Transcriptional Activation of a Pro-Inflammatory Response (NF-κB, AP-1, IL-1ß) by the Vibrio cholerae Cytotoxin (VCC) Monomer through the MAPK Signaling Pathway in the THP-1 Human Macrophage Cell Line.

This study describes, to some extent, the VCC contribution as an early stimulation of the macrophage lineage. Regarding the onset of the innate immune response caused by infection, the ß form of IL-1 is the most important interleukin involved in the onset of the inflammatory innate response. Activated macrophages treated in vitro with VCC induced the activation of the MAPK signaling pathway in a one-hour period, with the activation of transcriptional regulators for a surviving and pro-inflammatory response, suggesting an explanation inspired and supported by the inflammasome physiology. The mechanism of IL-1ß production induced by VCC has been gracefully outlined in murine models, using bacterial knockdown mutants and purified molecules; nevertheless, the knowledge of this mechanism in the human immune system is still under study. This work shows the soluble form of 65 kDa of the Vibrio cholerae cytotoxin (also known as hemolysin), as it is secreted by the bacteria, inducing the production of IL-1ß in the human macrophage cell line THP-1. The mechanism involves triggering the early activation of the signaling pathway MAPKs pERK and p38, with the subsequent activation of (p50) NF-κB and AP-1 (cJun and cFos), determined by real-time quantitation. The evidence shown here supports that the monomeric soluble form of the VCC in the macrophage acts as a modulator of the innate immune response, which is consistent with the assembly of the NLRP3 inflammasome actively releasing IL-1ß.

Mild heat shock at 40 °C increases levels of autophagy: Role of Nrf2.

The exposure to low doses of stress induces an adaptive survival response that involves the upregulation of cellular defense systems such as heat shock proteins (Hsps), anti-apoptosis proteins, and antioxidants. Exposure of cells to elevated, non-lethal temperatures (39-41 °C) is an adaptive survival response known as thermotolerance, which protects cells against subsequent lethal stress such as heat shock (>41.5 °C). However, the initiating factors in this adaptive survival response are not understood. This study aims to determine whether autophagy can be activated by heat shock at 40 °C and if this response is mediated by the transcription factor Nrf2. Thermotolerant cells, which were developed during 3 h at 40 °C, were resistant to caspase activation at 42 °C. Autophagy was activated when cells were heated from 5 to 60 min at 40 °C. Levels of acidic vesicular organelles (AVOs) and autophagy proteins Beclin-1, LC3-II/LC3-I, Atg7, Atg5, Atg12-Atg5, and p62 were increased. When Nrf2 was overexpressed or depleted in cells, levels of AVOs and autophagy proteins were higher in unstressed cells, compared to the wild type. Stress induced by mild heat shock at 40 °C further increased levels of most autophagy proteins in cells with overexpression or depletion of Nrf2. Colocalization of p62 and Keap1 occurred. When Nrf2 levels are low, activation of autophagy would likely compensate as a defense mechanism to protect cells against stress. An improved understanding of autophagy in the context of cellular responses to physiological heat shock could be useful for cancer treatment by hyperthermia and the protective role of adaptive responses against environmental stresses.

Insights into ovarian cancer: chemo-diversity, dose depended toxicities and survival responses.

Ovarian cancer has been one of the serious concerns for female health and medicinal practitioner all over the world. The wellness of over cancer patient is associated with survival responses which depends on many factors including chemotherapeutic diversity; treatment protocol; dose-dependent toxicity such as hematological toxicity and non-hematological toxicity. We found that the studied treatment regimens (TRs) (1-9) showed varying degree of hematological toxicities like moderate neutropenia (< 20%) critical neutropenia (> 20%), negligible leucopenia, critical leucopenia (> 20%), moderate thrombocytopenia (< 20%), critical thrombocytopenia (> 20%), moderate anemia (< 20%) and critical anemia (> 20%). The studied TRs showed varying degree of non-hematological toxicities like moderate nausea-vomiting (< 20%), critical nausea-vomiting (> 20%), moderate alopecia (< 20%), critical alopecia (> 20%), moderate fatigue (< 20%), critical fatigue (> 20%), moderate neurotoxicity (< 20%), critical neurotoxicity (> 20%), moderate diarrheas (< 20%). The studied TRs showed varying degree of survival responses like critical partial response (> 35%), remarkable overall responses (> 60%), critical overall responses (< 60%), remarkable stable disease (> 20%), critical stable disease (< 20%) and moderate progressive disease (< 20%). Out of the studied TRs 1-9, in case of TR 6, moderate non-hematological toxicity (NHT) and effective survival response (SR) is being diluted by critical hematological toxicity (HT). On the other hand, TR 8, 9 is showing critical HT, NHT and SR. Our analysis revealed that the toxicity of the existing therapeutic agents can be controlled through judicious decision of drug administration cycles and combination therapies.

