Selenium-containing polysaccharide from Spirulina platensis alleviates Cd-induced toxicity in mice by inhibiting liver inflammation mediated by gut microbiota

Could the gut microbiota be capable of making individuals more or less susceptible to environmental toxicants?

Environmental toxicants are chemical substances capable to impair environmental quality and exert adverse effects on humans and other animals. The main routes of exposure to these pollutants are through the respiratory tract, skin, and oral ingestion. When ingested orally, they will encounter trillions of microorganisms that live in a community - the gut microbiota (GM). While pollutants can disrupt the GM balance, GM plays an essential role in the metabolism and bioavailability of these chemical compounds. Under physiological conditions, strategies used by the GM for metabolism and/or excretion of xenobiotics include reductive and hydrolytic transformations, lyase and functional group transfer reactions, and enzyme-mediated functional transformations. Simultaneously, the host performs metabolic processes based mainly on conjugation, oxidation, and hydrolysis reactions. Thus, due to the broad variety of bacterial enzymes present in GM, the repertoire of microbial transformations of chemicals is considered a key component of the machinery involved in the metabolism of pollutants in humans and other mammals. Among pollutants, metals deserve special attention once contamination by metals is a worldwide problem, and their adverse effects can be observed even at very low concentrations due to their toxic properties. In this review, bidirectional interaction between lead, arsenic, cadmium, and mercury and the host organism and its GM will be discussed given the most recent literature, presenting an analysis of the ability of GM to alter the host organism's susceptibility to the toxic effects of heavy metals, as well as evaluating the extent to which interventions targeting the microbiota could be potential initiatives to mitigate the adverse effects resulting from poisoning by heavy metals. This study is the first to highlight the overlap between some of the bacteria found to be altered by metal exposure and the bacteria that also aid the host organism in the metabolism of these metals. This could be a key factor to determine the beneficial species able to minimize the toxicity of metals in future therapeutic approaches.

Shedding light on the impacts of Spirulina platensis on gut microbiota and related health benefits

Spirulina (S.) platensis is a blue-green algae with reported nutritional and health-promoting properties, such as immunomodulating, antioxidant, cholesterol-lowering properties, and beneficial effects on inflammatory diseases. Spirulina platensis can improve the function and composition of the gut microbiota and exert systemic beneficial effects. Gut dysbiosis is characterized by an imbalance in the composition and function of gut microbiota and is associated with several diseases. Some dietary bioactive compounds can restore the composition, diversity, and function of the gut microbiota and improve health-related parameters. This review proposes to gather relevant information on the effects of S. platensis supplementation on the modulation of the function and composition of gut microbiota and local and systemic measures related to gut health, such as inflammation, oxidative stress, and glucose and lipid metabolism. The body of evidence conducted with animals and clinical studies shows that S. platensis supplementation increased gut microbiota diversity and improved gut microbiota composition, as reported by a decrease in the Firmicutes/Bacteroides ratio, increase in the relative abundance of Prevotella and Lactobacillaceae, increase in short-chain fatty acid production and decrease of gut permeability. Improvements in gut microbiota have been associated with host health benefits such as anti-obesity, anti-diabetic, anti-hypertensive, anti-lipemic, anti-inflammatory, and antioxidant effects.

Isoliquiritin counteracts cadmium-induced intestinal damage in mice through enhancing intestinal barrier function and inhibiting apoptosis

Cadmium (Cd), a crucial toxic environmental pollutant, can induce damage to many organs, especially the gastrointestinal tract. Isoliquiritin (ISO), a critical flavonoid glycoside compound isolated from Glycyrrhiza uralensis, has anti-inflammatory, anticancer, antioxidant and other pharmaceutical value. However, the potential roles of ISO in Cd-induced intestinal damage have not been reported yet. This study aimed to research the beneficial effects of ISO on Cd-induced intestinal damage and identify its underlying mechanisms. Our results showed that ISO reduced inflammation by suppressing the production of pro-inflammatory cytokines and the activity of serum Lipopolysaccharide (LPS) in mice with Cd exposure. In terms of mechanism, ISO administration protected the intestinal barrier function through increasing the expression of tight junction proteins and Muc2. Furthermore, ISO could significantly suppress Cd-induced intestinal apoptosis and activation of NLRP3 inflammasome. Interestingly, inhibiting the activation of NLRP3 by nigericin completely blocking the effect of ISO on apoptosis. Most importantly, ISO markedly abrogated Cd-induced cell damage and NLRP3 inflammasome activation in vitro. Taken together, these findings suggest that ISO reduces Cd-induced intestinal damage by increasing the goblet cells, improving intestinal barrier, suppressing NLRP3 inflammasome activation and inhibiting apoptosis, which may offer a novel strategy against the toxic effects of heavy metals.

