Mental health during ecological crisis: translating and validating the Hogg Eco-anxiety Scale for Argentinian and Spanish populations

BACKGROUND

Eco-anxiety is increasingly recognized as a shared experience by many people internationally, encompassing fear of environmental catastrophe and anxiety about ecological crises. Despite its importance in the context of the changing climate, measures for this construct are still being developed in languages other than English.

METHODS

To contribute to global eco-anxiety research, we translated the Hogg Eco-Anxiety Scale (HEAS) into Spanish, creating the HEAS-SP. We validated this measure in samples from both Argentina (n = 990) and Spain (n = 548), performing measurement invariance and confirmatory factor analyses. Internal consistency of the scale and score stability over time were investigated through reliability analyses. Differences in eco-anxiety across sociodemographic variables were explored through Student's t-tests and Pearson's r tests.

RESULTS

The four-factor model of the HEAS-SP comprising affective and behavioural symptoms, rumination, and anxiety about personal impact demonstrated excellent model fit. We found good internal consistency for each subscale, and established measurement invariance between Spanish and Argentine samples, as well as across genders and participants' age. Spanish participants reported higher scores on the affective symptoms and personal impact anxiety factors compared to the Argentinian sample. Also, men reported lower levels than women on the subscales of affective symptoms, rumination, and personal impact anxiety. It was found that the relationship between both age and personal impact anxiety and age and affective symptoms varies significantly depending on the gender of the individuals. Younger participants tended to report higher scores on most dimensions of eco-anxiety.

CONCLUSIONS

These findings enhance the global initiative to investigate, explore and therefore comprehend eco-anxiety by introducing the first valid and reliable Spanish-language version of this psychometric instrument for its use within Spanish and Argentinian populations. This study augments the body of evidence supporting the robust psychometric properties of the HEAS, as demonstrated in prior validations for Australian, Turkish, Portuguese, German, French, and Italian populations.

Is conservative opposition to climate change threat-based? Articulating an integrated threat model of climate change attitudes

Throughout the literature, there are assertions that those endorsing conservative ideologies reject the science and solutions of climate change due to perceived threat. That is, they fear that accepting climate change means accepting problems with a favoured socioeconomic system and supporting action on climate change threatens to disrupt these systems. We draw together lines of research and reasoning on this topic to outline three key predictions this perspective makes about the drivers of conservative denial of climate change and opposition to climate policy. The first is that an asymmetry exists in climate-related threat perceptions, whereby greater endorsement of conservative ideology predicts lower perceived threat from climate change and greater perceived threat from climate reform. Second, climate-related threat perceptions are multifaceted, such that threats to economic and cultural well-being can be experienced, at personal or collective levels. Third, the asymmetry in threat perceptions explains conservatives' lower support for pro-climate reforms. We then specify a new integrated threat model of climate change attitudes, review the current evidence for and against each prediction in this model and outline ways to interrogate these theoretical predictions with empirical research. Doing so will advance understanding of the underpinnings of ideological disagreement on climate change.

Addressing climate change with behavioral science: A global intervention tournament in 63 countries

Effectively reducing climate change requires marked, global behavior change. However, it is unclear which strategies are most likely to motivate people to change their climate beliefs and behaviors. Here, we tested 11 expert-crowdsourced interventions on four climate mitigation outcomes: beliefs, policy support, information sharing intention, and an effortful tree-planting behavioral task. Across 59,440 participants from 63 countries, the interventions' effectiveness was small, largely limited to nonclimate skeptics, and differed across outcomes: Beliefs were strengthened mostly by decreasing psychological distance (by 2.3%), policy support by writing a letter to a future-generation member (2.6%), information sharing by negative emotion induction (12.1%), and no intervention increased the more effortful behavior-several interventions even reduced tree planting. Last, the effects of each intervention differed depending on people's initial climate beliefs. These findings suggest that the impact of behavioral climate interventions varies across audiences and target behaviors.

