Targeting the TLR2 Receptor With a Novel Thymopentin-Derived Peptide Modulates Immune Responses.

The innate and adaptive immune systems act in concert to protect us from infectious agents and other harmful substances. As a state of temporary or permanent immune dysfunction, immunosuppression can make an organism more susceptible to infection, organ injury, and cancer due to damage to the immune system. It takes a long time to develop new immunomodulatory agents to prevent and treat immunosuppressive diseases, with slow progress. Toll-like receptor 2 (TLR2) agonists have been reported as potential immunomodulatory candidates due to their effective activation of immune responses. It has been demonstrated that thymopentin (TP5) could modulate immunity by binding to the TLR2 receptor. However, the fairly short half-life of TP5 greatly reduces its pharmacological potential for immunosuppression therapy. Although peptide cathelicidin 2 (CATH2) has a long half-life, it shows poor immunomodulatory activity and severe cytotoxicity, which seriously hampers its clinical development. Peptide hybridization is an effective approach for the design and engineering of novel functional peptides because hybrid peptides combine the advantages and benefits of various native peptides. In this study, to overcome all these challenges faced by the parental peptides, six hybrid peptides (CaTP, CbTP, CcTP, TPCa, TPCb, and TPCc) were designed by combining the full-length TP5 with different active fragments of CATH2. CbTP, the most potent TLR2 agonist among the six hybrid peptides, was effectively screened through in silico analysis and in vitro experiments. The CbTP peptide exhibited lower cytotoxicity than either CATH2 or TP5. Furthermore, the immunomodulatory effects of CbTP were confirmed in a CTX-immunosuppressed mouse model, which showed that CbTP has increased immunopotentiating activity and physiological stability compared to the parental peptides. CbTP successfully inhibited immunosuppression and weight loss, increased immune organ indices, and improved CD4+/CD8+ T lymphocyte subsets. In addition, CbTP significantly increased the production of the cytokine TNF-α and IL-6, and the immunoglobulins IgA, IgM, and IgG. The immunoenhancing effects of CbTP were attributed to its TLR2-binding activity, promoting the formation of the TLR2 cluster, the activation of the TLR2 receptor, and thus activation of the downstream MyD88-NF-кB signaling pathway.

[Nitrogen and Phosphorus Removal in Surface Flow Constructed Wetland Planted with Myriophyllum elatinoides Treating Swine Wastewater in Subtropical Central China].

The loss of nitrogen (N) and phosphorus (P) from aquaculture has caused eutrophication of freshwater systems. Here, surface flow constructed wetland (SFCW) planted with Myriophyllum elatinoides were used to treat swine wastewater from a medium-sized hoggery in subtropical Central China. Inflow concentrations of NH4+-N, TN, TP, and COD ranged from 535.4 to 591.09, 682.09 to 766.96, 57.73 to 82.29, and 918.4 to 1940.43 mg·L-1, respectively. The mean removal efficiencies of NH4+-N, TN, TP, and COD were 97.4%, 97.1%, 91.0%, and 90.2%, respectively, and CW1 had the largest contributions of 37.3%, 38.4%, 43.3%, and 27.4%, respectively. Plant N and P uptake ranged 23.87-79.96 g·m-2 and 5.34-18.98 g·m-2, accounting for 19.1% and 20.2% of removal, respectively. Sediment N and P accumulation ranged 19.17-56.62 g·m-2 and 10.59-26.62 g·m-2, accounting for 19.8% and 61.7% of removal, respectively. Multiple linear regression showed that environmental factors explained 79.9% of the N removal and 70.1% of the P removal; DO was the main factor affecting N removal, and sediment adsorption was the key process in P removal. These results show that M. elatinoides constructed wetland can efficiently treat swine wastewater, thereby reduce the discharge of pollutants downstream.

A highly efficient hybrid peptide ameliorates intestinal inflammation and mucosal barrier damage by neutralizing lipopolysaccharides and antagonizing the lipopolysaccharide-receptor interaction.

