Evaluation of the effects of extracellular vesicles derived from Faecalibacterium prausnitzii on lung cancer cell line

Exploring the underlying correlation between microbiota, immune system, hormones, and inflammation with breast cancer and the role of probiotics, prebiotics and postbiotics

According to recent research, bacterial imbalance in the gut microbiota and breast tissue may be linked to breast cancer. It has been discovered that alterations in the makeup and function of different types of bacteria found in the breast and gut may contribute to growth and advancement of breast cancer in several ways. The main role of gut microbiota is to control the metabolism of steroid hormones, such as estrogen, which are important in raising the risk of breast cancer, especially in women going through menopause. On the other hand, because the microbiota can influence mucosal and systemic immune responses, they are linked to the mutual interactions between cancer cells and their local environment in the breast and the gut. In this regard, the current review thoroughly explains the mode of action of probiotics and microbiota to eradicate the malignancy. Furthermore, immunomodulation by microbiota and probiotics is described with pathways of their activity.

Antigenotoxicity and Cytotoxic Potentials of Cell-Free Supernatants Derived from Saccharomyces cerevisiae var. boulardii on HT-29 Human Colon Cancer Cell Lines

Microbial-derived postbiotics are of interest recently due to their lower side effects than chemotherapy for cancer treatment and prevention. This study aimed to investigate the potential antigenotoxic and cytotoxic effects of cell-free-supernatant (CFS) postbiotics derived from Saccharomyces boulardii by applying SOS chromotest and MTT assay on HT-29 cell lines. Also, further cellular pathway-related assays such as cell cycle, DAPI, and annexin V-FITC/PI staining were performed. Real-time PCR was utilized to assess the expression levels of some genes involved in apoptosis. Based on the outcomes, the CFSs of S. boulardii showed significant antigenotoxic effects (20-60%, P < 0.05), decreased cell viability (with the significant IC50 values of 33.82, 22.68, and 27.67 µg/mL after 24, 48, and 72 h respectively), suppressed the initial (G0/G1) phase of the cell's division, influenced the nucleus of the treated cells, induced apoptosis, and increased the expression of Caspas3 and PTEN genes after 48 h, while the RelA and Bcl-XL genes indicated diminished expression in treated HT-29 cells. Consequently, CFS postbiotics of S. boulardii exhibited significant antigenotoxic and cytotoxic effects and induced apoptosis responses in HT-29 cancer cells. The results of this investigation lead us to recommend that the CFS postbiotics generated from Saccharomyces cerevisiae var. boulardii be taken into consideration as a potential anticancer agent or in the design of supplementary medications to treat and prevent colon cancers.

Faecalibacterium: a bacterial genus with promising human health applications

In humans, many diseases are associated with alterations in gut microbiota, namely increases or decreases in the abundance of specific bacterial groups. One example is the genus Faecalibacterium. Numerous studies have underscored that low levels of Faecalibacterium are correlated with inflammatory conditions, with inflammatory bowel disease (IBD) in the forefront. Its representation is also diminished in the case of several diseases, including colorectal cancer (CRC), dermatitis, and depression. Additionally, the relative presence of this genus is considered to reflect, at least in part, intestinal health status because Faecalibacterium is frequently present at reduced levels in individuals with gastrointestinal diseases or disorders. In this review, we first thoroughly describe updates to the taxonomy of Faecalibacterium, which has transformed a single-species taxon to a multispecies taxon over the last decade. We then explore the links discovered between Faecalibacterium abundance and various diseases since the first IBD-focused studies were published. Next, we examine current available strategies for modulating Faecalibacterium levels in the gut. Finally, we summarize the mechanisms underlying the beneficial effects that have been attributed to this genus. Together, epidemiological and experimental data strongly support the use of Faecalibacterium as a next-generation probiotic (NGP) or live biotherapeutic product (LBP).

Bacterial extracellular vesicles and their novel therapeutic applications in health and cancer

Bacterial cells communicate with host cells and other bacteria through the release of membrane vesicles known as bacterial extracellular vesicles (BEV). BEV are established mediators of intracellular signaling, stress tolerance, horizontal gene transfer, immune stimulation and pathogenicity. Both Gram-positive and Gram-negative bacteria produce extracellular vesicles through different mechanisms based on cell structure. BEV contain and transfer different types of cargo such as nucleic acids, proteins and lipids, which are used to interact with and affect host cells such as cytotoxicity and immunomodulation. The role of these membranous microvesicles in host communication, intra- and inter-species cell interaction and signaling, and contribution to various diseases have been well demonstrated. Due to their structure, these vesicles can be easily engineered to be utilized for clinical application, as shown with its role in vaccine therapy, and could be used as a diagnostic and cancer drug delivery tool in the future. However, like other novel therapeutic approaches, further investigation and standardization is imperative for BEV to become a routine vector or a conventional treatment method.

