Early-Life Antibiotic Exposure Causes Intestinal Dysbiosis and Exacerbates Skin and Lung Pathology in Experimental Systemic Sclerosis.

Patients with systemic sclerosis (SSc) display altered intestinal microbiota. However, the influence of intestinal dysbiosis on the development of experimental SSc remains unknown. Topoisomerase I peptide-loaded dendritic cell immunization induces SSc-like disease, with progressive skin and lung fibrosis. Breeders were given streptomycin and pups continued to receive antibiotic (ATB) until endpoint (lifelongATB). Alternately, ATB was withdrawn (earlyATB) or initiated (adultATB) during adulthood. Topoisomerase I peptide-loaded dendritic cell (no ATB) immunization induced pronounced skin fibrosis, with increased matrix (Col1a1), profibrotic (Il13, Tweakr), and vascular function (Serpine1) gene expression. Remarkably, earlyATB exposure was sufficient to augment skin Col5a1 and Il13 expression, and inflammatory cell infiltration, which included IL-13+ cells, mononuclear phagocytes, and mast cells. Moreover, skin pathology exacerbation was also observed in lifelongATB and adultATB groups. Oral streptomycin administration induced intestinal dysbiosis, with exposure limited to early life (earlyATB) being sufficient to cause long-term modification of the microbiota and a shift toward increased Bacteroidetes/Firmicutes ratio. Finally, aggravated lung fibrosis and dysregulated pulmonary T-cell responses were observed in earlyATB and lifelongATB but not adultATB-exposed mice. Collectively, intestinal microbiota manipulation with streptomycin exacerbated pathology in two distinct sites, skin and lungs, with early life being a critical window to affect the course of SSc-like disease.

Dabigatran aggravates topoisomerase I peptide-loaded dendritic cells-induced lung and skin fibrosis.

OBJECTIVES: Dysregulated coagulation cascade has been implicated in development of fibrosis in systemic sclerosis (SSc). Thrombin, a key mediator of the coagulation pathway, has both proinflammatory and procoagulant properties. Here, we evaluated the efficacy of oral dabigatran, a direct thrombin inhibitor, on topoisomerase I dendritic cells (TOPOIA DCs)-induced lung and skin fibrosis, an experimental model of SSc. METHODS: Mice were repeatedly immunized with TOPOIA DCs. Dabigatran was administered in food either during the onset of fibrotic (late treatment) or inflammatory (early treatment) phase. RESULTS: Early administration of dabigatran caused an aggravation of pulmonary fibrosis associated with signs of severe perivascular inflammation while late treatment was not protective when compared to the untreated TOPOIA DCs group. Thrombin was increased in lungs of TOPOIA DCs immunized group and, paradoxically, further augmented by administration of dabigatran to immunized mice. As in lungs, early and not late drug administration exacerbated skin fibrosis. Moreover, early dabigatran treatment induced a profibrotic and inflammatory skin gene expression signature with upregulated expression of Col5a1, Timp1, Tweakr, Vwf, Il6, Il33, Il4 and Ifng. CONCLUSIONS: Dabigatran aggravated lung and skin fibrosis in a TOPOIA DCs-induced model of SSc-like disease. Therefore, our results argue against the use of dabigatran to treat patients with SSc.

Topoisomerase I peptide-loaded dendritic cells induce autoantibody response as well as skin and lung fibrosis.

DNA Topoisomerase I (TopoI) is a candidate autoantigen for diffuse cutaneous systemic sclerosis (dcSSc) associated with fatal lung disease. Dendritic cells (DCs) contribute to bleomycin-induced lung fibrosis. However, the possibility that TopoI-loaded DCs are involved in the initiation and/or perpetuation of dcSSc has not been explored. Here, we show that immunization with TopoI peptide-loaded DCs induces anti-TopoI autoantibody response and long-term fibrosis. Mice were repeatedly immunized with unpulsed DCs or DCs loaded with either TOPOIA or TOPOIB peptides, selected from different regions of TopoI. At week 12 after initial DC immunization, TOPOIA DCs but not TOPOIB DCs immunization induced mixed inflammation and fibrosis in lungs and skin. At a late time point (week 18), both TOPOIA DCs and TOPOIB DCs groups displayed increased alpha-smooth muscle actin expression in lungs and dermis along with skin fibrosis distal from the site of injection when compared with unpulsed DCs. Both TopoI peptide-DC-immunized groups developed IgG2a anti-TopoI autoantibody response. At week 10, signs of perivascular, peribronchial, and parenchymal pulmonary inflammation were already observed in the TOPOIA DCs group, together with transient elevation in bronchoalveolar lavage cell counts, IL-17A expression, and CXCL4 production, a biomarker of early human dcSSc. Collectively, TopoI peptide DCs induce progressive autoantibody response as well as development of protracted skin and lung dcSSc-like disease. Pronounced lung inflammation, transient IL-17A, and CXCL4 expression precede fibrosis development. Our immunization strategy, that uses self immune system and autoantigen, will help to further investigate the pathogenesis of this complex autoimmune disorder with unmet medical needs.