when we compared the ratio of IFN-γ or the IL-4 antagonist IL-4δ2 to IL-4, we saw a significant difference between HHC and TB groups in both cases (Figure 1B). These data suggest that there is a weak bias towards a more Th2-like response in the TB patients compared to healthy contacts when more than one cytokine is considered, but that the use of any single marker is not very informative. This is perhaps not surprising, considering the heterogeneous nature of the groups–the contacts may include individuals in the early stages of TB, those making protective immune responses as well as uninfected individuals–a result confirmed by other analyses [14].


Ex vivo cytokine mRNA levels correlate with changing clinical status of ethiopian TB patients and their contacts over time.

Wassie L, Demissie A, Aseffa A, Abebe M, Yamuah L, Tilahun H, Petros B, Rook G, Zumla A, Andersen P, Doherty TM, VACSEL Study Gro - PLoS ONE (2008)

Comparison of relative levels of IL-4, IL-4δ2 and IFN-γ mRNA from unstimulated leukocytes of healthy household contacts (HHC, n = 104) and TB patients (TB, n = 76).Results are presented as medians and ranges of either (A) cytokine message, assessed by RT-PCR, and normalized against β-actin as a housekeeping gene or (B) the ratio of the normalized values of IL-4δ2 and IFN-γ divided by the normalized IL-4 value, as a proxy for the Th1/Th2 balance. Levels of gene expression which were significantly different between groups are indicated, as are the associated p values. Analysis of differences between the groups was performed by Kruskal-Wallis.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2211401&req=5

pone-0001522-g001: Comparison of relative levels of IL-4, IL-4δ2 and IFN-γ mRNA from unstimulated leukocytes of healthy household contacts (HHC, n = 104) and TB patients (TB, n = 76).Results are presented as medians and ranges of either (A) cytokine message, assessed by RT-PCR, and normalized against β-actin as a housekeeping gene or (B) the ratio of the normalized values of IL-4δ2 and IFN-γ divided by the normalized IL-4 value, as a proxy for the Th1/Th2 balance. Levels of gene expression which were significantly different between groups are indicated, as are the associated p values. Analysis of differences between the groups was performed by Kruskal-Wallis.
Mentions: Participants were recruited first when sputum-positive TB patients presented at the local TB clinic. Once TB was diagnosed, the index case was asked to return with their household members so that they could also be examined-this is standard practice. If, after counselling and explanation of the study' aims, they were prepared to enter into the study, the adult members of the household were enrolled. At entry to the study, all participants received a clinical examination and a blood draw. Cells from the peripheral blood of each group were lysed (without in vitro culture) and mRNA extracted and reverse transcribed into cDNA to analyse the ex vivo responses. This cDNA was used for all subsequent analyses. We compared the expression of IL-4, IFN-γ, and IL-4δ2 mRNA in healthy household contacts (designated HHC, n = 104) and index cases (designated TB, n = 76). As seen in Figure 1A, there were no significant differences between these groups when individual cytokines were compared. This is consistent with earlier results (author's unpublished data and [14], [15]). However, there was a weak trend towards higher expression of IL-4 in TB patients and when we compared the ratio of IFN-γ or the IL-4 antagonist IL-4δ2 to IL-4, we saw a significant difference between HHC and TB groups in both cases (Figure 1B). These data suggest that there is a weak bias towards a more Th2-like response in the TB patients compared to healthy contacts when more than one cytokine is considered, but that the use of any single marker is not very informative. This is perhaps not surprising, considering the heterogeneous nature of the groups–the contacts may include individuals in the early stages of TB, those making protective immune responses as well as uninfected individuals–a result confirmed by other analyses [14].

Bottom Line: This correlated with a decrease in the relative amount of IL-4 expressed.IL-4 expression was disproportionately increased in this group.However, the data also suggest that there are no clear-cut differences between groups: the immune response over time appears to include changes in the expression of IFN-gamma, IL-4 and IL-4delta2, and it is the relative, not absolute levels of cytokine expression that are characteristic of clinical status.

View Article: PubMed Central - PubMed

Affiliation: Armauer Hansen Research Institute, Addis Ababa, Ethiopia.

ABSTRACT
There is an increasing body of evidence which suggests that IL-4 plays a role in the pathogenesis of TB, but a general consensus on its role remains elusive. We have previously published data from a cohort of Ethiopian TB patients, their contacts, and community controls suggesting that enhanced IL-4 production is associated with infection with M. tuberculosis, rather than overt disease and that long-term protection in infected community controls is associated with co-production of the IL-4 antagonist IL-4d2, alongside elevated IL-4. Here, for the first time, we compare data on expression of IFN-gamma, IL-4 and IL-4delta2 over time in TB patients and their household contacts. During the follow-up period, the TB patients completed therapy and ceased to display TB-like symptoms. This correlated with a decrease in the relative amount of IL-4 expressed. Over the same period, the clinical status of some of their contacts also changed, with a number developing TB-like symptoms or clinically apparent TB. IL-4 expression was disproportionately increased in this group. The findings support the hypothesis that elevated IL-4 production is generally associated with infection, but that TB disease is associated with a relatively increased expression of IL-4 compared to IFN-gamma and IL-4delta2. However, the data also suggest that there are no clear-cut differences between groups: the immune response over time appears to include changes in the expression of IFN-gamma, IL-4 and IL-4delta2, and it is the relative, not absolute levels of cytokine expression that are characteristic of clinical status.

Show MeSH
Related in: MedlinePlus