Downregulation of ACE, AGTR1, and ACE2 genes mediating SARS-CoV-2 pathogenesis by gut microbiota members and their postbiotics on Caco-2 cells

INTRODUCTION

Coronavirus disease-2019 (COVID-19) is a complex infection caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that can cause also gastrointestinal symptoms. There are various factors that determine the host susceptibility and severity of infection, including the renin-angiotensin system, the immune response, and the gut microbiota. In this regard, we aimed to investigate the gene expression of ACE, AGTR1, ACE2, and TMPRSS2, which mediate SARS-CoV-2 pathogenesis by Akkermansia muciniphila, Faecalibacterium prausnitzii, Bacteroides thetaiotaomicron, and Bacteroides fragilis on Caco-2 cells. Also, the enrichment analysis considering the studied genes was analyzed on raw data from the microarray analysis of COVID-19 patients.

MATERIALS AND METHODS

Caco-2 cells were treated with live, heat-inactivated form and cell free supernatants of A. muciniphila, F. prausnitzii, B. thetaiotaomicron and B. fragilis for overnight. After RNA extraction and cDNA synthesis, the expression of studied genes was assessed by RT-qPCR. DNA methylation of studied genes was analyzed by Partek® Genomics Suite® software on the GSE174818 dataset. We used GSE164805 and GSE166552 datasets from COVID-19 patients to perform enrichment analysis by considering the mentioned genes via GEO2R, DAVID. Finally, the related microRNAs to GO terms concerned on the studied genes were identified by miRPath.

RESULTS

The downregulation of ACE, AGTR1, and ACE2 genes by A. muciniphila, F. prausnitzii, B. thetaiotaomicron, and B. fragilis in live, heat-inactivated, and cell-free supernatants was reported for the first time. These genes had hypomethylated DNA status in COVID-19 patients' raw data. The highest fold enrichment in upregulated RAS pathways and immune responses belonged to ACE, AGTR1, and ACE2 by considering the protein-protein interaction network. The common miRNAs targeting the studied genes were reported as miR-124-3p and miR-26b-5p. In combination with our experimental data and bioinformatic analysis, we showed the potential of A. muciniphila, F. prausnitzii, B. thetaiotaomicron, and B. fragilis and postbiotics to reduce ACE, ATR1, and ACE2 expression, which are essential genes that drive upregulated biological processes in COVID-19 patients.

CONCLUSION

Accordingly, due to the potential of studied bacteria on the alteration of ACE, AGTR1, ACE2 genes expression, understanding their correlation with demonstrated miRNAs expression could be valuable. These findings suggest the importance of considering targeted gut microbiota intervention when designing the possible therapeutic strategy for controlling the COVID-19.

Changes of Intestinal Flora and Its Relationship with Nutritional Status for Patients with Cancer Pain

