POS0272 REDUCED ORAL HAEMOPHILUS PARAINFLUENZAE IN SJÖGREN’S SYNDROME PROMPTS DYSREGULATED T CELL RESPONSE THROUGH ALTERED SALIVARY GLAND EPITHELIAL CELLS
Authors: S. F. Wu, Y. C. Tseng
Journal: Annals of the Rheumatic Diseases (2024)

<h3>Background:</h3> <i>Haemophilus parainfluenzae</i> (<i>H</i>. <i>para</i>) constitutes the majority of oral <i>Haemophilus</i>. Despite the wide presence of decreased oral abundance of <i>Haemophilus</i> or <i>H</i>. <i>para</i> in systemic or organ-specific autoimmune diseases, the significance of this reduction remains unexplored. Sjögren's syndrome (SS) serves as a prototype of systemic autoimmune diseases. Salivary gland epithelial cells (SGECs) connect with the oral environment and coordinate the adaptive immune response, rendering them indispensable in the pathogenesis of SS [1]. This study focuses on the regulatory effects of <i>H</i>. <i>para</i> on SGECs and postulates an immunomodulation through the regulation of SGECs by <i>H</i>. <i>para</i>. <h3>Objectives:</h3> To explore the significance of the reduced oral <i>H. para</i> in SS through its relevance to SGECs. <h3>Methods:</h3> The salivary abundance of <i>H. para</i> in SS patients was determined through qPCR. A253 cells, derived from a human salivary gland with epithelial morphology, were pretreated by <i>H. para</i> and then co-cultured with CD4 or CD8 T cells. The proliferation of T cells was assessed using flow cytometry. To investigate the impact of <i>H. para</i> on A253 cells, RNA-sequencing was performed using the Illumina platform. Enrichment analysis was conducted by PANTHER against Gene Ontology (GO) terms, with FDR correction. <i>TNFAIP3</i> expression was quantified using qRT-PCR and Western blot. <h3>Results:</h3> Decreased <i>H. para</i> was found in saliva from 30 SS patients and 24 healthy controls (Figure 1A). <i>H. para</i>-pretreated A253 cells suppressed the proliferation of CD4 and CD8 T cells (Figure 1B). Transcriptomic analysis of <i>H. para</i>-pretreated A253 cells disclosed 7,291 upregulated and 7,709 downregulated genes. Enrichment analysis identified 27 GO terms (Figure 2A), including significant portions in translation and mitochondrial processes, showing active cellular response to stimuli and metabolic reprogramming. Notably, the GO term "NF-kappaB complex" exhibited the highest fold enrichment (7.22, FDR-corrected <i>p</i> = 0.024, Figure 2A), indicating a significant alteration in NF-κB complex. <i>TNFAIP3</i>, ranking in the 97.5<sup>th</sup> percentile of all upregulated genes, participated in the two GO terms involving the negative regulation of NF-κB (Figure 2B). The upregulation of <i>TNFAIP3</i> was confirmed by qRT-PCR and Western blot (Figure 2C and D). <h3>Conclusion:</h3> TNFAIP3 serves as a physiological negative-feedback mechanism following NF-κB activation. <i>TNFAIP3</i> polymorphism was associated with SS [2], and the loss of TNFAIP3 in SGECs has been attributed to the pathogenesis of SS <i>in vitro</i> and <i>in vivo</i> [3,4]. We conclude that the reduction of oral <i>H. para</i> in SS may lead to inappropriate T cell activation, potentially through the loss of TNFAIP3 upregulation in SGECs. This study provides a provisional insight into dissecting the possible mechanisms of <i>H. para</i> in SS. <h3>REFERENCES:</h3> [1] Verstappen, G. M., et al. (2021). <i>Nat Rev Rheumatol</i>, 17(6), 333–348. [2] Khatri, B., et al. (2022). <i>Nat Commun</i>, 13(1), 4287. [3] Sisto, M., et al. (2011). <i>Histochem Cell Biol</i>, 135(6), 615–625. [4] X, W., et al. (2018). <i>PLoS ONE</i>, 13(8). <h3>Acknowledgements:</h3> This study was subsidized by Ditmanson Medical Foundation Chia-Yi Christian Hospital Research Program (R109-001). <h3>Disclosure of Interests:</h3> <b>None declared.</b>