Predictors of individual mental health and psychological resilience after Australia's 2019-2020 bushfires

AIMS

We assessed the mental health effects of Australia's 2019-2020 bushfires 12-18 months later, predicting psychological distress and positive psychological outcomes from bushfire exposure and a range of demographic variables, and seeking insights to enhance disaster preparedness and resilience planning for different profiles of people.

METHODS

We surveyed 3083 bushfire-affected and non-affected Australian residents about their experiences of bushfire, COVID-19, psychological distress (depression, anxiety, stress, post-traumatic stress disorder) and positive psychological outcomes (resilient coping, wellbeing).

RESULTS

We found high rates of distress across all participants, exacerbated by severity of bushfire exposure. For people who were bushfire-affected, being older, having less financial stress, and having no or fewer pre-existing mental disorders predicted both lower distress and higher positive outcomes. Being male or having less income loss also predicted positive outcomes. Severity of exposure, higher education and higher COVID-19-related stressors predicted both higher distress and higher positive outcomes. Pre-existing physical health diagnosis and previous bushfire experience did not significantly predict distress or positive outcomes.

RECOMMENDATIONS

To promote disaster resilience, we recommend investment in mental health, particularly for younger adults and for those in rural and remote areas. We also recommend investment in mechanisms to protect against financial distress and the development of a broader definition of bushfire-related impacts than is currently used to capture brushfires' far-reaching effects.

Validating a measure for eco-anxiety in Portuguese young adults and exploring its associations with environmental action

BACKGROUND

Worsening environmental conditions may amplify people's emotional responses to an environmental crisis (eco-anxiety). In Portugal, young people seem to be especially concerned about climate change. However, this phenomenon needs to be interpreted using accurate instruments. Thus, this study aimed to validate the Portuguese version of the Hogg Eco-Anxiety Scale (HEAS) in young adults and examine the associations among eco-anxiety, sociodemographic characteristics, and pro-environmental behaviours.

METHODS

A survey was administered to 623 Portuguese university students aged between 18 and 25 years. The survey included our Portuguese translation of the HEAS (obtained through a back-translation and pretesting process), a sociodemographic assessment, and questions related to pro-environmental behaviours. Confirmatory factor analysis was conducted to assess the construct validity of the Portuguese version of the HEAS, and global fit indices were used to assess whether the original four-dimensional structure of the scale was reproduced. The reliability of the Portuguese version of the HEAS was evaluated by Cronbach's alpha and the intraclass correlation coefficient. Measurement invariance examined sex differences in scale interpretation. Linear regressions were used to detect whether sociodemographic variables predict eco-anxiety and whether eco-anxiety predicts pro-environmental behaviours.

RESULTS

The factorial structure of the original scale was replicated in the Portuguese version of the HEAS, showing good internal consistency, reliability over time and strict invariance between men and women. A higher paternal education level predicted greater eco-anxiety in children. Two dimensions of eco-anxiety-namely, rumination and anxiety about personal impacts on the environment-predicted higher engagement in pro-environmental behaviours.

CONCLUSIONS

The translated scale is an appropriate tool to measure eco-anxiety in the Portuguese context and should be used to collect evidence to drive environmental and health policies. An individual's education level should be considered a determinant of their emotional response to environmental conditions. Importantly, eco-anxiety can act as a protective emotional response to preserving the planet.

Social group connections support mental health following wildfire

PURPOSE

As environmental disasters become more common and severe due to climate change, there is a growing need for strategies to bolster recovery that are proactive, cost-effective, and which mobilise community resources.

AIMS

We propose that building social group connections is a particularly promising strategy for supporting mental health in communities affected by environmental disasters.

METHODS

We tested the social identity model of identity change in a disaster context among 627 people substantially affected by the 2019-2020 Australian fires.

RESULTS

We found high levels of post-traumatic stress, strongly related to severity of disaster exposure, but also evidence of psychological resilience. Distress and resilience were weakly positively correlated. Having stronger social group connections pre-disaster was associated with less distress and more resilience 12-18 months after the disaster, via three pathways: greater social identification with the disaster-affected community, greater continuity of social group ties, and greater formation of new social group ties. New group ties were a mixed blessing, positively predicting both resilience and distress.

