Eubacterium rectale Improves the Efficacy of Anti-PD1 Immunotherapy in Melanoma via l-Serine-Mediated NK Cell Activation

Nian Liu; Lihui Chen; Mingjie Yan; Qian Tao; Jie Wu; Jing Chen; Xiang Chen; Wei Zhang; Cong Peng

doi:10.34133/research.0127

Eubacterium rectale Improves the Efficacy of Anti-PD1 Immunotherapy in Melanoma via l-Serine-Mediated NK Cell Activation

Research (Wash D C). 2023 Apr 28:6:0127. doi: 10.34133/research.0127. eCollection 2023.

Authors

Nian Liu^{1

2

3

4

5}, Lihui Chen^{1

5}, Mingjie Yan^{1

2

3

4

5}, Qian Tao^{1

3

4}, Jie Wu^{1

3

4}, Jing Chen^{1

3

4}, Xiang Chen^{1

2

3

4

5}, Wei Zhang^{1

2

5}, Cong Peng^{1

2

3

4

5}

Affiliations

¹ Department of Clinical Pharmacology, Xiangya Hospital, Central South University, Changsha, Hunan, China.
² Department of Dermatology, Xiangya Hospital, Central South University, Changsha, Hunan, China.
³ Hunan Key Laboratory of Skin Cancer and Psoriasis, Xiangya Hospital, Central South University, Changsha, Hunan, China.
⁴ Furong Laboratory, Xiangya Hospital, Central South University, Changsha, Hunan, China.
⁵ National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan, China.

Abstract

Natural killer (NK) cells, as key immune cells, play essential roles in tumor cell immune escape and immunotherapy. Accumulating evidence has demonstrated that the gut microbiota community affects the efficacy of anti-PD1 immunotherapy and that remodeling the gut microbiota is a promising strategy to enhance anti-PD1 immunotherapy responsiveness in advanced melanoma patients; however, the details of the mechanism remain elusive. In this study, we found that Eubacterium rectale was significantly enriched in melanoma patients who responded to anti-PD1 immunotherapy and that a high E. rectale abundance was related to longer survival in melanoma patients. Furthermore, administration of E. rectale remarkably improved the efficacy of anti-PD1 therapy and increased the overall survival of tumor-bearing mice; moreover, application of E. rectale led to a significant accumulation of NK cells in the tumor microenvironment. Interestingly, conditioned medium isolated from an E. rectale culture system dramatically enhanced NK cell function. Gas chromatography-mass spectrometry/ultrahigh performance liquid chromatography-tandem mass spectrometry-based metabolomic analysis showed that l-serine production was significantly decreased in the E. rectale group; moreover, administration of an l-serine synthesis inhibitor dramatically increased NK cell activation, which enhanced anti-PD1 immunotherapy effects. Mechanistically, supplementation with l-serine or application of an l-serine synthesis inhibitor affected NK cell activation through Fos/Fosl. In summary, our findings reveal the role of bacteria-modulated serine metabolic signaling in NK cell activation and provide a novel therapeutic strategy to improve the efficacy of anti-PD1 immunotherapy in melanoma.