Microbiology
Abstract
Previous studies have demonstrated the presence of microbial DNA in the fetal environment. However, it remains unclear whether this DNA represents viable bacteria and how it relates to the maternal microbiota across different body sites. We studied the microbiota of human and mouse dyads to understand these relationships, localize bacteria in the fetus, and demonstrate bacterial viability. In human preterm and full-term mother-infant dyads at the time of Cesarean delivery, the oral cavity and meconium of newborn infants born as early as 24 weeks of gestation contained a microbiota that was predicted to originate from in utero sources including the placenta. Using operative deliveries of pregnant mice under highly controlled, sterile conditions in the laboratory, composition, visualization, and viability of bacteria in the in utero compartment and fetal intestine were demonstrated by 16S rRNA gene sequencing, fluorescence in situ hybridization, and bacterial culture. The composition and predicted source of the fetal gut microbiota shifted between mid- and late gestation. Cultivatable bacteria in the fetal intestine were found during mid-gestation but not late gestation. Our results demonstrate a dynamic, viable mammalian fetal microbiota during in utero development.
Authors
Noelle Younge, Jessica R. McCann, Julie Ballard, Catherine Plunkett, Suhail Akhtar, Félix Araújo-Pérez, Amy Murtha, Debra Brandon, Patrick C. Seed
Abstract
Although mucoactive proteins, such as epidermal growth factor (EGF), could improve clinical outcomes of intestinal ulcerative diseases, their gastrointestinal application is limited because of their proteolytic digestion or concerns about tumor promotion. In the present study, ATP-binding cassette (ABC) transporter–linked secretion of human EGF from probiotic Escherichia coli (EGF-EcN) was created to promote beneficial actions of the EGF receptor, which is notably attenuated in patients with intestinal ulcerative injuries. Preventive and postinjury treatment with EGF-EcN alleviated intestinal ulcers and other readouts of disease severity in murine intestinal ulcer models. EGF-EcN administration promoted the restitutive recovery of damaged epithelial layers, particularly via upward expansion of highly proliferating progenitor cells from the lower crypts. Along with the epithelial barrier benefit, EGF-EcN improved goblet cell–associated mucosal integrity, which controls the access of luminal microbiota to the underlying host tissues. Despite concern about the oncogenic action of EGF, EGF-EcN did not aggravate colitis-associated colon cancer; instead, it alleviated protumorigenic activities and improved barrier integrity in the lesions. All findings indicate that probiotic bacteria–based precision delivery of human EGF is a promising mucosal intervention against gastrointestinal ulcers and malignant distress through crypt-derived barrier restoration.
Authors
Mira Yu, Juil Kim, Jung Hoon Ahn, Yuseok Moon
Abstract
Chronic malaria is a major public health problem and significant challenge for disease eradication efforts. Despite its importance, the biological factors underpinning chronic malaria are not fully understood. Recent studies have shown that host metabolic state can influence malaria pathogenesis and transmission, but its role in chronicity is not known. Here, with the goal of identifying distinct modifications in the metabolite profiles of acute versus chronic malaria, metabolomics was performed on plasma from Plasmodium-infected humans and nonhuman primates with a range of parasitemias and clinical signs. In rhesus macaques infected with Plasmodium coatneyi, significant alterations in amines, carnitines, and lipids were detected during a high parasitemic acute phase and many of these reverted to baseline levels once a low parasitemic chronic phase was established. Plasmodium gene expression, studied in parallel in the macaques, revealed transcriptional changes in amine, fatty acid, lipid and energy metabolism genes, as well as variant antigen genes. Furthermore, a common set of amines, carnitines, and lipids distinguished acute from chronic malaria in plasma from human Plasmodium falciparum cases. In summary, distinct host-parasite metabolic environments have been uncovered that characterize acute versus chronic malaria, providing insights into the underlying host-parasite biology of malaria disease progression.
Authors
Regina Joice Cordy, Rapatbhorn Patrapuvich, Loukia N. Lili, Monica Cabrera-Mora, Jung-Ting Chien, Gregory K. Tharp, Manoj Khadka, Esmeralda V.S. Meyer, Stacey A. Lapp, Chester J. Joyner, AnaPatricia Garcia, Sophia Banton, ViLinh Tran, Viravarn Luvira, Siriwan Rungin, Teerawat Saeseu, Nattawan Rachaphaew, Suman B. Pakala, Jeremy D. DeBarry, MaHPIC Consortium, Jessica C. Kissinger, Eric A. Ortlund, Steven E. Bosinger, John W. Barnwell, Dean P. Jones, Karan Uppal, Shuzhao Li, Jetsumon Sattabongkot, Alberto Moreno, Mary R. Galinski
Abstract
Genomic studies revealed the existence of health- and acne-associated P. acnes strains and suggested novel approaches for broadening understanding of acne vulgaris. However, clinical association of P. acnes with disease or health has yet to be corroborated experimentally. Current animal models of acne do not closely mimic human disease and have unclear translational value. We have developed a murine model of acne by combining P. acnes inoculation with topical application of a synthetic human sebum. We showed that human sebum promoted persistence of intradermally injected P. acnes with little loss of viability after 1 week and permitted use of more physiologic inoculums. Application of acne-associated P. acnes RT4/5 strains led to development of moderate to severe skin pathology compared with application of health-associated type II P. acnes strains (RT2/6). RT4/5 P. acnes strains uniformly induced higher levels of KC (IL-8), IL-1α, IL-1β, and IL-6 in vitro and in vivo compared with type II P. acnes strains. Overall, our data provide immunopathologic corroboration of health and disease association of clinical P. acnes strains and inform on a platform to query putative virulence factors uncovered by genomic studies.
