A food-responsive switch modulates TFEB and autophagy, and determines susceptibility to coxsackievirus infection and pancreatitis

Almost a billion people worldwide are chronically undernourished. Herein, using a mouse model of coxsackievirus B3 (CVB3) infection, we report that a single day of food restriction (FR) markedly increases susceptibility to attenuated enterovirus infection, replication, and disease. These "pro-viral" effects, which are rapidly-reversed by the restoration of food, are mediated by several genes whose expression is altered by FR, and which support CVB3 replication. Central to this is TFEB, a protein whose expression and activation status are rapidly increased by FR. TFEB, which regulates the transcription of >100 genes involved in macroautophagy/autophagy and lysosomal biogenesis, responds similarly to both FR and CVB3 infection and plays a pivotal role in determining host susceptibility to CVB3. We propose that, by upregulating TFEB, FR generates an intracellular environment that is more hospitable to the incoming virus, facilitating its replication. This interplay between nutritional status and enterovirus replication has implications for human health and, perhaps, for the evolution of these viruses.Abbreviations: Atg/ATG: autophagy-related; CAR: Coxsackievirus and adenovirus receptor; Cas9: CRISPR associated protein 9; Cre: recombinase that causes recombination; CRISPR: clustered regularly interspaced short palindromic repeats; Ctsb/CTSB: cathepsin B; CVB3: coxsackievirus B3; DsRedCVB3: a recombinant CVB3 that encodes the Discosoma red fluorescent protein; EL: elastase; FR: food restriction; GFP: green fluorescent protein; gRNA: guide RNA; HBSS: Hanks Buffered Salt Solution; LYNUS: lysosomal nutrient sensing machinery; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; MFI: mean fluorescence intensity; MOI: multiplicity of infection; MTOR: mechanistic target of rapamycin kinase; Nluc: nanoluciferase; NlucCVB3: a recombinant CVB3 encoding nanoluciferase; pfu: plaque-forming unit(s); p.i.: post infection; rCVB: recombinant coxsackievirus B3; RPS6KB/p70S6K: ribosomal protein S6 kinase; RT: room temperature; siRNA: small interfering RNA; TFEB: transcription factor EB; tg: transgenic; TUBB: β-tubulin; UNINF: uninfected; wrt: with respect to; WT: wild type.

Hepatocytes engulf and rapidly silence coxsackievirus, protecting the host against systemic viral pathology

Liver has many biological functions, including (but by no means limited to) the removal, from the blood, of various pathogenic organisms. This phenomenon has been best-studied for bacteria, and is thought to be mainly mediated by Kupffer cells and sinusoidal endothelial cells; these cells, too, have been implicated in clearance of some viruses. However, to date, hepatocytes - which constitute ~90% of the liver’s biomass - have been thought to be bystanders in this activity. Herein we show that hepatocytes directly protect the host against type B coxsackieviruses (CVBs) by engulfing, then rapidly silencing, these pathogens. Novel CARHEP KO mice, which carry a hepatocyte-specific deletion of the coxsackievirus-adenovirus receptor (CAR), are unable to capture circulating CVB3, leading to a dramatic early rise in blood-borne virus, followed by markedly-elevated morbidity, mortality, and increased viral load. The enhanced pathogenicity in CARHEP KO mice occurs despite the production of abundant type I interferon (T1IFN), which is derived from plasmacytoid dendritic cells (pDCs). In addition, we show that in genetically-intact (wild type; WT) mice, the rapid hepatocyte silencing of trapped virus is dependent on IRF1; in its absence, CVB3 undergoes efficient productive replication in hepatocytes and, as a result, virus titers in all tested extrahepatic tissues are several logs higher than in WT animals. In summary, hepatocytes act as a trap for CVBs, internalizing the viruses and reducing systemic viral burden, and thereby protecting the host from systemic disease.

Biphasic and cardiomyocyte-specific IFIT activity protects cardiomyocytes from enteroviral infection

Viral myocarditis is a serious disease, commonly caused by type B coxsackieviruses (CVB). Here we show that innate immune protection against CVB3 myocarditis requires the IFIT (IFN-induced with tetratricopeptide) locus, which acts in a biphasic manner. Using IFIT locus knockout (IFITKO) cardiomyocytes we show that, in the absence of the IFIT locus, viral replication is dramatically increased, indicating that constitutive IFIT expression suppresses CVB replication in this cell type. IFNβ pre-treatment strongly suppresses CVB3 replication in wild type (wt) cardiomyocytes, but not in IFITKO cardiomyocytes, indicating that other interferon-stimulated genes (ISGs) cannot compensate for the loss of IFITs in this cell type. Thus, in isolated wt cardiomyocytes, the anti-CVB3 activity of IFITs is biphasic, being required for protection both before and after T1IFN signaling. These in vitro findings are replicated in vivo. Using novel IFITKO mice we demonstrate accelerated CVB3 replication in pancreas, liver and heart in the hours following infection. This early increase in virus load in IFITKO animals accelerates the induction of other ISGs in several tissues, enhancing virus clearance from some tissues, indicating that–in contrast to cardiomyocytes–other ISGs can offset the loss of IFITs from those cell types. In contrast, CVB3 persists in IFITKO hearts, and myocarditis occurs. Thus, cardiomyocytes have a specific, biphasic, and near-absolute requirement for IFITs to control CVB infection.

