Simultaneous analysis of T helper subsets (Th1, Th2, Th9, Th17, Th22, Tfh, Tr1 and Tregs) markers expression in periapical lesions reveals multiple cytokine clusters accountable for lesions activity and inactivity status.

Ana Claudia Araujo-Pires,Andreza Maria Fabio Aranha,Carolina Favaro Francisconi,Franco Cavalla,Ana Paula Favaro Trombone,Renato Menezes Silva,Gustavo Pompermaier Garlet,Claudia Cristina Biguetti,Ariadne Letra,Marcelo Faveri

doi:10.1590/1678-775720140140

Abstract

Previous studies demonstrate that the balance between pro- and anti-inflammatory mediators determines the stable or progressive nature of periapical granulomas by modulating the balance of the osteoclastogenic factor RANKL and its antagonist OPG. However, the cytokine networks operating in the development of periapical lesions are quite more complex than what the simple pro- versus anti-inflammatory mediators' paradigm suggests. Here we simultaneously investigated the patterns of Th1, Th2, Th9, Th17, Th22, Thf, Tr1 and Tregs cytokines/markers expression in human periapical granulomas.MethodsThe expression of TNF-α, IFN-γ, IL-17A, IL23, IL21, IL-33, IL-10, IL-4, IL-9, IL-22, FOXp3 markers (via RealTimePCR array) was accessed in active/progressive (N=40) versus inactive/stable (N=70) periapical granulomas (as determined by RANKL/OPG expression ratio), and also to compare these samples with a panel of control specimens (N=26). A cluster analysis of 13 cytokine levels was performed to examine possible clustering between the cytokines in a total of 110 granulomas. ResultsThe expression of all target cytokines was higher in the granulomas than in control samples. TNF-α, IFN-γ, IL-17A and IL-21 mRNA levels were significantly higher in active granulomas, while in inactive lesions the expression levels of IL-4, IL-9, IL-10, IL-22 and FOXp3 were higher than in active granulomas. Five clusters were identified in inactive lesion groups, being the variance in the expression levels of IL-17, IL-10, FOXp3, IFN-γ, IL-9, IL-33 and IL-4 statistically significant (KW p<0.05). Three clusters were identified in active lesions, being the variance in the expression levels of IL-22, IL-10, IFN-γ, IL-17, IL-33, FOXp3, IL-21 and RANKL statistically significant (KW p<0.05). ConclusionThere is a clear dichotomy in the profile of cytokine expression in inactive and active periapical lesions. While the widespread cytokine expression seems to be a feature of chronic lesions, hierarchical cluster analysis demonstrates the association of TNF-α, IL-21, IL-17 and IFN-γ with lesions activity, and the association of FOXP3, IL-10, IL-9, IL-4 and IL-22 with lesions inactivity.

Highlights

Periapical lesions triggered by bacterial infection of pulpal and endodontic environment are characterized by the destruction of mineralized tissues surrounding the root apex as a consequence of the local host response19
Initial cluster analysis performed with all the OHVLRQV )LJXUH UHVXOWHG LQ WKH LGHQWL¿FDWLRQ RI major clusters, comprised by 41 and 69 samples, presenting a 98% match with the clustering based in the RANKL/OPG patterns29
In an intermediate level within inactivity and activity poles, the cytokines IL-23 and IL-33 were QRW VLJQL¿FDQWO\ DVVRFLDWHG ZLWK OHVLRQV¶ VWDWXV (Table 3 and Figure 3). Regulatory molecules such as cytokines play a key role in the pathogenesis periapical lesions12,19

Summary

Introduction

Periapical lesions triggered by bacterial infection of pulpal and endodontic environment are characterized by the destruction of mineralized tissues surrounding the root apex as a consequence of the local host response19 In this context, cytokines play a major role in the modulation RI LQÀDPPDWRU\ LPPXQH UHVSRQVHV ZLWKLQ WKH periapical microenvironment, and, are critical determinants of lesions outcome. The cytokine networks operating in the development of periapical lesions are quite more complex than what the relatively simple SUR YHUVXV DQWLLQÀDPPDWRU\ PHGLDWRUV¶ paradigm could suggest, being the pathogenesis of FKURQLF LQÀDPPDWRU\ GLVHDVHV LQÀXHQFHG E\ VHYHUDO other cytokine classes12,19 In this scenario, Th1 cytokines (IFN-γ, IL-12) have been associated with bone destruction and lesion progression, while its classic Th2 antagonists (IL-4, IL-10, and the recently described IL-33) are described to limit or attenuate the tissue damage. The 7K7UHJV DUFKHW\SH ZDV VXJJHVWHG WR LQÀXHQFH the outcome of periapical lesions

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Results

Conclusion