Short-term dietary changes can result in mucosal and systemic immune depression

Impact of dietary carbohydrate, fat or protein restriction on the human gut microbiome: a systematic review

Restriction of dietary carbohydrates, fat and/or protein is often used to reduce body weight and/or treat (metabolic) diseases. Since diet is a key modulator of the human gut microbiome, which plays an important role in health and disease, this review aims to provide an overview of current knowledge of the effects of macronutrient-restricted diets on gut microbial composition and metabolites. A structured search strategy was performed in several databases. After screening for inclusion and exclusion criteria, thirty-six articles could be included. Data are included in the results only when supported by at least three independent studies to enhance the reliability of our conclusions. Low-carbohydrate (<30 energy%) diets tended to induce a decrease in the relative abundance of several health-promoting bacteria, including Bifidobacterium, as well as a reduction in short-chain fatty acid (SCFA) levels in faeces. In contrast, low-fat diets (<30 energy%) increased alpha diversity, faecal SCFA levels and abundance of some beneficial bacteria, including Faecalibacterium prausnitzii. There were insufficient data to draw conclusions concerning the effects of low-protein (<10 energy%) diets on gut microbiota. Although the data of included studies unveil possible benefits of low-fat and potential drawbacks of low-carbohydrate diets for human gut microbiota, the diversity in study designs made it difficult to draw firm conclusions. Using a more uniform methodology in design, sample processing and sharing raw sequence data could foster our understanding of the effects of macronutrient restriction on gut microbiota composition and metabolic dynamics relevant to health. This systematic review was registered at https://www.crd.york.ac.uk/prospero as CRD42020156929.

The importance of Ca2+ microdomains for the adaptive immune response

Calcium signaling stands out as the most widespread and universally used signaling system and is of utmost importance for immunity. Controlled elevations in cytosolic and organellar Ca2+ concentrations in T cells control complex and essential effector functions including proliferation, differentiation, cytokine secretion, and cytotoxicity, among others. Additionally, disruptions in Ca2+ regulation in T cells contribute to diverse autoimmune, inflammatory, and immunodeficiency conditions. Among the initial intracellular signals, which occurring even before T cell receptor (TCR) stimulation are highly localized, spatially and temporally restricted so-called Ca2+ microdomains, caused by adhesion to extracellular matrix proteins (ECM proteins). The Ca2+ microdomains present both before and within the initial seconds following TCR stimulation are likely to play a crucial role in fine-tuning the downstream activity of T cell activation and thus, shaping an adaptive immune response. In this review, the emphasis is on the recent advances of adhesion-dependent Ca2+ microdomains (ADCM) in the absence of TCR stimulation, initial Ca2+ microdomains evoked by TCR stimulation (TDCM), the downstream signaling processes as well as possible therapeutic targets for interventions.

Microbiota-gut-brain axis and its therapeutic applications in neurodegenerative diseases

The human gastrointestinal tract is populated with a diverse microbial community. The vast genetic and metabolic potential of the gut microbiome underpins its ubiquity in nearly every aspect of human biology, including health maintenance, development, aging, and disease. The advent of new sequencing technologies and culture-independent methods has allowed researchers to move beyond correlative studies toward mechanistic explorations to shed light on microbiome-host interactions. Evidence has unveiled the bidirectional communication between the gut microbiome and the central nervous system, referred to as the "microbiota-gut-brain axis". The microbiota-gut-brain axis represents an important regulator of glial functions, making it an actionable target to ameliorate the development and progression of neurodegenerative diseases. In this review, we discuss the mechanisms of the microbiota-gut-brain axis in neurodegenerative diseases. As the gut microbiome provides essential cues to microglia, astrocytes, and oligodendrocytes, we examine the communications between gut microbiota and these glial cells during healthy states and neurodegenerative diseases. Subsequently, we discuss the mechanisms of the microbiota-gut-brain axis in neurodegenerative diseases using a metabolite-centric approach, while also examining the role of gut microbiota-related neurotransmitters and gut hormones. Next, we examine the potential of targeting the intestinal barrier, blood-brain barrier, meninges, and peripheral immune system to counteract glial dysfunction in neurodegeneration. Finally, we conclude by assessing the pre-clinical and clinical evidence of probiotics, prebiotics, and fecal microbiota transplantation in neurodegenerative diseases. A thorough comprehension of the microbiota-gut-brain axis will foster the development of effective therapeutic interventions for the management of neurodegenerative diseases.

