Cell penetrating peptides-functionalized Licochalcone-A-loaded PLGA nanoparticles for ocular inflammatory diseases: evaluation of in vitro anti-proliferative effects, stabilization by freeze-drying and characterization of an in-situ forming gel

Licochalcone-A (Lico-A) PLGA NPs functionalized with cell penetrating peptides B6 and Tet-1 are proposed for the treatment of ocular anti-inflammatory diseases. In this work, we report the in vitro biocompatibility of cell penetrating peptides-functionalized Lico-A-loaded PLGA NPs in Caco-2 cell lines revealing a non-cytotoxic profile, and their anti-inflammatory activity against RAW 264.7 cell lines. Given the risk of hydrolysis of the liquid suspensions, freeze-drying was carried out testing different cryoprotectants (e.g., disaccharides, alcohols, and oligosaccharide-derived sugar alcohol) to prevent particle aggregation and mitigate physical stress. As the purpose is the topical eye instillation of the nanoparticles, to reduce precorneal wash-out, increase residence time and thus Lico-A bioavailability, an in-situ forming gel based on poloxamer 407 containing Lico-A loaded PLGA nanoparticles functionalized with B6 and Tet-1 for ocular administration has been developed. Developed formulations remain in a flowing semi-liquid state under non-physiological conditions and transformed into a semi-solid state under ocular temperature conditions (35 °C), which is beneficial for ocular administration. The pH, viscosity, texture parameters and gelation temperature results met the requirements for ophthalmic formulations. The gel has characteristics of viscoelasticity, suitable mechanical and mucoadhesive performance which facilitate its uniform distribution over the conjunctiva surface. In conclusion, we anticipate the potential clinical significance of our developed product provided that a synergistic effect is achieved by combining the high anti-inflammatory activity of Lico-A delivered by PLGA NPs with B6 and Tet-1 for site-specific targeting in the eye, using an in-situ forming gel.

Anti-inflammatory Effect by Cloves Treatment in LPS-induced RAW264.7 Cells

Background:

Cloves mean the dried flower bud harvested from a tree of Syzygium aromaticum L. (SA).

Objectives:

The current study was to identify the anti-inflammatory effects of SA on lipopolysaccharide (LPS) (0.2 µg/mL)-treated RAW264.7 cells.

Materials and Methods:

WST-8 cell proliferation assay kit (WST-8) and lactate dehydrogenase (LDH) assays were completed to observe cell proliferation and cytotoxicity effects of SA. Other biochemical analyses analyzed releases of nitric oxide (NO) and the production of dichlorofluorescin diacetate (DCF-DA). Besides, inflammation-related factors and Sirt1 were carried out through immunohistochemistry (IHC) and immunofluorescence (IF).

Results:

LPS exposure not only caused abnormal elevations of both NO and reactive oxygen species (ROS) secretions, but also markedly increased inflammation-related proteins including inducible NO synthase (iNOS), cluster of differentiation (CD) 14, and toll-like receptor (TLR) 4, and nuclear factor-κB (NF-κB). The above-listed alterations were notably attenuated by SA pretreatment in a dose-dependent manner. We further figured out that, SA particularly activated AMPKα/ Sirt1 signaling pathway. Furthermore, SA dramatically inhibited interleukin (IL)-1β production, which was mediated by NLR family Pyrin domain containing (NLRP) 3 mediated inflammasome signaling pathway.

Conclusion:

SA inhibits LPS-induced inflammation in RAW264.7 cells via the TRL4/CD14/NF-κB pathway and it can lead to the reduction of IL-1β release by the inhibition of NLRP3 inflammasome. Such an anti-inflammatory effect was closely related to AMPKα/Sirt1 activation. Taken together, the findings of this study support both the inhibition of NLRP3 inflammasome and activation of Sirt1 can alleviate inflammation.