Authors
Stacey L. Kolar, Chih-Ming Tsai, Juan Torres, Xuemo Fan, Huiying Li, George Y. Liu
Abstract
Fusobacterium nucleatum is an oral anaerobe prevalent in intrauterine infection associated with a wide spectrum of adverse pregnancy outcomes. We demonstrate here that F. nucleatum triggers placental inflammation through maternal, rather than paternal, TLR4-mediated signaling. Elimination of TLR4 from maternal endothelial cells alleviated placental inflammation and reduced fetal and neonatal death, while elimination of TLR4 in the hematopoietic cells had no effect. The placental inflammatory response followed a spatiotemporal pattern, with NF-κB activation observed first in the maternal endothelial cells and then in the decidual cells surrounding the endothelium, followed by induction of inflammatory cytokines and chemokines. Supplementation of pregnant mice with fish oil as a source of omega-3 fatty acids suppressed placental inflammation, reduced F. nucleatum proliferation in the placenta, and increased fetal and neonatal survival. In vitro analysis illustrates that omega-3 fatty acids inhibit bacterial-induced inflammatory responses from human umbilical cord endothelial cells. Our study therefore reveals a mechanism by which microbial infections affect pregnancy and identifies a prophylactic therapy to protect against intrauterine infections.
Authors
Jeewon Garcia-So, Xinwen Zhang, Xiaohua Yang, Mara Roxana Rubinstein, De Yu Mao, Jan Kitajewski, Kang Liu, Yiping W. Han
Abstract
Gut microbiota–derived metabolites play important roles in health and disease. D–amino acids and their L-forms are metabolites of gut microbiota with distinct functions. In this study, we show the pathophysiologic role of D–amino acids in association with gut microbiota in humans and mice with acute kidney injury (AKI). In a mouse kidney ischemia/reperfusion model, the gut microbiota protected against tubular injury. AKI-induced gut dysbiosis contributed to the altered metabolism of D–amino acids. Among the D–amino acids, only D-serine was detectable in the kidney. In injured kidneys, the activity of D–amino acid oxidase was decreased. Conversely, the activity of serine racemase was increased. The oral administration of D-serine mitigated the kidney injury in B6 mice and D-serine–depleted mice. D-serine suppressed hypoxia-induced tubular damage and promoted posthypoxic tubular cell proliferation. Finally, the D-serine levels in circulation were significantly correlated with the decrease in kidney function in AKI patients. These results demonstrate the renoprotective effects of gut-derived D-serine in AKI, shed light on the interactions between the gut microbiota and the kidney in both health and AKI, and highlight D-serine as a potential new therapeutic target and biomarker for AKI.
Authors
Yusuke Nakade, Yasunori Iwata, Kengo Furuichi, Masashi Mita, Kenji Hamase, Ryuichi Konno, Taito Miyake, Norihiko Sakai, Shinji Kitajima, Tadashi Toyama, Yasuyuki Shinozaki, Akihiro Sagara, Taro Miyagawa, Akinori Hara, Miho Shimizu, Yasutaka Kamikawa, Kouichi Sato, Megumi Oshima, Shiori Yoneda-Nakagawa, Yuta Yamamura, Shuichi Kaneko, Tetsuya Miyamoto, Masumi Katane, Hiroshi Homma, Hidetoshi Morita, Wataru Suda, Masahira Hattori, Takashi Wada
Abstract
We hypothesized that the gut microbiota influences survival of murine cardiac allografts through modulation of immunity. Antibiotic pretreated mice received vascularized cardiac allografts and fecal microbiota transfer (FMT), along with tacrolimus immunosuppression. FMT source samples were from normal, pregnant (immune suppressed), or spontaneously colitic (inflammation) mice. Bifidobacterium pseudolongum (B. pseudolongum) in pregnant FMT recipients was associated with prolonged allograft survival and lower inflammation and fibrosis, while normal or colitic FMT resulted in inferior survival and worse histology. Transfer of B. pseudolongum alone resulted in reduced inflammation and fibrosis. Stimulation of DC and macrophage lines with B. pseudolongum induced the antiinflammatory cytokine IL-10 and homeostatic chemokine CCL19 but induced lesser amounts of the proinflammatory cytokines TNFα and IL-6. In contrast, LPS and Desulfovibrio desulfuricans (D. desulfuricans), more abundant in colitic FMT, induced a more inflammatory cytokine response. Analysis of mesenteric and peripheral lymph node structure showed that B. pseudolongum gavage resulted in a higher laminin α4/α5 ratio in the lymph node cortical ridge, indicative of a suppressive environment, while D. desulfuricans resulted in a lower laminin α4/α5 ratio, supportive of inflammation. Discrete gut bacterial species alter immunity and may predict graft outcomes through stimulation of myeloid cells and shifts in lymph node structure and permissiveness.