CONCLUSIONS

We conclude that investment in social resources is key to supporting mental health outcomes, not just reactively in the aftermath of disasters, but also proactively in communities most at risk.

Masculinity Matters for Meat Consumption: An Examination of Self-Rated Gender Typicality, Meat Consumption, and Veg*nism in Australian Men and Women

Previous research shows that men eat more meat than women. We explore the extent to which self-rated gender typicality explains differences in meat consumption intentions and behaviour. We recruited a large sample (N = 4897) of Australian men and women to complete an online survey about their attitudes and intentions regarding meat consumption and abstention and measured their self-rated gender typicality (the extent men view themselves as masculine, and women view themselves as feminine). We used moderated regression analyses to investigate self-rated gender typicality as a moderator of the relationship between gender and meat-related variables. We demonstrated that for men, identifying as more masculine was associated with a lower likelihood of reducing meat consumption or considering veg*nism, and a greater belief that eating meat is normal. We also found that men, and those with more gender-typical self-ratings (regardless of gender), viewed meat as more natural, necessary, and nice. These findings suggest that self-rated gender typicality may be relevant for understanding gender differences in meat consumption behaviours. Appeals to adopt low- or no-meat diets may be more effective if they consider the ways Australian diets are interconnected with genders and identities. Increasing acceptance of alternative masculinities, and developing masculinity-friendly advertising of plant-based foods, could be useful in promoting meat reduction.

Science Denial

Abstract. Science denial has adverse consequences at individual and societal levels and even for the future of our planet. The present article aimed to answer the question: What leads people to deny even the strongest evidence and distrust the scientific method? The article provides a narrative review of research on the underpinnings of science denial, with the main focus on climate change denial. Perspectives that are commonly studied separately are integrated. We review key findings on the roles of disinformation and basic cognitive processes, motivated reasoning (focusing on ideology and populism), and emotion regulation in potentially shaping (or not shaping) views on science and scientific topics. We also include research on youth, a group in an important transition phase in life that is the future decision-makers but less commonly focused on in the research field. In sum, we describe how the manifestations of denial can stem from cognitive biases, motivating efforts to find seemingly rational support for desirable conclusions, or attempts to regulate emotions when feeling threatened or powerless. To foster future research agendas and mindful applications of the results, we identify some research gaps (most importantly related to cross-cultural considerations) and examine the unique features or science denial as an object of psychological research. Based on the review, we make recommendations on measurement, science communication, and education.

Australians underestimate social compliance with coronavirus restrictions: findings from a national survey

OBJECTIVE

We assessed differences between Australians' perceptions of their own compliance with coronavirus restrictions and their perceptions of community compliance.

METHODS

We surveyed a national quota sample of 1,691 Australians in August and September 2020. Participants reported their level of compliance with coronavirus restrictions and estimated compliance from others in their state/territory.

RESULTS

Overwhelmingly, most people reported complying with restrictions. They believed their fellow community members were much less compliant. Age and other demographics were only weakly associated with self-reported compliance and perceptions of others' compliance.

CONCLUSIONS

The results are consistent with prevalent cognitive biases, including the tendency to believe one is better-than-average, and to more easily recall instances of deviances from social norms.

IMPLICATIONS FOR PUBLIC HEALTH

We recommend public health messaging avoids amplifying instances of social transgressions of coronavirus restrictions. Instead, the widespread nature of social compliance with restrictions across the country should be emphasised.

Ideological bases of attitudes towards meat abstention: Vegetarianism as a threat to the cultural and economic status quo

Those on the political right engage in greater meat consumption and animal exploitation than their left-wing counterparts. Previous research suggests this is because they view vegetarianism as threatening the nation’s dietary customs and economy. Across two studies, I extend this concept of “vegetarianism threat” by showing that it separates into two distinct dimensions of concern: cultural (symbolic) threats and economic (realistic) threats. The resultant multidimensional scale allows a finer grained understanding of the roots of ideology-based threat responses to meat-free movements. Together, results implicate symbolic concerns as the key element of vegetarianism threat contributing to negative attitudes towards meat abstention and its proponents.