Objective. To study the changes in the intestinal flora and its relationship with nutritional status for patients with cancer pain. Methods. A prospective research method was adopted. One hundred twenty cancer patients with cancer pain were selected as the research objects, who were treated in our hospital from June 2019 to June 2020, and 120 cancer patients without cancer pain were selected as the control group, who were treated in the same period. The differences of the intestinal flora and nutritional status of patients with different severity between the observation group and the control group were compared to analyze the changes of intestinal flora in patients with cancer pain and its correlation with nutritional status. Results. Hemoglobin (HB) ( $t=17.141$ , $p\le 0.001$ ), albumin (ALB) ( $t=27.654$ , $p\le 0.001$ ), prealbumin (PAB) ( $t=96.192$ , $p\le 0.001$ ), and total protein (TP) ( $t=18.781$ , $p\le 0.001$ ) in the observation group were significantly lower than those in the control group. There were statistically significant differences in HB ( $f=13.569$ , $p\le 0.001$ ), ALB ( $f=22.229$ , $p\le 0.001$ ), PAB ( $f=19.521$ , $p\le 0.001$ ), and TP ( $f=21.451$ , $p\le 0.001$ ) among patients with cancer pain of different severity. Through these two comparisons, their nutritional indicators showed a significant downward trend with the increase in the severity for cancer pain patients; the levels of Lactobacillus ( $t=2.124$ , $p=0.035$ ), Bifidobacterium ( $t=4.823$ , $p\le 0.001$ ), Enterococcus ( $t=3.578$ , $p\le 0.001$ ), and Eubacterium ( $t=2.394$ , $p=0.017$ ) in the observation group were significantly lower than those in the control group. There were statistically significant differences in the levels of Lactobacillus ( $f=20.643$ , $p\le 0.001$ ), Bifidobacterium ( $f=19.129$ , $p\le 0.001$ ), Enterococcus ( $f=17.408$ , $p\le 0.001$ ), and Eubacterium ( $f=22.343$ , $p\le 0.001$ ) among patients with cancer pain of different severity. After pairwise comparison, their beneficial intestinal bacteria were significantly lower than those in the control group with the increase in pain in cancer pain patients. Nitric oxide (NO) ( $t=8.418$ , $p\le 0.001$ ), galectin-3 ( $t=14.043$ , $p\le 0.001$ ), occludin (OCLN) ( $t=47.308$ , $p\le 0.001$ ), galectin-1 ( $t=15.298$ , $p\le 0.001$ ), zonula occludens protein 1 (ZO-1) ( $t=23.093$ , $p\le 0.001$ ), and cingulin ( $t=340.198$ , $p\le 0.001$ ) in the observation group were significantly lower than those in the control group. There were statistically significant differences in NO, galectin-3, OCLN, galectin-1, ZO-1, and cingulin for patients with cancer pain of different severity. By comparison, the NO, galectin-3, OCLN, galectin-1, ZO-1, and cingulin of the patients showed a significant downward trend with the aggravation of cancer pain symptoms. Through correlation analysis, the nutritional indicators of patients were positively correlated with intestinal microorganisms and intestinal barrier function. Conclusion. There was a significant correlation between the changes in intestinal flora and nutritional status for patients with cancer pain, which could be used as an important basis for improving the treatment of cancer pain.

Faecalibacterium prausnitzii Ameliorates Colorectal Tumorigenesis and Suppresses Proliferation of HCT116 Colorectal Cancer Cells

Faecalibacterium prausnitzii is one of the most abundant commensals of gut microbiota that is not commonly administered as a probiotic supplement. Being one of the gut’s major butyrate-producing bacteria, its clinical significance and uses are on the rise and it has been shown to have anti-inflammatory and gut microbiota-modulating properties in the treatment of inflammatory bowel illness, Crohn’s disease, and colorectal cancer. Colorectal cancer (CRC) is a silent killer disease that has become one of the leading causes of cancer-related death worldwide. This study aimed to evaluate the anti-tumorigenic and antiproliferative role of F. prausnitzii as well as to study its effects on the diversity of gut microbiota in rats. Findings showed that F. prausnitzii probiotic significantly reduced the colonic aberrant crypt foci frequency and formation in Azoxymethane (AOM)-induced CRC in rats. In addition, the administration of F. prausnitzii lowered the lipid peroxidation levels in the colon tissues. For in vitro 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) assay, the cell-free supernatant of F. prausnitzii suppressed the growth of HCT116 colorectal cancer cells in a time/dose-dependent manner. 16S rRNA gene sequencing using rat stool samples showed that the administration of F. prausnitzii modulated the gut microbiota of the rats and enhanced its diversity. Hence, these findings suggest that F. prausnitzii as a probiotic supplement can be used in CRC prevention and management; however, more studies are warranted to understand its cellular and molecular mechanisms of action.

Commensal and Pathogenic Bacterial-Derived Extracellular Vesicles in Host-Bacterial and Interbacterial Dialogues: Two Sides of the Same Coin

Extracellular vesicles (EVs) cause effective changes in various domains of life. These bioactive structures are essential to the bidirectional organ communication. Recently, increasing research attention has been paid to EVs derived from commensal and pathogenic bacteria in their potential role to affect human disease risk for cancers and a variety of metabolic, gastrointestinal, psychiatric, and mental disorders. The present review presents an overview of both the protective and harmful roles of commensal and pathogenic bacteria-derived EVs in host-bacterial and interbacterial interactions. Bacterial EVs could impact upon human health by regulating microbiota–host crosstalk intestinal homeostasis, even in distal organs. The importance of vesicles derived from bacteria has been also evaluated regarding epigenetic modifications and applications. Generally, the evaluation of bacterial EVs is important towards finding efficient strategies for the prevention and treatment of various human diseases and maintaining metabolic homeostasis.

