Spirulina platensis aqueous extracts ameliorate colonic mucosal damage and modulate gut microbiota disorder in mice with ulcerative colitis by inhibiting inflammation and oxidative stress

Insights into the effects of chronic combined chromium-nickel exposure on colon damage in mice through transcriptomic analysis and in vitro gastrointestinal digestion assay

Heavy metals interact with each other in a coexisting manner to produce complex combined toxicity to organisms. At present, the toxic effects of chronic co-exposure to heavy metals hexavalent chromium [Cr(VI)] and divalent nickel [Ni(II)] on organisms are seldom studied and the related mechanisms are poorly understood. In this study, we explored the mechanism of the colon injury in mice caused by chronic exposure to Cr or/and Ni. The results showed that, compared with the control group, Cr or/and Ni chronic exposure affected the body weight of mice, and led to infiltration of inflammatory cells in the colon, decreased the number of goblet cells, fusion of intracellular mucus particles and damaged cell structure of intestinal epithelial. In the Cr or/and Ni exposure group, the activity of nitric oxide synthase (iNOS) increased, the expression levels of MUC2 were significantly down-regulated, and those of ZO-1 and Occludin were significantly up-regulated. Interestingly, factorial analysis revealed an interaction between Cr and Ni, which was manifested as antagonistic effects on iNOS activity, ZO-1 and MUC2 mRNA expression levels. Transcriptome sequencing further revealed that the expression of genes-related to inflammation, intestinal mucus and tight junctions changed obviously. Moreover, the relative contents of Cr(VI) and Ni(II) in the Cr, Ni and Cr+Ni groups all changed with in-vitro gastrointestinal （IVG）digestion, especially in the Cr+Ni group. Our results indicated that the chronic exposure to Cr or/and Ni can lead to damage to the mice colon, and the relative content changes of Cr(VI) and Ni(II) might be the main reason for the antagonistic effect of Cr+Ni exposure on the colon damage.

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.

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.

IGF2BP2 attenuates intestinal epithelial cell ferroptosis in colitis by stabilizing m6A-modified GPX4 mRNA

BACKGROUND

Ulcerative colitis (UC) is a chronic and uncontrolled inflammatory bowel disease. N6-methyladenine (m6A) is a reversible mRNA modification method. IGF2BP2 is an RNA-binding protein regulated by m6A methylation. However, understanding of m6A-related proteins in UC is limited. This study was to analyze the function and related mechanism of IGF2BP2 in UC.

METHODS

The UC models were established by dextran sulfate sodium (DSS) in NCM460 cells and mice. The expression of IGF2BP2 and GPX4 in UC were detected by qPCR and western blot. The effects of IGF2BP2 on inflammation, ferroptosis and colon injury were measured by gain- and loss-of-function experiments. This study conducted a clinical evaluation of mice using the Disease Activity Index score. The molecular mechanism of IGF2BP2 in ferroptosis were analyzed by m6A RNA methylation quantification kit, RNA immunoprecipitation-qPCR analysis, and RNA stability assay.

RESULTS

IGF2BP2 and GPX4 were under-expressed in DSS-treated UC. IGF2BP2 enhanced the stability of GPX4 mRNA modified by m6A. IGF2BP2 overexpression repressed the ROS, MDA, and iron levels but enhanced the GSH and GPX4 levels in DSS-triggered NCM460 cells, which were partially reversed by GPX4 silencing. In UC mice, IGF2BP2 high-expression ameliorated symptoms, Disease Activity Index score, pathological changes, inflammatory reaction, and ferroptosis, which were also partly neutralized by GPX4 inhibition.

CONCLUSIONS

IGF2BP2 augmented the GPX4 expression by the m6A modification to weaken UC progression via suppressing ferroptosis.

Rosa Roxburghii Tratt Fruit Extract Prevents Dss-Induced Ulcerative Colitis in Mice by Modulating the Gut Microbiota and the IL-17 Signaling Pathway

