Inhibition of JAK-STAT pathway corrects salivary gland inflammation and interferon driven immune activation in Sjögren's disease.

OBJECTIVES: Inflammatory cytokines that signal through the Janus kinases-signal transducer and activator of transcription (JAK-STAT) pathway, especially interferons (IFNs), are implicated in Sjögren's disease (SjD). Although inhibition of JAKs is effective in other autoimmune diseases, a systematic investigation of IFN-JAK-STAT signalling and the effect of JAK inhibitor (JAKi) therapy in SjD-affected human tissues has not been fully investigated. METHODS: Human minor salivary glands (MSGs) and peripheral blood mononuclear cells (PBMCs) were investigated using bulk or single-cell (sc) RNA sequencing (RNAseq), immunofluorescence (IF) microscopy and flow cytometry. Ex vivo culture assays on PBMCs and primary salivary gland epithelial cell (pSGEC) lines were performed to model changes in target tissues before and after JAKi. RESULTS: RNAseq and IF showed activated JAK-STAT pathway in SjD MSGs. Elevated IFN-stimulated gene (ISGs) expression associated with clinical variables (eg, focus scores, anti-SSA positivity). scRNAseq of MSGs exhibited cell type-specific upregulation of JAK-STAT and ISGs; PBMCs showed similar trends, including markedly upregulated ISGs in monocytes. Ex vivo studies showed elevated basal pSTAT levels in SjD MSGs and PBMCs that were corrected with JAKi. SjD-derived pSGECs exhibited higher basal ISG expressions and exaggerated responses to IFN-ß, which were normalised by JAKi without cytotoxicity. CONCLUSIONS: SjD patients' tissues exhibit increased expression of ISGs and activation of the JAK-STAT pathway in a cell type-dependent manner. JAKi normalises this aberrant signalling at the tissue level and in PBMCs, suggesting a putative viable therapy for SjD, targeting both glandular and extraglandular symptoms. Predicated on these data, a phase Ib/IIa randomised controlled trial to treat SjD with tofacitinib was initiated.

DNA methylation profiling of labial salivary gland tissues revealed hypomethylation of B-cell-related genes in primary Sjögren's syndrome.

The objective of this epigenetic study was to investigate the cellular proportions based on DNA methylation signatures and pathways of differentially methylated genes in labial salivary gland (LSG) tissues of individuals with Sjögren's syndrome (SS). Two methylation array datasets from the Gene Expression Omnibus repository (GSE166373 and GSE110007) were utilized, consisting of 159 LSG tissues from 77 SS cases and 82 non-SS controls. The raw data underwent analysis using the Chip Analysis Methylation Pipeline (ChAMP) in R statistical tool, which identified differential methylation probes and regions. The EpiDISH and minfi packages in R were employed to identify proportions of epithelial cells, fibroblasts, and immune cells, as well as immune cell subsets. The results showed that proportions of immune cells were increased, while proportions of epithelial cells and fibroblasts were significantly decreased in the LSG of individuals with SS compared to non-SS controls. Specifically, proportions of B-cells and CD8 T-cells were increased, while CD4 T-cells, Treg, monocytes, and neutrophils were decreased in the LSG of individuals with SS. Pathway analysis indicated that genes involved in immune responses to Epstein-Barr virus infection were significantly hypomethylated in SS, and gene set enrichment analysis highlighted the hypomethylation of genes involved in the somatic recombination of immune receptors in SS. Additionally, Disease Ontology analysis showed enriched pathways related to multiple myeloma, arthritis, and the human immunodeficiency virus. The study also revealed significant hypomethylation of the WAS gene on chromosome X in LSG tissues of individuals with SS. Overall, the findings suggest an increased proportion of B-cells and genes related to B-cell function, as well as hypomethylation of genes involved in immune responses and immune receptor recombination, in LSG tissues of individuals with SS compared to non-SS controls.

Amplified Type I Interferon Response in Sjögren's Disease via Ectopic Toll-Like Receptor 7 Expression in Salivary Gland Epithelial Cells Induced by Lysosome-Associated Membrane Protein 3.