The effects of a temporal framing manipulation on environmentalism: A replication and extension

Recent research promotes comparing the current state of the environment with the past (and not the future) to increase the pro-environmental attitudes of those on the political right. We aimed to replicate this temporal framing effect and extend on research in this area by testing the potential drivers of the effect. Across two large-scale replication studies, we found limited evidence that past comparisons (relative to future comparisons) increase pro-environmentalism among those with a more conservative political ideology, thus precluding a full investigation into the mediators of the effect. Where the effect was present, it was not consistent across studies. In Study One, conservatives reported greater certainty that climate change was real after viewing past comparisons, as the environmental changes were perceived as more certain. However, in Study Two, the temporal framing condition interacted with political orientation to instead undermine the certainty about climate change among political liberals in the past-focused condition. Together, these studies present the first evidence of backfire from temporal frames, and do not support the efficacy of past comparisons for increasing conservatives' environmentalism. We echo recent calls for open science principles, including preregistration and efforts to replicate existing work, and suggest the replication of other methods of inducing temporal comparisons.

The influence of social dominance orientation and right-wing authoritarianism on environmentalism: A five-year cross-lagged analysis

Social dominance orientation (SDO) and right-wing authoritarianism (RWA) are ideological attitudes that predict lower concern for the environment and less willingness to act on climate change. Research generally shows that SDO and RWA exhibit moderate, negative relationships with environmentalism. We examine the longitudinal influence of SDO and RWA on people's willingness to change their behaviour to benefit the environment in a national probability sample over five years. We show that both ideological attitudes relate to lower environmentalism across time and that the SDO effect was stronger than the RWA effect, yet the association from environmentalism to later endorsement of SDO is stronger than the reverse. Interestingly, these findings suggest that the more likely temporal association flows from environmentalism to SDO.

Effect of immune activation on the dynamics of human immunodeficiency virus replication and on the distribution of viral quasispecies

Virus replication in a human immunodeficiency virus (HIV)-infected individual, as determined by the steady-state level of plasma viremia, reflects a complex balance of viral and host factors. We have previously demonstrated that immunization of HIV-infected individuals with the common recall antigen, tetanus toxoid, disrupts this steady state, resulting in transient bursts of plasma viremia after immunization. The present study defines the viral genetic basis for the transient bursts in viremia after immune activation. Tetanus immunization was associated with dramatic and generally reversible shifts in the composition of plasma viral quasispecies. The viral bursts in most cases reflected a nonspecific increase in viral replication secondary to an expanded pool of susceptible CD4(+) T cells. An exception to this was in a patient who harbored viruses of differing tropisms (syncytium inducing and non-syncytium inducing [NSI]). In this situation, immunization appeared to select for the replication of NSI viruses. In one of three patients, the data suggested that immune activation resulted in the appearance in plasma of virus induced from latently infected cells. These findings illustrate certain mechanisms whereby antigenic stimulation may influence the dynamics of HIV replication, including the relative expression of different viral variants.

Increased in vitro tetanus-induced production of HIV type 1 following in vivo immunization of HIV type 1-infected individuals with tetanus toxoid

