Researchers have determined that a specific protein found in the gut plays a crucial role in combating bacterial proliferation. Owing to its dual protective capabilities, this protein holds promise for future therapeutic applications in conditions such as inflammatory bowel disease. The findings of this study are detailed in the journal Nature Communications.
While Intlectin-2 is not a novel protein to the scientific community, its precise function within the gastrointestinal tract remained elusive until now. Intlectin-2 belongs to the lectin family of proteins, which exert their effects by binding to particular sugar molecules.
A team from the Massachusetts Institute of Technology uncovered that Intlectin-2 operates via a two-pronged mechanism: primarily, it attaches to the mucus molecules lining the GI tract, thereby reinforcing the mucosal barrier that shields the intestinal tissues.
However, should the barrier’s integrity be compromised, Intlectin-2 is also capable of identifying and capturing various bacterial cells, either inhibiting their proliferation or leading to their complete elimination.
Consequently, Intlectin-2’s function is characterized by a combination of defensive and offensive actions aimed at preserving the body’s well-being.
“It is remarkable that Intlectin-2 possesses these two complementary modes of action,” notes Laura Kiessling, a chemist at MIT. “It assists in stabilizing the mucus layer, and if that barrier is breached, it can directly neutralize or suppress bacteria that start escaping beyond it.”
The researchers employed a combination of techniques to examine Intlectin-2’s activity. They analyzed tissues from mice, intestinal microbiota from both mice and humans, as well as laboratory-isolated versions of the protein—sourced from both humans and mice.
These approaches demonstrated that Intlectin-2 specifically targets galactose, a simple sugar present both within mucus molecules and on the carbohydrates covering the surface of certain bacterial cells (including those implicated in gastrointestinal infections).
In instances where Intlectin-2 successfully binds to and sequesters microbes, the bacteria appear to degrade over time, potentially because the protein compromises the integrity of their outer membrane.
Furthermore, some bacteria that are neutralized by Intlectin-2 have independently developed varying degrees of antibiotic resistance, rendering these discoveries even more significant in the context of drug development.
Such bacteria include Staphylococcus aureus, which can lead to sepsis, and Klebsiella pneumoniae, a cause of pneumonia and other infections.
“Intlectin-2 first fortifies the mucosal barrier itself, and then, if that barrier breaks down, it can control and limit the growth of bacteria,” Kiessling explains.
Scientists estimate that the human genome encodes for over 200 lectins, and ongoing work is focused on understanding their impact on intercellular communication and immune system function.
Prior to this investigation into Intlectin-2, scientists had linked Intlectin-1 in the gut to Crohn’s disease. This suggests that these proteins collectively play a vital role in maintaining gut health.
The researchers also observe that Intlectin-2 levels are frequently found to be abnormally low or high in individuals suffering from Inflammatory Bowel Disease (IBD). Based on this new study, this anomaly might suggest impaired mucosal barrier repair or the elimination of beneficial microbes.
Both the offensive and defensive aspects of Intlectin-2’s operation could prove valuable in the future, either through the development of pharmaceuticals that mimic some of the protein’s actions or by boosting the body’s inherent capabilities.
These lectins are ancient animal proteins believed to have existed long before the more sophisticated immune systems active in our bodies today. Yet, this research reveals they are not crude instruments; they engage in highly specific elimination of harmful bacteria.
“Harnessing human lectins as tools against antimicrobial resistance opens up a whole new strategy based on our own innate immune defenses,” states Kiessling. “Utilizing proteins that the body already employs for pathogen defense is a promising avenue, and it is precisely the direction we are pursuing.”
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