Importance of Lactobacilli for Human Health
Round 1
Reviewer 1 Report
Comments and Suggestions for Authors
It is a good review. Concise and easy to read. Minor revision is, however, necessary.
p1 L39 and p2 L48 and 51. The word "niches" is incorrect from the ecological point of view. Please use "habitats".
p2 L77-85. Please add a reference for this paragraph.
p6 L286-287. Please use "Gardnerella" instead of "G."
Author Response
Reviewer 1
In response to the comments and suggestions of the first reviewer, we’d like to thank for his/her positive opinion on our review and his/her useful suggestions. All of them were included.
It is a good review. Concise and easy to read. Minor revision is, however, necessary.
p1 L39 and p2 L48 and 51. The word "niches" is incorrect from the ecological point of view. Please use "habitats". Done
p2 L77-85. Please add a reference for this paragraph. Done
p6 L286-287. Please use "Gardnerella" instead of "G." Done
Reviewer 2 Report
Comments and Suggestions for Authors
This manuscript is titled "Importance of lactobacilli for human health". However, the reviewer has to point out that the content of the manuscript does not answer the question posed in the title of the manuscript. In general, the reviewer would like to point out that the titles of the sections of the manuscript also do not always reflect the content of these sections; this is especially noticeable for the sections that describe vaginal lactobacilli.
Section "Introduction". Here the authors write about the diversity of lactobacilli and their properties associated with this diversity; at the same time, the description here concerns exclusively lactobacilli living in the intestine. In essence, this section resembles an incomplete abstract of all the subsequent sections. Perhaps this section should formulate the main idea of this review? The reviewer asks this question because there are reviews of the same nature and it is not clear why another one is needed.
The remaining sections also focus exclusively on intestinal lactobacilli; In five of the eight sections of the manuscript (excluding the Conclusion section), the authors write about intestinal lactobacilli. However, Sections 6, 7, and 8 contain information that should have been sorted out in advance. For example, Section 7, which seems to be supposed to describe the effect of lactobacilli on the innate immunity of the vagina (based on the section title), describes the antagonistic activity of lactobacilli mediated by lactate production (lines 318-325). Then they talk about glycogen metabolism, and only at the very end of the section is there a mention of immunity factors, some of which are not innate factors.
It is unclear why Section 9, Adaptive Immunity, is needed. It does not describe the effect lactobacilli have on adaptive immunity.
The Conclusion section contains reasoning that is not based on the information in the previous sections.
Author Response
Reviewer 2
In response to the comments and suggestions of the second reviewer, we’d like to thank for his/her opinion on our review and his/her suggestions.
This manuscript is titled "Importance of lactobacilli for human health". However, the reviewer has to point out that the content of the manuscript does not answer the question posed in the title of the manuscript. In general, the reviewer would like to point out that the titles of the sections of the manuscript also do not always reflect the content of these sections; this is especially noticeable for the sections that describe vaginal lactobacilli.
We do not agree with the reviewer general opinion that “content of the manuscript does not answer the question posed in the title of the manuscript”. The title of our paper is not a question but a statement and to our opinion it reflects the entire content. Moreover, we do not understand why and where the reviewer sees a discrepancy between subtitle and content of the section on vaginal lactobacilli. The section contains all important clues related to the pivotal role of the vaginal lactobacilli in maintaining vaginal health and it is based on over 3 decades-long our personal experience in studying vaginal infections.
Section "Introduction". Here the authors write about the diversity of lactobacilli and their properties associated with this diversity; at the same time, the description here concerns exclusively lactobacilli living in the intestine.
Yes, this was our intention to show that the successful colonization of gut by lactobacilli is crucial for building a healthy gut microbiota and that all other human microbiota are incidentally colonized with lactobacilli originating from human gut.
In essence, this section resembles an incomplete abstract of all the subsequent sections. Perhaps this section should formulate the main idea of this review? The reviewer asks this question because there are reviews of the same nature and it is not clear why another one is needed.
Yes, the introduction should be a presentation of the entire content of ant review but not an abstract and it is so.
