Immune tolerance and the prevention of autoimmune diseases essentially depend on thymic tissue homeostasis

The intricate balance of immune reactions towards invading pathogens and immune tolerance towards self is pivotal in preventing autoimmune diseases, with the thymus playing a central role in establishing and maintaining this equilibrium. The induction of central immune tolerance in the thymus involves the elimination of self-reactive T cells, a mechanism essential for averting autoimmunity. Disruption of the thymic T cell selection mechanisms can lead to the development of autoimmune diseases. In the dynamic microenvironment of the thymus, T cell migration and interactions with thymic stromal cells are critical for the selection processes that ensure self-tolerance. Thymic epithelial cells are particularly significant in this context, presenting self-antigens and inducing the negative selection of autoreactive T cells. Further, the synergistic roles of thymic fibroblasts, B cells, and dendritic cells in antigen presentation, selection and the development of regulatory T cells are pivotal in maintaining immune responses tightly regulated. This review article collates these insights, offering a comprehensive examination of the multifaceted role of thymic tissue homeostasis in the establishment of immune tolerance and its implications in the prevention of autoimmune diseases. Additionally, the developmental pathways of the thymus are explored, highlighting how genetic aberrations can disrupt thymic architecture and function, leading to autoimmune conditions. The impact of infections on immune tolerance is another critical area, with pathogens potentially triggering autoimmunity by altering thymic homeostasis. Overall, this review underscores the integral role of thymic tissue homeostasis in the prevention of autoimmune diseases, discussing insights into potential therapeutic strategies and examining putative avenues for future research on developing thymic-based therapies in treating and preventing autoimmune conditions.

Thymoquinone protects against 5-Fluorouracil-induced mucositis by NF-κβ and HIF-1 mechanisms in mice

Mucositis is among the most common side effects of 5-Fluorouracil (5-FU) and other cancer therapeutic drugs. Thymoquinone (TQ), a bioactive constituent extracted from Nigella sativa, has antioxidant and anti-inflammatory properties and can modify acute gastrointestinal injury. To investigate the effects of TQ on mucositis induced by 5-FU, studied animals were divided into four groups: control, 5-FU unit dose (300 mg/kg) to cause oral and intestinal mucositis (OM and IM), TQ (2.5 mg/kg) and TQ (2.5 mg/kg) plus 5-FU. Due to The molecular mechanisms, it was confirmed that the expression of NF-κβ and HIF-1 increases in OM. The serum levels of malondialdehyde (MDA), catalase (CAT), and superoxide dismutase (SOD), as well as pathological parameters, were assessed. Based on our results, the nuclear factor-kappa β gene expression in the tongue was downregulated significantly in the 5-FU + TQ compared to the 5-FU. TQ treatment can diminish MDA, and a reduction in oxidative stress was shown. TQ could also reduce the severity of tissue destruction and damaging effects induced by 5-FU on the tongue and intestine. We also observed lower villus length and width in the intestine of the 5-FU group compared to the control group. According to our research's pathological, biochemical, and molecular results, treatment with TQ as an anti-inflammatory and antioxidant compound may be the potential to improve and treat 5-FU-induced OM and IM, and TQ could be used against cancer treatment drugs and exhibit fewer adverse effects.

The protective effects of silymarin nanoemulsion on 5-fluorouracil-induced gastrointestinal toxicity in rats

5-Fluorouracil (5FUra) is the third most popular chemotherapeutic component employed to treat solid tumors. In the present study, we aimed to appraise the silymarin (SM) and silymarin nanoemulsion (SMN) effect on 5FUra-induced gastrointestinal toxicity in adult male rats. A total of 30 male Wistar rats were divided into 6 groups including the control (Crl) group, and groups treated with SMN (5 mg.kg^-1), SM (5 mg.kg^-1), 5FUra + SMN (5 mg.kg^-1), and 5FUra + SM (5 mg.kg^-1) by IP injection for 14 days. And gastrointestinal toxicity was induced by a single intraperitoneal (IP) injection of 5FUra (100 mg.kg^-1) for the last group in the study. Treating rats with SM and SMN diminished elevating malondialdehyde (MDA) levels, and improved total antioxidant capacity (TAC) levels. Also, the intensity of mRNA expression of interleukin-2 (IL-2) and tumor necrosis factor-alpha (TNF-α) caused by 5FUra in the gastrointestinal tissue tract, and macroscopic oral ulcerations decreased, ass well as weight loss was prevented, particularly in the SMN group. Moreover, in the microscopic scope, there were significant improvements in the levels of hyperemia, hyaline, and inflammatory cell infiltration in the tongue, esophagus, and intestinal tissues in the FUra + SMN and FUra + SM groups compared to 5FUra. Hence, treatment with SM and SMN reduced oxidative stress, histopathological degeneration, and gene expression of inflammatory markers in the gastrointestinal tract. According to the results, treatment with SM and SMN markedly decreases the gastrointestinal toxicity caused by 5FUra.

