Module 12 - Genetic Tools Flashcards
LAB and Bifidobacterium as Delivery Sytems (3)
GRAS status + live mucosal vectors for production and delivery of therapeutic molecules + survive stress
LAB and Bifidobacterium survive
Low pH of stomach and bile salts
Survive harsh condtions up to 48 hours
L. lactis
Persist 4 and 7 days under harsh conditions
Lactobacillus and Bifidobacterium
Pioneer bacterium
L. lactis
Best studied from physiological aspect
L. lactis
Why poineer (8)
Several sequences available + GRAS + model for mucosal delivery + high transformation via electroporation + does not colonize GI tract + several genetic tools + simple secretion system + best studies from physiological aspect
No intestinal colonization
Non-invasive
L. lactis genetic tools
Plasmids and Expression Systems
Lactobacillus as delivery vector
Persist longer than Lactococcus in GI tract + might be part of native microbiota and have interacted with host IS
Very difficult to transform and genetically manipulate
Lactobacillus and Bifidobacterium
Bifidobacterium as new delivery vector
Similar advantages as Lactobacillus
Nisin-Controlled Gene Expression (NICE) Expression Vector
Nisin –> binds NisK on membrane –> ST to NisR –> regulates gene expression of PnisZ –> makes device protein
Based on expression of heterologous proteins from nisZ promoter
Nisin-Controlled Gene Expression (NICE)
NisK and NisR are
Regulatory Proteins
NICE mostly in…
Bacillus subtilis
Increasing NICE in
L. lactic and L. plantarum
Zinc Inducible Expression Systems
PZNZitR-driven Heterologous Expression and Xirex
Xirex
Expression highly inducible but protein quality low
Xylose-inducible expression vector (XIES)
Cytoplasmic and secreted proteins + high amounts
pSIP
Similar to NICE for expression of cytoplasmic, cell wall anchoring, and secretion proteins
SICE and P170
Self-regulated promoters for environmental conditions
Controlled by pGroEL Chaperon promoter
Stress-inducible Controlled Expression (SICE)
SICE
pGroEL chaperon promoter controlled where a variety of conditions produce highly inducible proteins via constitutive expression
P170 System
pH inducible of pH 6 or below
High recombinant protein production
P170 system
pSIP System proteins
SapIP protein triggers membrane protein sapK which triggers sapR and acts on PsapA to get POI
Vectors for mucosal delivery of molecules…
Requires mastering thief targeting mode
Protein location important for
Efficiency of treatment of therapeutic molecule and IR modulation
Three main expression vectors (signal peptides)
pCYT, pSEC, pCWA
Extra signal peptide
Fusion to cell wall
pCTY
Cytoplasmic expression
pSEC
Proteins fused to a signal peptide
pCWA
anchors to cell wall
Anti-protease Roles
Prevent inflammation and restore mucosal homeostasis
Elafin Secretion
Inhibits high proteolytic activity, CXCL-8, MCP-1, and IP-10 + increase intestinal integrity
Anti-protease
Elafin Secretion
Secreted SOD
Enzyme produced that prevent neutrophil and Mac ROS release
DNA Delivery Roles
Production of epithelial cells or POI + transfer DNA depending on capacity of LAB to do so
Enzyme protein expression roles
Caecal and colonic inflammation decreases
Plasmid transfer
DNA delivery to produce protein expression of eukaryotic cells
Cytokine and Antigen POI Role
Long term diabetes reversion in NOD mice + Local T-reg increase
Cytokines and antigens produced by recLAB
IL-10 and pro-insulin
Mechanism of IL-10 and Pro-insulin
Interact with Tregs to make functional after migration to intestine
IBD
Group of gut disorders characterised by uncontrollable and chronic inflammation of GIT
Two major forms of IBD
Crohn’s disease and UC
IBD Characterised by
Microbiota disturbances + Significant production of inflammatory Mediators
Inflammatory Mediators of IBD
Protease, ROS, and cytokines
Prevent IBD via expression of