The remaining sections also focus exclusively on intestinal lactobacilli; In five of the eight sections of the manuscript (excluding the Conclusion section), the authors write about intestinal lactobacilli. However, Sections 6, 7, and 8 contain information that should have been sorted out in advance.
For example, Section 7, which seems to be supposed to describe the effect of lactobacilli on the innate immunity of the vagina (based on the section title), describes the antagonistic activity of lactobacilli mediated by lactate production (lines 318-325). Then they talk about glycogen metabolism, and only at the very end of the section is there a mention of immunity factors, some of which are not innate factors.
It is simply not true since the innate immunity is also based on antimicrobial chemicals produced by host cells but also by inhabiting microbes. The current knowledge and key concepts link the microbiome to development and function of the immune system including innate immunity.
Appropriate sentences and citations were added.
It is unclear why Section 9, Adaptive Immunity, is needed. It does not describe the effect lactobacilli have on adaptive immunity.
This section (8 but not 9) is needed for the same reason as section 7: The current knowledge and key concepts link the microbiome to development and function of the immune system including adaptive immunity.
The Conclusion section contains reasoning that is not based on the information in the previous sections.
Right. A new para was added
Reviewer 3 Report
Comments and Suggestions for Authors
The authors of the paper present the roles of bacteria from the Lactobacillus group, an important component of microbiota in maintaining human health. The vast majority of the text concerns the development of gut microbiota throughout human life. Further, the authors characterize Lactobacillus in the vaginal microbiota and the immunity of these two environments. The work concerns a current and recently intensively analyzed topic. It is written in an interesting way, based on well-selected literature. However, I have some comments and questions for the authors which I am posting below.
- why was the role and presence of Lactobacillus in the urinary tract omitted? Lactobacillus is present in the urine of both women and men, where it also plays an important role in ensuring this homeostasis niche. And considering its origins, it will well combine two environments that have already been characterized by the authors.
- There is no consistency in the spelling of lactobacilli, sometimes it is written in capital letters
- it seems that the introduction does not make sufficient use of literature, e.g. the fragment from lines 45 to 53 does not contain any of the items
- line 32, „dissolving biofilm structures” please explain this formulation. The influence of various factors on biofilm is more about destroying this structure than dissolving it. And in the case of biofilm formation, about competition for adhesion sites with pathogens. Furthermore, the literature cited here indicates the influence of Lactobacillus on Gardnerella biofilms, does this influence also apply to other biofilms?
- line 322 „except for lactic acid, there are multiple organic acids produced by lactobacilli in the vagina at lower amounts but possessing much stronger antimicrobial activities [75, 76]” The given literature indicates the antimicrobial role of lactic acid {75} and the activity of different extraction phases being a mixture of compounds [76] which also does not indicate a better effect of other organic acids. Please complete the literature and provide more detailed information on the subject.
- the literature items are wrongly numbered so it is difficult to check their proper use.
Author Response
Microorganisms – 3rd reviewer
(our answers are given in italics)
The authors of the paper present the roles of bacteria from the Lactobacillus group, an important component of microbiota in maintaining human health. The vast majority of the text concerns the development of gut microbiota throughout human life. Further, the authors characterize Lactobacillus in the vaginal microbiota and the immunity of these two environments. The work concerns a current and recently intensively analyzed topic. It is written in an interesting way, based on well-selected literature. However, I have some comments and questions for the authors which I am posting below.
- why was the role and presence of Lactobacillus in the urinary tract omitted? Lactobacillus is present in the urine of both women and men, where it also plays an important role in ensuring this homeostasis niche. And considering its origins, it will well combine two environments that have already been characterized by the authors.
In fact, lactobacilli although present in urinary tract are derived from the anus and/or vagina but there are no serious studies documenting a protective role of the lactobacilli in situ, they prevent colonization of the urinary orifice by stopping transmission of uropathogens from anus and/or vagina. However, appropriate paragraph on urinary lactobacilli and the new citation was added.