We have previously demonstrated that immunization of HIV-1-infected individuals with the common recall antigen, tetanus, induced transient increases in plasma viremia as well as an increased ability to isolate virus from CD8+ T cell-depleted peripheral blood mononuclear cells (PBMCs) under minimally stimulated culture conditions (IL-2 plus IL-4) postimmunization. In this study, HIV-1-infected individuals were immunized with tetanus toxoid and PBMCs were examined at multiple time points following immunization. Tetanus-induced production of virus was defined as an increased ability to isolate HIV-1 from CD8+ T cell-depleted PBMCs in vitro in the presence of tetanus antigen as opposed to no antigen or control antigen alone. Following immunization, in vitro tetanus-induced production of HIV-1 was observed in 8 of 13 (62%) patients compared to 2 of 13 (15%) patients prior to immunization. In four of these patients, virus could also be isolated from CD8+ T cell-depleted PBMCs in the presence of tetanus without the addition of any exogenous IL-2. Furthermore, virus could be isolated from the unfractionated PBMCs of two patients when tetanus antigen alone was added to the culture in the absence of added PHA or PHA blasts. HIV-1 was isolated predominantly from CD4+ T cells with a CD45RO+, CD25+ phenotype and was associated with a trend to elevated levels in culture supernatants of IFN-gamma, IL-6, TNF-alpha, and IL-4. These findings have important implications with regard to the role of ongoing antigen-specific immune responses in the induction of HIV-1 expression in vivo.

Effect of immunization with a common recall antigen on viral expression in patients infected with human immunodeficiency virus type 1

BACKGROUND

Activation of the immune system is a normal response to antigenic stimulation, and such activation enhances the replication of human immunodeficiency virus type 1 (HIV-1). We studied the effect of immunization with a common recall antigen on viral expression in HIV-1-infected patients, on the ability to isolate virus, and on the susceptibility to HIV-1 infection of peripheral-blood mononuclear cells (PBMCs) from control subjects not infected with HIV-1.

METHODS

Thirteen HIV-1-infected patients and 10 uninfected adults were given a 0.5-ml booster dose of tetanus toxoid. Studies were performed to evaluate changes in the degree of plasma viremia, proviral burden, the ability to isolate HIV-1, and the susceptibility of PBMCs to acute infection in vitro. Two patients underwent sequential lymph-node biopsies for the assessment of viral burden in these tissues.

RESULTS

All 13 HIV-1-infected patients had transient increase in plasma viremia after immunization, and the proviral burden increased in 11. These changes did not correlate with the base-line CD4+ T-cell counts. The lymph-node tissue also had increases in the proviral burden and viral RNA after immunization. The virus was more easily isolated from PBMCs from nine of the patients after immunization than before immunization. Despite considerable variability in the results, PBMCs from 7 of the 10 normal subjects were more easily infected in vitro with HIV-1 after immunization than before immunization.

CONCLUSIONS

Activation of the immune system by an ongoing antigen-specific immune response to an exogenous stimulus transiently increases the expression of HIV-1 and may enhance the susceptibility of uninfected subjects to HIV-1.

Human immunodeficiency virus infection of the human thymus and disruption of the thymic microenvironment in the SCID-hu mouse

Infection with the human immunodeficiency virus (HIV) results in immunosuppression and depletion of circulating CD4+ T cells. Since the thymus is the primary organ in which T cells mature it is of interest to examine the effects of HIV infection in this tissue. HIV infection has been demonstrated in the thymuses of infected individuals and thymocytes have been previously demonstrated to be susceptible to HIV infection both in vivo, using the SCID-hu mouse, and in vitro. The present study sought to determine which subsets of thymocytes were infected in the SCID-hu mouse model and to evaluate HIV-related alterations in the thymic microenvironment. Using two different primary HIV isolates, infection was found in CD4+/CD8+ double positive thymocytes as well as in both the CD4+ and CD8+ single positive subsets of thymocytes. The kinetics of infection and resulting viral burden differed among the three thymocyte subsets and depended on which HIV isolate was used for infection. Thymic epithelial (TE) cells were also shown to endocytose virus and to often contain copious amounts of viral RNA in the cytoplasm by in situ hybridization, although productive infection of these cells could not be definitively shown. Furthermore, degenerating TE cells were observed even without detection of HIV in the degenerating cells. Two striking morphologic patterns of infection were seen, involving either predominantly thymocyte infection and depletion, or TE cell involvement with detectable cytoplasmic viral RNA and/or TE cell toxicity. Thus, a variety of cells in the human thymus is susceptible to HIV infection, and infection with HIV results in a marked disruption of the thymic microenvironment leading to depletion of thymocytes and degeneration of TE cells.

