Use of Specialized Pro-Resolving Mediators to Alleviate Cold Platelet Storage Lesion

Gut microbiome composition and dysbiosis in immune thrombocytopenia: A review of literature

Immune thrombocytopenia (ITP) is an autoimmune bleeding disorder characterized by excessive reticuloendothelial platelet destruction and inadequate compensatory platelet production. However, the pathogenesis of ITP is relatively complex, and its exact mechanisms and etiology have not been definitively established. The gut microbiome, namely a diverse community of symbiotic microorganisms residing in the gastrointestinal system, affects health through involvement in human metabolism, immune modulation, and maintaining physiological balance. Emerging evidence reveals that the gut microbiome composition differs in patients with ITP compared to healthy individuals, which is related with platelet count, disease duration, and response to treatment. These findings suggest that the microbiome and metabolome profiles of individuals could unveil a new pathway for aiding diagnosis, predicting prognosis, assessing treatment response, and formulating personalized therapeutic approaches for ITP. However, due to controversial reports, definitive conclusions cannot be drawn, and further investigations are needed.

Associations of Gut Microbiota and Fatty Metabolism With Immune Thrombocytopenia

Objective

To determine whether gut microbiota, fatty metabolism and cytokines were associated with immune thrombocytopenia (ITP).

Methods

In total, 29 preliminarily diagnosed ITP patients and 33 healthy volunteers were enrolled. Fecal bacterial were analyzed based on 16S rRNA sequencing. Plasma cytokines and motabolites were analyzed using flow cytometry and liquid chromatography-mass spectrometry (LC-MS), respectively.

Results

Bacteroides, Phascolarctobacterium, and Lactobacillus were enriched at the genus level in ITP patients, while Ruminococcaceae UCG-002, Eubacterium coprostanoligeues, Megamonas, and Lachnospiraceae NC2004 were depleted. At the phylum level, the relative abundance of Proteobacteria and Chloroflexi increased in ITP patients, while Firmicutes, Actinobacteria, and the Firmicutes/Bacteroidetes ratio decreased. Plasma levels of 5-hydroxyeicosatetraenoic acid (5-HETE), 6-trans-12-epi-leukotriene B4 (6t,12e-LTB₄), and resolvin D2 (RvD₂) were upregulated, and stachydrine, dowicide A, dodecanoylcarnitine were downregulated in ITP patients. Furthermore, RvD₂ is positively correlated with order Bacteroidetes VC2.1 Bac22, 5-HETE is positively correlated with genus Azospirillum, and 6t,12e-LTB₄ is positively correlated with genus Cupriavidus. In addition, stachydrine is positively correlated with family Planococcaceae, dowicide A is positively correlated with class MVP-15, and dodecanoylcarnitine is positively correlated with order WCHB1-41. Plasma levels of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) were upregulated in ITP patients.

Conclusion

Our study revealed a relationship between microbiota and fatty metabolism in ITP. Gut microbiota may participate in the pathogenesis of ITP through affecting cytokine secretion, interfering with fatty metabolism.

The Missing Pieces to the Cold-Stored Platelet Puzzle

Cold-stored platelets are making a comeback. They were abandoned in the late 1960s in favor of room-temperature stored platelets due to the need for longer post-transfusion platelet recoverability and survivability in patients with chronic thrombocytopenia. However, the current needs for platelet transfusions are rapidly changing. Today, more platelets are given to patients who are actively bleeding, such as ones receiving cardiac surgeries. It has been established that cold-stored platelets are more hemostatically effective, have reduced bacterial growth, and have longer potential shelf lives. These compelling characteristics led to the recent interest in bringing back cold-stored platelets to the blood systems. However, before reinstating cold-stored platelets in the clinics again, a thorough investigation of in vitro storage characteristics and in vivo transfusion effects is required. This review aims to provide an update on the recent research efforts into the storage characteristics and functions of cold-stored platelets using modern investigative tools. We will also discuss efforts made to improve cold-stored platelets to be a better and safer product. Finally, we will finish off with discussing the relevance of in vitro data to in vivo transfusion results and provide insights and directions for future investigations of cold-stored platelets.

Specialized pro-resolving mediator network: an update on production and actions

Today, persistent and uncontrolled inflammation is appreciated to play a pivotal role in many diseases, such as cardiovascular diseases, neurodegenerative diseases, metabolic syndrome and many other diseases of public health concern (e.g. Coronavirus Disease 2019 (COVID-19) and periodontal disease). The ideal response to initial challenge in humans is a self-limited inflammatory response leading to complete resolution. The resolution phase is now widely recognized as a biosynthetically active process, governed by a superfamily of endogenous chemical mediators that stimulate resolution of inflammatory responses, namely specialized proresolving mediators (SPMs). Because resolution is the natural ideal response, the SPMs have gained attention. SPMs are mediators that include ω-6 arachidonic acid-derived lipoxins, ω-3 eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)-derived resolvins, protectins and maresins, cysteinyl-SPMs, as well as n-3 docosapentaenoic acid (DPA)-derived SPMs. These novel immunoresolvents, their biosynthetic pathways and receptors have proven to promote resolution of inflammation, clearance of microbes, reduce pain and promote tissue regeneration via specific cellular and molecular mechanisms. As of 17 August, 2020, PubMed.gov reported >1170 publications for resolvins, confirming their potent protective actions from many laboratories worldwide. Since this field is rapidly expanding, we provide a short update of advances within 2-3 years from human and preclinical animal studies, together with the structural-functional elucidation of SPMs and identification of novel SPM receptors. These new discoveries indicate that SPMs, their pathways and receptors could provide a basis for new approaches for treating inflammation-associated diseases and for stimulating tissue regeneration via resolution pharmacology and precision nutrition.