Editing Lactococcus lactis (section)

==Therapeutic benefits==
The feasibility of using [[lactic acid bacteria]] (LAB) as functional protein delivery vectors has been widely investigated.<ref>{{cite journal |vauthors=Wyszyńska A, Kobierecka P, Bardowski J, Jagusztyn-Krynicka EK |date= 2015|title= Lactic acid bacteria—20 years exploring their potential as live vectors for mucosal vaccination |journal=Appl Microbiol Biotechnol |volume= 99|issue= 7|pages= 2967–2977 |doi=10.1007/s00253-015-6498-0 |pmid= 25750046|pmc= 4365182 }}</ref> ''Lactococcus lactis'' has been demonstrated to be a promising candidate for the delivery of functional proteins because of its noninvasive and nonpathogenic characteristics.<ref>{{cite journal |vauthors=Varma NR, Toosa H, Foo HL, Alitheen NB, Nor Shamsudin M, Arbab AS, Yusoff K, Abdul Rahim R |date= 2013|title= Display of the viral epitopes on Lactococcus lactis: a model for food grade vaccine against EV71 |journal= Biotechnology Research International|volume= 2013|issue= 11|pages= 4032–4036|doi= 10.1155/2013/431315|pmid= 1069289|pmc= 431315|doi-access= free}}</ref> Many different expression systems of ''L. lactis'' have been developed and used for [[heterologous expression|heterologous]] [[gene expression|protein expression]].<ref>{{cite journal |vauthors=Mierau I, Kleerebezem M |date= 2005|title= 10 years of the nisin-controlled gene expression system (NICE) in Lactococcus lactis |journal=Appl Microbiol Biotechnol |volume= 68|issue= 6|pages= 705–717 |doi=10.1007/s00253-005-0107-6 |pmid= 16088349|s2cid= 24151938}}</ref><ref>{{cite journal |vauthors=Desmond C, Fitzgerald G, Stanton C, Ross R |date= 2004|title= Improved stress tolerance of GroESL-overproducing Lactococcus lactis and probiotic Lactobacillus paracasei NFBC 338|journal= Appl Environ Microbiol|volume= 70 |issue= 10|pages=5929–5936|doi= 10.1128/AEM.70.10.5929-5936.2004|pmid= 15466535|pmc= 522070|bibcode= 2004ApEnM..70.5929D}}</ref><ref>{{cite journal |vauthors=Benbouziane B, Ribelles P, Aubry C, Martin R, Kharrat P, Riazi A, Langella P, Bermudez-Humaran LG|date= 2013|title= Development of a Stress-Inducible Controlled Expression (SICE) system in Lactococcus lactis for the production and delivery of therapeutic molecules at mucosal surfaces|journal= J. Biotechnol. |volume=168|issue= 2|pages= 120–129|doi=10.1016/j.jbiotec.2013.04.019 |pmid= 23664884}}</ref>

'''Lactose fermentation'''
In one study that sought to prove that some [[fermentation]] produced by ''L. lactis'' can hinder motility in pathogenic bacteria, the motilities of ''[[Pseudomonas]]'', ''[[Vibrio]]'', and ''[[Leptospira]]'' strains were severely disrupted by lactose utilization on the part of ''L. lactis''.<ref>{{cite journal |vauthors=Nakamura S, Morimoto YV, Kudo S |date= 2015|title= A lactose fermentation product produced by Lactococcus lactis subsp. lactis, acetate, inhibits the motility of flagellated pathogenic bacteria|journal= Microbiology|volume= 161|issue= 4|pages= 701–707|doi=10.1099/mic.0.000031|pmid= 25573770|s2cid= 109572|doi-access= free}}</ref> Using [[flagellar]] ''[[Salmonella]]'' as the experimental group, the research team found that a product of lactose fermentation is the cause of motility impairment in ''[[Salmonella]]''. It is suggested that the ''L. lactis'' [[supernatant]] mainly affects ''Salmonella'' motility through disruption of flagellar rotation rather than through irreversible damage to morphology and physiology. Lactose fermentation by ''L. lactis'' produces [[acetate]] that reduces the [[intracellular pH]] of ''Salmonella'', which in turn slows the rotation of their flagella.<ref>{{cite journal |vauthors=Kihara M, Macnab RM |date= 1981|title= Cytoplasmic pH mediates pH taxis and weak-acid repellent taxis of bacteria|journal= J Bacteriol |volume=145|issue= 3|pages= 1209–1221 |doi= 10.1128/JB.145.3.1209-1221.1981|pmid= 7009572|pmc= 217121}}</ref><ref>{{cite journal |vauthors=Repaske DR, Adler J |date= 1981|title= Change in intracellular pH of Escherichia coli mediates the chemotactic response to certain attractants and repellents|journal= J Bacteriol |volume= 145|issue= 3|pages= 1196–1208 |doi= 10.1128/JB.145.3.1196-1208.1981|pmid= 7009571|pmc= 217120}}</ref> These results highlight the potential use of ''L. lactis'' for preventing infections by multiple bacterial species.