Interferon gamma induces the expression of human immunodeficiency virus in persistently infected promonocytic cells (U1) and redirects the production of virions to intracytoplasmic vacuoles in phorbol myristate acetate-differentiated U1 cells

Interferon gamma (IFN-gamma), a lymphokine that exerts multiple immunoregulatory effects, has been found to be elevated in the plasma, cerebrospinal fluid, and lymph nodes of human immunodeficiency virus (HIV)-infected individuals and has shown variable effects on HIV replication in acutely infected cells. In the present study, we have demonstrated that IFN-gamma is a potent modulator of HIV expression in persistently infected U1 promonocytic cells in which virus production is characterized by a constitutive state of relative latency. Direct stimulation of U1 cells with IFN-gamma (10-1,000 U/ml) activated HIV expression, as measured by reverse transcriptase (RT) activity in the culture supernatant and increased levels of cell-associated viral protein and mRNAs. These effects on virus expression were not accounted for by the induction of endogenous TNF-alpha secretion, as previously described in U1 cells stimulated with phorbol myristate acetate (PMA). At the ultrastructural level, the stimulatory activity of IFN-gamma was correlated with HIV particle production in intracytoplasmic vacuoles along with the differentiation of U1 into macrophage-like cells. Furthermore, costimulation of U1 cells with IFN-gamma and PMA significantly increased the accumulation of vacuole-associated HIV concomitant with decreasing membrane-associated particles and RT activity production, as compared with cells stimulated with PMA alone. No evidence of spontaneous secretion of intracellular vacuole-associated virus was obtained by kinetic analysis of the RT activity released in the supernatants throughout the culture period unless cells were deliberately disrupted. These findings suggest that vacuole-associated virions likely represent a relatively stable intracellular reservoir of HIV, as previously described in primary macrophages infected in vitro or in infected macrophages in the brains of patients with acquired immune deficiency syndrome. The reduced levels of RT activity observed in the culture supernatants of U1 cells stimulated with PMA in the presence of IFN-gamma were not indicative of a suppressive effect of IFN-gamma on PMA-induced expression of HIV proteins and mRNAs, either directly or mediated by the release of IFN-alpha/beta. This study suggests that IFN-gamma may play an important role as an inducer of HIV expression in infected mononuclear phagocytes.

CD34+ bone marrow cells are infected with HIV in a subset of seropositive individuals

Individuals infected with HIV frequently develop cytopenias and suppressed hematopoiesis. The role of direct HIV infection of hematopoietic progenitor cells in this process has not been defined. In this study, purified CD34+ bone marrow progenitor cells from 74 Zairian and American patients were studied by both coculture viral isolation and polymerase chain reaction for evidence of HIV infection. A total of 36.5% of Zairian and 14% of American patients had HIV infection of the CD34+ cell subset, with as many as 1 in 500 CD34+ cells infected. Most of the Zairian patients in this study had advanced HIV infection and markedly decreased CD4/CD8 T lymphocyte ratios (mean 0.160 +/- 0.08), and no laboratory value predicted the presence of infection in the CD34+ subset of a given Zairian individual. In contrast, American patients with CD34+ cell infection had total CD4 cells less than 20/mm3 and a greater decrease of the CD4/CD8 T lymphocyte ratio compared to seropositive Americans without CD34+ cell infection (p = 0.003). Hematopoiesis, studied by methylcellulose colony assays, was depressed in all seropositive patients studied with no significant further suppression when CD34+ cells were infected. Thus, CD34+ bone marrow progenitor cells are infected in vivo in a subset of seropositive individuals and may serve as an additional reservoir of virus in HIV-infected individuals.

