Background & Aims
Sickle cell disease (SCD) is a complex inherited disorder, with pain as the major symptom. Sickle cell pain manifests as both acute pain episodes and persistent ongoing chronic pain, resulting in lifelong suffering for the patients. Despite our firm grasp on the disease pathophysiology, our understanding of SCD pain remains incomplete resulting in inadequate pain management. With the growing understanding of the gut microbiome’s significance in host health and disease, recent evidence suggests a more pivotal role of gut microbiome in sickle cell pathophysiology. With the current study, we aim to redirect the attention towards understanding the gut-brain axis and investigating the impact of this bidirectional signaling on pain perception and processing in SCD.
To achieve this, we explore the changes in the gut microbiome and gut-derived metabolome of sickle cell disease transgenic mouse model and investigate the impact of these changes on sickle cell pain and comorbidities.
Methods
To explore the changes in the gut microbiome, we employed 16S rRNA sequencing from fecal samples and identified compositional differences and specific genera with differential abundance between sickle cell transgenic mice and their healthy non-sickle littermates using ALDEx2. Furthermore, to identify the functional differences within the gut microbiome of the two groups, LC-MS and GC-MS were used. To understand how these differences in the gut microbiome and gut-derived metabolome impact sickle cell pain, we reshaped the gut microbiome, either by using antibiotics, causing depletion, or by fecal material transplantation (FMT). The sickle cell pain was evaluated by testing for mechanical allodynia, heat hyperalgesia and cold allodynia. Additionally, the ongoing spontaneous pain was evaluated by CPP. The mice were also tested for pain comorbidities using elevated plus maze (EPM) and open field test (OFT) to further explore the impact of gut microbiome.
Results
The analysis of the gut microbiome composition depicted significant differences based on the diversity matrices, wherein the SCD mice depicted low species diversity and we were able to identify specific genera that were differentially abundant. Using metabolomics, we found significant differences in the functional metabolite profile. To further explore how these differences potentially contributed to SCD pain, we used antibiotics to deplete the gut microbiome, which didn’t change the evoked pain, but significantly attenuated ongoing spontaneous pain. In keeping with the objective of restoring the gut microbiota, we used FMT as an intervention, where the transplant from healthy non-sickle mice to sickle mice resulted in attenuation of pain, as evidenced by reduced evoked pain as well as reduced pain comorbidities like anxiety. Furthermore, FMT from sickle mice to healthy non-sickle mice resulted in induction of pain and anxiety-like behaviors.
Conclusions
These findings provide new insights on the impact of gut dysbiosis and bidirectional signaling of the gut-brain axis on sickle cell pain, highlighting the differential gut microbial communities and gut-derived metabolites which may serve as potential intervention targets and may ultimately lead to rational design of new pain therapies.
References
Funding: This study was supported in part by a grant from the National Heart, Lung, and Blood Institute (NHLBI) R35 HL140021 (Z.W.). Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the NHLBI or NIH.
Presenting Author
Yavnika Yashyap
Poster Authors
Zaijie Jim Wang
PhD
University of Illinois
Lead Author
Topics
- Models: Chronic Pain - Neuropathic