Could the Spike Protein Derived from mRNA Vaccines Negatively Impact Beneficial Bacteria in the Gut?

Me: If vaccinated, how is your gut these days?

Could the Spike Protein Derived from mRNA Vaccines Negatively Impact Beneficial Bacteria in the Gut?

A new hypothesis suggests that the synthetic spike protein from mRNA vaccines could negatively affect beneficial gut bacteria, potentially disrupting gut health.

Although the mechanism by which SARS-CoV-2 infects these beneficial bacteria has been described [17,18,19,20,55], it is still unknown how the vaccine-derived spike protein caused such a reduction of helpful bacteria. In a later work, Hazan et al. [56] demonstrated that there was a persistent reduction in Bifidobacterium abundance following mRNA SARS-CoV-2 vaccination. They longitudinally recorded the relative abundance of the genus Bifidobacterium in four subjects before receiving the mRNA vaccine (Pfizer or Moderna), approximately one month after the vaccine, and 6 to 9 months later. After that period, all Bifidobacterium relative abundance had decreased to 15%, 0%, 35%, and 60% of pre-vaccine levels. Despite this significant reduction, no subjects in the study demonstrated significant clinical complications [56]. In our opinion, it is likely that the presence of other beneficial bacteria, such as Faecalibacterium prausnitzii and Dorea formicigenerans, could dampen the damage caused by the synthetic spike protein.

Investigating whether the spike protein from vaccines can directly or indirectly interact with and potentially harm the GM is essential for several reasons:

(1)

The GM affects digestion, metabolism, immunological response, and even neurological functions. It is essential for preserving general health [57,58]. This delicate ecosystem might be altered if the spike protein or its components were discovered to interact with and damage beneficial commensal bacteria in the gut.

(2)

Proper development and control of the immune system depend on gut microbes. Dysbiosis, or changes in the GM composition, has been connected to several immune-related diseases and disorders [59]. Investigating the potential effects of the spike protein on the GM could provide insight into possible immune dysregulation mechanisms.

(3)

The ACE2 receptor is the primary route via which SARS-CoV-2 infects human cells [60]; however, the spike protein may also interact with other receptors or parts of the cell, such as those found on the surface of bacteria [61]. Studying these interactions is intriguing from a scientific standpoint because it may shed light on hitherto undiscovered aspects of viral biology and host-virus dynamics.

In summary, while the mRNA vaccines played a crucial role in reducing disease severity and death, it is essential to investigate their long-term impact on gut health. The proposed hypothesis and experimental protocol provide a foundation for future studies to explore these effects. Understanding the long-term clinical implications will help in optimizing vaccine strategies and managing any potential adverse outcomes associated with changes in the GM. Variations in the composition of the microbiome have been linked to modifications in the effectiveness of certain immunological treatments, such as the COVID-19 vaccines [62,63,64]. The immunogenicity and effectiveness of vaccines can be enhanced by the GM [65,66,67]. Conversely, the opposite is also valid: the COVID-19 vaccines can have a major negative or positive impact on the GM, which could decrease or increase the overall number of organisms and species diversity [68].

A beneficial effect of an inactivated SARS-CoV-2 vaccine on GM was recently reported [64]. Researchers collected fecal samples from individuals who were injected with two doses of the BBIBP-CorV vaccine and from unvaccinated controls. The diversity and physiological functions of the microbiota of vaccinated and unvaccinated subjects were compared. The phylum Firmicutes was discovered to be more abundant in vaccinated people in this study, whereas the unvaccinated group had more Bacteroidetes detected. As a result, the vaccinated subjects had an elevated Firmicutes/Bacteroidetes ratio [64]. Inflammatory bowel conditions such as ulcerative colitis and Crohn’s disease have been associated with a lower F/B ratio [69].

Furthermore, the vaccinated participants showed a substantial increase in the butyrate-producing bacterium Faecalibacterium prausnitzii [64]. This is a relevant finding, since it was discovered that SARS-CoV-2 can infect and destroy this bacterium [17,18,19,20]. On the other hand, individuals who had received vaccinations did not exhibit a higher abundance of opportunistic pathogens like Enterococcus and Prevotella [64]. According to some studies, higher Prevotella abundance in HIV patients may be a contributing factor to the gut’s chronic inflammation, which can cause mucosal dysfunction and systemic inflammation [70,71]. The study by Shen et al. [64] showed substantially enhanced profiles and physiological capabilities of the GM influenced by vaccination with the BBIBP-CorV vaccine, which may have profound impacts on the host’s ability to build a strong immunological barrier.

On the contrary, a negative impact on certain bacterial species (Bifidobacterium) has been demonstrated for mRNA vaccines [47,56]. Unfortunately, those studies focused only on one species. It is suggested that the global diversity profile of the GM should be studied in future investigations. By measuring the relative abundance of the most beneficial and harmful species, more valid conclusions could be obtained about the effects of mRNA vaccines on GM. These different results suggest that inactivated COVID-19 vaccines induce a beneficial effect on GM, while mRNA vaccines do not. However, more studies are necessary to reach a definitive conclusion.

The reduction in Bifidobacterium abundance found by Hazan et al. [47,56] after the administration of mRNA vaccines should be further investigated, because there is a growing body of research suggesting a connection between reduced Bifidobacterium abundance and colorectal cancer [72,73,74,75,76]. Although Hazan et al. [47,56] did not report significant clinical complications in the mRNA-vaccinated individuals in the short term (1 year), continuous exposure to these vaccines could further reduce Bifidobacterium numbers, thus facilitating cancer growth. It is generally accepted that it takes approximately 10 to 15 years for benign polyps, specifically adenomas, to develop into colon and colorectal cancer [77,78,79,80,81].

Bifidobacterium can reduce inflammation by producing short-chain fatty acids (SCFAs) like butyrate, which have anti-inflammatory properties. SCFAs can inhibit the expression of pro-inflammatory cytokines and promote regulatory T cell differentiation, thereby reducing inflammation and potentially lowering cancer risk [82]. Animal studies have demonstrated that the administration of Bifidobacterium can reduce tumor growth, particularly by activating dendritic cells and enhancing T cell responses [83]. This immune modulation is also crucial in preventing cancer and improving the efficacy of immunotherapy [84].

Finally, for individuals who have received multiple mRNA vaccines and those who suffered severe COVID-19, it is suggested to consider consuming prebiotics and probiotic supplements containing Bifidobacterium, Faecalibacterium prausnitzii, and other beneficial species to recolonize their GM be considered, thus reestablishing the functionality of their gut immune system.

MDPI

Me: If vaccinated, how is your gut these days?