CD34+ bone marrow cells are infected with HIV in a subset of seropositive individuals

Individuals infected with HIV frequently develop cytopenias and suppressed hematopoiesis. The role of direct HIV infection of hematopoietic progenitor cells in this process has not been defined. In this study, purified CD34+ bone marrow progenitor cells from 74 Zairian and American patients were studied by both coculture viral isolation and polymerase chain reaction for evidence of HIV infection. A total of 36.5% of Zairian and 14% of American patients had HIV infection of the CD34+ cell subset, with as many as 1 in 500 CD34+ cells infected. Most of the Zairian patients in this study had advanced HIV infection and markedly decreased CD4/CD8 T lymphocyte ratios (mean 0.160 +/- 0.08), and no laboratory value predicted the presence of infection in the CD34+ subset of a given Zairian individual. In contrast, American patients with CD34+ cell infection had total CD4 cells less than 20/mm3 and a greater decrease of the CD4/CD8 T lymphocyte ratio compared to seropositive Americans without CD34+ cell infection (p = 0.003). Hematopoiesis, studied by methylcellulose colony assays, was depressed in all seropositive patients studied with no significant further suppression when CD34+ cells were infected. Thus, CD34+ bone marrow progenitor cells are infected in vivo in a subset of seropositive individuals and may serve as an additional reservoir of virus in HIV-infected individuals.

Thymic microenvironment induces HIV expression. Physiologic secretion of IL-6 by thymic epithelial cells up-regulates virus expression in chronically infected cells

The hallmark of infection with HIV-1 is progressive depletion and qualitative dysfunction of the CD4+ Th cell population in infected individuals. Clinical trials of antiretroviral agents have shown that, despite suppression of virus replication, regeneration of the T cell pool does not occur. One proposed explanation for the defective regenerative capacity of the CD4+ T cell pool is infection of early T lymphocyte progenitors or stem cells. An additional explanation could be failure of cells of the intrathymic microenvironment (thymic epithelial (TE) cells) to carry out critical nurturing functions for developing thymocytes, i.e., secretion of thymocyte-trophic cytokines and expression of adhesion molecules. This study examines the effect of HIV on cultured TE cells and determines the role of TE cells in the regulation of viral expression in chronically HIV-infected cells. We found no evidence of infection of TE cells after exposure to HIV-1. However, normal human serum induced secretion of IL-6 by TE cells; induction of TE IL-6 was partially blocked by anti-IFN-gamma antibodies. Moreover, supernatants from TE cells maintained in normal human serum up-regulated HIV replication in chronically HIV-1-infected cells. Because intrathymic T cell precursors can be infected with HIV and T cell precursors come into close contact with TE cells in the thymus, IL-6 secreted by TE cells during normal intrathymic development may induce HIV expression in infected thymocytes in vivo and promote the intrathymic spread of HIV.

Thymic microenvironment induces HIV expression. Physiologic secretion of IL-6 by thymic epithelial cells up-regulates virus expression in chronically infected cells

The hallmark of infection with HIV-1 is progressive depletion and qualitative dysfunction of the CD4+ Th cell population in infected individuals. Clinical trials of antiretroviral agents have shown that, despite suppression of virus replication, regeneration of the T cell pool does not occur. One proposed explanation for the defective regenerative capacity of the CD4+ T cell pool is infection of early T lymphocyte progenitors or stem cells. An additional explanation could be failure of cells of the intrathymic microenvironment (thymic epithelial (TE) cells) to carry out critical nurturing functions for developing thymocytes, i.e., secretion of thymocyte-trophic cytokines and expression of adhesion molecules. This study examines the effect of HIV on cultured TE cells and determines the role of TE cells in the regulation of viral expression in chronically HIV-infected cells. We found no evidence of infection of TE cells after exposure to HIV-1. However, normal human serum induced secretion of IL-6 by TE cells; induction of TE IL-6 was partially blocked by anti-IFN-gamma antibodies. Moreover, supernatants from TE cells maintained in normal human serum up-regulated HIV replication in chronically HIV-1-infected cells. Because intrathymic T cell precursors can be infected with HIV and T cell precursors come into close contact with TE cells in the thymus, IL-6 secreted by TE cells during normal intrathymic development may induce HIV expression in infected thymocytes in vivo and promote the intrathymic spread of HIV.