The Role of Viral Infections in the Onset of Autoimmune Diseases

Autoimmune diseases (AIDs) are the consequence of a breach in immune tolerance, leading to the inability to sufficiently differentiate between self and non-self. Immune reactions that are targeted towards self-antigens can ultimately lead to the destruction of the host's cells and the development of autoimmune diseases. Although autoimmune disorders are comparatively rare, the worldwide incidence and prevalence is increasing, and they have major adverse implications for mortality and morbidity. Genetic and environmental factors are thought to be the major factors contributing to the development of autoimmunity. Viral infections are one of the environmental triggers that can lead to autoimmunity. Current research suggests that several mechanisms, such as molecular mimicry, epitope spreading, and bystander activation, can cause viral-induced autoimmunity. Here we describe the latest insights into the pathomechanisms of viral-induced autoimmune diseases and discuss recent findings on COVID-19 infections and the development of AIDs.

Cardioprotective effect of silymarin nanoemulsion on 5-fluorouracil-induced cardiotoxicity in rats

5-Fluorouracil (5-FU)-associated cardiotoxicity has been ranked as the second most common cause of cardiotoxicity induced by chemotherapeutic drugs after anthracyclines. In the present study, we investigated the protective impacts of silymarin (SIL) and silymarin nanoemulsion (SLN) against cardiotoxicity caused by 5-FU in rats. Thirty male Wistar rats were divided into six groups as follows: control, SLN (5 mg/kg), SIL (5 mg/kg), 5-FU + SLN, 5-FU + SIL, and 5-FU. Cardiotoxicity was induced by a single intraperitoneal injection of 5-FU (100 mg/kg). The control group received an intraperitoneal injection (ip) of normal saline and the treatment groups received ips of SIL and SLN for 14 days. 5-FU resulted in significant cardiotoxicity, represented by an increase in the serum levels of cardiac enzymes and malondialdehyde, as well as cyclooxygenase-2 (COX-2) and tumor necrosis factor-α (TNF-α) expression, and histopathological degeneration. 5-FU treatment also induced a decrease in body weight, total antioxidant capacity (TAC), and catalase values. Evaluation of electrocardiographic parameters in 5-FU-treated rats showed increases in the ST segment, QRS duration, and RR interval. Treatment with SIL and SLN reduced oxidative stress, cardiac enzymes, histopathological degeneration, and the expression of TNF-α and COX-2 in cardiac tissue. Our results demonstrated that treatment with SIL and SLN significantly improved cardiotoxicity induced by 5-FU in rats.

Protective Effect of Kaempferol and Its Nanoparticles on 5-Fluorouracil-Induced Cardiotoxicity in Rats

BACKGROUND

Fluorouracil (5-FU) is the third most common chemotherapeutic agent used in the treatment of solid tumors. 5-FU-associated cardiotoxicity ranks the second causes of cardiotoxicity induced by chemotherapeutic drugs after anthracyclines. Kaempferol (KPF), a common flavonoid, possessing anti-inflammatory, antiapoptotic, antioxidative properties, and its protective effects on cardiovascular disease has been reported in various studies. The current study is aimed at appraising the effect of KPF and KPF nanoparticles (NPs) on 5-FU-induced cardiotoxicity in rats.