Ulcerative colitis (UC) is a non-specific inflammatory bowel illness characterized by intestinal mucosal barrier degradation, inflammation, oxidative damage, and gut microbiota imbalances. Rosa roxburghii Tratt Fruit extract (RRTE) was extracted from Rosa roxburghii Tratt fruit, exhibiting an excellent prevention effect against UC; RRTE could prevent the damage of DSS-induced human normal colonic epithelial (NCM 460) cells, especially in cell viability and morphology, and oxidative damage. Additionally, in UC mice, RRTE could limit the intestinal mucosal barrier by increasing the expression of intestinal tight junction proteins and mucin, reducing inflammation and oxidative damage in colon tissue. More importantly, RRTE can increase the abundance of beneficial bacteria to regulate gut microbiota such as Ruminococcus, Turicibacter, and Parabacteroides, and reduce the abundance of harmful bacteria such as Staphylococcus and Shigella. Furthermore, transcriptomics of colonic mucosal findings point out that the beneficial effect of RRTE on UC could be attributed to the modulation of inflammatory responses such as the IL-17 and TNF signaling pathways. The qPCR results confirm that RRTE did involve the regulation of several genes in the IL-17 signaling pathway. In conclusion, RRTE could prevent DSS-induced damage both in vitro and in vivo.

The effects of spirulina supplementation on serum iron and ferritin, anemia parameters, and fecal occult blood in adults with ulcerative colitis: A randomized, double-blinded, placebo-controlled trial

BACKGROUND & AIMS

The present clinical trial aimed to evaluate the efficacy of spirulina administration on serum iron, ferritin, anemia parameters, and fecal occult blood test (FOBT) in adults with ulcerative colitis (UC).

METHODS

Eighty participants with UC were randomly assigned to take, either 1 g/day (two 500 mg capsules) spirulina (n = 40) or placebo (n = 40) in a double-blinded clinical trial for eight weeks. Dietary intake, physical activity status, serum iron and ferritin levels, anemia parameters, and FOBT were assessed in each participant at baseline and following the intervention. Seventy-three participants completed the trial.

RESULTS

Our results indicated significantly increased (p = 0.04) serum iron after eight weeks of spirulina supplementation compared to the placebo group. The spirulina group also demonstrated significantly increased mean corpuscular volume (p = 0.004) whereas red blood cell count (p = 0.01) and hematocrit (p = 0.03) were significantly lowered in the placebo group. No significant changes in FOBT outcomes were seen between groups at baseline (p = 0.12) and the end of the trial (p = 0.34). Eight weeks of 1 g/day spirulina supplementation improved anemia parameters in adults with UC compared to placebo.

CONCLUSIONS

These outcomes suggest that spirulina administration may be beneficial in the management of anemia in UC. Further clinical trials of longer duration are necessary to corroborate and expand our findings. Registered at: http://www.IRCT.ir (code: IRCT20170802035460N3).

A topical thermosensitive hydrogel system with cyclosporine A PEG-PCL micelles alleviates ulcerative colitis induced by TNBS in mice

Ulcerative colitis (UC) is an idiopathic, chronic, relapsing disease. In most cases, only the distal colon is affected, and the colonic stasis or fast colonic transit through the inflamed colon usually results in reduced exposure of the distal inflamed colon. Although the immunosuppressant cyclosporine A (CsA) has been used in patients with severe colitis who do not respond to corticosteroids, the clinical application of CsA remains limited due to the systemic toxicities and insufficient accumulation at the site of action for the intravenous and oral routes. In this study, we loaded CsA into the amphipathic poly(ethylene glycol)-poly(ε-caprolactone) (PEG-PCL) micelles and then embedded them in hydrogels consisting of chitosan, poloxamer 188, and poloxamer 407 to construct a thermosensitive and mucoadhesive hydrogel drug delivery system (PLCP). The PLCP presented a high drug-loading capacity and showed a stable and rapid gelation rate after rectal administration into the body. Compared to CsA-loaded micelles and Sandimmun (Neoral®), the developed thermosensitive gel exhibited prolonged retention on the inflamed colon, as seen from in vitro adhesion and in vivo distribution experiments. It also fast mitigated colitis symptoms in TNBS-treated mice by regulating the expression levels of proinflammatory cytokines (TNF-α, IL-1β, COX-2, and iNOS2), anti-inflammatory cytokines (IL-10, Nrf2, NQO1, and HO-1), and other relevant biochemical factors. Our results suggested that CsA-loaded micelle thermal hydrogel system could be a promising strategy by enhancing the retention in the diseased colon and promoting the relief and recovery of UC.

