Low humoral and cellular immune responses early after breakthrough infection may contribute to severe COVID-19.

Background: Little is known about the immune determinants for severe coronavirus disease 2019 (COVID-19) in individuals vaccinated against severe acute respiratory syndrome coronavirus 2. We therefore attempted to identify differences in humoral and cellular immune responses between patients with non-severe and severe breakthrough COVID-19. Methods: We prospectively enrolled hospitalized patients with breakthrough COVID-19 (severe and non-severe groups) and uninfected individuals who were vaccinated at a similar time (control group). Severe cases were defined as those who required oxygen therapy while hospitalized. Enzyme-linked immunosorbent assays and flow cytometry were used to evaluate humoral and cellular immune responses, respectively. Results: Anti-S1 IgG titers were significantly lower in the severe group than in the non-severe group within 1 week of symptom onset and higher in the non-severe group than in the control group. Compared with the control group, the cellular immune response tended to be diminished in breakthrough cases, particularly in the severe group. In multivariate analysis, advanced age and low anti-S1 IgG titer were associated with severe breakthrough COVID-19. Conclusions: Severe breakthrough COVID-19 might be attributed by low humoral and cellular immune responses early after infection. In the vaccinated population, delayed humoral and cellular immune responses may contribute to severe breakthrough COVID-19.

Tacrolimus regulates endoplasmic reticulum stress-mediated osteoclastogenesis and inflammation: In vitro and collagen-induced arthritis mouse model.

Tacrolimus is an immunosuppressive drug that inhibits the release of inflammatory cytokines involved in rheumatoid arthritis development by blocking T cell activation. "Endoplasmic reticulum stress," an imbalance between protein folding load and capacity leading to the accumulation of unfolded proteins in the endoplasmic reticulum lumen, has been implicated in rheumatoid arthritis and other inflammatory and metabolic diseases. We aimed to investigate the effect of tacrolimus on endoplasmic reticulum stress-mediated osteoclastogenesis and inflammation and elucidate the underlying mechanisms. In vitro studies were performed using mouse bone marrow cells that were cultured with or without interleukin-1ß, thapsigargin, or tacrolimus to induce osteoclast differentiation. A mouse model of arthritis was established by immunizing mice with bovine type II collagen. Tacrolimus was orally administered to mice from day 20 to 45 following the initial immunization, and histopathological changes and expression of specific biomarkers of endoplasmic reticulum stress-mediated inflammatory signaling pathways were examined. In vitro, tacrolimus inhibited receptor activator of nuclear factor-κB ligand-mediated osteoclast formation augmented by interleukin-1ß, thapsigargin, or both. Furthermore, tacrolimus inhibited glucose-regulated protein (GRP78), protein kinase R-like endoplasmic reticulum kinase, inositol-requiring enzyme 1 (IRE 1), and activating transcription factor 6 (ATF6) augmented by interleukin-1ß, thapsigargin, or both. Tacrolimus significantly ameliorated osteolysis and endoplasmic reticulum stress intensity in mice. Simultaneously, it reduced inflammatory cell infiltration, osteoclastogenesis, and inflammatory responses by inhibiting GRP78, IRE 1, and ATF6. These findings suggest that tacrolimus exhibits an anti-inflammation effect in rheumatoid arthritis and might inhibit joint damage progression by inhibiting endoplasmic reticulum stress.

Anti-asthmatic activities of an ethanol extract of Aster yomena in an ovalbumin-induced murine asthma model.

Aster yomena is used in traditional remedies to treat cough, asthma and insect bites; however, its therapeutic mechanism is not completely understood. To elucidate the anti-asthmatic effect of A. yomena, we investigated the anti-asthmatic characteristics of an alcohol extract of A. yomena in an ovalbumin (OVA)-induced murine asthma model. In this study, we showed that A. yomena extract inhibited the overall pathophysiological features of asthma by suppressing Th2 responses and enzymes associated with the production of inflammatory mediators. This suppression resulted in decreased Th2 type cytokines and eosinophils in the bronchoalveolar lavage fluid and OVA-specific IgE in serum. Additionally, A. yomena extract significantly decreased airway hyperresponsiveness and abrogated the histopathological changes in the lungs, which reached normal levels in the OVA-challenged mice treated with A. yomena extract. These findings suggest that A. yomena could be a promising natural agent for treating bronchial asthma in humans.

