D-mannose ameliorates autoimmune phenotypes in mouse models of lupus

Microbiota metabolites in bone: Shaping health and Confronting disease

The intricate interplay between the gut microbiota and bone health has become increasingly recognized as a fundamental determinant of skeletal well-being. Microbiota-derived metabolites play a crucial role in dynamic interaction, specifically in bone homeostasis. In this sense, short-chain fatty acids (SCFAs), including acetate, propionate, and butyrate, indirectly promote bone formation by regulating insulin-like growth factor-1 (IGF-1). Trimethylamine N-oxide (TMAO) has been found to increase the expression of osteoblast genes, such as Runt-related transcription factor 2 (RUNX2) and bone morphogenetic protein-2 (BMP2), thus enhancing osteogenic differentiation and bone quality through BMP/SMADs and Wnt signaling pathways. Remarkably, in the context of bone infections, the role of microbiota metabolites in immune modulation and host defense mechanisms potentially affects susceptibility to infections such as osteomyelitis. Furthermore, ongoing research elucidates the precise mechanisms through which microbiota-derived metabolites influence bone cells, such as osteoblasts and osteoclasts. Understanding the multifaceted influence of microbiota metabolites on bone, from regulating homeostasis to modulating susceptibility to infections, has the potential to revolutionize our approach to bone health and disease management. This review offers a comprehensive exploration of this evolving field, providing a holistic perspective on the impact of microbiota metabolites on bone health and diseases.

Sweet regulation - The emerging immunoregulatory roles of hexoses

BACKGROUND

It is widely acknowledged that dietary habits have profound impacts on human health and diseases. As the most important sweeteners and energy sources in human diets, hexoses take part in a broad range of physiopathological processes. In recent years, emerging evidence has uncovered the crucial roles of hexoses, such as glucose, fructose, mannose, and galactose, in controlling the differentiation or function of immune cells.

AIM OF REVIEW

Herein, we reviewed the latest research progresses in the hexose-mediated modulation of immune responses, provided in-depth analyses of the underlying mechanisms, and discussed the unresolved issues in this field.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Owing to their immunoregulatory effects, hexoses affect the onset and progression of various types of immune disorders, including inflammatory diseases, autoimmune diseases, and tumor immune evasion. Thus, targeting hexose metabolism is becoming a promising strategy for reversing immune abnormalities in diseases.

PMI-controlled mannose metabolism and glycosylation determines tissue tolerance and virus fitness

Host survival depends on the elimination of virus and mitigation of tissue damage. Herein, we report the modulation of D-mannose flux rewires the virus-triggered immunometabolic response cascade and reduces tissue damage. Safe and inexpensive D-mannose can compete with glucose for the same transporter and hexokinase. Such competitions suppress glycolysis, reduce mitochondrial reactive-oxygen-species and succinate-mediated hypoxia-inducible factor-1α, and thus reduce virus-induced proinflammatory cytokine production. The combinatorial treatment by D-mannose and antiviral monotherapy exhibits in vivo synergy despite delayed antiviral treatment in mouse model of virus infections. Phosphomannose isomerase (PMI) knockout cells are viable, whereas addition of D-mannose to the PMI knockout cells blocks cell proliferation, indicating that PMI activity determines the beneficial effect of D-mannose. PMI inhibition suppress a panel of virus replication via affecting host and viral surface protein glycosylation. However, D-mannose does not suppress PMI activity or virus fitness. Taken together, PMI-centered therapeutic strategy clears virus infection while D-mannose treatment reprograms glycolysis for control of collateral damage.

