How does the immunomodulatory parasitic worm product ES-62 rewire bone marrow cells to increase healthspan and lifespan in obesity-accelerated ageing?

Around a quarter of the global human population is infected with parasitic worms. Although undoubtedly a public health problem, increasingly there is acceptance that these traditionally unwelcome visitors may actually confer some health benefits. In particular, the evidence, from a combination of studies on human patients and experiments employing mouse models, indicates that worm infection can protect against development of a range of debilitating diseases including allergic (e.g., asthma), autoimmune (e.g. RA) and cardiovascular conditions. What all these illnesses have in common is an association with persistent, unnecessary inflammatory responses and it is therefore not surprising that the protection afforded by parasitic worms has been correlated with their ability to secrete anti-inflammatory molecules, which can resolve these. One particularly well-characterised molecule is ES-62, which we have previously found to protect against disease development in mouse models of RA, kidney disease and accelerated atherosclerosis associated with systemic lupus erythematosus, and both lung and skin allergy.

A risk factor for the development of many diseases linked with harmful inflammatory responses is ageing, which is itself associated with chronic low-level inflammation and this risk is further increased by obesity. As the human population is becoming both progressively older and increasingly obese, it is thus inevitable that the prevalence of such ailments is rising. We therefore recently turned our attention to investigating whether ES-62 could act to counter this by assessing its impact on well-being in a C57BL/6J mouse model of obesity-accelerated ageing where animals are fed high calorie diet (HCD) over their lifetime. Not surprisingly, we found ES-62 to inhibit systemic obesity-induced inflammation but a number of other protective effects were noted, intriguingly including within the ageing bone marrow (BM) niche. The BM contains various types of cells - "stem cells" - which following a process of maturation have the job of replenishing certain cell types in the body, e.g., cells of the immune system and those required for healthy bone and other tissues. As is observed in humans, obesity and ageing led to impairment of stem cell populations in our HCD-fed ageing mice. This however was significantly reduced in male mice by ES-62 treatment and furthermore, the worm product also protected against the bone loss arising from the changes in BM cells occurring during obesity-accelerated ageing in these animals.

As far as we aware, being able to prevent the effects of ageing on BM cells has not previously been attributed to a parasitic worm product. Our central aim is thus to employ our mouse model of obesity-accelerated ageing to determine how ES-62 achieves this. In particular, we will address the following objectives:

1. Determine whether ES-62's effects on BM cells reflect changes in the expression of particular genes within the cells and how the worm product "rewires" the cellular machinery controlling this.
2. Define how ES-62-mediated changes in gene expression are linked to rescue of defective BM cells.
3. Use BM transfer experiments to determine whether ES-62-conditioned BM promotes improved health in recipient mice and also establish whether its protective effects are due to direct or indirect, for example via the microbiome, interaction with BM cells.

Successful achievement of our objectives will provide knowledge and understanding of the mechanisms underpinning the BM-protective, anti-inflammatory actions of ES-62. ES-62's properties dictate that it is already considered to possess therapeutic potential for a range of illnesses associated with harmful inflammation but our new BM-data clearly suggest that its potential disease-coverage may be even wider, for example, extending to protection against ageing-associated degenerative bone disorders like osteoporosis and malignancies such as leukemia.

Molecules secreted by parasitic worms are increasingly being considered as potential novel therapeutics, due to their ability to modify host inflammatory responses. One particularly well-characterised example is ES-62. Intriguingly, when tested in a C57BL/6J mouse model of obesity-accelerated ageing, in addition to its established role in suppressing inflammation, ES-62 prevented HCD-induced dysregulation of a number of physiological systems. One system that particularly interested us, due to the unexpected nature of its targeting, was the bone marrow (BM), where in male mice, ES-62-treatment prevented skewing of haematopoietic stem cells towards myeloid and megakaryocyte lineages. Furthermore, this reversal was accompanied by significant slowing of the accompanying loss of bone architecture. Overall therefore, our data suggest that ES-62 targets BM-progenitors to prevent the damaging changes in immune responses and osteoporosis that are associated with ageing.

Our overarching aim is thus to employ our mouse model of obesity-accelerated ageing to determine how ES-62 achieves this. We will:

1. Identify how BM is impacted by ES-62-exposure, via characterisation of global transcriptomic (RNA-seq) and epigenetic (chromatin accessibility, DNA methylation and histone marks) landscapes using BM cells from our unique ageing mouse tissue biobank.
2. Define how ES-62-mediated changes in epigenetic and target gene signatures are linked to prevention of HCD-induced stem cell changes via assessment of a wide range of markers of ageing and consequent immune system dysfunction in recipient animals following BM transfer.
3. Determine whether transfer of ES-62-conditioned BM promotes improved health of organ systems previously shown to be protected by ES-62 and whether its rewiring effects are direct or indirect by assessing the impact of direct exposure of BM cells to ES-62 in vitro and ES-62-dependence on the microbiome, respectively.

Short term impacts:
1. Training of a young postdoctoral researcher (PDRA): this multidisciplinary project will provide the PDRA, Dr Felicity Lumb, with new research training in the areas of Omics (epigenomics, transcriptomics and metagenomics) and associated bioinformatic analysis and further training in immunology and inflammation, stem cells, ageing and in vivo biology. The multi-site nature of the project will also foster the ability of the PDRA to network and increase project management and oral and written communication skills, all of which will promote her development as an independent scientist, thereby enhancing employability in either Academia or Biopharma. With respect to the latter, Dr Lumb will continue to be involved in our ES-62/SMA drug development program and hence gain understanding of commercial exploitation of research findings.
2. Knowledge exchange: added value will be provided to our related projects on allergy and autoimmunity, particularly in terms of gaining new theoretical and technical expertise and understanding. In addition, dissemination of the new data will be of benefit to our collaborators and peers working on helminth immunomodulation research and also to the wider community of scientists (for example, working on research areas such as ageing, stem cells, inflammation and drug discovery) and clinicians (for example, those working in ageing co-morbidities like type 2 diabetes and cardiovascular diseases, but also extending to diseases of the bone marrow such as malignancies).

Long term impacts:
1. Fostering the economic competitiveness of UK and global Biopharma industry: identification of novel drug targets, or future drug development based on ES-62 SMAs, could have significant impact, particularly as drugs based on ES-62, a "natural" mechanism of immunomodulation that has evolved over millennia, should be safer and have less side effects than traditional generalised immunosuppressants. They should also be cheaper and easier to produce than biologics and this is certainly our experience to date with the SMAs, which also do not suffer from problems of immunogenicity. In addition, any licensing agreement/spin-out company arising out of the project would raise the global profile and economy of UoS and UoG.
2. Public Services and Policy: As there are currently no fully effective therapies for the range of co-morbidities linked to obesity-accelerated ageing, future development of ES-62-based drugs, based for example on our SMAs, could ultimately impact on regulatory bodies such as the Medicines and Healthcare Products Regulatory Agency (MHRA) in the UK and also globally, for example, via the USA Federal Drug Agency (FDA) in terms of drug licensing and patient treatment guidelines.
3. Patients: Obesity-accelerated ageing is a progressively debilitating disease that predisposes to a range of attendant life-threatening comorbidities. In many cases there is no cure and existing treatments often suffer from inadequate responsiveness or unwanted side effects. Thus, the ultimate development of ES-62-based drugs could make a real difference to the quality of life and health of such patients.