'''Secretion of Interleukin-10'''
Genetically engineered ''L. lactis'' can secrete the [[cytokine]] [[interleukin-10]] (IL-10) for the treatment of [[inflammatory bowel diseases]] (IBD), since IL-10 has a central role in [[downregulation|downregulating]] [[Inflammation|inflammatory]] cascades<ref>{{cite journal |vauthors=Stordeur P, Goldman M |title=Interleukin-10 as a regulatory cytokine induced by cellular stress: molecular aspects |date=1998 |journal=Int. Rev. Immunol. |volume=16|issue=5–6 |pages=501–522 |pmid=9646174|doi=10.3109/08830189809043006 }}</ref> and [[matrix metalloproteinases]].<ref>{{cite journal |vauthors=Pender SL, etal |title=Suppression of T cell-mediated injury in human gut by interleukin 10: role of matrix metalloproteinases |date= 1998 |journal= Gastroenterology |volume= 115|issue=3 |pages=573–583 |pmid=9721154|doi=10.1016/S0016-5085(98)70136-2 |doi-access=free }}</ref> A study by Lothar Steidler and Wolfgang Hans<ref>{{cite journal |vauthors=Steidler L, Hans W, Schotte L, Neirynck S, Obermeier F, Falk W, Fiers W, Remaut E |date= 2000 |title= Treatment of Murine Colitis by Lactococcus lactis Secreting Interleukin-10|journal= Science |volume= 289|issue= 5483|pages= 1352–1355|doi= 10.1126/science.289.5483.1352|pmid= 10958782 |bibcode= 2000Sci...289.1352S }}</ref> shows that [[in situ]] synthesis of IL-10 by genetically engineered ''L. lactis'' requires much lower doses than systemic treatments like antibodies to [[tumor necrosis factor]] (TNF) or [[recombinant protein|recombinant]] IL-10.

The authors propose two possible routes by which IL-10 can reach its therapeutic target. Genetically engineered ''L. lactis'' may produce [[murine]] IL-10 in the [[Lumen (anatomy)|lumen]], and the protein may diffuse to responsive cells in the [[epithelium]] or the [[lamina propria]]. Another route involves ''L. lactis'' being taken up by [[Microfold cell|M cells]] because of its bacterial size and shape, and the major part of the effect may be due to recombinant IL-10 production in situ in intestinal lymphoid tissue. Both routes may involve [[paracellular transport]] mechanisms that are enhanced in [[inflammation]]. After transport, IL-10 may directly downregulate inflammation. In principle, this method may be useful for intestinal delivery of other protein therapeutics that are unstable or difficult to produce in large quantities and an alternative to the systemic treatment of IBD.{{citation needed|date=February 2023}}

'''Tumor-suppressor through Tumor metastasis-inhibiting peptide KISS1'''
Another study, led by Zhang B, created a ''L. lactis'' strain that maintains a plasmid containing a tumor metastasis-inhibiting peptide known as [[KISS1]].<ref>{{cite journal |vauthors=Zhang B, Li A, Zuo F, Yu R, Zeng Z, Ma H, Chen S |date= 2016 |title= Recombinant Lactococcus lactis NZ9000 secretes a bioactive kisspeptin that inhibits proliferation and migration of human colon carcinoma HT-29 cells|journal= Microbial Cell Factories|volume= 15|issue= 1|pages= 102|doi= 10.1186/s12934-016-0506-7|pmid= 27287327 |pmc= 4901401 |doi-access= free }}</ref> ''L. lactis'' NZ9000 was demonstrated to be a cell factory for the secretion of biologically active KiSS1 protein, exerting [[wikt:inhibition|inhibition]] effects on human colorectal cancer HT-29 cells.