Chronic vitamin C insufficiency aggravated thioacetamide-induced liver fibrosis in gulo-knockout mice.

Given the involvement of oxidative stress in liver-disease- or hepato-toxicant-induced hepatic damage and fibrosis, antioxidants are an effective preventive and therapeutic tool. The beneficial results of vitamin C, one of the physiological antioxidants, have been observed both in experimental animals and in humans. However, most of these studies have been concerned with supplementary vitamin C; the effects of under vitamin C insufficiency, which humans sometimes confront, have not been substantially investigated. In the present study, we established a vitamin C-insufficient animal model (half-to-normal serum vitamin C concentration) with gulo(-/-) mice that cannot synthesize vitamin C, and induced hepatotoxicity by means of thioacetamide (TAA) injections twice a week for 18 weeks. Additionally, we explored the direct effects of vitamin C both on immortalized human hepatic stellate LX-2 cells and on rat primary hepatic stellate cells. Vitamin C insufficiency resulted in a decreased survival rate and increased serum markers for hepatocyte damage, such as alanine aminotransferase and aspartate aminotransferase. Concomitantly, the levels of reactive oxygen species (ROS) and lipid peroxides in the liver were increased. Histological examinations of the vitamin C-insufficient liver revealed increases in collagen fiber deposition and activated-hepatic-stellate-cell number. Vitamin C, when directly applied to the LX-2 cells as well as the rat primary hepatic stellate cells, suppressed not only proliferation but hydrogen peroxide-induced collagen expression as well. In conclusion, vitamin C insufficiency exacerbated TAA-induced hepatotoxicity. These effects seem to be mainly from insufficient scavenging of ROS in the liver, and possibly in part, by directly affecting hepatic stellate cells.

Vitamin C prevents stress-induced damage on the heart caused by the death of cardiomyocytes, through down-regulation of the excessive production of catecholamine, TNF-α, and ROS production in Gulo(-/-)Vit C-Insufficient mice.

It is thought that vitamin C has protective roles on stress-induced heart damage and the development of cardiovascular diseases, but its precise role and mechanisms are unclear. In the present study, we investigated the specific mechanisms by which vitamin C leads to protecting the heart from stress-induced damage in the Gulo(-/-) mice which cannot synthesize vitamin C like humans. By exposure to stress (1h/day), the heartbeat and cardiac output in vitamin C-insufficient Gulo(-/-) mice were definitely decreased, despite a significant increase of adrenaline (ADR) and noradrenaline (NA) production. A change of cardiac structure caused by the death of cardiomyocytes and an increased expression of matrix metalloprotease (MMP)-2 and -9 were also found. Moreover, lipid peroxidation and the production of tumor necrosis factor-alpha (TNF-α) in the heart were increased. Finally, all vitamin C-insufficient Gulo(-/-) mice were expired within 2 weeks. Interestingly, all of the findings in vitamin C-insufficient Gulo(-/-) mice were completely prevented by the supplementation of a sufficient amount of vitamin C. Taken together, vitamin C insufficiency increases the risk of stress-induced cardiac damage with structural and functional changes arising from the apoptosis of cardiomyocytes.

In vivo consequence of vitamin C insufficiency in liver injury: vitamin C ameliorates T-cell-mediated acute liver injury in gulo(-/-) mice.