Oral Microalgae-Nano Integrated System against Radiation-Induced Injury

The increasing applications of ionizing radiation in society raise the risk of radiation-induced intestinal and whole-body injury. Astaxanthin is a powerful antioxidant to reduce the reactive oxygen generated from radiation and the subsequent damage. However, the oral administration of astaxanthin remains challenging owing to its low solubility and poor bioavailability. Herein, we facilely construct an orally used microalgae-nano integrated system (SP@ASXnano) against radiation-induced intestinal and whole-body injury, combining natural microalgae Spirulina platensis (SP) with astaxanthin nanoparticles (ASXnano). SP and ASXnano show complementation in drug delivery to improve distribution in the intestine and blood. SP displays limited gastric drug loss, prolonged intestinal retention, constant ASXnano release, and progressive degradation. ASXnano improves drug solubility, gastric stability, cell uptake, and intestinal absorption. SP and ASXnano have synergy in many aspects such as anti-inflammation, microbiota protection, and fecal short-chain fatty acid up-regulation. In addition, the system is ensured with biosafety for long-term administration. The system organically combines the properties of microalgae and nanoparticles, which was expected to expand the medical application of SP as a versatile drug delivery platform.

Nogo-B inhibition restricts ulcerative colitis via inhibiting p68/miR-155 signaling pathway

BACKGROUND & AIMS

Ulcerative colitis (UC) is a main type of inflammatory bowel diseases which spreads globally during the westernization of lifestyle over the past few decades. However, the cause of UC is still not fully understood. We aimed to disclose the role of Nogo-B in the development of UC.

METHODS

Nogo-deficiency (Nogo^-/-) and wild-type male mice were treated with dextran sodium sulfate (DSS) to conduct a UC model, followed by determination of colon and serum inflammatory cytokines level. RAW264.7, THP1 and NCM460 cells were used to determine macrophage inflammation as well as proliferation and migration of NCM460 cells under Nogo-B or miR-155 intervention.

RESULTS

Nogo deficiency significantly reduced DSS-induced weight loss, colon length and weight reduction, and inflammatory cells accumulation in the intestinal villus, while increased the expression of tight junctions (TJs) proteins (Zonula occludens-1, Occludin) and adherent junctions (AJs) proteins (E-cadherin, α-catenin), implying that Nogo deficiency attenuated DSS-induced UC. Mechanistically, Nogo-B deficiency reduced TNFα, IL-1β and IL-6 levels in the colon, serum, RAW264.7 cells and THP1-derived macrophages. Furthermore, we identified that Nogo-B inhibition can reduce the maturation of miR-155, which is essential for Nogo-B-affected inflammatory cytokines expression. Interestingly, we determined that Nogo-B and p68 can interact with each other to promote the expression and activation of Nogo-B and p68, thus facilitating miR-155 maturation to induce macrophage inflammation. Blocking p68 inhibited Nogo-B, miR-155, TNFα, IL-1β and IL-6 expression. Moreover, the culture medium collected from Nogo-B overexpressed macrophages can inhibit enterocytes NCM460 cells proliferation and migration.

CONCLUSION

We disclose that Nogo deficiency reduced DSS-induced UC via inhibiting p68-miR-155-activated inflammation. Our results indicate that Nogo-B inhibition serves as a new potential therapeutic candidate for the prevention and treatment of UC.

Exploring the links between gut microbiome changes and irritable bowel syndrome in Han populations in the Tibetan Plateau

The gut microbiome shows changes under a plateau environment, while the disbalance of intestinal microbiota plays an important role in the pathogenesis of irritable bowel syndrome (IBS); however, the relationship between the two remains unexplored. In this work, we followed up a healthy cohort for up to a year before and after living in a plateau environment and performed 16S ribosomal RNA (rRNA) sequencing analysis of their fecal samples. Through evaluating the participants' clinical symptoms, combined with an IBS questionnaire, we screened the IBS sub-population in our cohort. The sequencing results showed that a high-altitude environment could lead to changes in the diversity and composition of gut flora. In addition, we found that the longer the time volunteers spent in the plateau environment, the more similar their gut microbiota composition and abundance became compared to those before entering the plateau, and IBS symptoms were significantly alleviated. Therefore, we speculated that the plateau may be a special environment that induces IBS. The taxonomic units g_Alistipes, g_Oscillospira, and s_Ruminococcus_torques, which had been proved to play important roles in IBS pathogenesis, were also abundant in the IBS cohort at high altitudes. Overall, the disbalance of gut microbiota induced by the plateau environment contributed to the high frequency of IBS and the psychosocial abnormalities associated with IBS. Our results prompt further research to elucidate the relevant mechanism.

Modified Gegen Qinlian decoction ameliorated ulcerative colitis by attenuating inflammation and oxidative stress and enhancing intestinal barrier function in vivo and in vitro

ETHNOPHARMACOLOGICAL RELEVANCE

Modified Gegen Qinlian decoction (MGQD), which was first documented in Treatise on Febrile Disease, is recognized as a classic prescription to treat ulcerative colitis (UC). However, its protective mechanism against UC remains to be fully elucidated.