D-Mannose reduces cellular senescence and NLRP3/GasderminD/IL-1β-driven pyroptotic uroepithelial cell shedding in the murine bladder

Aging is a risk factor for disease via increased susceptibility to infection, decreased ability to maintain homeostasis, inefficiency in combating stress, and decreased regenerative capacity. Multiple diseases, including urinary tract infection (UTI), are more prevalent with age; however, the mechanisms underlying the impact of aging on the urinary tract mucosa and the correlation between aging and disease remain poorly understood. Here, we show that, relative to young (8-12 weeks) mice, the urothelium of aged (18-24 months) female mice accumulates large lysosomes with reduced acid phosphatase activity and decreased overall autophagic flux in the aged urothelium, indicative of compromised cellular homeostasis. Aged bladders also exhibit basal accumulation of reactive oxygen species (ROS) and a dampened redox response, implying heightened oxidative stress. Furthermore, we identify a canonical senescence-associated secretory phenotype (SASP) in the aged urothelium, along with continuous NLRP3-inflammasome- and Gasdermin-D-dependent pyroptotic cell death. Consequently, aged mice chronically exfoliate urothelial cells, further exacerbating age-related urothelial dysfunction. Upon infection with uropathogenic E. coli, aged mice harbor increased bacterial reservoirs and are more prone to spontaneous recurrent UTI. Finally, we discover that treatment with D-mannose, a natural bioactive monosaccharide, rescues autophagy flux, reverses the SASP, and mitigates ROS and NLRP3/Gasdermin/interleukin (IL)-1β-driven pyroptotic epithelial cell shedding in aged mice. Collectively, our results demonstrate that normal aging affects bladder physiology, with aging alone increasing baseline cellular stress and susceptibility to infection, and suggest that mannose supplementation could serve as a senotherapeutic to counter age-associated urothelial dysfunction.

A nanobody based ultrasensitive electrochemical biosensor for the detection of soluble CTLA-4 -A candidate biomarker for cancer development and progression

A soluble isoform of cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) has been found in the serum of healthy individuals and alterations in its expression level have been linked with the development and progression of various cancers. Conventionally, soluble CTLA-4 (sCTLA-4) has been quantified by techniques such as ELISA, western blot, and flow cytometry, which however are time-consuming, highly expensive and require large sample volumes. Therefore, rapid, cost-effective and real-time monitoring of soluble CTLA-4 levels is much needed to facilitate timely diagnosis of a worsening disease and help patient selection for immunotherapeutic interventions in cancer. Here, for the first time, we report an ultrasensitive, highly selective electrochemical nanobody (NAb) based biosensor for the quantitative detection of soluble CTLA-4 employing poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) and gold nanoparticles modified electrode with attomole sensitivity. Incorporating nanomaterials with conductive polymers enhances the sensitivity of the electrochemical biosensor, while the nanobody's stability, specificity and ease of production make it a suitable choice as a bioreceptor. The proposed NAb-based sensor can detect sCTLA-4 from pure recombinant protein in a wide concentration range of 100 ag mL-1- 500 μg mL-1, with a limit of detection of 1.19 ag mL-1 (+3σ of the blank signal). The sensor's relative standard deviation for reproducibility is less than 0.4% and has effective real sample analytics for cell culture supernatant with no significant difference with pure recombinant protein (p < 0.05). Our proposed nanobody based sensor exhibits stability for up to 2 weeks (<3% variation). Moreover, this nanobody-based sensor presents a future opportunity for quantitative, ultrasensitive, and economical biosensor development that can be adapted to monitor the immune landscape of cancer patients to provide a larger therapeutic window.

T Lymphocyte Metabolic Features and Techniques to Modulate Them

T cells demonstrate high degree of complexity and broad range of functions, which distinguish them from other immune cells. Throughout their lifetime, T lymphocytes experience several functional states: quiescence, activation, proliferation, differentiation, performance of effector and regulatory functions, memory formation, and apoptosis. Metabolism supports all functions of T cells, providing lymphocytes with energy, biosynthetic substrates, and signaling molecules. Therefore, T cells usually restructure their metabolism as they transition from one functional state to another. Strong association between the metabolism and T cell functions implies that the immune response can be controlled by manipulating metabolic processes within T lymphocytes. This review aims to highlight the main metabolic adaptations necessary for the T cell function, as well as the recent progress in techniques to modulate metabolic features of lymphocytes.

