Biological Modulation of Bacterial QSSMs, Innate and Adaptive Immunity by Antibiotics, Probiotics and Prebiotics in Healthy Individuals

Sepsis Clinical Trial

Official title:

Biological Modulation of Bacterial QSSMs, Innate and Adaptive Immunity by Antibiotics, Probiotics and Prebiotics in Healthy Individuals

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT01201577
• Other study ID #: 09GA014
• Status: Completed
• Phase: Phase 1
• First received: September 13, 2010
• Last updated: May 31, 2011
• Start date: October 2009
• Est. completion date: May 2011

Study information

• Verified date: May 2011
• Source: University of Nottingham
• Contact: n/a
• Is FDA regulated: No
• Health authority: United Kingdom: National Institute for Health Research
• Study type: Interventional

Clinical Trial Summary

It has recently been discovered that bacteria are able to communicate using specialised molecules known as Quorum Sensing Signalling Molecules (QSSMs). An accumulation of QSSMs in their surrounding environment allow for the bacteria to quantify the size of colonies. At specific colony sizes the concentration of QSSMs reaches a critical threshold leading to the activation of genes that cause an infection. It is by this mechanism that bacteria within a colony coordinate behaviour to activate infectivity when colony sizes are large enough to withstand defensive measures from the host's immune system. A disruption of quorum sensing may reduce the severity of infection and this has led to the development of inhibitors of quorum sensing as a new strategy in antibacterial therapy.

QSSMs are also thought to facilitate infection by other mechanisms and are able to influence the number and function of a specific type of immune cell known as an 'antigen presenting cell'. These cells are pivotal in allowing the immune system to recognise components of bacteria as foreign and thereby mount the appropriate response. It was found that large numbers of these types of cells underwent programmed cell death (cell suicide) in the presence of QSSMs compared to when QSSMs were absent. This mirrors the situation in blood sampled from patients with severe infections where there is a greater proportion of cell deaths among antigen presenting cells than other types of immune cell.

This study aims to establish in healthy volunteers, the mechanisms by which QSSMs affect immune cells and facilitate the spread of infection. Antibiotic administration in humans can alter the environment of the intestine and can lead to an overgrowth of harmful bacteria to potentially cause an infection. Probiotics supplements can prevent bacterial overgrowth and potentially reduce infective complications. The mechanism, which we aim to clarify, may involve changes in both the production of QSSMs and the function of immune cells.

Hypothesis

1. Antibiotic use alters gut flora, leading to the appearance in the systemic circulation of bacterial QSSMs and changes in immune function of the host.

2. Probiotics and/or prebiotics have beneficial effects by preserving the normal resident gut flora, thereby, modulating bacterial QSSMs and preserving the immune function of the host.

Aims

The aims of our study are 2 fold:

1. Firstly, to study the effect of orally administered antibiotic on QSSMs (in faeces and blood) and on innate and adaptive immunity in healthy humans.

2. Secondly, to study the effect of orally administered combinations of prebiotic, probiotic and antibiotic on QSSMs (in faeces and blood) and on innate and adaptive immunity in healthy humans.

Recruitment information / eligibility

• Status: Completed
• Enrollment: 40
• Est. completion date: May 2011
• Est. primary completion date: May 2011
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: Male
• Age group: 18 Years to 75 Years

Eligibility

Inclusion Criteria:

• Male volunteers

• Age 18-55 years

• Willing to participate and able to give informed consent

• Alcohol abstinence during study

Exclusion Criteria:

• Smokers/substance abusers

• Individuals with diabetes mellitus

• Oral/Intravenous steroids

• Allergy to azithromycin

• Individuals already taking regular medications/probiotics/nutritional supplements

• Individuals with chronic disease or currently under investigation

• Individuals with =3 bowel movements/week

• Individuals with =2 bowel movements/day

Study Design

Allocation: Randomized, Intervention Model: Factorial Assignment, Masking: Double Blind (Subject, Investigator), Primary Purpose: Basic Science

Related Conditions & MeSH terms

• Prebiotics
• Probiotics
• Quorum Sensing
• Sepsis

Intervention

Dietary Supplement:
• Bifidobacterium longum BB536
2 capsules od
• Active hexose correlated compound (AHCC)
One capsule tds
• Bifidobacterium longum BB536 and Active hexose correlated compound (AHCC)
One capsule tds (prebiotic) and two capsules od (probiotic)
• Corn starch placebo capsule
One capsule tds and two capsules od

Drug:
• Azithromycin
250mg od

Locations

Country	Name	City	State
United Kingdom	University of Nottingham	Nottingham	Nottinghamshire

Sponsors (1)

Lead Sponsor	Collaborator
University of Nottingham

Country where clinical trial is conducted

United Kingdom, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Serum QSSM level		14 days	No
Secondary	T cell Th1/Th2 ratio		14 days	No