Sialidase inhibitors attenuate pulmonary fibrosis in a mouse model

Abstract

Fibrosis involves increasing amounts of scar tissue appearing in a tissue, but what drives this is unclear. In fibrotic lesions in human and mouse lungs, we found extensive desialylation of glycoconjugates, and upregulation of sialidases. The fibrosis-associated cytokine TGF-β1 upregulates sialidases in human airway epithelium cells, lung fibroblasts, and immune system cells. Conversely, addition of sialidases to human peripheral blood mononuclear cells induces accumulation of extracellular TGF-β1, forming what appears to be a sialidase - TGF-β1 - sialidase positive feedback loop. Monocyte-derived cells called fibrocytes also activate fibroblasts, and we found that sialidases potentiate fibrocyte differentiation. A sialylated glycoprotein called serum amyloid P (SAP) inhibits fibrocyte differentiation, and sialidases attenuate SAP function. Injections of the sialidase inhibitors DANA and oseltamivir (Tamiflu) starting either 1 day or 10 days after bleomycin strongly attenuate pulmonary fibrosis in the mouse bleomycin model, and by breaking the feedback loop, cause a downregulation of sialidase and TGF-β1 accumulation. Together, these results suggest that a positive feedback loop involving sialidases potentiates fibrosis, and suggest that sialidase inhibitors could be useful for the treatment of fibrosis.

Sialidases From Clostridium perfringens and Their Inhibitors

“…Recently, researchers have reported encouraging findings. One study showed that sialidase inhibitors could attenuate pulmonary fibrosis in mice, suggesting that sialidase inhibitors may be helpful in the treatment of fibrosis (Karhadkar et al, 2017). Another study indicated that C9-BA-DANA inhibits endogenous and ectopically expressed sialidase activity and established NEU1-mediated bioactivities in human airway epithelia, lung microvascular endothelia, and fibroblasts in vitro and murine lungs in vivo (Hyun et al, 2016).…”

Targeting glycosphingolipid metabolism as a potential therapeutic approach for treating disease in female MRL/lpr lupus mice

“…Mice administered OP at 10 mg/kg/day have similar plasma levels of oseltamivir carboxylate, the active metabolite of OP, with the same area under the curve (AUC) as humans administered OP at 75 mg/kg twice daily [19]. Moreover, a 10 mg/kg dose in mice was effective in blocking mammalian neuraminidase activity in vivo [20,21]. Therefore, mice received vehicle (water) or 10 mg/kg/day oseltamivir phosphate (OP) (Santa Cruz Biotechnology sc-208135A; Dallas, TX) by gavage daily for four weeks.…”

“…Several studies demonstrated OP blocks endogenous mammalian NEU activity in vitro and in vivo with concentrations in the μM range depending on the cell type and study (compared to nM range for viral NEUs) [20,[37][38][39][40][41][42][43]. We chose a 10 mg/kg dose based on previous studies in mice demonstrating it was effective in blocking mammalian neuraminidase activity in vivo to decrease GM1 levels in T cells [20] and reduce bleomycin-induced lung fibrosis [21]. Although many of these studies suggest OP inhibits NEU1, the major NEU expressed in the kidney, activity of the other NEUs could be compensating if OP does not effectively inhibit all four mammalian NEUs.…”

Serum Amyloid P inhibits single stranded RNA-induced lung inflammation, lung damage, and cytokine storm in mice

“…At 24 and 48 hours after ORN06 insult, the control mice and some of the ORN06-treated mice were given intraperitoneal injections of 100 µl PBS, or SAP diluted to a dose of 2.5 mg/kg in 100 µl PBS. At day 3, mice were euthanized by CO 2 inhalation, and bronchoalveolar lavage fluid (BALF) was obtained as previously described (55,57). The experiment was performed in accordance with the recommendations in the Guide for the Care and use of Laboratory Animals of the National Institutes of Health.…”

“…Immunochemistry on BALF cell spots and counts of cells was performed as described previously (57,60,61). Slides were incubated with monoclonal antibodies overnight at…”