Biological function, regulatory mechanism, and clinical application of mannose in cancer

Studies examining the regulatory roles and clinical applications of monosaccharides other than glucose in cancer have been neglected. Mannose, a common type of monosaccharide found in human body fluids and tissues, primarily functions in protein glycosylation rather than carbohydrate metabolism. Recent research has demonstrated direct anticancer effects of mannose in vitro and in vivo. Simply supplementing cell culture medium or drinking water with mannose achieved these effects. Moreover, mannose enhances the effectiveness of current cancer treatments including chemotherapy, radiotherapy, targeted therapy, and immune therapy. Besides the advancements in basic research on the anticancer effects of mannose, recent studies have reported its application as a biomarker for cancer or in the delivery of anticancer drugs using mannose-modified drug delivery systems. This review discusses the progress made in understanding the regulatory roles of mannose in cancer progression, the mechanisms underlying its anticancer effects, and its current application in cancer diagnosis and treatment.

D-mannose reduces adipogenesis by inhibiting the PI3K/AKT signaling pathway

PURPOSE

To explore the effects and potential mechanisms of D-mannose on adipogenic differentiation of two kinds of representative mesenchymal stem cells (MSCs).

METHODS

We cultured two kinds of representative MSCs, human adipose tissue-derived stromal cells (hADSCs) as well as human bone marrow mesenchymal stem cells (hBMSCs), with adipogenic-induced medium containing D-mannose or D-fructose as the control. Oil red O staining, quantitative real-time polymerase chain reaction (qRT-PCR), and western blot (WB) were used to detect whether D-mannose had effects on adipogenic differentiation of MSCs. RNA sequencing (RNA-seq) transcriptomic analysis was further used to explore the potential mechanisms of D-mannose on adipogenic differentiation of MSCs. After that, qRT-PCR and WB were used to verify the results of RNA-seq. Last, we removed bilateral ovaries of female rats to establish an estrogen deficiency obesity model, and gave D-mannose intragastric administration. One month later, the femurs of rats were sliced for oil red O staining, and the inhibitory effect of D-mannose on lipid formation in vivo was studied.

RESULTS

Oil red O staining, qRT-PCR and WB in vitro demonstrated that D-mannose inhibited the adipogenic differentiation of both hADSCs and hBMSCs. Oil red O staining of femur sections proved that D-mannose was able to reduce in vivo adipogenesis. The results of RNA-seq transcriptomic analysis revealed that the adipogenesis-inhibition effects of D-mannose were performed by antagonizing the PI3K/AKT signaling pathway. Besides, qRT-PCR and WB further verified the results of RNA-seq.

CONCLUSION

Our study indicated that D-mannose was able to reduce adipogenic differentiation of both hADSCs and hBMSCs by antagonizing the PI3K/AKT signaling pathway. D-mannose is expected to be a safe and effective treatment strategy for obesity.

Immunometabolomics provides a new perspective for studying systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a chronic multi-organ autoimmune disease characterized by clinical heterogeneity, unpredictable progression, and flare ups. Due to the heterogeneous nature of lupus, it has been challenging to identify sensitive and specific biomarkers for its diagnosis and monitoring. Despite the fact that the mechanism of SLE remains unknown, impressive progress has been made over the last decade towards understanding how different immune cells contribute to its pathogenesis. Research suggests that cellular metabolic programs could affect the immune response by regulating the activation, proliferation, and differentiation of innate and adaptive immune cells. Many studies have shown that the dysregulation of the immune system is associated with changes to metabolite profiles. The study of metabolite profiling may provide a means for mechanism exploration and novel biomarker discovery for disease diagnostic, classification, and monitoring. Here we review the latest advancements in understanding the role of immunometabolism in SLE, as well as the systemic metabolite profiling of this disease along with possible clinical application.

