Investigating the role of Lactobacillus Crispatus in healthy skin and psoriasis

Psoriasis is a life-long condition that causes unsightly red, flaky patches of skin. It is also linked with other problems including obesity and depression. Although some treatments exist for psoriasis, many patients do not have adequate control with currently available creams and ointments. More severe psoriasis is treated with tablets and injections that act on the immune system, but these are associated with considerable side effects and require long term monitoring with many blood tests and clinic visits.

New genetic techniques have shown a diverse collection of 'harmless' bacteria that reside on the surface of human skin. A large study of patients with psoriasis and healthy volunteers have shown that there is are differences in the types and numbers of bacteria between the two groups. Lactobacillus Crispatus is a type of bacteria found on the skin that is more common in healthy skin than psoriasis.

The meaning of this finding is not yet clear. However there is evidence that rather than acting as 'innocent bystanders', these bacteria may have an important role in altering the immune system response in the skin. Previous research has shown that overactivity of the immune system is important in promoting psoriasis. The presence of Lactobacillus Crispatus in healthy skin but not psoriasis suggests it may be important in preventing overactivity of the immune system. The exact way that the bacteria do this is not known, but previous studies have shown the importance of certain immune signaling pathways in preventing excess skin inflammation. Our study looks to answer if Lactobacillus Crispatus activates this particular pathway in the skin to prevent inflammation.

There are three main parts to our study:

1) Test how skin samples (biopsies) from healthy volunteers and psoriasis patients are affected by Lactobacillus Crispatus by mixing them with the bacterium in test tubes
2) Test how skin cells from healthy volunteers and psoriasis patients are affected by Lactobacillus Crispatus by mixing them with the bacterium in test tubes
3) Test the effects of Lactobacillus Crispatus on psoriasis severity by applying extracts of the bacterium to a model of psoriasis

To answer this I will take skin biopsies from healthy volunteers and psoriasis patients and mix them with extracts of Lactobacillus Crispatus. We also separate skin cells (keratinocytes) from biopsies and treat these with extracts of the bacterium. We then remove DNA from the cells and biopsies to measure the levels of genes and chemical messengers linked to psoriasis.

To further understand the effects that bacteria have on live systems, we will use well established models of human psoriasis. We treat the inflamed area with extracts of the bacterium to see if this improves the appearance and severity of psoriasis and also asses the effect on genes and messengers.

Learning more about the role of these bacteria in psoriasis may help us identify if we can use them medically (for example in the form of creams or ointments) to treat psoriasis in the future.

Background: Lactobacillus Crispatus is a skin resident bacterium more abundant in healthy skin than psoriasis and correlates transcriptomically with key skin immunity pathways.

Aim: Characterise the role of L. crispatus on key immunity pathways and skin inflammation

Objectives
1. Determine effects of L. crispatus on immune pathway and psoriasis-relevant genes and inflammatory mediators in a human skin explant model
2. Determine effects of L. crispatus on immune pathway genes in primary keratinocyte cultures derived from healthy and psoriasis skin
3. Interrogate functional role of L. crispatus through in-vivo models of psoriasis

Methodology: Whole skin explants and primary keratinocytes derived from healthy and psoriatic skin will be incubated with L. crispatus extracts. Relevant expression of immune pathway genes, core psoriasis cytokines and antimicrobial peptides will be analysed through quantitative PCR (qPCR). Whole transcriptome gene expression profiling through RNA sequencing will identify novel gene transcripts modulated by L. crispatus. In-vivo models of psoriasiform inflammation will be treated with topical L. crispatus extracts to assess the effect on psoriasis severity and immune pathway activation. In all models, severity is graded histologically and using immunohistochemistry. qPCR is performed to quantify relative immune pathway gene and psoriasis relevant cytokine expression. A humanized in-vivo model of psoriasis will also be treated with topical L. crispatus to confirm microbial anti-inflammatory effects.

Medical Opportunities: We will further characterise the mechanisms controlling skin homeostasis and inflammation and how skin-resident bacteria interact with the immune system. This could lead to clinical trials of novel therapeutics (e.g. L. crispatus probiotics or immunomodulatory drugs) for psoriasis, other inflammatory dermatoses such as eczema and acne and related cross-disciplinary diseases (e.g. Crohn's disease).

Our project has potential beneficiaries including patients, clinicians, scientists, the government, private sector companies, charities, the media and the general public.

Psoriasis is a debilitating, unsightly skin condition affecting approximately 1 million people in the UK. It is associated with cardiovascular, metabolic (including obesity) and psychosocial morbidity and represents a significant social and economic burden. Many patients experience inadequate disease control and newer therapies for advanced disease are costly, associated with significant side effects and require long term monitoring. Our research may identify novel therapeutic targets that result in more effective drugs that improve quality of life. Psoriasis patients are therefore key beneficiaries through improved understanding about their condition and potentially new treatments. We will engage patients through charities such as the Psoriasis Association and British Association of Dermatologists with guidance from our psoriasis patient representative on the research project steering committee. More broadly, our research could advance knowledge of skin inflammation of relevance to patients with other common inflammatory skin conditions in which microbes are implicated in the pathogenesis including acne, rosacea and eczema.

The role bacteria play in health and disease is a popular topic in the media with regular newspaper and television coverage. The media would be interested in our research outputs and consequently the general public, who are well educated on the concept of 'good bacteria' through commercially available probiotic products for digestive health (many incidentally based on Lactobacillus species).

Novel therapeutics could include probiotics or immunomodulatory therapies. King's partners our comprehensive NIHR Biomedical Research Centre, which has an active translational research programme to facilitate drug discovery. Possible economic beneficiaries include pharmaceutical companies who could jointly formulate and develop novel therapies after we have sought intellectual property to protect our work. The UK economy would benefit from cheaper, safer drugs that require less monitoring which would be directly advantageous for the NHS and government and indirectly from effective disease control resulting in reduced medical and psychosocial morbidity.

Dissecting the role of L.crispatus on the innate and adaptive immune system would be of interest to researchers in immunology and genetics, and microbiome researchers focusing on other organ systems. Clinicians may benefit from translating our findings to their particular clinical niches. This may include gastroenterologists working in inflammatory bowel disease where microbial dysbiosis is thought to be crucial and also clinicians investigating other autoimmune diseases (e.g. rheumatologists). Characterising the importance of skin resident bacteria may also influence antibiotic prescribing policies and may be relevant to public health bodies in the long term.

Investigating the role of environmental factors in healthy skin could benefit the private sector including cosmetics companies, as these findings may influence the formulation of personal care products that maintain the optimum microbial microenviroment. In addition, biotechnology companies could benefit from use of our in-vitro models of human skin for product pilot studies.

Project staff would develop skills in the interpretation of large microbiomic datasets and functional immunology studies. These skills will enable development of expertise in skin microbiome studies allowing the UK to remain competitive in skin research globally. Other researchers would benefit from shared knowledge on the use of analytical bioinformatics pipelines. Team working and communication skills developed would have personal benefits and aid inspiration of the next generation of scientists through engaging in schools visits