2024-25 Project (Chong & Friedland)

The role of hunger hormones on inflammation and tissue remodelling in Tuberculosis

SUPERVISORY TEAM

Supervisor

Dr Deborah Chong at SGUL
Email: dchong@sgul.ac.uk

Co-Supervisor

Prof Jon Friedland at SGUL
Email: jonfriedland@sgul.ac.uk

PROJECT SUMMARY

Project Summary

Tuberculosis (TB) is one of the of the most prevalent and lethal infectious diseases worldwide, with an estimated 10 million people infected with Mycobacterium tuberculosis (Mtb), the causative agent of TB. Weight loss is a characteristic clinical feature of TB suggesting major changes in metabolism, whilst at the microscopic level, the hallmark features include inflammation and tissue remodelling. Hormones such as leptin (“weight-loss hormone”) and ghrelin (“hunger hormone”) work together to regulate body weight. However, there is growing evidence demonstrating that, aside from regulating body weight homeostasis, leptin and ghrelin modulate inflammatory and wound healing processes. It is unclear whether these hormones modulate inflammation or tissue remodelling in TB.    

This PhD project will investigate the effects of hunger hormones, such as leptin and ghrelin, on inflammatory and tissue remodelling responses mediated by fibroblasts during Mtb infection. This will be achieved through many different in vitro molecular immunological and cellular techniques including cell culture, ELISA, Western blot, qRT-PCR and confocal microscopy. It is intended to develop CRISPR-Cas9 technology to examine the effect of blocking specific cell signalling pathway.

Project Key Words

Tuberculosis  Innate immunity  Inflammation  Wound healing  Hormones  Fibroblasts

MRC LID Themes

  • Global Health = Yes
  • Health Data Science = No
  • Infectious Disease = Yes
  • Translational and Implementation Research = No

Skills

MRC Core Skills

  • Quantitative skills = Yes
  • Interdisciplinary skills = No
  • Whole organism physiology = No

Skills we expect a student to develop/acquire whilst pursuing this project

The student will be trained in various aspects focused towards studying immunological and cellular responses.   

Specific techniques that the student will acquire include: 
(i) cell biology techniques including cell culture of primary fibroblasts, monocyte isolation from blood, functional assays such as cell proliferation, migration or collagen deposition assays. 
(ii) biochemical techniques including Western blot, qRT-PCR and immunofluorescence microscopy. 
(iii) immunological techniques including ELISA and Luminex multiplex 
(iv) microbiology techniques including culturing Mtb and how to work safely with a category 3 pathogen 
(v) gene silencing and editing techniques such as siRNA and CRISPR-Cas9 
(vi) verbal and written communication skills to scientific and lay audiences

Routes

Which route/s is this project available for?

  • 1+4 = Yes
  • +4 = Yes

Possible Master’s programme options identified by supervisory team for 1+4 applicants:

  • SGUL – MRes Biomedical Science – Infection and Immunity
  • SGUL – MSc Global Health

Full-time/Part-time Study

Is this project available for full-time study? Yes
Is this project available for part-time study? Yes

Eligibility/Requirements

Particular prior educational requirements for a student undertaking this project

  • SGUL’s standard institutional eligibility criteria for doctoral study.
  • BSc at 2.1 or above or MSc in an appropriate related subject area.

Other useful information

  • Potential CASE conversion? = No

PROJECT IN MORE DETAIL

Scientific description of this research project

Scientific rationale:
Tuberculosis (TB) is the leading cause of death from a single infectious disease, with 10.6 million people infected with Mycobacterium tuberculosis (Mtb). Mtb typically causes pulmonary disease characterised by tissue remodelling. Lung fibroblasts drive tissue destruction in a Mtb-monocyte-dependent network, although the regulation of fibroblast-induced tissue remodelling is ill-defined.  A characteristic symptom in TB patients is weight loss. Hormones, such as leptin and ghrelin, regulate body weight and plasma concentrations of leptin and ghrelin are differentially expressed in TB patients. Additionally, leptin induces pro-inflammatory responses, while ghrelin promotes tissue repair in fibroblasts. Whether hunger hormones modulate inflammation or tissue remodelling in TB is unknown.     Project aim: to investigate whether hunger hormones are regulators of inflammation and tissue remodelling in TB.    

Project objectives: 
1.) Investigate the effects of leptin and ghrelin on inflammatory and tissue remodelling mediators expression from primary human lung fibroblasts (PHLF). 
2.) Investigate the effects of leptin or ghrelin on PHLF cell remodelling processes. 
3.) Define signalling pathways regulating hormone-induced responses in PHLF. 
4.) Assess cellular sources of leptin and ghrelin during Mtb infection.   

Techniques to be used:
PHLF will be stimulated with recombinant leptin or ghrelin for 24, 48 or 72 h. Cell supernatants or lysates will be collected and expression of inflammatory (e.g. IL-6, IL-8) or tissue remodelling mediators (e.g. MMP1, TGF-beta) will be measured by ELISA or qRT-PCR. To investigate cellular effects of leptin/ghrelin, extracellular collagen deposition, cell proliferation or migration will be assessed by confocal or live cell microscopy in PHLF. To define signalling pathways regulating hormone-induced responses, PHLF will be pre-treated with specific inhibitors (e.g. LY294002 or rapamycin) to inhibit PI3K/Akt/mTOR-induced signalling, pathways downstream of leptin- or ghrelin-receptors. Key signalling molecules will be investigated further using siRNA or CRISPR-Cas9. Lastly, to investigate cellular sources of leptin/ghrelin during Mtb infection, monocytes isolated from human leukocyte cones will be infected with Mtb at a multiplicity of infection of 1 for 24 or 48 h before secreted leptin or ghrelin quantified by ELISA.    

Confirmed availability of required materials:
Ethical approval has been obtained to use human leukocyte cones from the blood transfusion service. PHLF are commercially available. Approval to work with Mtb within the CL3 suite at SGUL is established and training will be provided to the student.    

Expected outcomes:
To define the mechanisms by which leptin and ghrelin regulate inflammatory and tissue remodelling responses in fibroblasts in TB. The student will learn a broad range of immunological techniques and how to work in a CL3 laboratory. This project is novel and offers the potential to produce high impact factor publications and the opportunity to present at national and international meetings as part of the PhD experience. The student will gain experience in presenting to lay audiences and training in communication skills.   

Potential risk to project & mitigation plans:
Pilot data indicates that leptin and ghrelin modulate fibroblast phenotype, although the regulation of responses is unknown. If focused approaches to study cell signalling pathway are inconclusive, a broader phospho-kinase array will be used. 

Further reading

(Relevant preprints and/or open access articles)

  • DOI: 10.1084/jem.20191593. De Candia P, Prattichizzo F. Garavelli, S. Alviggi C. La Cava A. Matarese G. The pleiotropic roles of leptin in metabolism, immunity, and cancer. J Exp Med. 2021. 218:e20191593
  • DOI: 10.1371/journal.pone.0054564. Chang SW, Pan, WS, Lozano Beltran D, Oleyda Baldelomar, L. Antonio Solano M, Tuero I, Friedland JS, Torrico F, Gilman RH. Gut hormones, appetite suppression and cachexia in patients with pulmonary TB. PLoS One. 2013. 8:e

Additional information from the supervisory team

  • The supervisory team has provided a recording for prospective applicants who are interested in their project. This recording should be watched before any discussions begin with the supervisory team.
    Chong-Friedland Recording

MRC LID LINKS