The vaginal microbiome is known to play a key role in the maintenance of vaginal pH and the prevention of various urogenital diseases. Evidence suggests that vaginal lactobacilli confer a level of protection against bacterial vaginosis, sexually transmitted diseases, and UTIs
(Advances in Understanding the Human Urinary Microbiome and Its Potential Role in Urinary Tract Infection.
Neugent ML, Hulyalkar NV, Nguyen VH, Zimmern PE, De Nisco NJ.mBio. 2020 Apr 28;11(2):e00218-20. doi: 10.1128/mBio.00218-20.)
- There is no consistency in the spelling of lactobacilli, sometimes it is written in capital letters.
Right, this was corrected.
- it seems that the introduction does not make sufficient use of literature, e.g. the fragment from lines 45 to 53 does not contain any of the items.
Two more citations were added to the introduction.
- line 32, „dissolving biofilm structures” please explain this formulation. The influence of various factors on biofilm is more about destroying this structure than dissolving it. And in the case of biofilm formation, about competition for adhesion sites with pathogens. Furthermore, the literature cited here indicates the influence of Lactobacillus on Gardnerella biofilms, does this influence also apply to other biofilms?
We used expression “dissolving” after Professor Swidsinski, who discovered this activity of certain Lactobacillus strains against Gardnerella and his followers (as Professor Gregor Reid for example). As far as we know, anti-biofilm activity of the lactobacilli against other bacteria has not been described at least in medical field. There are several articles on antibiofilm activity of Lactobacillus in food industry (for example:
Lactobacillus-derived components for inhibiting biofilm formation in the food industry. Li J, Zhang Q, Zhao J, Zhang H, Chen W.World J Microbiol Biotechnol. 2024 Mar 2;40(4):117. doi: 10.1007/s11274-024-03933-z
Lactobacillus-derived components for inhibiting biofilm formation in the food industry.
Li J, Zhang Q, Zhao J, Zhang H, Chen W.World J Microbiol Biotechnol. 2024 Mar 2;40(4):117. doi: 10.1007/s11274-024-03933-z
- line 322 „except for lactic acid, there are multiple organic acids produced by lactobacilli in the vagina at lower amounts but possessing much stronger antimicrobial activities [75, 76]” The given literature indicates the antimicrobial role of lactic acid {75} and the activity of different extraction phases being a mixture of compounds [76] which also does not indicate a better effect of other organic acids. Please complete the literature and provide more detailed information on the subject.
The new sentence and two citations were added.
A range of antifungal-active acids like 3-phenyllactic acid, 4-hydroxyphenyllactic acid and 2-hydroxyisocaproic acid in quantities between 0.1 and 360 mg/kg were present in the freeze-dried sourdoughs.
Antifungal activities of three different Lactobacillus species and their production of antifungal carboxylic acids in wheat sourdough. Axel C, Brosnan B, Zannini E, Peyer LC, Furey A, Coffey A, Arendt EK.Appl Microbiol Biotechnol. 2016 Feb;100(4):1701-1711. doi: 10.1007/s00253-015-7051-x
Using LC-MS/MS and spectrophotometric techniques, lactic, citric, and succinic acids were determined qualitatively and quantitatively. The influence of these acids on the P. mirabilis growth and biofilm formation and their influence on membrane permeability were also investigated. The results indicate that organic acids secreted by Lactobacillus strains have a high antibacterial potential and could be used as novel agents in the treatment of urinary tract infections caused by P. mirabilis.
Szczerbiec D, Piechocka J, Głowacki R, Torzewska A. Organic Acids Secreted by Lactobacillus spp. Isolated from Urine and Their Antimicrobial Activity against Uropathogenic Proteus mirabilis. Molecules. 2022 Aug 29;27(17):5557. doi: 10.3390/molecules27175557.
Further, L. plantarum UM55 CFS was analysed for the presence of organic acids and the main differences compared to controls were found in the levels of lactic acid, phenyllactic acid (PLA), hydroxyphenyllactic acid (OH-PLA), and indole lactic acid (ILA).