Authors
Jonathan S. Bromberg, Lauren Hittle, Yanbao Xiong, Vikas Saxena, Eoghan M. Smyth, Lushen Li, Tianshu Zhang, Chelsea Wagner, W. Florian Fricke, Thomas Simon, Colin C. Brinkman, Emmanuel F. Mongodin
Abstract
When draining lymph nodes become infected by Yersinia pestis (Y. pestis), a massive influx of phagocytic cells occurs, resulting in distended and necrotic structures known as buboes. The bubonic stage of the Y. pestis life cycle precedes septicemia, which is facilitated by trafficking of infected mononuclear phagocytes through these buboes. However, how Y. pestis convert these immunocytes recruited by host to contain the pathogen into vehicles for bacterial dispersal and the role of immune cell death in this context are unknown. We show that the lymphatic spread requires Yersinia outer protein J (YopJ), which triggers death of infected macrophages by downregulating a suppressor of receptor-interacting protein kinase 1–mediated (RIPK1-mediated) cell death programs. The YopJ-triggered cell death was identified as necroptotic, which released intracellular bacteria, allowing them to infect new neighboring cell targets. Dying macrophages also produced chemotactic sphingosine 1-phosphate, enhancing cell-to-cell contact, further promoting infection. This necroptosis-driven expansion of infected macrophages in buboes maximized the number of bacteria-bearing macrophages reaching secondary lymph nodes, leading to sepsis. In support, necrostatins confined bacteria within macrophages and protected mice from lethal infection. These findings define necrotization of buboes as a mechanism for bacterial spread and a potential target for therapeutic intervention.
Authors
Mohammad Arifuzzaman, W.X. Gladys Ang, Hae Woong Choi, Matthew L. Nilles, Ashley L. St. John, Soman N. Abraham
Abstract
Studies in patients with genetic defects can provide unique insights regarding the role of specific genes and pathways in humans. Patients with defects in the Th17/IL-17 axis, such as patients harboring loss-of-function STAT3 mutations (autosomal-dominant hyper IgE syndrome; AD-HIES) present with recurrent oral fungal infections. Our studies aimed to comprehensively evaluate consequences of STAT3 deficiency on the oral commensal microbiome. We characterized fungal and bacterial communities in AD-HIES in the presence and absence of oral fungal infection compared with healthy volunteers. Analyses of oral mucosal fungal communities in AD-HIES revealed severe dysbiosis with dominance of Candida albicans (C. albicans) in actively infected patients and minimal representation of health-associated fungi and/or opportunists. Bacterial communities also displayed dysbiosis in AD-HIES, particularly in the setting of active Candida infection. Active candidiasis was associated with decreased microbial diversity and enrichment of the streptococci Streptococcus oralis (S. oralis) and S. mutans, suggesting an interkingdom interaction of C. albicans with oral streptococci. Increased abundance of S. mutans was consistent with susceptibility to dental caries in AD-HIES. Collectively, our findings illustrate a critical role for STAT3/Th17 in the containment of C. albicans as a commensal organism and an overall contribution in the establishment of fungal and bacterial oral commensal communities.
Authors
Loreto Abusleme, Patricia I. Diaz, Alexandra F. Freeman, Teresa Greenwell-Wild, Laurie Brenchley, Jigar V. Desai, Weng-Ian Ng, Steven M. Holland, Michail S. Lionakis, Julia A. Segre, Heidi H. Kong, Niki M. Moutsopoulos
Abstract
Obesity is a risk factor for osteoarthritis (OA), the greatest cause of disability in the US. The impact of obesity on OA is driven by systemic inflammation, and increased systemic inflammation is now understood to be caused by gut microbiome dysbiosis. Oligofructose, a nondigestible prebiotic fiber, can restore a lean gut microbial community profile in the context of obesity, suggesting a potentially novel approach to treat the OA of obesity. Here, we report that — compared with the lean murine gut — obesity is associated with loss of beneficial Bifidobacteria, while key proinflammatory species gain in abundance. A downstream systemic inflammatory signature culminates with macrophage migration to the synovium and accelerated knee OA. Oligofructose supplementation restores the lean gut microbiome in obese mice, in part, by supporting key commensal microflora, particularly Bifidobacterium pseudolongum. This is associated with reduced inflammation in the colon, circulation, and knee and protection from OA. This observation of a gut microbiome–OA connection sets the stage for discovery of potentially new OA therapeutics involving strategic manipulation of specific microbial species inhabiting the intestinal space.
Authors
Eric M. Schott, Christopher W. Farnsworth, Alex Grier, Jacquelyn A. Lillis, Sarah Soniwala, Gregory H. Dadourian, Richard D. Bell, Madison L. Doolittle, David A. Villani, Hani Awad, John P. Ketz, Fadia Kamal, Cheryl Ackert-Bicknell, John M. Ashton, Steven R. Gill, Robert A. Mooney, Michael J. Zuscik
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