METHODS

Thirty Male Wistar rats were divided into five groups as follows: control, 5-FU, 5-FU+10 mg/kg vitamin C, 5-FU+ 1 mg/kg KPF, and 5-FU+ 1 mg/kg KPF-NPs. Cardiotoxicity was induced with an intraperitoneal injection of a single dose of 5-FU (100 mg/kg). The control group received normal saline, and the treatment groups received KPF and KPF-NPs with an intraperitoneal injection for 14 days. Each heart histopathological lesions were given a score of 0 to 3 in compliance with the articles for statistical analysis.

RESULTS

5-FU resulted in a significant cardiotoxicity represented by an increase in cardiac enzymes, MDA (malondialdehyde) levels, COX-2 (cyclooxygenase-2) expression, and histopathological degenerations. 5-FU treatment also decreased body weight, TAC (total antioxidant capacity) values, VEGF (vascular endothelial growth factor) expression, blood cells, and hemoglobin (Hb) levels. Treatment with KPF and KPF-NPs reduced oxidative stress, cardiac enzymes, COX-2 expression, and VEGF expression. The number of blood cells, Hb levels, and histopathological degenerations, in cardiac tissue also body weight of animals, increased, followed by treatment with KPF and KPF-NPs.

CONCLUSION

Our results demonstrated that treatment with KPF and KPF-NPs significantly improved cardiotoxicity induced by 5-FU in rats.

The protective effects of quercetin nano-emulsion on intestinal mucositis induced by 5-fluorouracil in mice

BACKGROUND

Intestinal mucositis is one of chemotherapeutics' most common adverse effects, such as 5-fluorouracil (5-FU). Quercetin (QRC), a naturally occurring flavonoid, has approved antioxidant and anti-inflammatory properties. Thus, in this article, the preventive and curative effects of emulsion and nano-emulsion formulations of QRC were investigated in a model of 5-FU-induced intestinal mucositis using biochemical, histopathological, and molecular approaches.

METHOD

Thirty-six mice were divided into six different groups: Control (normal saline), 5-FU (a single dose of 5-FU 300 mg/kg), pre-treatment groups (pre-QRC, and pre-QRC-nano, receiving QRC 5 mg/kg emulsion and nano-emulsion before the induction of mucositis, respectively), and post-treatment groups (post-QRC, and post-QRC-nano, receiving QRC 5 mg/kg emulsion and nano-emulsion after the induction of mucositis, respectively).

FINDING

The administration of quercetin emulsion and nano-emulsion could significantly alleviate the oxidant-antioxidant balance of mice serum samples and reverse the destructive histopathologic changes induced by 5-FU in the intestine tissue. Nevertheless, although the expression of both pro-inflammatory genes, NF-κB and HIF-1α, was decreased when quercetin was administered to mice, this reduction was not statistically significant.

CONCLUSION

The administration of quercetin emulsion and nano-emulsion formulations could ameliorate the oxidative damage induced by chemotherapeutics, such as the 5-FU. Therefore, if confirmed in further studies, it could be used in clinical settings as a preventive and curative agent to decrease such catastrophic adverse events in chemotherapy patients.

Pathophysiological roles of chronic low-grade inflammation mediators in polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is the most common hormonal imbalance disease in reproductive-aged women. Its basic characteristics are ovulatory dysfunction and ovarian overproduction of androgens that lead to severe symptoms such as insulin resistance, hirsutism, infertility, and acne. Notwithstanding the disease burden, its underlying mechanisms remain unknown, and no causal therapeutic exists. In recent years, further studies showed that inflammation processes are involved in ovulation and play a key role in ovarian follicular dynamics. Visceral adipose tissue can cause inflammatory response and maintenance of the inflammation state in adipocytes by augmented production of inflammatory cytokines, monocyte chemoattractant proteins, and recruitment of the immune cell. Therefore, the PCOS can be related to a low-grade inflammation state and inflammatory markers. Investigating the inflammatory processes and mediators that contribute to the commencement and development of PCOS can be a critical step for better understanding the pathophysiology of the disease and its treatment through inhibition or control of related pathways. In the present review, we discuss the pathophysiological roles of chronic low-grade inflammation mediators including inflammasome-related cytokines, interleukin-1β (IL-1β), and IL-18 in PCOS development.