Intestinal inflammatory disorders, such as inflammatory bowel disease, are major contributors to mortality and morbidity in humans and animals worldwide. While some native peptides have great potential as therapeutic agents against intestinal inflammation, potential cytotoxicity, anti-inciting action, and suppression of anti-inflammatory activity may limit their development as anti-inflammatory agents. Peptide hybridization is an effective approach for the design and engineering of novel functional peptides because hybrid peptides combine the advantages and benefits of various native peptides. In the present study, a novel hybrid anti-inflammatory peptide that combines the active center of Cecropin A (C) and the core functional region of LL-37 (L) was designed [C-L peptide; C (1-8)-L (17-30)] through in silico analysis to reduce cytotoxicity and improve the anti-inflammatory activity of the parental peptides. The resulting C-L peptide exhibited lower cytotoxicity than either C or L peptides alone. C-L also exerted a protective effect against lipopolysaccharide (LPS)-induced inflammatory responses in RAW264.7 macrophages and in the intestines of a mouse model. The hybrid peptide exhibited increased anti-inflammatory activity compared to the parental peptides. C-L plays a role in protecting intestinal tissue from damage, LPS-induced weight loss, and leukocyte infiltration. In addition, C-L reduces the expression levels of tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), IL-1ß, and interferon-gamma (IFN-γ), as well as reduces cell apoptosis. It also reduced mucosal barrier damage caused by LPS. The anti-inflammatory effects of the hybrid peptide were mainly attributed to its LPS-neutralizing activity and antagonizing the activation of LPS-induced Toll-like receptor 4-myeloid differentiation factor 2 (TLR4/MD2). The peptide also affected the TLR4-(nuclear factor κB) signaling pathway, modulating the inflammatory response upon LPS stimulation. Collectively, these findings suggest that the newly designed peptide, C-L, could be developed into a novel anti-inflammatory agent for animals or humans.

A Novel Cecropin-LL37 Hybrid Peptide Protects Mice Against EHEC Infection-Mediated Changes in Gut Microbiota, Intestinal Inflammation, and Impairment of Mucosal Barrier Functions.

Intestinal inflammation can cause impaired epithelial barrier function and disrupt immune homeostasis, which increases the risks of developing many highly fatal diseases. Enterohemorrhagic Escherichia coli (EHEC) O157:H7 causes intestinal infections worldwide and is a major pathogen that induces intestinal inflammation. Various antibacterial peptides have been described as having the potential to suppress and treat pathogen-induced intestinal inflammation. Cecropin A (1-8)-LL37 (17-30) (C-L), a novel hybrid peptide designed in our laboratory that combines the active center of C with the core functional region of L, shows superior antibacterial properties and minimized cytotoxicity compared to its parental peptides. Herein, to examine whether C-L could inhibit pathogen-induced intestinal inflammation, we investigated the anti-inflammatory effects of C-L in EHEC O157:H7-infected mice. C-L treatment improved the microbiota composition and microbial community balance in mouse intestines. The hybrid peptide exhibited improved anti-inflammatory effects than did the antibiotic, enrofloxacin. Hybrid peptide treated infected mice demonstrated reduced clinical signs of inflammation, reduced weight loss, reduced expression of pro-inflammatory cytokines [tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and interferon-gamma (IFN-γ)], reduced apoptosis, and reduced markers of jejunal epithelial barrier function. The peptide also affected the MyD88-nuclear factor κB signaling pathway, thereby modulating inflammatory responses upon EHEC stimulation. Collectively, these findings suggest that the novel hybrid peptide C-L could be developed into a new anti-inflammatory agent for use in animals or humans.

A Novel Peptide Ameliorates LPS-Induced Intestinal Inflammation and Mucosal Barrier Damage via Its Antioxidant and Antiendotoxin Effects.

Intestinal inflammation is an inflammatory disease resulting from immune dysregulation in the gut. It can increase the risk of enteric cancer, which is a common malignancy globally. As a new class of anti-inflammatory agents, native peptides have potential for use in the treatment of several intestinal inflammation conditions; however, their potential cytotoxicity and poor anti-inflammatory activity and stability have prevented their development. Hybridization has been proposed to overcome this problem. Thus, in this study, we designed a hybrid peptide (LL-37-TP5, LTP) by combing the active centre of LL-37 (13-36) with TP5. The half-life and cytotoxicity were tested in vitro, and the hybrid peptide showed a longer half-life and lower cytotoxicity than its parental peptides. We also detected the anti-inflammatory effects and mechanisms of LTP on Lipopolysaccharide (LPS)-induced intestinal inflammation in murine model. The results showed that LTP effectively prevented LPS-induced weight loss, impairment of intestinal tissues, leukocyte infiltration, and histological evidence of inflammation. Additionally, LTP decreased the levels of tumour necrosis factor-alpha, interferon-gamma, and interleukin-6; increased the expression of zonula occludens-1 and occludin; and reduced permeability in the jejunum of LPS-treated mice. Notably, LTP appeared to be more potent than the parental peptides LL-37 and TP5. The anti-inflammatory effects of LTP may be associated with the neutralization of LPS, inhibition of oxidative stress, and inhibition of the NF-κB signalling pathway. The findings of this study suggest that LTP might be an effective therapeutic agent for treating intestinal inflammation.