Tonic immobility as a survival, adaptive response and as a recovery mechanism.

In this conclusive chapter, we review findings giving support to the hypothesis that TI represents an adaptive, survival response to threatening situations. In models of prey-predator interactions, in vertebrates and invertebrates, there are evidence that immobility per se contributes to survival, as the predator loses interest for a prey in which TI is experimentally induced. TI duration is also reciprocally modulated by the evaluation of the risk factors in the environment, and by the opportunity to reach a safe refuge. This supports the adaptive value of TI and suggests that, during TI, the animal may be transiently aware of the environmental situation. As for the adaptive value of TI, genetic correlations with other behavioral systems contributing to fitness (e.g., mating) are taken into account. Moreover, neurophysiological and endocrine findings in mammals support our hypothesis that TI activates the mechanisms responsible for recovery from disruptive experiences and body lesions.

Heat shock increases levels of reactive oxygen species, autophagy and apoptosis.

Hyperthermia is a promising anticancer treatment used in combination with radiotherapy and chemotherapy. Temperatures above 41.5 °C are cytotoxic and hyperthermia treatments can target a localized area of the body that has been invaded by a tumor. However, non-lethal temperatures (39-41 °C) can increase cellular defenses, such as heat shock proteins. This adaptive survival response, thermotolerance, can protect cells against subsequent cytotoxic stress such as anticancer treatments and heat shock (>41.5 °C). Autophagy is another survival process that is activated by stress. This study aims to determine whether autophagy can be activated by heat shock at 42 °C, and if this response is mediated by reactive oxygen species (ROS). Autophagy was increased during shorter heating times (<60 min) at 42 °C in cells. Levels of acidic vesicular organelles (AVO) and autophagy proteins Beclin-1, LC3-II/LC-3I, Atg7 and Atg12-Atg5 were increased. Heat shock at 42 °C increased levels of ROS. Increased levels of LC3 and AVOs at 42 °C were inhibited by antioxidants. Therefore, increased autophagy during heat shock at 42 °C (<60 min) was mediated by ROS. Conversely, heat shock at 42 °C for longer times (1-3 h) caused apoptosis and activation of caspases in the mitochondrial, death receptor and endoplasmic reticulum (ER) pathways. Thermotolerant cells, which were developed at 40 °C, were resistant to activation of apoptosis at 42 °C. Autophagy inhibitors 3-methyladenine and bafilomycin sensitized cells to activation of apoptosis by heat shock (42 °C). Improved understanding of autophagy in cellular responses to heat shock could be useful for optimizing the efficacy of hyperthermia in the clinic.

Sex steroid hormones as neuroprotective elements in ischemia models.

Among sex steroid hormones, progesterone and estradiol have a wide diversity of physiological activities that target the nervous system. Not only are they carried by the blood stream, but also they are locally synthesized in the brain and for this reason, estradiol and progesterone are considered 'neurosteroids'. The physiological actions of both hormones range from brain development and neurotransmission to aging, illustrating the importance of a deep understanding of their mechanisms of action. In this review, we summarize key roles that estradiol and progesterone play in the brain. As numerous reports have confirmed a substantial neuroprotective role for estradiol in models of neurodegenerative disease, we focus this review on traumatic brain injury and stroke models. We describe updated data from receptor and signaling events triggered by both hormones, with an emphasis on the mechanisms that have been reported as 'rapid' or 'cytoplasmic actions'. Data showing the therapeutic effects of the hormones, used alone or in combination, are also summarized, with a focus on rodent models of middle cerebral artery occlusion (MCAO). Finally, we draw attention to evidence that neuroprotection by both hormones might be due to a combination of 'cytoplasmic' and 'nuclear' signaling.

Oncogenic potential of Nrf2 and its principal target protein heme oxygenase-1.

Nuclear factor erythroid 2-related factor 2 (Nrf2) is an essential component of cellular defense against a vast variety of endogenous and exogenous insults, including oxidative stress. Nrf2 acts as a master switch in the circuits upregulating the expression of various stress-response proteins, especially heme oxygenase-1 (HO-1). Paradoxically, however, recent studies have demonstrated oncogenic functions of Nrf2 and its major target protein HO-1. Levels of Nrf2 and HO-1 are elevated in many different types of human malignancies, which may facilitate the remodeling of the tumor microenvironment making it advantageous for the autonomic growth of cancer cells, metastasis, angiogenesis, and tolerance to chemotherapeutic agents and radiation and photodynamic therapy. In this context, the cellular stress response or cytoprotective signaling mediated via the Nrf2-HO-1 axis is hijacked by cancer cells for their growth advantage and survival of anticancer treatment. Therefore, Nrf2 and HO-1 may represent potential therapeutic targets in the management of cancer. This review highlights the roles of Nrf2 and HO-1 in proliferation of cancer cells, their tolerance/resistance to anticancer treatments, and metastasis or angiogenesis in tumor progression.