Astaxanthin exerts an adjunctive anti-cancer effect through the modulation of gut microbiota and mucosal immunity

This study aimed to investigate the function of gut microbiota in astaxanthin's adjuvant anticancer effects. Our prior research demonstrated that astaxanthin enhanced the antitumor effects of sorafenib by enhancing the body's antitumor immune response; astaxanthin also regulated the intestinal flora composition of tumor-bearing mice. However, it is presently unknown whether this beneficial effect is dependent on the gut microbiota. We first used broad-spectrum antibiotics to eradicate gut microbiota of tumor-bearing mice, followed by the transplantation of fecal microbiota. The results of this study indicate that the beneficial effects of astaxanthin when combined with molecular targeting are dependent on the presence of intestinal microbiota. Astaxanthin facilitates the infiltration of CD8+ T lymphocytes into the tumor microenvironment and increases Granzyme B production by modulating the intestinal flora. Therefore, it strengthens the body's anti-tumor immune response and synergistically boosts the therapeutic efficacy of drugs. Astaxanthin stimulates the production of cuprocytes and mucus in the intestines by promoting the proliferation of Akkermansia. In addition, astaxanthin enhances the intestinal mucosal immunological function. Our research supports the unique ability of astaxanthin to sustain intestinal flora homeostasis and its function as a dietary immune booster for individuals with tumors.

Nutritional regulation of microbiota-derived metabolites: Implications for immunity and inflammation

Nutrition profoundly shapes immunity and inflammation across the lifespan of mammals, from pre- and post-natal periods to later life. Emerging insights into diet-microbiota interactions indicate that nutrition has a dominant influence on the composition-and metabolic output-of the intestinal microbiota, which in turn has major consequences for host immunity and inflammation. Here, we discuss recent findings that support the concept that dietary effects on microbiota-derived metabolites potently alter immune responses in health and disease. We discuss how specific dietary components and metabolites can be either pro-inflammatory or anti-inflammatory in a context- and tissue-dependent manner during infection, chronic inflammation, and cancer. Together, these studies emphasize the influence of diet-microbiota crosstalk on immune regulation that will have a significant impact on precision nutrition approaches and therapeutic interventions for managing inflammation, infection, and cancer immunotherapy.

A metabolic perspective of the neutrophil life cycle: new avenues in immunometabolism

Neutrophils are the most abundant innate immune cells. Multiple mechanisms allow them to engage a wide range of metabolic pathways for biosynthesis and bioenergetics for mediating biological processes such as development in the bone marrow and antimicrobial activity such as ROS production and NET formation, inflammation and tissue repair. We first discuss recent work on neutrophil development and functions and the metabolic processes to regulate granulopoiesis, neutrophil migration and trafficking as well as effector functions. We then discuss metabolic syndromes with impaired neutrophil functions that are influenced by genetic and environmental factors of nutrient availability and usage. Here, we particularly focus on the role of specific macronutrients, such as glucose, fatty acids, and protein, as well as micronutrients such as vitamin B3, in regulating neutrophil biology and how this regulation impacts host health. A special section of this review primarily discusses that the ways nutrient deficiencies could impact neutrophil biology and increase infection susceptibility. We emphasize biochemical approaches to explore neutrophil metabolism in relation to development and functions. Lastly, we discuss opportunities and challenges to neutrophil-centered therapeutic approaches in immune-driven diseases and highlight unanswered questions to guide future discoveries.

Exploring the Action Mechanism and Validation of the Key Pathways of Dendrobium officinale Throat-clearing Formula for the Treatment of Chronic Pharyngitis Based on Network Pharmacology

AIM

This study investigated the molecular action mechanism of a compound herb, also known as the Dendrobium officinale throat-clearing formula (QYF), by using network pharmacology and animal experimental validation methods to treat chronic pharyngitis (CP).

METHODS

The active ingredients and disease targets of QYF were determined by searching the Batman-TCM and GeneCards databases. Subsequently, the drug-active ingredient-target and protein-protein interaction networks were constructed, and the core targets were obtained through network topology. The Metascape database was screened, and the core targets were enriched with Gene Ontology and the Kyoto Encyclopedia of Genes and Genomes.

RESULTS

In total, 1403 and 241 potential targets for drugs and diseases, respectively, and 81 intersecting targets were yielded. The core targets included TNF, IL-6, and IL-1β, and the core pathways included PI3K-Akt. The QYF treatment group exhibited effectively improved general signs, enhanced anti-inflammatory ability in vitro, reduced serum and tissue expressions of TNF- α, IL-6, and IL-1β inflammatory factors, and decreased blood LPS levels and Myd88, TLR4, PI3K, Akt, and NF-κB p65 protein expression in the tissues.

CONCLUSION

QYF could inhibit LPS production, which regulated the expression of the TLR4/PI3K/Akt/NF-κB signaling pathway to suppress the expression of the related inflammatory factors (i.e., TNF-α, IL-6, and IL-1β), thereby alleviating the CP process.