KiSS1 secreted from recombinant ''L. lactis'' strain effectively downregulated the expression of [[Matrix metalloproteinases]] (MMP-9), a crucial key in the invasion, [[metastasis]], and regulation of the signaling pathways controlling [[tumor cell]] growth, survival, invasion, inflammation, and [[angiogenesis]].<ref>{{cite journal |vauthors=Bauvois B |date= 2012|title= New facets of matrix metalloproteinases MMP-2 and MMP-9 as cell surface transducers: outside-in signaling and relationship to tumor progression|journal= Biochim Biophys Acta|volume= 1825|issue= 1|pages= 29–36|doi=10.1016/j.bbcan.2011.10.001|pmid= 22020293}}</ref><ref>{{cite journal |vauthors=Kessenbrock K, Plaks V, Werb Z |date= 2010|title= Matrix metalloproteinases: regulators of the tumor microenvironment|journal= Cell|volume= 141|issue= 1|pages= 52–67|doi= 10.1016/j.cell.2010.03.015|pmid= 20371345|pmc= 2862057}}</ref><ref>{{cite journal |vauthors=Klein T, Bischoff R |date= 2011|title= Physiology and pathophysiology of matrix metalloproteases |journal= Amino Acids |volume= 41 |issue= 2|pages= 271–290 |doi= 10.1007/s00726-010-0689-x|pmid= 20640864|pmc= 3102199}}</ref> The reason for this is that KiSS1 expressed in ''L. lactis'' activates the MAPK pathway via GPR54 signaling, suppressing [[NFκB]] binding to the MMP-9 promoter and thus downregulating MMP-9 expression.<ref>{{cite journal |vauthors=Nash KT, Welch DR |date= 2006|title= The KISS1 metastasis suppressor: mechanistic insights and clinical utility|journal= Frontiers in Bioscience|volume= 11 |pages= 647–659|doi= 10.2741/1824|pmid= 16146758|pmc= 1343480}}</ref> This, in turn, reduces the survival rate, inhibits [[metastasis]], and induces [[dormancy]] of cancer cells.

In addition, it was demonstrated that tumor growth can be inhibited by the LAB strain itself,<ref>{{cite journal |vauthors=Gorbach SL |date= 1990|title= Lactic acid bacteria and human health |journal=Annals of Medicine |volume= 22 |issue= 1|pages= 37–41|doi= 10.3109/07853899009147239|pmid= 2109988}}</ref><ref>{{cite book |vauthors=Hirayama K, Rafter J  |chapter= The role of lactic acid bacteria in colon cancer prevention: Mechanistic considerations|date= 1999|title= Lactic Acid Bacteria: Genetics, Metabolism and Applications |journal= Antonie van Leeuwenhoek|volume= 76|issue= 1–4|pages= 391–394|doi= 10.1007/978-94-017-2027-4_25|pmid= 10532395|isbn= 978-90-481-5312-1}}</ref> due to the ability of LAB to produce exopolysaccharides.<ref>{{cite journal |vauthors=Ruas-Madiedo P, Hugenholtz J, Zoon P |date= 2002|title= An overview of the functionality of exopolysaccharides produced by lactic acid bacteria|journal= Int Dairy J|volume= 12|issue= 2–3|pages= 163–171|doi= 10.1016/S0958-6946(01)00160-1}}</ref><ref>{{cite journal |vauthors=Looijesteijn PJ, Trapet L, de Vries E, Abee T, Hugenholtz J |date= 2001|title= Physiological function of exopolysaccharides produced by Lactococcus lactis|journal=International Journal of Food Microbiology |volume= 64|issue= 1–2|pages= 71–80|doi= 10.1016/S0168-1605(00)00437-2|pmid= 11252513}}</ref> This study shows that ''L. lactis'' NZ9000 can inhibit HT-29 proliferation and induce cell apoptosis by itself. The success of this strain's construction helped to inhibit migration and expansion of cancer cells, showing that the secretion properties of ''L. lactis'' of this particular [[peptide]] may serve as a new tool for cancer therapy in the future.<ref>{{cite journal |vauthors=Ji K, Ye L, Ruge F, Hargest R, Mason MD, Jiang WG |date= 2014|title= Implication of metastasis suppressor gene, Kiss-1 and its receptor Kiss-1R in colorectal cancer|journal= BMC Cancer |volume= 14 |pages= 723|doi= 10.1186/1471-2407-14-723|pmid= 25260785|pmc= 4190326|doi-access= free}}</ref>