Evidence that endogenous thymosin alpha-1 is present in the rat central nervous system

MultiPep: a hierarchical deep learning approach for multi-label classification of peptide bioactivities

Peptide-based therapeutics are here to stay and will prosper in the future. A key step in identifying novel peptide-drugs is the determination of their bioactivities. Recent advances in peptidomics screening approaches hold promise as a strategy for identifying novel drug targets. However, these screenings typically generate an immense number of peptides and tools for ranking these peptides prior to planning functional studies are warranted. Whereas a couple of tools in the literature predict multiple classes, these are constructed using multiple binary classifiers. We here aimed to use an innovative deep learning approach to generate an improved peptide bioactivity classifier with capacity of distinguishing between multiple classes. We present MultiPep: a deep learning multi-label classifier that assigns peptides to zero or more of 20 bioactivity classes. We train and test MultiPep on data from several publically available databases. The same data are used for a hierarchical clustering, whose dendrogram shapes the architecture of MultiPep. We test a new loss function that combines a customized version of Matthews correlation coefficient with binary cross entropy (BCE), and show that this is better than using class-weighted BCE as loss function. Further, we show that MultiPep surpasses state-of-the-art peptide bioactivity classifiers and that it predicts known and novel bioactivities of FDA-approved therapeutic peptides. In conclusion, we present innovative machine learning techniques used to produce a peptide prediction tool to aid peptide-based therapy development and hypothesis generation.

Immunopotentiator thymosin alpha-1 attenuates inflammatory pain by modulating the Wnt3a/β-catenin pathway in spinal cord

The mechanism of inflammatory pain involves the central nervous system (CNS) and the immune system. It is reported that immunopotentiator thymosin alpha-1 (Tα1) can reduce inflammation, protect neurons and strengthen the immune function. However, the roles of Tα1 in inflammatory pain still remain unclear. In this study, we found Tα1 can attenuate the complete Freund's adjuvant (CFA)-induced mechanical allodynia and heat hyperalgesia. Meanwhile, it reduced the upregulation of CFA-induced inflammatory mediators (interferon (IFN)-γ, tumor necrosis factor-α and brain-derived neurotrophic factor). In addition, we found the Wnt3a/β-catenin pathway was activated in spinal cord after the injection of CFA, paralleling with pain hypersensitivity. However, Tα1 reversed this status. In summary, Tα1 could attenuate inflammatory pain by modulating the Wnt3a/β-catenin pathway. It might be related to the downregulation of inflammatory mediators.

Thymosin Alpha-1 Inhibits Complete Freund's Adjuvant-Induced Pain and Production of Microglia-Mediated Pro-inflammatory Cytokines in Spinal Cord

Activation of inflammatory responses regulates the transmission of pain pathways through an integrated network in the peripheral and central nervous systems. The immunopotentiator thymosin alpha-1 (Tα1) has recently been reported to have anti-inflammatory and neuroprotective functions in rodents. However, how Tα1 affects inflammatory pain remains unclear. In the present study, intraperitoneal injection of Tα1 attenuated complete Freund's adjuvant (CFA)-induced pain hypersensitivity, and decreased the up-regulation of pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6) in inflamed skin and the spinal cord. We found that CFA-induced peripheral inflammation evoked strong microglial activation, but the effect was reversed by Tα1. Notably, Tα1 reversed the CFA-induced up-regulation of vesicular glutamate transporter (VGLUT) and down-regulated the vesicular γ-aminobutyric acid transporter (VGAT) in the spinal cord. Taken together, these results suggest that Tα1 plays a therapeutic role in inflammatory pain and in the modulation of microglia-induced pro-inflammatory cytokine production in addition to mediation of VGLUT and VGAT expression in the spinal cord.

The peptide molecular links between the central nervous and the immune systems

The central nervous system (CNS) and the immune system were for many years considered as two autonomous systems. Now, the reciprocal connections between them are generally recognized and very well documented. The links are realized mainly by various immuno- and neuropeptides. In the review the influence of the following immunopeptides on CNS is presented: tuftsin, thymulin, thymopoietin and thymopentin, thymosins, and thymic humoral factor. On the other side, the activity in the immune system of such neuropeptides as substance P, neurotensin, some neurokinins, enkephalins, and endorphins is discussed.

Thymosin alpha-1 modulates excitatory synaptic transmission in cultured hippocampal neurons in rats

Thymosin alpha-1 (Talpha1) not only possesses immunoregulatory properties in periphery but also is expressed in the central nervous system (CNS) and affects the function of the CNS. To further elucidate the role of Talpha1 in the CNS, the whole-cell recording technique was used to observe the effect of Talpha1 on the spontaneous excitatory synaptic transmission in cultured rat hippocampal neurons. The results showed that acute treatment with Talpha1 significantly enhanced the frequency of AMPA-mediated spontaneous excitatory postsynaptic current (sEPSC) at the concentrations of 1 and 10 microg/ml and also enhanced the frequency of AMPA-mediated miniature excitatory postsynaptic current (mEPSC) at 10 microg/ml. However, the amplitude of both sEPSC and mEPSC were not changed by Talpha1. Those results suggested that Talpha1 involves in the regulation of excitatory synaptic transmission in hippocampal neurons, which contribute to its neurophysiological function in the CNS.