VISTA Stimulation of VSIG4-Positive Macrophages Strongly Suppresses T Cell Proliferation via Excessive Nitric Oxide Production in Sepsis

Organ damage and immune deficiency are important problems in sepsis caused by an excessive immune response. There is controversy about the cause of immune suppression. In this study, we investigated the roles of macrophages that exhibit excessive activity on T cell immunity. Peritoneal macrophages from mice with cecal ligation and puncture (CLP)-induced sepsis migrated to different organs. In particular, V-set immunoglobulin (Ig)-domain-containing 4 (VSIG4) positive macrophages appeared in the spleen 48 h after CLP induction. When cocultured with splenic T cells, VSIG4(+) cells inhibited the proliferation of activated T cells through the release of nitric oxide (NO) compared to VSIG4(-) cells. Stimulation of VSIG4(+) cells with V-domain Ig suppressor of T cell activation (VISTA) antibody increased the expression of several cytokine genes and the release of NO, but not phagocytosis, compared to those of hamster IgG-stimulated VSIG4(+) cells. When cocultured with splenic T cells, VISTA-stimulated VSIG4(+) cells induced excessive T cell suppression via more NO secretion compared to hamster IgG-stimulated VSIG4(+) cells. Taken together, the current study demonstrates that VSIG4(+) peritoneal macrophages play important roles in inducing immunosuppression and that VISTA acts as a costimulatory receptor in these cells. These data suggest that blocking the migration of VSIG4(+) cells might alleviate excessive immune activity and that blocking VISTA on VSIG4(+) macrophages might play a crucial role in the development of new therapies to prevent T cell suppression in sepsis.

Targeting SHP2 as a therapeutic strategy for inflammatory diseases

With the change of lifestyle and the acceleration of aging process, inflammatory diseases have increasingly become one of the most vital threats to global human health. SHP2 protein is a non-receptor tyrosine phosphatase encoded by PTPN11 gene, and it is widely expressed in various tissues and cells. Numerous studies have shown that SHP2 plays important roles in the regulation of inflammatory diseases, including cancer-related inflammation, neurodegenerative diseases and metabolic diseases. In this paper, the roles of SHP2 in inflammatory diseases of various physiological systems were reviewed. At the same time, the latest SHP2 inhibitors were summarized, which will hold a promise for the therapeutic potential in future.

Specific inhibition of SHP2 suppressed abdominal aortic aneurysm formation in mice by augmenting the immunosuppressive function of MDSCs

AIMS

To address the roles of SHP2 in regulating angiotensin II (Ang II) induced abdominal aortic aneurysm (AAA) and the potential molecular mechanisms.

MAIN METHODS

AAA model was established in apolipoprotein E-deficient (apoE^-/-) mice infused with Ang II. Suprarenal aortic luminal diameters were ultrasonically measured to determine the presentation of AAA in mice. The inflammatory and immunosuppressive factors in serum were detected by ELISA. AAA lesion size, positive macrophages and elastic laminae degradation were examined by histological analysis. Myeloid-derived suppressor cells (MDSCs) were measured by flow cytometry after magnetic bead sorting. Bioinformatics analysis was applied to screen the crucial genes related the progression of AAA.

KEY FINDINGS

Treatment with PHPS1 (SHP2 inhibitor) significantly decreased the vascular diameter of AAA. Histological analysis showed that PHPS1 obviously reduced the Masson positive area, macrophages positive area, as well as the damage rate of elastic laminae. Moreover, PHPS1 suppressed the expression of INF-γ, TNF-α and MMPs, as well as elevated IL-10 and arginase-1 expression. Additionally, PHPS1 enhanced the expression of granulocytic MDSCs (G-MDSCs). By consulting with bioinformatics, STAT3 was selected. In G-MDSCs, PHPS1 stimulation obviously increased the phosphorylation level of STAT3, as well as elevated the protein expression of C/EBPβ and arginase-1. However, the above phenomena can be blocked after Stattic (STAT3 inhibitor) treatment.

SIGNIFICANCE

SHP2 may affect the AAA progression by interfering with expansion and function of MDSCs to regulate the body immunity, which might afford a novel direction for the treatment of patients with AAA.