Diet and immune response: how today's plate shapes tomorrow's health

Nutrition is emerging as a promising therapeutic tool to modulate the immune system in health and disease. We propose that the timing of dietary interventions is probably what determines their success. In this context, we explore recent research that identifies the early phases of dietary intervention as critical time windows for modulating immunity and optimizing cancer therapy. Furthermore, we highlight how the timing of intervention can yield different outcomes. The data suggest that nutrient availability and absorption over a short period can significantly impact mammalian immune and even non-immune landscapes. This, in turn, can lead to changes in mucosal and systemic immunity, potentially exacerbating or ameliorating inflammation, and perhaps influencing tumor cells and their response to cancer therapies.

Protocol for performing consecutive bone marrow transplants in mice to study the role of marrow niche in supporting hematopoiesis

Hematopoietic stem and progenitor cells depend on bone marrow (BM) stromal cells for survival. Here, we present a protocol for performing three consecutive BM transplants in mice to study the role of BM niche in supporting hematopoiesis. We describe steps for transplanting cells to condition the marrow of the recipient mice and transplanting wild-type cells to examine the effect of the conditioned marrow in supporting hematopoiesis. We then detail procedures for transplanting into wild-type recipients to measure bone marrow chimerism. For complete details on the use and execution of this protocol, please refer to Gopal et al. (2022).1.

Maternal antibiotic exposure enhances ILC2 activation in neonates via downregulation of IFN1 signaling

Microbiota have an important function in shaping and priming neonatal immunity, although the cellular and molecular mechanisms underlying these effects remain obscure. Here we report that prenatal antibiotic exposure causes significant elevation of group 2 innate lymphoid cells (ILC2s) in neonatal lungs, in both cell numbers and functionality. Downregulation of type 1 interferon signaling in ILC2s due to diminished production of microbiota-derived butyrate represents the underlying mechanism. Mice lacking butyrate receptor GPR41 (Gpr41-/-) or type 1 interferon receptor IFNAR1 (Ifnar1-/-) recapitulate the phenotype of neonatal ILC2s upon maternal antibiotic exposure. Furthermore, prenatal antibiotic exposure induces epigenetic changes in ILC2s and has a long-lasting deteriorative effect on allergic airway inflammation in adult offspring. Prenatal supplementation of butyrate ameliorates airway inflammation in adult mice born to antibiotic-exposed dams. These observations demonstrate an essential role for the microbiota in the control of type 2 innate immunity at the neonatal stage, which suggests a therapeutic window for treating asthma in early life.

Modulating a prebiotic food source influences inflammation and immune-regulating gut microbes and metabolites: insights from the BE GONE trial

BACKGROUND

Accessible prebiotic foods hold strong potential to jointly target gut health and metabolic health in high-risk patients. The BE GONE trial targeted the gut microbiota of obese surveillance patients with a history of colorectal neoplasia through a straightforward bean intervention.

METHODS

This low-risk, non-invasive dietary intervention trial was conducted at MD Anderson Cancer Center (Houston, TX, USA). Following a 4-week equilibration, patients were randomized to continue their usual diet without beans (control) or to add a daily cup of study beans to their usual diet (intervention) with immediate crossover at 8-weeks. Stool and fasting blood were collected every 4 weeks to assess the primary outcome of intra and inter-individual changes in the gut microbiome and in circulating markers and metabolites within 8 weeks. This study was registered on ClinicalTrials.gov as NCT02843425, recruitment is complete and long-term follow-up continues.

FINDINGS

Of the 55 patients randomized by intervention sequence, 87% completed the 16-week trial, demonstrating an increase on-intervention in diversity [n = 48; linear mixed effect and 95% CI for inverse Simpson index: 0.16 (0.02, 0.30); p = 0.02] and shifts in multiple bacteria indicative of prebiotic efficacy, including increased Faecalibacterium, Eubacterium and Bifidobacterium (all p < 0.05). The circulating metabolome showed parallel shifts in nutrient and microbiome-derived metabolites, including increased pipecolic acid and decreased indole (all p < 0.002) that regressed upon returning to the usual diet. No significant changes were observed in circulating lipoproteins within 8 weeks; however, proteomic biomarkers of intestinal and systemic inflammatory response, fibroblast-growth factor-19 increased, and interleukin-10 receptor-α decreased (p = 0.01).

INTERPRETATION

These findings underscore the prebiotic and potential therapeutic role of beans to enhance the gut microbiome and to regulate host markers associated with metabolic obesity and colorectal cancer, while further emphasizing the need for consistent and sustainable dietary adjustments in high-risk patients.

FUNDING

This study was funded by the American Cancer Society.