The anti-inflammatory effects of Akkermansia muciniphila and its derivates in HFD/CCL4-induced murine model of liver injury

Inflammation plays a critical role in the promotion of hepatocyte damage and liver fibrosis. In recent years the protective role of Akkermansia muciniphila, a next-generation beneficial microbe, has been suggested for metabolic and inflammatory disorders. In this study, we aimed to evaluate the effects of live and pasteurized A. muciniphila and its extra cellular vesicles (EVs) on inflammatory markers involved in liver fibrosis in a mouse model of a high-fat diet (HFD)/carbon tetrachloride (CCl₄)-induced liver injury. Firstly, the responses of hepatic stellate cells (HSCs) to live and pasteurized A. muciniphila and its EVs were examined in the quiescent and LPS-activated LX-2 cells. Next, the anti-inflammatory effects of different forms of A. muciniphila were examined in the mouse model of HFD/CCl₄-induced liver injury. The gene expression of various inflammatory markers was evaluated in liver, colon, and white adipose tissues. The cytokine secretion in the liver and white adipose tissues was also measured by ELISA. The results showed that administration of live and pasteurized A. muciniphila and its EVs leads to amelioration in HSCs activation. Based on data obtained from the histopathological analysis, an improvement in gut health was observed through enhancing the epithelium and mucosal layer thickness and strengthening the intestinal integrity in all treatments. Moreover, live A. muciniphila and its EVs had inhibitory effects on liver inflammation and hepatocytes damage. In addition, the tissue cytokine production and inflammatory gene expression levels revealed that live A. muciniphila and its EVs had more pronounced anti-inflammatory effects on liver and adipose tissues. Furthermore, EVs had better effects on the modulation of gene expression related to TLRs, PPARs, and immune response in the liver. In conclusion, the present results showed that oral administration of A. muciniphila and its derivatives for four weeks could enhance the intestinal integrity and anti-inflammatory responses of the colon, adipose, and liver tissues and subsequently prevent liver injury in HFD/CCL₄ mice.

Dysbiotic microbes and how to find them: a review of microbiome profiling in prostate cancer

The role of the microbiota in human health and disease is well established, including its effects on several cancer types. However, the role of microbial dysbiosis in prostate cancer development, progression, and response to treatment is less well understood. This knowledge gap could perhaps be implicated in the lack of better risk stratification and prognostic tools that incorporate risk factors such as bacterial infections and inflammatory signatures. With over a decade’s research investigating associations between microbiome and prostate carcinogenesis, we are ever closer to finding the crucial biological link between the two. Yet, definitive answers remain elusive, calling for continued research into this field. In this review, we outline the three frequently used NGS based analysis methodologies that are used for microbiome profiling, thereby serving as a quick guide for future microbiome research. We next provide a detailed overview of the current knowledge of the role of the human microbiome in prostate cancer development, progression, and treatment response. Finally, we describe proposed mechanisms of host-microbe interactions that could lead to prostate cancer development, progression or treatment response.

Microbes in lung cancer initiation, treatment, and outcome: Boon or bane?

Lung cancer is the top reason for cancer-related deaths worldwide. The 5-year overall survival rate of lung cancer is approximately 20 % due to the delayed diagnosis and low response rate to regular treatments. Microbiota, both host-microbiota and alien pathogenic microbiota, have been investigated to be involved in a complicated and contradictory relationship with lung cancer initiation, treatments, and prognosis. Disorders of certain host-microbiota and pathogen infection are associated with the risk of lung cancers based on epidemiological evidence, and antibiotics (ATBs) could dramatically impair anti-cancer treatment efficacy, including chemotherapy and immunotherapy. Moreover, probiotics and microbe-mediated drugs are potential approaches to enhance regular anti-tumor treatments. Therefore, the knowledge of the complex dual effect of microbes on lung cancer is beneficial to take their essence and remove their dross. This review offers insight into the current trends and advancements in microbiota or microbial components related to lung cancer.

The biological activities of postbiotics in gastrointestinal disorders

According to outcomes from clinical studies, an intricate relationship occurs between the beneficial microbiota, gut homeostasis, and the host's health status. Numerous studies have confirmed the health-promoting effects of probiotics, particularly in gastrointestinal diseases. On the other hand, the safety issues regarding the consumption of some probiotics are still a matter of debate, thus to overcome the problems related to the application of live probiotic cells in terms of clinical, technological, and economic aspects, microbial-derived biomolecules (postbiotics) were introducing as a potential alternative agent. Presently scientific literature confirms that the postbiotic components can be used as promising tools for both prevention and treatment strategies in gastrointestinal disorders with less undesirable side-effects, particularly in infants and children. Future head-to-head trials are required to distinguish appropriate strains of parent cells, optimal dosages of postbiotics, and assessment of the cost-effectiveness of postbiotics compared to alternative drugs. This review provides an overview of the concept and safety issues regarding postbiotics, with emphasis on their biological role in the treatment of some important gastrointestinal disorders.