Viruses can infect the heart, causing inflammation–termed myocarditis–which is a serious, and sometimes fatal, disease. One way to combat the infection is by stimulating our immune system, encouraging it to fight the virus. However, the treatment that is currently used “revs up” many different parts of our immune system, including some that play little or no role in clearing the virus, and this wide-ranging activation increases the risk of potentially-harmful side effects. We want to identify the parts of the immune system that fight virus infections of the heart, so that we can improve the treatment of viral myocarditis by selectively stimulating only those immune responses, thereby retaining the benefit of treatment (i.e., clearing the virus) while reducing its cost (i.e. lowering the risk of harmful side effects). In this paper, we demonstrate that a family of proteins called IFITs play a role in protecting many tissues against these infections, but are particularly important in heart muscle cells, in which they are indispensable. Thus, IFITs represent a possible target for the treatment of viral myocarditis.

TCR independent suppression of CD8(+) T cell cytokine production mediated by IFNγ in vivo

CD8(+) memory T cells produce IFNγ within hours of secondary infection, but this is quickly terminated in vivo despite the presence of stimulatory viral antigen, suggesting that active suppression occurs. Herein, we investigated the in vivo effector function of CD8(+) memory T cells during successive encounters with viral antigen. CD8(+) T cells in immune mice receiving prior viral or peptide challenge failed to reproduce IFNγ during LCMV rechallenge. Surprisingly, this refractory state was induced even in memory cells that had not encountered their cognate antigen, indicating that the silencing of CD8(+) T cell responses is TCR-independent. Direct injection of IFNγ also suppressed the ability of virus-specific memory cells to respond to subsequent viral challenge. We propose the existence of a negative feedback loop whereby IFNγ, produced by memory CD8(+) T cells to combat viral challenge, acts - directly or indirectly - to limit its further production.

Type I IFN Signaling Is Dispensable during Secondary Viral Infection

Innate immune responses in general, and type I interferons (T1IFNs) in particular, play an important and often essential role during primary viral infections, by directly combatting the virus and by maximizing the primary adaptive immune response. Several studies have suggested that T1IFNs also contribute very substantially to the secondary (recall) response; they are thought (i) to be required to drive the early attrition of memory T cells, (ii) to support the subsequent expansion of surviving virus-specific memory cells, and (iii) to assist in the suppression and clearance of the infectious agent. However, many of these observations were predicated upon models in which T1IFN signaling was interrupted prior to a primary immune response, raising the possibility that the resulting memory cells might be intrinsically abnormal. We have directly addressed this by using an inducible-Cre model system in which the host remains genetically-intact during the primary response to infection, and in which T1IFN signaling can be effectively ablated prior to secondary viral challenge. We report that, in stark contrast to primary infection, T1IFN signaling is not required during the recall response. IFNαβR-deficient memory CD8+ and CD4+ memory T cells undergo attrition and expansion with kinetics that are indistinguishable from those of receptor-sufficient cells. Moreover, even in the absence of functional T1IFN signaling, the host's immune capacity to rapidly suppress, and then to eradicate, a secondary infection remains intact. Thus, this study shows that T1IFN signaling is dispensable during the recall response to a virus infection. Moreover, two broader implications may be drawn. First, a T cell's requirement for a cytokine is highly dependent on the cell's maturation / differentiation status. Consequently, second, these data underscore the importance of evaluating a gene's impact by modulating its expression or function in a temporally-controllable manner.

Coxsackievirus can exploit LC3 in both autophagy-dependent and -independent manners in vivo

RNA viruses modify intracellular membranes to produce replication scaffolds. In pancreatic cells, coxsackievirus B3 (CVB3) hijacks membranes from the autophagy pathway, and in vivo disruption of acinar cell autophagy dramatically delays CVB3 replication. This is reversed by expression of GFP-LC3, indicating that CVB3 may acquire membranes from an alternative, autophagy-independent, source(s). Herein, using 3 recombinant CVB3s (rCVB3s) encoding different proteins (proLC3, proLC3(G120A), or ATG4B(C74A)), we show that CVB3 is, indeed, flexible in its utilization of cellular membranes. When compared with a control rCVB3, all 3 viruses replicated to high titers in vivo, and caused severe pancreatitis. Most importantly, each virus appeared to subvert membranes in a unique manner. The proLC3 virus produced a large quantity of LC3-I which binds to phosphatidylethanolamine (PE), affording access to the autophagy pathway. The proLC3(G120A) protein cannot attach to PE, and instead binds to the ER-resident protein SEL1L, potentially providing an autophagy-independent source of membranes. Finally, the ATG4B(C74A) protein sequestered host cell LC3-I, causing accumulation of immature phagophores, and massive membrane rearrangement. Taken together, our data indicate that some RNA viruses can exploit a variety of different intracellular membranes, potentially maximizing their replication in each of the diverse cell types that they infect in vivo.

