Mucin O-glycans protect host cells by tempering pneumolysin expression in Streptococcus pneumoniae

The ability of mucosal epithelia to sustain asymptomatic colonization by pathogens, such as Streptococcus pneumoniae (Spn), remains a significant and unresolved scientific question. This study reveals that mucins—the main gel-forming elements of mucus—and their associated glycans, suppress the expression of pneumolysin, a Spn toxin that causes tissue injury and triggers inflammatory responses. These findings highlight a unique protective function of mucins, offering insights into potential therapeutic strategies. Examination of differential gene expression in Streptococcus pneumoniae TIGR4 in response to MUC5AC mucins and MUC5AC glycans in THY medium