Guimarães A, Santiago A, Teixeira JA, Venâncio A, Abrunhosa L.
Anti-aflatoxigenic effect of organic acids produced by Lactobacillus plantarum.
Int J Food Microbiol. 2018 Jan 2;264:31-38. doi: 10.1016/j.ijfoodmicro.2017.10.025. Epub 2017 Oct 21.
- the literature items are wrongly numbered so it is difficult to check their proper use.
Right. This was corrected.
Round 2
Reviewer 2 Report
Comments and Suggestions for Authors
The authors' revision of this manuscript has improved its quality; however, the reviewer believes that the manuscript should be revised. In the previous review, the reviewer already noted the lack of novelty in this manuscript and its somewhat secondary nature.
The reviewer still insists that the "Introduction" section should contain information that would provide an understanding of why the authors took up writing this review; when searching, for example, in Google Scholar, there are approximately 18,300 review articles published over the past five years (from 2019 inclusive) that describe the role of lactobacilli in the health of humans and other mammals. This raises the question, what new did the authors want to communicate with their review? The reviewer believes that the answer to this question is very important, especially considering that the authors plan to publish this manuscript in a special issue “Probiotic and Postbiotic Properties of Lactobacilli”, which is aimed at “…to present recent research on any aspect of the novel Lactobacillus derived from diverse sources of natural, animal, and plant origin in addition to their fermented products, in addition to recent research findings on postbiotics…” (as in the announcement of the special issue).
The reviewer still has comments regarding section 7 (Innate immunity in the vagina, lines 319-349); in its current form, this section is misleading.
It describes the antagonistic activity of lactobacilli mediated by lactate production, mentions other organic acids, antimicrobial peptides, etc.; that is, we are talking about how lactobacilli can, with the help of their metabolites, prevent the introduction of foreign species of microorganisms into the vagina. The reviewer would like to note that at present, innate immunity is understood as components of host defense, that is, immunity that is present at birth and persists, for example, in humans, throughout life. Taking this into account, metabolites of microorganisms, the number and species composition of which change throughout the life of the organism, cannot be classified as factors of innate immunity. The reference to the review [82] provided by the authors for such argumentation is incorrect here; this review examined the innate immunity system in relation to the skin of mammals, while innate immunity is described as a complex of physical, cellular and chemical barriers necessary to resist infection. Nothing is said in this review about the possibility of considering microorganisms, in particular lactobacilli, and their metabolites as factors of innate immunity. The reviewer believes that in this case the authors should not justify their point of view on the content of this section by their thirty years of experience in combating vaginal infections, but rather study more closely the currently existing literature, of which there is a lot. For example, when searching in Google Scholar (using the keywords effect AND lactobacilli AND innate AND vaginal AND immunity), you can find more than 12,000 publications, including 4,000 review articles published over the past five years (since 2019 inclusive). And most importantly. How do lactobacilli affect the innate immunity of the vagina or its formation? There is no answer to this question in this section. It should be noted that the section devoted to intestinal lactobacilli contains answers to side questions. Just as in the previous version of the manuscript, the purpose of section No. 8 “Adaptive immunity” is unclear. It does not describe what effect lactobacilli have on adaptive immunity.
Author Response
microorganisms-3201200
Reviewer 2, 2nd round
Dear reviewer:
Thank you for your review and comments on this manuscript, below are our answers in red color:
The authors' revision of this manuscript has improved its quality; however, the reviewer believes that the manuscript should be revised. In the previous review, the reviewer already noted the lack of novelty in this manuscript and its somewhat secondary nature.
Yes, by definition, every review has a secondary nature.
The reviewer still insists that the "Introduction" section should contain information that would provide an understanding of why the authors took up writing this review;
We have added information about our intentions when writing this review to Introduction.
when searching, for example, in Google Scholar, there are approximately 18,300 review articles published over the past five years (from 2019 inclusive) that describe the role of lactobacilli in the health of humans and other mammals.