CD8+ T cells maintain suppression of simian immunodeficiency virus in the central nervous system

Human immunodeficiency virus (HIV) accesses the brain early in infection and can lead to neurocognitive disorders. The brain can also serve as a viral reservoir, but how virus is controlled in the brain is unknown. To examine this, CD8-depleting monoclonal antibody was injected into the cerebrospinal fluid of rhesus monkeys with chronic simian immunodeficiency virus (SIV) infection. This treatment led to the rapid increase of SIV in the brain. Virus in the brain is maintained by active suppression from the host immune system. This dynamic interaction can be manipulated in efforts to control and eradicate virus from the brain and other reservoirs.

Antigen-specific naive CD8+ T cells produce a single pulse of IFN-γ in vivo within hours of infection, but without antiviral effect

In vitro studies have shown that naive CD8(+) T cells are unable to express most of their effector proteins until after at least one round of cell division has taken place. We have reassessed this issue in vivo and find that naive CD8(+) T cells mount Ag-specific responses within hours of infection, before proliferation has commenced. Newly activated naive Ag-specific CD8(+) T cells produce a rapid pulse of IFN-γ in vivo and begin to accumulate granzyme B and perforin. Later, in vivo cytolytic activity is detectable, coincident with the initiation of cell division. Despite the rapid development of these functional attributes, no antiviral effect was observed early during infection, even when the cells are present in numbers similar to those of virus-specific memory cells. The evolutionary reason for the pulse of IFN-γ synthesis by naive T cells is uncertain, but the lack of antiviral impact suggests that it may be regulatory.

CD8+ memory T cells appear exhausted within hours of acute virus infection

CD8(+) memory T cells are abundant and are activated in a near-synchronous manner by infection, thereby providing a unique opportunity to evaluate the coordinate functional and phenotypic changes that occur in vivo within hours of viral challenge. Using two disparate virus challenges of mice, we show that splenic CD8(+) memory T cells rapidly produced IFN-γ in vivo; however, within 18-24 h, IFN-γ synthesis was terminated and remained undetectable for ≥ 48 h. A similar on/off response was observed in CD8(+) memory T cells in the peritoneal cavity. Cessation of IFN-γ production in vivo occurred despite the continued presence of immunostimulatory viral Ag, indicating that the initial IFN-γ response had been actively downregulated and that the cells had been rendered refractory to subsequent in vivo Ag contact. Downregulation of IFN-γ synthesis was accompanied by the upregulation of inhibitory receptor expression on the T cells, and ex vivo analyses using synthetic peptides revealed a concurrent hierarchical loss of cytokine responsiveness (IL-2, then TNF, then IFN-γ) taking place during the first 24 h following Ag contact. Thus, within hours of virus challenge, CD8(+) memory T cells display the standard hallmarks of T cell exhaustion, a phenotype that previously was associated only with chronic diseases and that is generally viewed as a gradually developing and pathological change in T cell function. Our data suggest that, instead, the "exhaustion" phenotype is a rapid and normal physiological T cell response.

Pancreatic acinar cell-specific autophagy disruption reduces coxsackievirus replication and pathogenesis in vivo

Autophagy protects against many infections by inducing the lysosomal-mediated degradation of invading pathogens. However, previous in vitro studies suggest that some enteroviruses not only evade these protective effects but also exploit autophagy to facilitate their replication. We generated Atg5(f/f)/Cre(+) mice, in which the essential autophagy gene Atg5 is specifically deleted in pancreatic acinar cells, and show that coxsackievirus B3 (CVB3) requires autophagy for optimal infection and pathogenesis. Compared to Cre(-) littermates, Atg5(f/f)/Cre(+) mice had an ∼2,000-fold lower CVB3 titer in the pancreas, and pancreatic pathology was greatly diminished. Both in vivo and in vitro, Atg5(f/f)/Cre(+) acinar cells had reduced intracellular viral RNA and proteins. Furthermore, intracellular structural elements induced upon CVB3 infection, such as compound membrane vesicles and highly geometric paracrystalline arrays, which may represent viral replication platforms, were infrequently observed in infected Atg5(f/f)/Cre(+) cells. Thus, CVB3-induced subversion of autophagy not only benefits the virus but also exacerbates pancreatic pathology.