Cancer trigger or remedy: two faces of the human microbiome

Currently, increasing attention cancer treatment has focused on molecularly targeted therapies and more recently on immunotherapies targeting immune checkpoints. However, even such advanced treatment may be ineffective. The reasons for this are sought, inter alia, in the human microbiome. In our intestines, there are bacteria that are beneficial to us, but pathogenic microorganisms may also be present. Microbial imbalance (dysbiosis) is now perceived as one of the gateways to cancer. However, it is feasible to use bacteria and their metabolites to restore the natural, beneficial microbiome during oncological treatment. Akkermansia mucinifila, Enterococcus hirae, or Faecalibacterium prausnitzii are bacteria that exhibit this beneficial potential. Greater benefits of therapy can be observed in cancer patients enriched in these bacterial species and treated with anti-PD-1, anti-PD-L1, or anti-CTLA-4 monoclonal antibodies. In this review, we present issues related to the role of bacteria in carcinogenesis and their therapeutic potential "supporting" modern anti-cancer therapies.Key Points• Bacteria can be directly or indirectly a cancer trigger.• Bacterial metabolites regulate the pathways associated with carcinogenesis.• Intestinal bacteria activate the immune system to fight cancer.

Potential in vivo delivery routes of postbiotics

Bioactive micro- and macro-molecules (postbiotics) derived from gut beneficial microbes are among natural chemical compounds with medical significance. Currently, a unique therapeutic strategy has been developed with an emphasis on the small molecular weight biomolecules that are made by the microbiome, which endow the host with several physiological health benefits. A large number of postbiotics have been characterized, which due to their unique pharmacokinetic properties in terms of controllable aspects of the dosage and various delivery routes, could be employed as promising medical tools since they exert both prevention and treatment strategies in the host. Nevertheless, there are still main challenges for the in vivo delivery of postbiotics. Currently, scientific literature confirms that targeted delivery systems based on nanoparticles, due to their appealing properties in terms of high biocompatibility, biodegradability, low toxicity, and significant capability to carry both hydrophobic and hydrophilic postbiotics, can be used as a novel and safe strategy for targeted delivery or/and release of postbiotics in various (oral, intradermal, and intravenous) in vivo models. The in vivo delivery of postbiotics are in their emerging phase and require massive investigation and randomized double-blind clinical trials if they are to be applied extensively as treatment strategies. This manuscript provides an overview of the various postbiotic metabolites derived from the gut beneficial microbes, their potential therapeutic activities, and recent progressions in the drug delivery field, as well as concisely giving an insight on the main in vivo delivery routes of postbiotics.

Novel Odoribacter splanchnicus Strain and Its Outer Membrane Vesicles Exert Immunoregulatory Effects in vitro

Odoribacter splanchnicus, belonging to the order Bacteroidales, is a common, short-chain fatty acid producing member of the human intestinal microbiota. A decreased abundance of Odoribacter has been linked to different microbiota-associated diseases, such as non-alcoholic fatty liver disease, cystic fibrosis and inflammatory bowel disease (IBD). The type strain of O. splanchnicus has been genome-sequenced, but otherwise very little is known about this anaerobic bacterium. The species surfaces in many microbiota studies and, consequently, comprehension on its interactions with the host is needed. In this study, we isolated a novel strain of O. splanchnicus from a healthy fecal donor, identified it by genome sequencing and addressed its adhesive, epithelium reinforcing and immunoregulatory properties. Our results show that O. splanchnicus strain 57 is non-adherent to enterocytes or mucus, does not reinforce nor compromise Caco-2 monolayer integrity and most likely harbors penta-acylated, less endotoxic lipid A as part of its lipopolysaccharide (LPS) structure based on the lack of gene lpxM and in vitro results on low-level NF-κB activity. The studies by transmission electron microscopy revealed that O. splanchnicus produces outer membrane vesicles (OMV). O. splanchnicus cells, culture supernatant i.e., spent medium or OMVs did not induce interleukin-8 (IL-8) response in HT-29 enterocyte cells suggesting a very low proinflammatory capacity. On the contrary, the treatment of HT-29 cells with O. splanchnicus cells, spent medium or OMVs prior to exposure to Escherichia coli LPS elicited a significant decrease in IL-8 production as compared to E. coli LPS treatment alone. Moreover, O. splanchnicus spent supernatant induced IL-10 production by immune cells, suggesting anti-inflammatory activity. Our in vitro findings indicate that O. splanchnicus and its effector molecules transported in OMVs could potentially exert anti-inflammatory action in the gut epithelium. Taken together, O. splanchnicus seems to be a commensal with a primarily beneficial interaction with the host.