TMDL for phosphorus and contributing factors in subtropical watersheds of southern China.

Water eutrophication, particularly that caused by phosphorus runoff, is of major concern in China due to the serious threats it poses to watershed environments. We investigated one forested and nine agricultural watersheds with areas of 9-5212 ha in a hilly region of Hunan Province in a subtropical region of southern China from 2010 to 2012 to study total phosphorus (TP) loads and contributing factors. The annual TP loads varied from 35.7 to 222.1 kg P km(-2) year(-1) among the different watersheds, with the rainy season of spring and summer accounting for 56.3-82.0% of TP loss. The highest total maximum daily load (TMDL, 0.5 kg P km(-2) day(-1)) and existing exported daily TP loads (DTPL, 1.8 kg P km(-2) day(-1)) were observed under high flow and moist flow conditions in the ten watersheds. However, the target daily reduction ratios for the DTPLs to reach the water quality standard of 0.05 mg P L(-1) varied little with flow condition in the stream but depended on the type of watershed, i.e., <50, <80, and 80-90% for forested, agricultural, and livestock-dominated watersheds, respectively. Gray relational analysis (GRA) suggested that livestock density was the most important factor for watershed TP load under various hydrologic conditions, while livestock density (LD), soil available phosphorous (SAP), cropland percentage, and mean shape index (SHMN) were notable factors for daily reduction rate (DRR) under high and moist flow conditions. Therefore, to protect the local watershed environments, watershed management approaches that include the regulation of livestock production are recommended as the most effective means of reducing P loads at the watershed scale in subtropical areas of southern China.

[Impact of rice agriculture on nitrogen and phosphorus exports in streams in hilly red soil earth region of central subtropics].

The research selected the Tuojia catchment and Jianshan catchment in Changsha County, Hunan Province, to comparatively study the effects of rice agriculture on the nitrogen and phosphorus concentrations and exports in streams in the typical agricultural catchments of the hilly red soil earth region. The monitoring of 16 months suggested that, there was a moderate stream nutrient pollution in both Tuojia and Jianshan catchments, especially for nitrogen pollution. Comparing the two catchments, the nitrogen and phosphorus concentrations were higher and the water quality was worse in the Tuojia catchment than that in the Jianshan catchment. From the nutrient composition of view, ammonia nitrogen was the main species of total nitrogen in the Tuojia catchment (accounting for 58.5% of total nitrogen), while it was nitrate nitrogen in the Jianshan catchment (accounting for 76. 1% of total nitrogen). The proportion of dissolved phosphorus in total phosphorus was 47. 1% in the Tuojia catchment, higher than the proportion of 37.5% in the Jianshan catchment. From temporal variations of nutrient dynamics of view, concentrations of all forms of nitrogen were higher during January to February and in July, respectively, and total phosphorus and dissolved phosphorus were higher during May to June and during October to December. Since the stream discharge in the catchments concentrated during the rice growing period from April to October, the higher nutrient concentrations during the period suggested potential risks of nitrogen and phosphorus losses. The total nitrogen mass flux was 1.67 kg x (hm2 x month)(-1) and TP was 0.06 kg x (hm2 x month)(-1) in the Tuojia catchment, which were greater than the 0.44 kg x (hm2 x month)(-1) and 0.02 kg x (hm2 x month)(-1) in the Jianshan catchment. Given the similar climate, geomorphology, soil type and cultivation patterns but the different area proportion of rice agriculture between two catchments, results suggested that, under the traditional crop management in hilly red soil earth region of central subtropics, the higher area proportion of rice agriculture has the potential to degrade stream aquatic environment.