Interactions between enteroviruses and autophagy in vivo

Autophagy plays a protective role during many viral and bacterial infections. Predictably, evolution has led to several viruses developing mechanisms by which to evade the inhibitory effects of the pathway. However, one family of viruses, the picornaviruses, has gone one step further, by actively exploiting autophagy. Using mice in which Atg5 has been conditionally deleted in pancreatic acinar cells, we have studied the outcome of infection by coxsackievirus B3 (CVB3), a member of the enterovirus genus and picornavirus family. Two key findings emerged: disruption of autophagy (1) dramatically compromised virus replication in vivo, and (2) significantly limited pancreatic disease.

Wild-type coxsackievirus infection dramatically alters the abundance, heterogeneity, and immunostimulatory capacity of conventional dendritic cells in vivo

In vitro studies have shown that enteroviruses employ strategies that may impair the ability of DCs to trigger T cell immunity, but it is unclear how these viruses affect DCs in vivo. Here, we evaluate the effects of wild-type (wt) coxsackievirus B3 on DCs in vitro and in a murine model in vivo. Although CVB3 does not productively infect the vast majority of DCs, virus infection profoundly reduces splenic conventional DC numbers and diminishes their capacity to prime naïve CD8(+) T cells in vitro. In contrast to recombinant CVB3, highly pathogenic wt virus infection significantly diminishes the host's capacity to mount T cell responses, which is temporally associated with the loss of CD8α(+) DCs. Our findings demonstrate that enterovirus infection substantially alters the number, heterogeneity, and stimulatory capacity of DCs in vivo, and these dramatic immunomodulatory effects may weaken the host's capacity to mount antiviral T cell responses.

Upregulation of cathepsin D in the caudate nucleus of primates with experimental parkinsonism

BACKGROUND

In Parkinson's disease there is progressive loss of dopamine containing neurons in the substantia nigra pars compacta. The neuronal damage is not limited to the substantia nigra but progresses to other regions of brain, leading to loss of motor control as well as cognitive abnormalities. The purpose of this study was to examine causes of progressive damage in the caudate nucleus, which plays a major role in motor coordination and cognition, in experimental Parkinson's disease.

RESULTS

Using chronic 1-methyl-4phenyl-1,2,3,6-tetrahydropyridine treatment of rhesus monkeys to model Parkinson's disease, we found a upregulation of Cathepsin D, a lysosomal aspartic protease, in the caudate nucleus of treated monkeys. Immunofluorescence analysis of caudate nucleus brain tissue showed that the number of lysosomes increased concurrently with the increase in Cathepsin D in neurons. In vitro overexpression of Cathepsin D in a human neuroblastoma cell line led to a significant increase in the number of the lysosomes. Such expression also resulted in extralysosomal Cathepsin D and was accompanied by significant neuronal death associated with caspase activation. We examined apoptotic markers and found a strong correlation of Cathepsin D overexpression to apoptosis.

CONCLUSIONS

Following damage to the substantia nigra resulting in experimental Parkinson's disease, we have identified pathological changes in the caudate nucleus, a likely site of changes leading to the progression of disease. Cathepsin D, implicated in pathogenic mechanisms in other disorders, was increased, and our in vitro studies revealed its overexpression leads to cellular damage and death. This work provides important clues to the progression of Parkinson's, and provides a new target for strategies to ameliorate the progression of this disease.

Short-term fasting induces profound neuronal autophagy

Disruption of autophagy--a key homeostatic process in which cytosolic components are degraded and recycled through lysosomes--can cause neurodegeneration in tissue culture and in vivo. Upregulation of this pathway may be neuroprotective, and much effort is being invested in developing drugs that cross the blood brain barrier and increase neuronal autophagy. One well-recognized way of inducing autophagy is by food restriction, which upregulates autophagy in many organs including the liver; but current dogma holds that the brain escapes this effect, perhaps because it is a metabolically privileged site. Here, we have re-evaluated this tenet using a novel approach that allows us to detect, enumerate and characterize autophagosomes in vivo. We first validate the approach by showing that it allows the identification and characterization of autophagosomes in the livers of food-restricted mice. We use the method to identify constitutive autophagosomes in cortical neurons and Purkinje cells, and we show that short-term fasting leads to a dramatic upregulation in neuronal autophagy. The increased neuronal autophagy is revealed by changes in autophagosome abundance and characteristics, and by diminished neuronal mTOR activity in vivo, demonstrated by a reduction in levels of phosphorylated S6 ribosomal protein in Purkinje cells. The increased abundance of autophagosomes in Purkinje cells was confirmed using transmission electron microscopy. Our data lead us to speculate that sporadic fasting might represent a simple, safe and inexpensive means to promote this potentially therapeutic neuronal response.

