Antibiotics make skin cancer worse by depleting the gut microbiome: What a new study says


A new study by researchers at Emory University in Atlanta indicates that the use of broad-spectrum antibiotics in mice with malignant melanoma, an aggressive form of skin cancer, accelerated their metastatic bone growth. The research noted that this likely happened due to the drugs depleting the mice’s gut flora and weakening their immune response.

Subhashis Pal, Ph.D., postdoctoral fellow in endocrinology at Emory University School of Medicine, said the findings highlight the importance of the gut microbiome in overall health and suggest physicians should carefully weigh the effects gastrointestinal when using antibiotic treatments while treating cancer or other diseases.

He said: “Any disease or therapy that harms the gut microbiome could negatively impact our health. In our study, we found that the gut microbiome inhibits the progression of melanoma bone lesions in mice by promoting the expansion of intestinal natural killer (NK) cells and helper T cells (Th1) and enhancing their migration to the tumor site.

Dr. Pal pointed out that “use of oral antibiotics depleted the gut microbiome and reduced the population of gut NK cells and Th1 cells. This made the mice more vulnerable to tumor growth. They had a higher melanoma tumor burden than control mice whose gut microbiomes were intact. »

Impact of antibiotics on the gut microbiome:

It is important to note that osteolytic bone metastasis is a complication of malignant melanoma. The researchers hypothesized that using antibiotics to deplete the gut microbiome of mice would affect their gut immune cells and thereby alter their immune response, leading to accelerated bone metastasis. They injected B16-F10 melanoma cells into the hearts and bones of mice that had been treated with broad-spectrum antibiotics. As expected, the antibiotic injections accelerated metastatic bone growth in these mice, compared to control mice that did not receive the injections, according to ANI report.

The study revealed the mechanism of metastatic growth of melanoma. Flow cytometry analysis of Peyer’s patches and bone marrow cells in tumor lesions revealed that microbiome depletion prevented melanoma-induced expansion of intestinal NK and Th1 cells and their migration from the intestine to tumor-bearing bones. Direct measurement of NK and Th1 cell migration using Kaede mice, a strain expressing a photo-convertible fluorescent protein that allows direct tracking of intestinal lymphocytes, revealed that antibiotics decreased migration approximately eight-fold NK and Th1 cells from the intestine to the tumor site.

Why maintaining a healthy gut microbiota is important:

This study strongly indicates that antibiotic-induced changes in the microbiome could have negative clinical consequences not only with melanoma, but also with other diseases, Dr. Pal said. “For example, inflammatory bowel disease or other bowel conditions that create inflammation can lead to an increase in Th17 cell counts, with TNF producing cell counts in the gut, which ultimately has a negative impact on the health of our bones. Similarly, we have seen that in a mouse model of surgical menopause, reduced levels of estrogen make it easier for bacterial metabolites to pass through the intestinal barrier and overactivate the immune system. As a result, the number of intestinal and bone marrow cytokine-producing T cells increases, largely contributing to the development of bone loss.”

In order to address the issue, Dr Pal said, “We need to be very careful about our gut microbiome and the unintended adverse consequences of antibiotic regimens. Conversely, probiotics can play a major role in maintaining a healthy gut microbiome and better overall health.”

(With ANI entries)

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