Fucosylation of HLA-DRB1 regulates CD4+ T cell-mediated anti-melanoma immunity and enhances immunotherapy efficacy

Immunotherapy efficacy is limited in melanoma, and combinations of immunotherapies with other modalities have yielded limited improvements but also adverse events requiring cessation of treatment. In addition to ineffective patient stratification, efficacy is impaired by paucity of intratumoral immune cells (itICs); thus, effective strategies to safely increase itICs are needed. We report that dietary administration of L-fucose induces fucosylation and cell surface enrichment of the major histocompatibility complex (MHC)-II protein HLA-DRB1 in melanoma cells, triggering CD4+ T cell-mediated increases in itICs and anti-tumor immunity, enhancing immune checkpoint blockade responses. Melanoma fucosylation and fucosylated HLA-DRB1 associate with intratumoral T cell abundance and anti-programmed cell death protein 1 (PD1) responder status in patient melanoma specimens, suggesting the potential use of melanoma fucosylation as a strategy for stratifying patients for immunotherapies. Our findings demonstrate that fucosylation is a key mediator of anti-tumor immunity and, importantly, suggest that L-fucose is a powerful agent for safely increasing itICs and immunotherapy efficacy in melanoma.

Mannose: a potential saccharide candidate in disease management

There are a plethora of antibiotic resistance cases and humans are marching towards another big survival test of evolution along with drastic climate change and infectious diseases. Ever since the first antibiotic [penicillin], and the myriad of vaccines, we were privileged to escape many infectious disease threats. The survival technique of pathogens seems rapidly changing and sometimes mimicking our own systems in such a perfect manner that we are left unarmed against them. Apart from searching for natural alternatives, repurposing existing drugs more effectively is becoming a familiar approach to new therapeutic opportunities. The ingenious use of revolutionary artificial intelligence-enabled drug discovery techniques is coping with the speed of such alterations. D-Mannose is a great hope as a nutraceutical in drug discovery, against CDG, diabetes, obesity, lung disease, and autoimmune diseases and recent findings of anti-tumor activity make it interesting along with its role in drug delivery enhancing techniques. A very unique work done in the present investigation is the collection of data from the ChEMBL database and presenting the targetable proteins on pathogens as well as on humans. It shows Mannose has 50 targets and the majority of them are on human beings. The structure and conformation of certain monosaccharides have a decisive role in receptor pathogen interactions and here we attempt to review the multifaceted roles of Mannose sugar, its targets associated with different diseases, as a natural molecule having many success stories as a drug and future hope for disease management.

Graphical abstract

A cutback in Imiquimod cutaneous toxicity; comparative cutaneous toxicity analysis of Imiquimod nanotransethosomal gel with 5% marketed cream on the BALB/c mice

Herein, Imiquimod (IMQ) was incorporated in nanotransethosomes (nTES) to develop the IMQ-nTES nano-drug delivery system. IMQ-nTES was optimized using 23 factorial design. The optimized formulation was expressed with a particle size of 192.4 ± 1.60 nm, Poly-dispersibility of 0.115 ± 0.008, and IMQ percent entrapment efficiency of 91.05 ± 3.22%. Smooth and round morphology of IMQ-nTES vesicles was confirmed by TEM micrographs. Moreover, FTIR results have shown drug-excipient compatibility. The IMQ-nTES was laden inside the low molecular weight chitosan gel, which exhibited easy application, spreadability and no irritation to the applied skin. The release pattern has clearly exhibited improved dissolution properties of IMQ with the provision of the sustain release pattern. Higher IMQ content was deposited in deeper epidermis and dermis with IMQ-nTES gel, in contrast to ALDARA. In vivo, comparative toxicity study on BALB/c mice has shown significantly reduced (p < 0.001) psoriatic area severity index (PASI) score and less increment in ear thickness. Epidermal hyperplasia was an obvious finding with ALDARA which was, providentially, minimal in IMQ-nTES gel-treated skin. FTIR analysis of skin tissue has shown an enhancement of lipid and protein content in the ALDARA group, however, in the IMQ-nTES group no such change was observed. With ALDARA application, CD4+ T-cells and constitutive NF-κβ expression were significantly elevated, in comparison to the IMQ-nTES gel treated group. Moreover, the adequate expression of IFN-γ and cytotoxic CD8+ T-cells were suggesting the preserved IMQ efficacy with IMQ-nTES gel. Quantification of cutaneous as well as systemic inflammatory markers has also suggested the reduced psoriatic potential of IMQ-nTES gel. In essence, IMQ-nTES gel can be a suitable alternative to ALDARA owing to its better safety profile.