This is simply unbelievable: this means that every day including weekend days for 5 years there were 10 articles published to describe the role of lactobacilli in the health of humans and other mammals (by the way: we did not included studies on animals in our review). It should be also mentioned that Google Scholar collects research papers from all over the web, including grey literature and non-peer reviewed papers and reports.
This raises the question, what new did the authors want to communicate with their review? The reviewer believes that the answer to this question is very important, especially considering that the authors plan to publish this manuscript in a special issue “Probiotic and Postbiotic Properties of Lactobacilli”, which is aimed at “…to present recent research on any aspect of the novel Lactobacillus derived from diverse sources of natural, animal, and plant origin in addition to their fermented products, in addition to recent research findings on postbiotics…” (as in the announcement of the special issue).
It is not true; we have written this review from medical microbiology point to show the importance of the Lactobacillus sensu lato for human organism by summarizing data on the interactions between these bacteria and human host. Moreover, we tried to minimize information on lactobacilli as probiotics, which is something else, but it was sometimes impossible to find data in medical literature on some properties of the Lactobacillus sensu lato when the investigated strains were regarded as probiotics. We have been invited to submit our review to this special issue of the Microorganisms, but we agree with the reviewer it should be better if it would be in Medical Microbiology section.
The reviewer still has comments regarding section 7 (Innate immunity in the vagina, lines 319-349); in its current form, this section is misleading.
It describes the antagonistic activity of lactobacilli mediated by lactate production, mentions other organic acids, antimicrobial peptides, etc.; that is, we are talking about how lactobacilli can, with the help of their metabolites, prevent the introduction of foreign species of microorganisms into the vagina. The reviewer would like to note that at present, innate immunity is understood as components of host defense, that is, immunity that is present at birth and persists, for example, in humans, throughout life. Taking this into account, metabolites of microorganisms, the number and species composition of which change throughout the life of the organism, cannot be classified as factors of innate immunity. The reference to the review [82] provided by the authors for such argumentation is incorrect here; this review examined the innate immunity system in relation to the skin of mammals, while innate immunity is described as a complex of physical, cellular and chemical barriers necessary to resist infection. Nothing is said in this review about the possibility of considering microorganisms, in particular lactobacilli, and their metabolites as factors of innate immunity. The reviewer believes that in this case the authors should not justify their point of view on the content of this section by their thirty years of experience in combating vaginal infections, but rather study more closely the currently existing literature, of which there is a lot. For example, when searching in Google Scholar (using the keywords effect AND lactobacilli AND innate AND vaginal AND immunity), you can find more than 12,000 publications, including 4,000 review articles published over the past five years (since 2019 inclusive).
Reference 82 was replaced with a more recent study on vaginal microbiome and innate immunity.
And most importantly. How do lactobacilli affect the innate immunity of the vagina or its formation? There is no answer to this question in this section. It should be noted that the section devoted to intestinal lactobacilli contains answers to side questions. Just as in the previous version of the manuscript, the purpose of section No. 8 “Adaptive immunity” is unclear. It does not describe what effect lactobacilli have on adaptive immunity.
To answer this question, which was already raised by the reviewer in his/her first review, we asked our colleague, who is a head of the immunology at our medical school. Since 2011 a view of the immunologists on innate immunity changed a lot since it had been demonstrated that the cells of the innate immunity came into interactions with microorganisms. After that the trained innate immunity has been commonly accepted. Thus, interactions of the products and cell wall components of the lactobacilli with vaginal immunity system also form innate immunity. To clarify this, we have added term “trained innate immunity” to the text of this chapter and inserted more explanations. Also, new citations were added.
Reviewer 3 Report
Comments and Suggestions for Authors
I thank the authors for responding to my comments. I have no further comments and in my opinion the article can be published in this form.
Author Response
microorganisms-3201200
Reviewer 2, 2nd round
Dear editor and reviewer
Thank you for your review and comments on this manuscript, below are our answers in red color:
The authors' revision of this manuscript has improved its quality; however, the reviewer believes that the manuscript should be revised. In the previous review, the reviewer already noted the lack of novelty in this manuscript and its somewhat secondary nature.