AIM OF THE STUDY

To explore the impact and the potential molecular mechanism of MGQD on dextran sodium sulfate (DSS)-induced UC mice and tumor necrosis factor alpha (TNF-α)-induced Caco-2 cell monolayer model of intestinal barrier.

MATERIALS AND METHODS

The chemical components of MGQD and MGQD drug containing serum (MGQD-DS) were characterized by LC-MS/MS. The therapeutic effect of MGQD on DSS-induced UC was evaluated based on body weight, disease activity index (DAI), colon length, colonic histopathological injury, inflammatory cytokines, oxidative stress response and intestinal barrier function. Cell Counting Kit (CCK)-8 assay was applied to detect the effect of MGQD-DS on the viability of Caco-2 cells. Additionally, TNF-α-induced Caco-2 cell monolayer model of intestinal barrier was established in vitro. The Caco-2 cell monolayers were administered blank serum or MGQD-DS to observe the effects of MGQD-DS on transepithelial electrical resistance (TEER), permeability of fluorescein isothiocyanate (FITC)-dextran, inflammatory cytokines, oxidative stress indicators and intestinal epithelial barrier (IEB).

RESULTS

MGQD significantly improved symptoms and pathological damage in UC mice by downregulating the expression of interleukin (IL)-1β and malondialdehyde (MDA), attenuating the loss of goblet cells and the destruction of intestinal epithelial ultrastructure, and upregulating the expression of superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), zonula occludens-1 (ZO-1), Occludin, Claudin-1 and E-cadherin. In vitro, MGQD-DS significantly reduced the flux of FITC-dextran, increased the TEER, inhibited the expression of IL-21, IL-17A and MDA, and promoted the expression of IL-4, IL-10, transforming growth factor-β (TGF-β), SOD, CAT, GSH, Occludin and E-cadherin in TNF-α-induced Caco-2 cell monolayer model of intestinal barrier.

CONCLUSION

MGQD can ameliorate DSS-induced UC mice and TNF-α-induced Caco-2 cell monolayer model of intestinal barrier, and the protective effect is related to its inhibition of inflammation, alleviation of oxidative stress, and repair of intestinal barrier damage.

Polysaccharides from Spirulina platensis: Extraction methods, structural features and bioactivities diversity

Spirulina platensis, a well-known blue-green microalga cultivated and consumed in China and United States, is traditionally used as a food supplement and medical ingredient. Increasing evidence has confirmed that the Spirulina platensis polysaccharides (SPPs) are vital and representative pharmacologically active biomacromolecules and exhibit multiple health-promoting activities both in vivo and in vitro, such as those of anti-cancer, anti-oxidant, immunomodulatory, hypolipidemic and hypoglycemic, anti-thrombotic, anti-viral, regulation of the gut microbiota properties and other biological activity. The purpose of this review aims to comprehensively and systematically outline the extraction and purification methods, structural features, biological activities, underlying mechanisms, and toxicities of SPPs to support their potential utilization value in pharmaceuticals fields and functional foods. The structural and activities relationship of SPPs is also discussed. Besides, new valuable insights for future research with SPPs have also been proposed in the important areas of structural characterization and pharmacological activities.

Effects of Dietary Supplementation of Spirulina platensis on the Immune System, Intestinal Bacterial Microbiome and Skin Traits of Mink

The impact of dietary inclusion of Spirulina platensis on the immune system, intestinal microbiome and skin of mink was investigated. Forty-eight animals were equally separated into four groups. Groups B and D were control animals, while groups A and C had their feed supplemented daily with 100 mg/kg of body weight Spirulina. Mink in groups A and B were descended from dams supplemented with spirulina during their reproductive period, while those in groups C and D were descended from dams fed the control diets. Fur growth rate and quality were graded semi-quantitatively. Fecal microbiome analysis, skin thickness histomorphometry, immunohistochemical labeling and counts of immune cells in the colon, mesenteric lymph nodes and spleen and quantitative gene expression analysis of cytokines in the colon were performed. Skin thickness, fur growth rate and skin quality were similar among groups (p > 0.05). However, differences were observed among groups concerning the relative and differential abundance of bacterial species. Tgf-β expression was lower in group A, whereas IL-β1 was lower in group C compared to group B (p < 0.05). Group D had significantly lower numbers of inflammatory cells in the colon and mesenteric lymph nodes. The results revealed that Spirulina decreased indices of subclinical inflammation in mink gut, while differences in the bacterial communities among groups were observed.