Coxsackievirus B3 inhibits antigen presentation in vivo, exerting a profound and selective effect on the MHC class I pathway

Many viruses encode proteins whose major function is to evade or disable the host T cell response. Nevertheless, most viruses are readily detected by host T cells, and induce relatively strong T cell responses. Herein, we employ transgenic CD4⁺ and CD8⁺ T cells as sensors to evaluate in vitro and in vivo antigen presentation by coxsackievirus B3 (CVB3), and we show that this virus almost completely inhibits antigen presentation via the MHC class I pathway, thereby evading CD8⁺ T cell immunity. In contrast, the presentation of CVB3-encoded MHC class II epitopes is relatively unencumbered, and CVB3 induces in vivo CD4⁺ T cell responses that are, by several criteria, phenotypically normal. The cells display an effector phenotype and mature into multi-functional CVB3-specific memory CD4⁺ T cells that expand dramatically following challenge infection and rapidly differentiate into secondary effector cells capable of secreting multiple cytokines. Our findings have implications for the efficiency of antigen cross-presentation during coxsackievirus infection.

Many viruses—for example, large DNA viruses like smallpox virus and herpesviruses—encode several proteins whose major function is to combat the host's immune response, but these proteins usually battle in vain; in general, the mammalian immune system is sufficiently accomplished to penetrate this viral armor, allowing the infected animal to mount an immune response that can eradicate—or, at least, suppress—the infectious agent. Here, we show that coxsackievirus, a small RNA virus, carries a far more powerful punch than its larger DNA cousins; it almost entirely evades detection by host CD8⁺ T cells, which usually are one of the key components of an antiviral immune response. How does the virus achieve such success? Normally, when a virus infects a cell, certain host proteins capture small fragments of the virus and display them on the cell's surface, allowing them to be detected by the host immune system—usually, by cells called CD8⁺ T cells. We show here that coxsackievirus very effectively prevents these “flags” from reaching the cell surface in a form that can trigger naïve T cells to respond; in effect, the virus renders the cell “invisible” to CD8⁺ T cells, creating a cocoon in which the virus can multiply undisturbed by host immunity.

Coxsackievirus B3 has profoundly different inhibitory effects on the MHC class I and class II antigen presentation pathways (131.2)

Coxsackievirus B (CVB) infections cause considerable morbidity and mortality, and strategies to treat or prevent CVB-associated disease may benefit from a clearer understanding of the host immune response to virus infection. CVB3 induces minimal endogenous naïve CD8 and CD4 T cell responses, possibly because viral antigen (Ag) presentation is extremely limited. Several CVB3 proteins are known to cooperatively downregulate MHC class I on infected cells in vitro. In this study, we used transgenic (Tg) CD4 and CD8 T cells as sensors to evaluate viral Ag presentation by the MHC class I and class II pathways in vivo. Our analysis revealed a striking difference in Tg T cell responses: CD4 Tg T cells proliferated in CVB3-infected mice whereas CD8 Tg T cells failed to divide. Moreover, virus infection generated multi-functional memory CD4 T cells, which expanded dramatically following challenge infection, and rapidly differentiated into secondary effector Th1 cells. Although naïve CD8 Tg T cells were unresponsive to CVB3, they persisted in the host and responded vigorously when stimulated by a different virus encoding their cognate Ag. These data suggest that CVB3 utilizes a powerful immune evasion strategy in vivo that differentially affects the two Ag presentation pathways, and that this difference regulates the host's capacity to mount CD4 and CD8 T cell responses. This work was supported by NIH R01 AI42314 and T32 NS41219.

Elevated ATG5 expression in autoimmune demyelination and multiple sclerosis

Multiple sclerosis (MS) is an inflammatory central nervous system (CNS) disorder characterized by T cell-mediated demyelination. In MS, prolonged T cell survival and increased T cell proliferation have been linked to disease relapse and progression. Recently, the autophagy-related gene 5 (Atg5) has been shown to modulate T cell survival. In this study, we examined the expression of Atg5 using both a mouse model of autoimmune demyelination as well as blood and brain tissues from MS cases. Quantitative real-time PCR analysis of RNA isolated from blood samples of experimental autoimmune encephalomyelitis (EAE) mice revealed a strong correlation between Atg5 expression and clinical disability.Analysis of protein extracted from these cells confirmed both upregulation and post-translational modification of Atg5, the latter of which was positively correlated with EAE severity. Analysis of RNA extracted from T cells isolated by negative selection indicated that Atg5 expression was significantly elevated in individuals with active relapsing-remitting MS compared to non-diseased controls. Brain tissue sections from relapsing-remitting MS cases examined by immunofluorescent histochemistry suggested that encephalitogenic T cells are a source of Atg5 expression in MS brain samples. Together these data suggest that increased T cell expression of Atg5 may contribute to inflammatory demyelination in MS.