Recurrent Urinary Tract Infection Incidence Rates Decrease in Women With Cystitis Cystica After Treatment With d-Mannose: A Cohort Study

OBJECTIVES

d-Mannose is a promising nonantibiotic prophylaxis for recurrent urinary tract infection (rUTI). Recurrent UTI is common in postmenopausal women and may be especially prevalent in those with cystitis cystica (CC) lesions found on cystoscopy. Our objectives were to determine whether CC lesions are associated with a higher UTI incidence rate and whether d-mannose reduces this rate in women with CC.

METHODS

This is a retrospective cohort study of patients with rUTI who underwent cystoscopy at our institution (from which CC status was identified) and who were treated with d-mannose as a single agent for UTI prophylaxis. Participants were required to have at least 1 year of follow-up for UTIs both before and after d-mannose initiation to allow for a pre-post comparison.

RESULTS

Twenty-seven patients were included in the analysis (13 with CC, 14 without CC). Most patients (88.9%) were postmenopausal. Patients with CC had a higher UTI incidence rate than patients without CC (4.69 vs 2.93 UTIs/year before starting d-mannose prophylaxis, P = 0.021). After initiating d-mannose prophylaxis, the UTI incidence rate decreased significantly in patients with CC (rate decrease = 2.23 UTIs/year, P = 0.0028). This decrease was similar in magnitude to that observed in patients without CC (rate decrease = 1.64 UTIs/year, P = 0.0007; P interaction = 0.58).

CONCLUSIONS

Patients with rUTI with CC had more frequent UTI episodes than patients without CC. Patients in both groups had fewer UTI episodes after beginning d-mannose prophylaxis. These findings add to the body of literature supporting d-mannose for the prevention of rUTI in women, including those with CC.

D-Mannose Suppresses γδ T Cells and Alleviates Murine Psoriasis

Psoriasis is a chronic skin disorder associated with multiple sequelae, such as psoriatic arthritis and cardiovascular diseases. Increasing evidence has shown that γδ T cells, as sources of IL-17A, play critical roles in psoriatic inflammations. However, there still lack effective ways to manipulate these pathogenic γδ T cells, which are less well studied than αβ T cells. The present study aims to characterize the phenotype of γδ T cells and evaluate the impact of D-mannose (a C-2 epimer of glucose) on γδ T cell-mediated psoriasis. We found that skin-draining LN γδ T cells underwent robust proliferation and acquired an IL-17-producing phenotype during psoriasis. The transcriptomic profiles of these psoriatic γδ T cells had elevated glycolytic signatures. Importantly, D-mannose treatment suppressed the γδ T cell reaction and successfully alleviated the local and systematic inflammation induced by imiquimod. The decreased AKT/mTOR/HIF-1α signaling and glycolytic ability may contribute to the suppression of γδ T cells achieved by D-mannose. Our study increased understanding of γδ T cells in psoriasis and promoted D-mannose utilization as a potential clinical application for autoimmune diseases driven by γδ T cells.

D-mannose alleviates osteoarthritis progression by inhibiting chondrocyte ferroptosis in a HIF-2α-dependent manner

OBJECTIVES

Chondrocyte ferroptosis contributes to osteoarthritis (OA) progression, and D-mannose shows therapeutic value in many inflammatory conditions. Here, we investigated whether D-mannose interferes in chondrocyte ferroptotic cell death during osteoarthritic cartilage degeneration.

