Talabostat, fibroblast activation protein inhibitor, attenuates inflammation and fibrosis in systemic sclerosis

Systemic sclerosis (SSc) is a connective tissue disorder characterized by excessive fibrosis, where activated fibroblasts play a pivotal role in disease progression. This study aimed to investigate the potential of Talabostat, a small molecule inhibitor of dipeptidyl peptidases, in alleviating fibrosis and inflammation associated with SSc pathogenesis.

Dermal fibroblasts were obtained from skin biopsies of ten diffuse cutaneous SSc patients and healthy controls. These fibroblasts were subjected to treatment with either TGF-β alone or in combination with Talabostat. Immunofluorescence staining was conducted to evaluate FAPα and α-SMA protein levels. The expression of activated fibroblast markers (FAPα and ACAT2), pro-fibrotic (COL1A1 and COL1A2), anti-fibrotic (MMP1, MMP2, and MMP9), and inflammatory (IL-6 and TGFβ1) related genes was measured by quantitative real-time PCR. Talabostat-treated fibroblasts were assessed for their migratory capacity using a scratch assay and for their viability through MTT assay and Annexin V staining.

The basal expression of COL1A1 and TGFβ1 was notably higher in healthy subjects, while MMP1 expression showed a significant increase in SSc patients. Furthermore, TGF-β stimulation led to upregulation of activated fibroblast markers, pro-fibrotic, and inflammatory-related genes in SSc-derived fibroblasts, which were attenuated upon Talabostat treatment. Interestingly, Talabostat treatment resulted in an upregulation of MMP9 expression. Moreover, Talabostat exhibited a concentration-dependent inhibition of activated fibroblast viability in both healthy and SSc fibroblasts, and suppressed fibroblast migration specifically in SSc patients.

In summary, Talabostat modulates fibrotic genes in SSc, thereby inhibiting myofibroblast differentiation, activation, and migration. These findings suggest promising therapeutic avenues for targeting fibrosis in SSc.