Disruption of neuronal autophagy by infected microglia results in neurodegeneration

There is compelling evidence to support the idea that autophagy has a protective function in neurons and its disruption results in neurodegenerative disorders. Neuronal damage is well-documented in the brains of HIV-infected individuals, and evidence of inflammation, oxidative stress, damage to synaptic and dendritic structures, and neuronal loss are present in the brains of those with HIV-associated dementia. We investigated the role of autophagy in microglia-induced neurotoxicity in primary rodent neurons, primate and human models. We demonstrate here that products of simian immunodeficiency virus (SIV)-infected microglia inhibit neuronal autophagy, resulting in decreased neuronal survival. Quantitative analysis of autophagy vacuole numbers in rat primary neurons revealed a striking loss from the processes. Assessment of multiple biochemical markers of autophagic activity confirmed the inhibition of autophagy in neurons. Importantly, autophagy could be induced in neurons through rapamycin treatment, and such treatment conferred significant protection to neurons. Two major mediators of HIV-induced neurotoxicity, tumor necrosis factor-alpha and glutamate, had similar effects on reducing autophagy in neurons. The mRNA level of p62 was increased in the brain in SIV encephalitis and as well as in brains from individuals with HIV dementia, and abnormal neuronal p62 dot structures immunoreactivity was present and had a similar pattern with abnormal ubiquitinylated proteins. Taken together, these results identify that induction of deficits in autophagy is a significant mechanism for neurodegenerative processes that arise from glial, as opposed to neuronal, sources, and that the maintenance of autophagy may have a pivotal role in neuroprotection in the setting of HIV infection.

Effects of simian immunodeficiency virus on the circadian rhythms of body temperature and gross locomotor activity

In monkeys infected with simian immunodeficiency virus (SIV), changes in body temperature and locomotor activity occur after the acute retroviral syndrome stage of the disease. However, alterations to the circadian rhythm of these factors in SIV-infected monkeys have not been reported. To determine whether the circadian rhythm of body temperature and locomotor activity are disrupted during SIV infection, we analyzed the temperature and activity patterns of SIV-infected monkeys through different stages of the disease, progressing to SIV encephalitis by using the cosinor model for circadian oscillation. We found that SIV infection resulted in significant impairments of the amplitude and mean of the circadian rhythm of body temperature and activity and in the acrophase of the circadian rhythm for temperature. These alterations were not related to changes observed in the acute febrile response induced after viral inoculation. In animals killed once marked circadian anomalies were evident, microglia infiltration and macrophage accumulation in the hypothalamus were observed. Together, these results clearly demonstrate that SIV infection compromises aspects of circadian regulation in monkeys, with important implications for physiological functions, including cognition, in HIV-infected individuals.

Host response and dysfunction in the CNS during chronic simian immunodeficiency virus infection

CNS abnormalities can be detected during chronic human immunodeficiency virus (HIV) infection, before the development of opportunistic infections or other sequelae of immunodeficiency. However, although end-stage dementia caused by HIV has been linked to the presence of infected and activated macrophages and microglia in the brain, the nature of the changes resulting in the motor and cognitive disorders in the chronic stage is unknown. Using simian immunodeficiency virus-infected rhesus monkeys, we sought the molecular basis for CNS dysfunction. In the chronic stable stage, nearly 2 years after infection, all animals had verified CNS functional abnormalities. Both virus and infiltrating lymphocytes (CD8+ T-cells) were found in the brain. Molecular analysis revealed that the expression of several immune response genes was increased, including CCL5, which has pleiotropic effects on neurons as well as immune cells. CCL5 was significantly upregulated throughout the course of infection, and in the chronic phase was present in the infiltrating lymphocytes. We have identified an altered state of the CNS at an important stage of the viral-host interaction, likely arising to protect against the virus but in the long term leading to damaging processes.

Modeling human methamphetamine exposure in nonhuman primates: chronic dosing in the rhesus macaque leads to behavioral and physiological abnormalities

Acute high dose methamphetamine (METH) dosing regimens are frequently used in animal studies, however, these regimens can lead to considerable toxicity and even death in experimental animals. Acute high dosing regimens are quite distinct from the chronic usage patterns found in many human METH abusers. Furthermore, such doses, especially in nonhuman primates, can result in unexpected death, which is unacceptable, especially when such deaths fail to accurately model effects of human usage. As a model of chronic human METH abuse we have developed a nonlethal chronic METH administration procedure for the rhesus macaque that utilizes an escalating dose protocol. This protocol slowly increases the METH dosage from 0.1 to 0.7 mg/kg b.i.d. over a period of 4 weeks, followed by a period of chronic METH administration at 0.75 mg/kg b.i.d. (= total daily METH administration of 1.5 mg/kg). In parallel to human usage patterns, METH injections were given 20-23 times a month. This regimen produced a number of behavioral and physiological effects including decreased food intake and a significant increase in urinary cortisol excretion.