Comparison of Sodium Selenite and Selenium-Enriched Spirulina Supplementation Effects After Selenium Deficiency on Growth, Tissue Selenium Concentrations, Antioxidant Activities, and Selenoprotein Expression in Rats

Selenium contributes to physiological functions through its incorporation into selenoproteins. It is involved in oxidative stress defense. A selenium deficiency results in the onset or aggravation of pathologies. Following a deficiency, the repletion of selenium leads to a selenoprotein expression hierarchy misunderstood. Moreover, spirulina, a microalga, exhibits antioxidant properties and can be enriched in selenium.. Our objective was to determine the effects of a sodium selenite or selenium-enriched spirulina supplementation. Thirty-two female Wistar rats were fed for 12 weeks with a selenium-deficient diet. After 8 weeks, rats were divided into 4 groups and were fed with water, sodium selenite (20 μg Se/kg body weight), spirulina (3 g/kg bw), or selenium-enriched spirulina (20 μg Se/kg bw + 3 g spirulina/kg bw). Another group of 8 rats was fed with normal diet during 12 weeks. Selenium concentration and antioxidant enzyme activities were measured in plasma, urine, liver, brain, kidney, heart, and soleus. Expression of GPx (1, 3), Sel (P, S, T, W), SEPHS2, TrxR1, ApoER2, and megalin were quantified in liver, kidney, brain, and heart. We showed that a selenium deficiency leads to a growth delay, reversed by selenium supplementation despite a minor loss of weight in week 12 for SS rats. All tissues displayed a decrease in selenium concentration following deficiency. The brain seemed protected. We demonstrated a hierarchy in selenium distribution and selenoprotein expression. A supplementation of sodium selenite improved GPx activities and selenoprotein expression while a selenium-enriched spirulina was more effective to restore selenium concentration especially in the liver, kidney, and soleus.

Polysaccharides derived from Spirulina platensis inhibited Singapore grouper iridovirus by impeding the entry of viral particles

Attributable to the rapid dissemination and high lethality of Singapore grouper iridovirus (SGIV), it has caused significant economic losses for marine fish aquaculture in China and Southeast Asian nations. Hence, there is an urgent need to find antiviral drugs that are both safe and effective. In this study, a novel heteropolysaccharide named Spirulina platensis polysaccharides (SPP) was purified and characterized from S. platensis. The molecular weight of SPP is 276 kDa and it mainly consists of Glc and Rha, followed by minor components such as Gal, Xyl, and Fuc. The backbone of SPP was determined to be →2) -β-Rhap-(1 → 4) -α-Fucp-(1 → [2) -α-Rhap-(1] 2[→6)-α-Glcp-(1] 4[→ 4) -α-Glcp-(1] 8[→ 4) -β-Glcp-(1]2→, with branches of β-Galp, α-Xylp and α-Glcp. SPP significantly inhibited SGIV-induced cytopathic effects (CPEs), viral gene replication and viral protein expression. The antiviral mechanism of SPP was associated with the disruption of SGIV entry to host cells. Furthermore, it was not observed that SPP made statistically significant impact on the expression of interferon-related cytokines. Our results offered novel insights into the potential utilization of spirulina polysaccharides for combating aquatic animal viruses.

The potential, challenges, and prospects of the genus Spirulina polysaccharides as future multipurpose biomacromolecules

Spirulina has been widely used worldwide as a food and medicinal ingredient for centuries. Polysaccharides are major bioactive constituents of Spirulina and are of interest because of their functional properties and unlimited application potential. However, the clinical translation and market industrialization of the polysaccharides from genus Spirulina (PGS) are retarded due to the lack of a further understanding of their isolation, bioactivities, structure-activity relationships (SARs), toxicity, and, most importantly, versatile applications. Herein, we provide an overview of the extraction, purification, and structural features of PGS; meanwhile, the advances in bioactivities, SARs, mechanisms of effects, and toxicity are discussed and summarized. Furthermore, the applications, potential developments, and future research directions are scrutinized and highlighted. This review may help fill the knowledge gap between theoretical insights and practical applications and guide future research and industrial application of PGS.