Elafin, antioxidant enzymes (SOD), and cytokines from Lactococcus and Lactobacillus
Bacteria used to treat IBD
Lactococcus and Lactobacillus
Elafin produced by LAB
Oral administration in mice –> reduced local inflammation and epithelial damage to restrole colon homeostasis
SOD
Antioxidant enzyme
SOD (superoxide dismutase)
Converts superoxide anion to H2O2
Present in very few LABs
SOD
Produce SOD to protect mice
L. plantarum and L. Lactis –> colitis protection
Enzyme expression that is similar to SOD
CAT
Production of IL-10 leads to
Reduced inflammation
Reduced inflammation in DSS-inducible colitis mice models
recombinant L. lactis producing IL10
Recombinant L. lactis producing IL-10
Reduce inflammation in colitis mouse models + decrease activity of Crohn’s disease in human trial
IL27 production
Reduce inflammation in DSS-iduced colitis mouse models
IL27 produced by
L. lactis
IL27 mechanism
Th1 response induced –> suppress Th17 and Th2 differentiation + induce IL-10
Allergy to Cow’s Milk
Common in young infants due to response to milk proteins such as B-lactoglobulin (BLG)
B-galactoglobulin (BLG)
Cow’s milk protein
Treatment of milk allergy
Express BLG in L. lactis –> BLG-specfic IgA in mice –> protect from further sensitization
Asthma
Chronic inflammatory disease correlated with airway inflammation driven by Th2 cytokines
Drivers of asthma
Th2 cytokines IL4 and IL5 and reduced Th1 response
Allergic Airway Diseases
Asthma
Asthma reduction via
Expression of Th1 inducer IL12 by L. lactis in OVA-induced asthma –> switch from Th2 to Th1 in mice
T1DM
Autoimmune disease characterised by destruction of pancreatic Beta cells
Heterologous Protein Expression for T1DM
Produce auto-antigenic peptide in NOD model of diabetes in mice
Human insulin gene
Express in murine model as auto-antigenic peptide
Auto-antigenic peptide
Human insulin gene
Autoantigens that help reduce DM1 (4)
Human insulin gene, glutamic acid decarboxylase GAD-65, HSP65, P277
Celiac Disease
Autoimmune disease characterised by insufficient tolerance toward gliadin
Gliadin
Component of gluten
Celiac Disease Protein Expression
Deaminated gliadin epitope carried by L. lactis can suppress local and systemic responses + Elafin
Elafin role in celiac disease reduction
Inhibit TG-2 activity to restore intestinal barrier and reduce inflammation
TG-2
Involved in deamination of gliadin
Mucosal Delivery of Bacterial Antigens
S. mutant PAc + Tatanus toxin (TTFC) + Listeriolysin O
Surface protein antigen (Pac)
On S. mutant and first antigen tested for carries prevention by increasing salivary IgA and IgG
Tetanus toxoid (TTFC)
L. lactis expression of fragment C of TT produced by C. tetani
Listeriolysin O-secreted
L. lactis –> Pore-forming toxin LLO
Only IP and not Oral route
LLO expression
HPV-16 E7 Antigen
Administer L. lactis IN –> specific humoral and cellular responses
HPV bacteria
L. lactis, L. plantarum, L. casei
HPV better results when…
Protein anchored on the surface of bacteria
Rotavirus
Most common cause of diarrhea in infants and young children
Rotavirus LAB
L. lactis and L. casei
Rotavirus antigen delivered
NSP4 and VP7
H5N1
Avian Influenza Virus with a 60% mortality rate in humans
H5N1 Antigens
HA via L. lactis –> HA-specfic serum IgG and fecal IgA
Parasitic diseases and LAB
Malaria + Giardiasis + Crytosporidiosis
Malaria
L. lactis expressing fusion protein (MSP3 and GLIRP from parasite) –> high levels of antibodies in mice
Giardiasis (Giardia intestinalis)
Water borne parasite that disseminates as cysts
Giardiasis treatment
Use cyst form antigen expressed in L. lactis
Giardiasis antigen
CWP2
Cryptosporidosis
Waster borne disease mainly by Cryptosporidium parvum that can be lethal in immunosuppressed hosts
Crytosporidiosis treatment
L. casei expressing P23 ahesion protein –> IgG and IgA