Controlled and behaviorally relevant levels of oral ethanol intake in rhesus macaques using a flavorant-fade procedure

BACKGROUND

Flavorant-fading procedures can initiate and maintain oral ethanol intake in rodents. The present study developed a similar procedure to achieve controlled and behaviorally relevant levels of ethanol intake in monkeys.

METHODS

Male rhesus macaques (N = 13) were initially given the opportunity to consume 0.5 g/kg of a 1% (w/v) ethanol plus 4% (w/v) Tang solution in 1-hr limited-access sessions without the requirement of an operant response. Once consumption was stable at a particular concentration (%) and/or amount (g/kg), animals were given access to higher concentrations and/or amounts of ethanol. Animals were tested on a bimanual motor skill (BMS) task 20 and 90 min after consumption to assess behavioral impairment. Blood alcohol levels (BALs) were assessed after a session in which animals had the opportunity to consume up to 3.0 g/kg of 6% (w/v) ethanol.

RESULTS

The gradual fading up of higher concentrations and amounts of ethanol resulted in controlled and robust levels (>2.0 g/kg) of ethanol intake in half of the subjects. Increasing the concentration of the sweetener from 4 to 6% (w/v) was effective in initiating consumption in three animals. Two monkeys required the additional step of presenting the increased-sweetener solutions after a meal (postprandial consumption) to initiate significant ethanol intake. Animals were significantly impaired on the BMS task after consumption of 2.0, 2.5, and 3.0 g/kg of ethanol. Individual consumption ranging from 0.8 to 3.0 g/kg of ethanol produced BALs of 18 to 269 mg/dl.

CONCLUSIONS

The flavorant-fading procedure was effective in producing behaviorally relevant levels of ethanol consumption in rhesus macaques. This model facilitated a randomized-dose procedure to determine the behavioral effects of 0.5 to 3.0 g/kg of ethanol. This procedure therefore is of significant utility in determining behavioral or physiologic effects of specific doses of consumed ethanol in monkeys.

CD8+ cell depletion amplifies the acute retroviral syndrome

The duration and severity of the symptomatology present during the early phase of human immunodeficiency virus (HIV) infection (known as the acute retroviral syndrome) is associated with alterations in the clinical profile of infection, such as a shortening of duration between infection with HIV and the onset of neurocognitive impairment and acquired immunodeficiency syndrome (AIDS). Viral-specific CD8+ cytotoxic T lymphocytes (CTLs) and CD8+ natural killer (NK) cells play a key role in antiviral immunity. Loss of CD8+ cells or their functional impairment during the early period of infection is associated with a rapid progression to AIDS in nonhuman primate studies. However, no studies have determined whether CD8+ cell loss or impairment is associated with symptoms of acute retroviral illness such as fever. In this study, the authors compared the early phase of simian immunodeficiency virus (SIV) infection in animals that were treated with the anti-CD8 monoclonal antibody cM-T807 to deplete CD8+ cells during the early period of infection (SIV+ CD8- group) to those with intact CD8+ cells (SIV+ CD8+ group). The SIV+ CD8- group had an enhanced acute retroviral syndrome when compared to the SIV+ CD8+ group. The SIV+ CD8- group also had prolonged high viral loads and distinct alterations in the proinflammatory cytokines interleukin (IL)-6 and interferon (IFN)-alpha, as well as in monocyte chemoattractant protein (MCP)-1. CD8+ cell depletion, therefore, appears to enhance symptoms of the acute retroviral syndrome and alters several of the immunological factors associated with the early phase of infection.

Patient and technique survival for blind and sighted diabetics on continuous ambulatory peritoneal dialysis: a ten-year analysis

A retrospective analysis of patient and technique survival over 10 years in a group of 66 diabetics (40 being blind) and 71 non-diabetics was undertaken. Patient survival profiles showed that the blind diabetics lived longer than the sighted, but for a shorter time than the nondiabetics. In technique success, the sighted diabetics out did the blind and the non-diabetics, long term. Short term, the blind performed better than sighted diabetics. The key to success and longer survival on CAPD depended on motivation on the part of the patient, patient's acceptance of given disability, family (social) support, and willingness on the part of renal care personnel to train the disabled diabetic to perform CAPD. With adequate education and support, blind diabetics did CAPD as well as sighted patients. There was no increased frequency of peritonitis in blind diabetics compared to sighted diabetics. Both blind diabetics and non-diabetics had fewer episodes than sighted diabetics. Intraperitoneal route of insulin administration achieved good glycemic control in diabetic population. Refractory congestive cardiac failure and/or fatal arrhythmias was the most common cardiac cause of death in diabetics on CAPD.

