Impact of a Human Origin Heat Inactivated Probiotic-Lactobacillus Paracasei D3.5 (LpD3.5) as Dietary Supplement on Gut Mucin and Intestinal Permeability in Adults With IBD

IBD is becoming more common in both developed and developing nations, putting a significant strain on the healthcare system. IBD is now a major public health problem that affects ~3.6 million people in the United States and Europe. In 2019, there were approximately 4.9 million cases of IBD worldwide, with China and the USA having the maximum number of cases (911 405 and 762 890 (66.9 and 245.3 cases per 100,000 people, respectively). Accumulating evidence suggests that an abnormal gut microbiota composition, termed as dysbiosis, plays a key role in the pathogenesis of IBDs such as ulcerative colitis (UC) and Crohn's disease (CD). Individuals with IBDs experience pain, extreme discomfort, and numerous other symptoms caused by continuously relapsing and remitting inflammatory lesions in the layer of cells that lines the intestinal lumen (mucosa). The exact causes for IBD still are poorly understood. IBD pathogenesis is perpetuated by abnormal immune responses, which are and related with abnormalities in the intestinal epithelial barrier, enteric nervous system, and changes in microbiota composition.

While anti-inflammatory medications and antibiotics can reduce acute inflammation and fight local infections during IBD flare-ups, their usage is not without consequences. Anti-inflammatory drugs can have severe side effects, and antibiotics can disrupt the beneficial parts of the microbiome. Importantly, there are no wound treatments available that could be given to inflamed lesions directly from inside the gut lumen to speed up healing and reduce the use of those drugs.

On the other hand, probiotics have shown promise in reducing the symptoms of IBD; however, probiotics therapy has limitations. For example, (1) the beneficial effects of probiotics are highly variable, and their significance in clinical settings remains elusive; and (2) probiotics are live bacteria, posing the threat of them leaking into the blood circulation, which can increase the risk of bacterial sepsis. Moreover, there is a lack of preclinical research and clinical trials on probiotics as preventive and therapeutic treatments for CD, particularly at an early age.

We recently discovered a human-origin probiotic strain called LpD3.5 which strengthens intestinal barrier functions and reduces inflammation by restoring intestinal mucus layer. We found that this strain is effective and beneficial even when heat-killed; thus, we call it a postbiotic. Postbiotics are non-viable bacterial products or metabolic byproducts produced by probiotic microorganisms that have biologic activity in the host. Their advantages over probiotics include a lower risk of infection and reducing negative effects caused by certain microorganisms. Indeed, administering live probiotics to persons with weaker immune systems may boost inflammatory reactions and change "generally recognized as safe" harmless probiotic bacteria into harmful pathogens. Hence, the postbiotics LpD3.5 strain is under production in the Good Manufacturing Practice (GMP) facilities for human consumption and will be ready for clinical use. In our previous animal studies, we showed that LpD3.5 feeding significantly increases mucin production and proportionately increases in the abundance of the mucin-degrading bacterium Akkermansia muciniphila. Thus, we hypothesize that postbiotics LpD3.5 may elevate mucin levels in the gut which in turn may be associated with reduced gut permeability, inflammation, and better QOL in individuals with IBD.

The LpD3.5 is a common probiotic and has been isolated from human infant gut. This is one of the most common probiotic strains that are listed as Generally Recognized As Safe (GRAS) by the Food and Drug Administration (FDA) and many international lists.

Since L. paracasei is a common probiotic and widely used as a dietary supplement for human consumption. Here, we will use its heat-inactivated form, which is even safer, to determine if its oral consumption changes fundamental biological outcomes such as mucin levels in the gut. These changes may be associated with other physiological but non-clinical outcomes such as gut permeability, inflammation, and QOL in individuals with IBD. This study is planned to address major gaps in knowledge, including the effects of human-origin heat-inactivated postbiotic L. paracasei on the fundamental biology in the gut of individuals with IBD, which may impact their QOL. However, this study is not intended for any commercial purposes, changing labeling, or making medical claims related to L. paracasei. Rather, it is fully academic, aiming to determine the mechanistic action of L. paracasei and decipher ways to modulate gut mucin, permeability, and inflammation, which can aid us in designing future strategies to improve the QOL in individuals with IBD.