OBJECTIVE: Lysosome-associated membrane protein 3 (LAMP3) misexpression in salivary gland epithelial cells plays a causal role in the development of salivary gland dysfunction and autoimmunity associated with Sjögren's disease (SjD). This study aimed to clarify how epithelial LAMP3 misexpression is induced in SjD. METHODS: To explore upstream signaling pathways associated with LAMP3 expression, we conducted multiple RNA sequencing analyses of minor salivary glands from patients with SjD, submandibular glands from a mouse model of SjD, and salivary gland epithelial cell lines. A hypothesis generated by the RNA sequencing analyses was further tested by in vitro and in vivo assays with gene manipulation. RESULTS: Transcriptome analysis suggested LAMP3 expression was associated with enhanced type I interferon (IFN) and IFNγ signaling pathways in patients with SjD. In vitro studies showed that type I IFN but not IFNγ stimulation could induce LAMP3 expression in salivary gland epithelial cells. Moreover, we discovered that LAMP3 overexpression could induce ectopic Toll-like receptor 7 (TLR-7) expression and type I IFN production in salivary gland epithelial cells both in vitro and in vivo. TLR-7 knockout mice did not develop any SjD-related symptoms following LAMP3 induction. CONCLUSION: Epithelial LAMP3 misexpression can be induced through enhanced type I IFN response in salivary glands. In addition, LAMP3 can promote type I IFN production via ectopic TLR-7 expression in salivary gland epithelial cells. This positive feedback loop can contribute to maintaining LAMP3 misexpression and amplifying type I IFN production in salivary glands, which plays an essential role in the pathophysiology of SjD.

Sindrome de Sjogren asociado a cirrosis hepática / Sjogren's syndrome associated with hepatic cirrhosis

Se ha observado que pacientes con cirrosis hepática presentan un cuadro clínico semejante al sindrome de Sjogren. Se presentan resultados preliminares de un estudio inmunohistológico de glándulas salivales en pacientes con cirrosis hepática alcohólica (CHA). Se obtuvieron especímenes de glándulas salivales menores de 8 pacientes con CHA; se realizó estudio histopatológico e inmunohistoquímico de éstas. Se emplearon anticuerpos monoclonales específicos para células T totales, linfocitos TCR1+ (receptor de anígeno gamma), sus subpoblaciones principales (V1 y V2), linfocito TCR2 (receptor de antígeno alfa-beta) y su subpoblación VB8. Se encontraron datos de sialoadenitis crónica focal en la mayor parte de las glándulas estudiadas. El infiltrados linfocitario fue de intensidad variable y constituido en su mayor parte por linfocitos T. La mayor parte de los linfocitos fueron TCR2+ y sólo en un caso se encontró predominio de células TCR1+. La mayor parte de los linfocitos TCR1+ fueron Vd1+,J1+, mientras que no se encontró predominio de células VB8 en linfocitos TCR2. Los resultados obtenidos hasta ahora sugieren que la CHA se asocia a sialoadenitis crónica focal y que ésta es mediada principalmente por linfocitos TCR2+

Respuesta inmune humoral de glándulas salivales menores en pacientes con parotiditis crónica recurrente / Humoral immunity response of minor salival glands in patients with chronic recurrent parotiditis

La parotiditis crónica recurrente inespecífica, es una enfermedad que afecta las glándulas parótidas de niños prepúberes, siendo de carácter inflamatorio. A pesar de ser la segunda enfermedad parotídea de mayor prevalencia en niños, no se sabe con certeza su etiología, y su tratamiento sigue siendo sólo paliativo. Dentro de las posibles etilogías que se proponen se encuentran algunas enfermedades de carácter inmune, es por esto que se investigó, si existían variaciones en la cantidad de inmunoglobulina G y M presente en las glándulas de estos niños. Para esto se tomó biopsias de glándulas salivales de labio inferior de niños enfermos y se sometieron a tinción inmunohistoquímica policlonal para IgG e IgM. Se realizó el conteo de los plasmocitos que presentaban IgG y M, comparándose con glándulas salivales menores sanas, sometidas a la misma tinción. Los resultados obtenidos permiten descartar, como causante de la enfermedad, respuestas anormales del sistema humoral, ya que la presencia de IgM e IgG no presentó diferencias significativas entre glándulas de pacientes enfermos y sanos