Yes, by definition, every review has a secondary nature.
The reviewer still insists that the "Introduction" section should contain information that would provide an understanding of why the authors took up writing this review;
We have added information about our intentions when writing this review to Introduction.
when searching, for example, in Google Scholar, there are approximately 18,300 review articles published over the past five years (from 2019 inclusive) that describe the role of lactobacilli in the health of humans and other mammals.
This is simply unbelievable: this means that every day including weekend days for 5 years there were 10 articles published to describe the role of lactobacilli in the health of humans and other mammals (by the way: we did not included studies on animals in our review). It should be also mentioned that Google Scholar collects research papers from all over the web, including grey literature and non-peer reviewed papers and reports.
This raises the question, what new did the authors want to communicate with their review? The reviewer believes that the answer to this question is very important, especially considering that the authors plan to publish this manuscript in a special issue “Probiotic and Postbiotic Properties of Lactobacilli”, which is aimed at “…to present recent research on any aspect of the novel Lactobacillus derived from diverse sources of natural, animal, and plant origin in addition to their fermented products, in addition to recent research findings on postbiotics…” (as in the announcement of the special issue).
It is not true; we have written this review from medical microbiology point to show the importance of the Lactobacillus sensu lato for human organism by summarizing data on the interactions between these bacteria and human host. Moreover, we tried to minimize information on lactobacilli as probiotics, which is something else, but it was sometimes impossible to find data in medical literature on some properties of the Lactobacillus sensu lato when the investigated strains were regarded as probiotics. We have been invited to submit our review to this special issue of the Microorganisms, but we agree with the reviewer it should be better if it would be in Medical Microbiology section.
The reviewer still has comments regarding section 7 (Innate immunity in the vagina, lines 319-349); in its current form, this section is misleading.
It describes the antagonistic activity of lactobacilli mediated by lactate production, mentions other organic acids, antimicrobial peptides, etc.; that is, we are talking about how lactobacilli can, with the help of their metabolites, prevent the introduction of foreign species of microorganisms into the vagina. The reviewer would like to note that at present, innate immunity is understood as components of host defense, that is, immunity that is present at birth and persists, for example, in humans, throughout life. Taking this into account, metabolites of microorganisms, the number and species composition of which change throughout the life of the organism, cannot be classified as factors of innate immunity. The reference to the review [82] provided by the authors for such argumentation is incorrect here; this review examined the innate immunity system in relation to the skin of mammals, while innate immunity is described as a complex of physical, cellular and chemical barriers necessary to resist infection. Nothing is said in this review about the possibility of considering microorganisms, in particular lactobacilli, and their metabolites as factors of innate immunity. The reviewer believes that in this case the authors should not justify their point of view on the content of this section by their thirty years of experience in combating vaginal infections, but rather study more closely the currently existing literature, of which there is a lot. For example, when searching in Google Scholar (using the keywords effect AND lactobacilli AND innate AND vaginal AND immunity), you can find more than 12,000 publications, including 4,000 review articles published over the past five years (since 2019 inclusive).
Reference 82 was replaced with a more recent study on vaginal microbiome and innate immunity.
And most importantly. How do lactobacilli affect the innate immunity of the vagina or its formation? There is no answer to this question in this section. It should be noted that the section devoted to intestinal lactobacilli contains answers to side questions. Just as in the previous version of the manuscript, the purpose of section No. 8 “Adaptive immunity” is unclear. It does not describe what effect lactobacilli have on adaptive immunity.
To answer this question, which was already raised by the reviewer in his/her first review, we asked our colleague, who is a head of the immunology at our medical school. Since 2011 a view of the immunologists on innate immunity changed a lot since it had been demonstrated that the cells of the innate immunity came into interactions with microorganisms. After that the trained innate immunity has been commonly accepted. Thus, interactions of the products and cell wall components of the lactobacilli with vaginal immunity system also form innate immunity. To clarify this, we have added term “trained innate immunity” to the text of this chapter and inserted more explanations. Also, new citations were added.