Heat shock induction of HIV production from chronically infected promonocytic and T cell lines

HIV infection is associated with a long period of clinical latency before the development of symptoms and HIV-related disease. Two chronically HIV-infected cell lines, U1 (promonocytic) and ACH-2 (T-lymphocytic) have been developed as models for studying the mechanisms governing viral latency and the reactivation of virus expression. We have previously shown that a variety of physiologic stimuli, including cytokines and cell stress, can up-regulate HIV expression from these cell lines. In this study we demonstrate that heat shock can also up-regulate the production of virus from both ACH-2 and U1 cells. Heat induction of virus appears to be mediated at the transcriptional level as established in long terminal repeat-chloramphenicol acetyl transferase transient transfection experiments with the use of U937 cells. This inductive effect in part requires the NF-kappa B-binding region of the HIV-long terminal repeat. Furthermore, although physiologic levels of heat are not sufficient to directly induce virus production from these cells, these temperatures are able to synergistically enhance virus production in U1 cells stimulated with IL-6 and granulocyte macrophage-CSF. In contrast, the inductive effect of other cytokines (i.e., TNF-alpha) was not affected by heat stimulation. These in vitro observations suggest that the hyperthermia associated with opportunistic infections, particularly in conjunction with certain cytokines that are released during immune reactions, may play a role in the in vivo induction of HIV expression in infected cells.

Heat shock induction of HIV production from chronically infected promonocytic and T cell lines

HIV infection is associated with a long period of clinical latency before the development of symptoms and HIV-related disease. Two chronically HIV-infected cell lines, U1 (promonocytic) and ACH-2 (T-lymphocytic) have been developed as models for studying the mechanisms governing viral latency and the reactivation of virus expression. We have previously shown that a variety of physiologic stimuli, including cytokines and cell stress, can up-regulate HIV expression from these cell lines. In this study we demonstrate that heat shock can also up-regulate the production of virus from both ACH-2 and U1 cells. Heat induction of virus appears to be mediated at the transcriptional level as established in long terminal repeat-chloramphenicol acetyl transferase transient transfection experiments with the use of U937 cells. This inductive effect in part requires the NF-kappa B-binding region of the HIV-long terminal repeat. Furthermore, although physiologic levels of heat are not sufficient to directly induce virus production from these cells, these temperatures are able to synergistically enhance virus production in U1 cells stimulated with IL-6 and granulocyte macrophage-CSF. In contrast, the inductive effect of other cytokines (i.e., TNF-alpha) was not affected by heat stimulation. These in vitro observations suggest that the hyperthermia associated with opportunistic infections, particularly in conjunction with certain cytokines that are released during immune reactions, may play a role in the in vivo induction of HIV expression in infected cells.

Induction of expression of human immunodeficiency virus in a chronically infected promonocytic cell line by ultraviolet irradiation

Infection with the human immunodeficiency virus (HIV) is often followed by a prolonged latent state, and mechanisms of maintaining latency or inducing expression from latency are active areas in AIDS research. It has been previously shown using a variety of viruses and cell systems that ultraviolet (UV) irradiation is capable of inducing the expression of latent viruses as well as augmenting the effects of acute viral infection. The ability of UV irradiation to affect HIV latency was investigated using a chronically HIV-infected, virus nonexpressing promonocytic cell line termed U1. After exposure to UV-C in doses ranging from 0.75 to 2.0 mJ/cm2, U1 cells were induced to express virus as assessed by detection of elevated reverse transcriptase activity and p24 antigen levels in culture supernatants of treated cells compared with unstimulated controls. In addition, immunofluorescence on cytospin preparations of UV-irradiated cells revealed a time-dependent increase in viral antigen production after UV stimulation. A similar increase in RT levels was seen after exposure of U1 cells to UV-B, although somewhat higher doses of UV-B (mJ) were required compared with UV-C (mJ). Viral induction by UV irradiation was associated with a drop in viability and a static growth curve, suggesting that a certain level of cellular stress was most likely necessary to initiate viral expression. The potential role of UV-induced cell damage with activation of a cellular "SOS" repair response is a probable explanation of the enhanced viral production observed.