MATERIALS AND METHODS

In vivo anterior cruciate ligament transection (ACLT)-induced OA mouse model and an in vitro study of chondrocytes in an OA microenvironment induced by interleukin-1β (IL-1β) exposure were employed. Combined with Epas1 gene gain- and loss-of-function, histology, immunofluorescence, quantitative RT-PCR, Western blot, cell viability and flow cytometry experiments were performed to evaluate the chondroprotective effects of D-mannose in OA progression and the role of hypoxia-inducible factor 2 alpha (HIF-2 α) in D-mannose-induced ferroptosis resistance of chondrocytes.

RESULTS

D-mannose exerted a chondroprotective effect by attenuating the sensitivity of chondrocytes to ferroptosis and alleviated OA progression. HIF-2α was identified as a central mediator in D-mannose-induced ferroptosis resistance of chondrocytes. Furthermore, overexpression of HIF-2α in chondrocytes by Ad-Epas1 intra-articular injection abolished the chondroprotective effect of D-mannose during OA progression and eliminated the role of D-mannose as a ferroptosis suppressor.

CONCLUSIONS

D-mannose alleviates osteoarthritis progression by suppressing HIF-2α-mediated chondrocyte sensitivity to ferroptosis, indicating D-mannose to be a potential therapeutic strategy for ferroptosis-related diseases.

Mannose Treatment: A Promising Novel Strategy to Suppress Inflammation

High glucose and fructose intake have been proven to display pro-inflammatory roles during the progression of inflammatory diseases. However, mannose has been shown to be a special type of hexose that has immune regulatory functions. In this review, we trace the discovery process of the regulatory functions of mannose and summarize some past and recent studies showing the therapeutic functions of mannose in inflammatory diseases. We conclude that treatment with mannose can suppress inflammation by inducing regulatory T cells, suppressing effector T cells and inflammatory macrophages, and increasing anti-inflammatory gut microbiome. By summarizing all the important findings, we highlight that mannose treatment is a safe and promising novel strategy to suppress inflammatory diseases, including autoimmune disease and allergic disease.

Blockade of TGF-βR improves the efficacy of doxorubicin by modulating the tumor cell motility and affecting the immune cells in a melanoma model

TGF-β contributes to drug resistance and the invasiveness of tumor cells and weakens the anti-tumor immune responses. The present study aimed at examining the efficacy of the combination of SB431542, as a specific inhibitor of TGF-βR, and doxorubicin in controlling the melanoma tumor in mice. The impact of the combination of the doxorubicin and SB431542 on the cell growth, apoptosis, migration, and invasiveness of B16-F10 cells was examined. Besides, the B16-F10 tumor was induced in C57BL/6 mice, and the effects of the mentioned treatment on the tumor volume, survival, and the exhaustion state of T cells were evaluated. Although the combination of doxorubicin and SB431542 did not exhibit synergism in the inhibition of cell growth and apoptosis induction, it efficiently prohibited the migration and the epithelial to mesenchymal transition of B16-F10 cells, and the combination of doxorubicin and SB431542 caused an increase in mRNA levels of E-cadherin and, on the other hand, led to a decline in the expression of Vimentin. Tumor volume and the survival of tumor-bearing mice were efficiently controlled by the combination therapy. This treatment also eventuated in a decrease in the percentage of PD-L1⁺, TCD4⁺, and TCD8⁺ cells as indicators of exhausted T cells within the spleens of tumor-bearing mice. Blockade of TGF-βR also propelled the RAW 264.7 cells towards an anti-tumor M1 macrophage phenotype. The inhibition of TGF-βR demonstrated a potential to increase the efficacy of doxorubicin chemotherapy by the means of affecting cellular motility and restoring the anti-tumor immune responses.