AIM: l-ascorbic acid (vitamin C) insufficiency is considered one of the major risk factors for the development of liver disease. However, its specific effects and related mechanisms in vivo are largely unknown. The objective of this study was to investigate the in vivo protective role of vitamin C and its related mechanisms in liver injury with Gulo(-/-) mice that cannot synthesize vitamin C like humans due to the lack of l-gulonolactone-γ-oxidase (Gulo), an essential enzyme for vitamin C synthesis. RESULTS: When liver injury was induced in Gulo(-/-) mice by injection of concanavalin A (Con A), there was greater extensive liver damage accompanied by an increased number of apoptotic hepatocytes in vitamin C-insufficient Gulo(-/-) mice. Additionally, the plasma and hepatic levels of the proinflammatory cytokines, such as TNF-α and IFN-γ, were much higher in the vitamin C-insufficient Gulo(-/-) mice than in the control mice. Moreover, increased numbers of liver-infiltrating T-cells in the vitamin C-insufficient Gulo(-/-) mice were related to the increased hepatic levels of IFN-inducible factor (IP-10). Although the vitamin C-insufficient Gulo(-/-) mice had higher amounts of interleukin-22 (IL-22), a hepatoprotective cytokine, a defect in IL-22Rα expression and its downstream STAT3 activation in hepatocytes were found. INNOVATION: We first demonstrate the novel in vivo action mechanisms of vitamin C on the prevention of disease development in the liver, through the regulation of excessive immune activation and maintenance of the IL-22Rα signaling pathways. CONCLUSION: These results suggest that severe liver damage induced by inflammation could be prevented by sufficient supplementation with vitamin C.

The analysis of vitamin C concentration in organs of gulo(-/-) mice upon vitamin C withdrawal.

BACKGROUND: Vitamin C is an essential nutrient for maintaining human life. Vitamin C insufficiency in the plasma is closely related with the development of scurvy. However, in vivo kinetics of vitamin C regarding its storage and consumption is still largely unknown. METHODS: We used Gulo(-/-) mice, which cannot synthesize vitamin C like human. Vitamin C level in plasma and organs from Gulo(-/-) mice was examined, and it compared with the level of wild-type mice during 5 weeks. RESULTS: The significant weight loss of Gulo(-/-) mice was shown at 3 weeks after vitamin C withdrawal. However, there was no differences between wild-type and vitamin C-supplemented Gulo(-/-) mice (3.3 g/L in drinking water). The concentration of vitamin C in plasma and organs was significantly decreased at 1 week after vitamin C withdrawal. Vitamin C is preferentially deposited in adrenal gland, lymph node, lung, and brain. There were no significant changes in the numbers and CD4/CD8 ratio of splenocytes in Gulo(-/-) mice with vitamin C withdrawal for 4 weeks. And the architecture of spleen in Gulo(-/-) mice was disrupted at 5 weeks after vitamin C withdrawal. CONCLUSION: The vitamin C level of Gulo(-/-) mice was considerably decreased from 1 week after vitamin C withdrawal. Vitamin C is preferentially stored in some organs such as brain, adrenal gland and lung.

Anti-dermatitis effects of oak wood vinegar on the DNCB-induced contact hypersensitivity via STAT3 suppression.

AIMS OF THE STUDY: The aim of this study was to evaluate the anti-dermatitis effects of oak wood vinegar (OWV) in a 2,4-dinitrochlorobenzene (DNCB)-induced contact dermatitis mice model. MATERIALS AND METHODS: Immunoglobulin E (IgE) production, infiltration of immune cells (neutrophils, CD3+ cells), inducible nitric oxide synthase (iNOS) expression, skin thickness, and expression of phosphorylated STAT3 (signal transducers and activators of transcription 3) protein were tested in a DNCB-induced contact dermatitis model. In vitro wound healing and proliferative assays were also performed. RESULTS: OWV showed anti-inflammatory effects on DNCB-induced dermatitis in mice, leading to inhibition of IgE production, immune cell infiltration, and iNOS expression. Skin thickness and the level of phospho-STAT3 were dramatically reduced by OWV. Using the HaCaT human keratinocyte cell line, we confirmed that constitutive STAT3 activation induced faster proliferation of epithelial cells. In addition, OWV suppressed HaCaT proliferative ability and phospho-STAT3 levels. CONCLUSIONS: The study revealed that OWV has anti-inflammatory and anti-proliferative effects in a DNCB-induced contact dermatitis mice model. Furthermore, we showed that the mechanism by which OWV most likely inhibits epithelial proliferation is through STAT3 inactivation.