Postbiotics as Promising Tools for Cancer Adjuvant Therapy

As many investigations have reported, there is a complicated relation between fermented foods, lactic acid bacteria (LAB), and human health. It seems that bioactive components such as prebiotics, probiotics, and postbiotics are key mediators of the complex and direct association between these factors. LAB activity in the matrix of fermented foods and improving their growth by prebiotic compounds ultimately results in the production of bioactive molecules (postbiotics), which possess specific biological and physiological properties. The term "postbiotics" refers to a complex of biological micro- and macromolecules, if consumed in adequate amounts, provides the host with different health-promoting effects. Different reports have suggested that postbiotics possess the ability to moderate the effectiveness of cancer treatment and reduce the side-effects of conventional therapies in cancer patients due to their anti-proliferative, anti-inflammatory and anti-cancer properties. Consequently, postbiotics, for their unique characteristics, have gained great scientific attention and are considered as a novel approach for adjuvant therapy in patients with cancer.

Molecular mechanisms of postbiotics in colorectal cancer prevention and treatment

The occurrence of colorectal cancer (CRC) has been rising expeditiously and anticipated that 2.4 million new occasions of CRC will be detected yearly around the world until the year 2035. Due to some side-effects and complications of conventional CRC therapies, bioactive components such as microbial-derived biomolecules (postbiotics) have been attaining great significance by researchers for adjuvant therapy in CRC patients. The term 'postbiotics' encompasses an extensive range of complex micro- and macro-molecules (<50, 50-100, and 100< kDa) such as inactivated microbial cells, cell fractions or metabolites, which confer various physiological health benefits to the host when administered in adequate amounts. Postbiotics modulate the composition of the gut microbiota and the functionality of the immune system, as well as promote the CRC treatment effectiveness and reduces its side-effects in CRC patients due to possessing anti-oxidant, anti-proliferative, anti-inflammatory, and anti-cancer activities. Presently scientific literature confirms that postbiotics with their unique characteristics in terms of clinical (safe origin), technological (stability), and economic (low production costs) aspects can be used as promising tools for both prevent and adjuvant treat strategies in CRC patients without any serious undesirable side-effects. This review provides an overview of the concept and safety issues regarding postbiotics, with emphasis on their biological role in the prevention and treatment of CRC.

The impact of bacteria-derived ultrafine dust particles on pulmonary diseases

The relationship between ambient particulate matter exposure and health has been well established. Ultrafine particles (UFP) with a diameter of 100 nm or less are known to increase pulmonary disease risk. Biological factors in dust containing UFP can cause severe inflammatory reactions. Pulmonary diseases develop primarily as a result of chronic inflammation caused by immune dysfunction. Thus, this review focuses on the adverse pulmonary effects of biological UFP, principally lipopolysaccharide (LPS), and bacterial extracellular vesicles (EVs), in indoor dust and the pathophysiological mechanisms involved in the development of chronic pulmonary diseases. The impact of LPS-induced pulmonary inflammation is based primarily on the amount of inhaled LPS. When relatively low levels of LPS are inhaled, a cascade of immune responses leads to Th2 cell induction, and IL-5 and IL-13 released by Th2 cells contributes to asthma development. Conversely, exposure to high levels of LPS induces a Th17 cell response, leading to increased production of IL-17, which is associated with asthma, COPD, and lung cancer incidence. Responses to bacterial EV exposure can similarly be broadly divided based on whether one of two mechanisms, either intracellular or extracellular, is activated, which depends on the type of the parent cell. Extracellular bacteria-derived EVs can cause neutrophilic inflammation via Th17 cell induction, which is associated with asthma, emphysema, COPD, and lung cancer. On the other hand, intracellular bacteria-derived EVs lead to mononuclear inflammation via Th1 cell induction, which increases the risk of emphysema. In conclusion, future measures should focus on the overall reduction of LPS sources in addition to the improvement of the balance of inhaled bacterial EVs in the indoor environment to minimize pulmonary disease risk.