Acute abdominal events and their impact on morbidity and mortality in a CAPD program

A retrospective analysis was done to explore the impact of acute abdominal events other than peritonitis, on morbidity and mortality in a CAPD program over a span of 6 years. Subtlety of clinical manifestations and low yield from investigational attempts (except microbiologic) made decision-making as to whether or not to continue CAPD, hard. An increased prevalence of septicemic shock with its inevitable high risk of morbidity and mortality was striking. Timely termination of CAPD and change over to hemodialysis may help to prevent dissemination of infection in these patients. Among the vascular causes of death in CAPD patients, bowel infarction seemed to be the most common.

Why blind diabetics with renal failure should be offered treatment

During May 1978 to April 1983 this renal dialysis unit treated 65 patients by continuous ambulatory peritoneal dialysis. Of these, 24 had type I (insulin dependent) diabetes, of whom 20 were blind; eight had type II (non-insulin dependent) diabetes, of whom three were blind; and 33 did not have diabetes and were not blind. The cumulative actuarial survival rates of these patients at five years were 60% for blind diabetics, 40% for sighted diabetics, and 46% for the non-diabetics. Of the 23 blind patients, 22 successfully achieved self care, including the self administration of insulin into the peritoneal dialysis solution. Blind patients had the least peritonitis and fewest complications of continuous ambulatory peritoneal dialysis, and none objected to the treatment or requested to be taken off it or be allowed to die. It was concluded that blind diabetic patients with renal failure showed both the will and the ability to stay alive and that their treatment was worth while.

Long-term continuous ambulatory peritoneal dialysis

This paper reports experience with 65 patients treated by continuous ambulatory peritoneal dialysis (CAPD) during the past five years. The patients are divided into 33 non-diabetic and 32 diabetic and the latter are subdivided into blind and sighted. Cumulative actuarial survival on CAPD calculated at five years was highest for blind diabetics, intermediate for non-diabetic and lowest for sighted diabetics. Blind diabetics had the lowest rate of drop-out from CAPD. Many patients, especially in the non-diabetic and sighted diabetic groups required temporary haemodialysis which allowed them to return to CAPD.

Percutaneous subclavian vein catheter hemodialysis--impact on vascular access surgery

The problem of the immediate need for access to the circulation for hemodialysis arises because of an acute renal failure (ARF), the failure of an established access route, or the acute presentation of end-stage renal disease. Prior to 1976 emergent hemodialysis at our center necessitated either surgical placement of an external shunt or intermittent femoral vein cannulization, Since 1976 indwelling percutaneous subclavian vein catheterization (SVC) has been used on a routine basis for emergency hemodialysis. We have evaluated retrospectively the clinical courses of 50 patients with ARF and 48 patients with chronic renal failure (CRF) who underwent SVC dialysis in comparison with the clinical courses of 50 patients with ARF and 35 patients with CRF who had external shunt dialysis. In the ARF group, SVC dialysis resulted in lower incidences of serious infection, hemorrhage, and access thrombosis and reduced the number of replacement access procedures needed. In the CRF group, SVC permitted creation of more autogenous fistulas, rarely failed because of infection or thrombosis, and could therefore be used for extended periods, allowing primary autogenous fistula placement and maturation. Future access sites were also saved. SVC dialysis has become our primary interval angioaccess procedure for acute hemodialysis.

A comparison of continuous ambulatory peritoneal dialysis in diabetic and nondiabetic patients

Between May of 1978 and December of 1980 we have treated 33 patients with continuous ambulatory peritoneal dialysis (CAPD) for a total of 1209 patient weeks. Thirteen patients were diabetic, 14 nondiabetic but with complications that made CAPD the treatment of choice, and six were nondiabetic without complications. Good control of plasma glucose was obtained n diabetics by the use of intraperitoneal insulin. Overall plasma glucose control, as estimated by glycohemoglobin and fasting plasma glucose levels was the same in both groups. Plasma triglyceride levels were normal in most of the diabetic patients and elevated in most of te nondiabetic patients. Visual difficulties did not prevent self-dialysis in seven diabetic patients who were legally blind, and these patients spent the least time in hospital and had the least peritonitis. Diabetic patients seem at least as able to cope with CAPD as nondiabetic patients and may derive some special advantages from the technique.

Improvement in lacrimal and salivary secretions after alkali therapy in Sjøgren's syndrome with renal tubular acidosis

A patient with Sjøgren's syndrome developed renal tubular acidosis which led to systemic acidosis and potassium depletion. Treatment with Shohl's solution and potassium supplements was followed by subjective improvement in tear flow, salivary flow, and by disappearance of bronchitic symptoms. Detailed objective assessments were then made during the next year, twice on treatment and twice without. These confirmed the subjective impression of improvement.

Post-traumatic renal failure, including the use of the mobile artificial kidney

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