[Free Radical Production and Production Mechanism in the Early and Advanced Stages of Gastrointestinal Lesions]

Disruption of redox balance due to the overproduction of free radicals and reactive oxygen species (ROS) could cause protein denaturation, lipid peroxidation, and DNA mutation. These lead to an induction of gastrointestinal diseases such as gastric ulcers induced by long-term administration of non-steroidal anti-inflammatory drugs (NSAIDs) and ulcerative colitis. Magnetic resonance technique, which is non-invasive and free of radiation exposure, is a promising tool for evaluating redox status in the living body. This study investigated ROS production in rats with gastric ulcers induced by a typical NSAIDs indomethacin using in vivo ESR/spin probe technique. The ESR signal intensity of membrane-permeable nitroxyl probe in the indomethacin group showed enhanced decay compared with the vehicle group, but the enhancement was not observed in the presence of a membrane-permeable ROS scavenger, suggesting the intracellular ROS production. The imaging analysis using Overhauser-enhanced MRI (OMRI) with dual probes labeled with ¹⁴N and ¹⁵N enabled visualization of ROS production in the glandular stomach of rat with indomethacin-induced gastric ulcers. The intracellular ROS production in the distal and proximal colon in the initiation stage and intra- and extra-cellular ROS production of the advanced stage of colitis induced by dextran sodium sulfate (DSS) using the OMRI/dual-probe technique was observed. Furthermore, nitration of src homology protein tyrosine phosphatase 2 in macrophages might be involved in the activation of Toll-like receptor 4 and NF-κB, inducing infiltration of activated neutrophils into colonic mucosa to produce ROS in DSS-induced colitis mice.

Chemical modification of pro-inflammatory proteins by peroxynitrite increases activation of TLR4 and NF-κB: Implications for the health effects of air pollution and oxidative stress

Environmental pollutants like fine particulate matter can cause adverse health effects through oxidative stress and inflammation. Reactive oxygen and nitrogen species (ROS/RNS) such as peroxynitrite can chemically modify proteins, but the effects of such modifications on the immune system and human health are not well understood. In the course of inflammatory processes, the Toll-like receptor 4 (TLR4) can sense damage-associated molecular patterns (DAMPs). Here, we investigate how the TLR4 response and pro-inflammatory potential of the proteinous DAMPs α-Synuclein (α-Syn), heat shock protein 60 (HSP60), and high-mobility-group box 1 protein (HMGB1), which are relevant in neurodegenerative and cardiovascular diseases, changes upon chemical modification with peroxynitrite.

For the peroxynitrite-modified proteins, we found a strongly enhanced activation of TLR4 and the pro-inflammatory transcription factor NF-κB in stable reporter cell lines as well as increased mRNA expression and secretion of the pro-inflammatory cytokines TNF-α, IL-1β, and IL-8 in human monocytes (THP-1). This enhanced activation of innate immunity via TLR4 is mediated by covalent chemical modifications of the studied DAMPs.

Our results show that proteinous DAMPs modified by peroxynitrite more potently amplify inflammation via TLR4 activation than the native DAMPs, and provide first evidence that such modifications can directly enhance innate immune responses via a defined receptor. These findings suggest that environmental pollutants and related ROS/RNS may play a role in promoting acute and chronic inflammatory disorders by structurally modifying the body's own DAMPs. This may have important consequences for chronic neurodegenerative, cardiovascular or gastrointestinal diseases that are prevalent in modern societies, and calls for action, to improve air quality and climate in the Anthropocene.

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Pollutants and oxidative stress can cause protein nitration and oligomerization.

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Peroxynitrite amplifies inflammatory potential of disease-related proteins in vitro.

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Chemical modification of damage-associated molecular patterns (DAMPs).

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Positive feedback of modified DAMPs via pattern recognition receptor (TLR4).

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Air pollution may promote inflammatory disorders in the Anthropocene.

Senescence and Cancer: Role of Nitric Oxide (NO) in SASP

Cellular senescence is a cell state involved in both physiological and pathological processes such as age-related diseases and cancer. While the mechanism of senescence is now well known, its role in tumorigenesis still remains very controversial. The positive and negative effects of senescence on tumorigenesis depend largely on the diversity of the senescent phenotypes and, more precisely, on the senescence-associated secretory phenotype (SASP). In this review, we discuss the modulatory effect of nitric oxide (NO) in SASP and the possible benefits of the use of NO donors or iNOS inducers in combination with senotherapy in cancer treatment.