Bimoclomol (BRLP-42) ameliorates peripheral neuropathy in streptozotocin-induced diabetic rats

Resolution of inflammation in chronic disease via restoration of the heat shock response (HSR)

Effective resolution of inflammation via the heat shock response (HSR) is pivotal in averting the transition to chronic inflammatory states. This transition characterizes a spectrum of debilitating conditions, including insulin resistance, obesity, type 2 diabetes, nonalcoholic fatty liver disease, and cardiovascular ailments. This manuscript explores a range of physiological, pharmacological, and nutraceutical interventions aimed at reinstating the HSR in the context of chronic low-grade inflammation, as well as protocols to assess the HSR. Monitoring the progression or suppression of the HSR in patients and laboratory animals offers predictive insights into the organism's capacity to combat chronic inflammation, as well as the impact of exercise and hyperthermic treatments (e.g., sauna or hot tub baths) on the HSR. Interestingly, a reciprocal correlation exists between the expression of HSR components in peripheral blood leukocytes (PBL) and the extent of local tissue proinflammatory activity in individuals afflicted by chronic inflammatory disorders. Therefore, the Heck index, contrasting extracellular 70 kDa family of heat shock proteins (HSP70) (proinflammatory) and intracellular HSP70 (anti-inflammatory) in PBL, serves as a valuable metric for HSR assessment. Our laboratory has also developed straightforward protocols for evaluating HSR by subjecting whole blood samples from both rodents and human volunteers to ex vivo heat challenges. Collectively, this discussion underscores the critical role of HSR disruption in the pathogenesis of chronic inflammatory states and emphasizes the significance of simple, cost-effective tools for clinical HSR assessment. This understanding is instrumental in the development of innovative strategies for preventing and managing chronic inflammatory diseases, which continue to exert a substantial global burden on morbidity and mortality.

HSF1 and Its Role in Huntington's Disease Pathology

PURPOSE OF REVIEW

Heat shock factor 1 (HSF1) is the master transcriptional regulator of the heat shock response (HSR) in mammalian cells and is a critical element in maintaining protein homeostasis. HSF1 functions at the center of many physiological processes like embryogenesis, metabolism, immune response, aging, cancer, and neurodegeneration. However, the mechanisms that allow HSF1 to control these different biological and pathophysiological processes are not fully understood. This review focuses on Huntington's disease (HD), a neurodegenerative disease characterized by severe protein aggregation of the huntingtin (HTT) protein. The aggregation of HTT, in turn, leads to a halt in the function of HSF1. Understanding the pathways that regulate HSF1 in different contexts like HD may hold the key to understanding the pathomechanisms underlying other proteinopathies. We provide the most current information on HSF1 structure, function, and regulation, emphasizing HD, and discussing its potential as a biological target for therapy.

DATA SOURCES

We performed PubMed search to find established and recent reports in HSF1, heat shock proteins (Hsp), HD, Hsp inhibitors, HSF1 activators, and HSF1 in aging, inflammation, cancer, brain development, mitochondria, synaptic plasticity, polyglutamine (polyQ) diseases, and HD.

STUDY SELECTIONS

Research and review articles that described the mechanisms of action of HSF1 were selected based on terms used in PubMed search.

RESULTS

HSF1 plays a crucial role in the progression of HD and other protein-misfolding related neurodegenerative diseases. Different animal models of HD, as well as postmortem brains of patients with HD, reveal a connection between the levels of HSF1 and HSF1 dysfunction to mutant HTT (mHTT)-induced toxicity and protein aggregation, dysregulation of the ubiquitin-proteasome system (UPS), oxidative stress, mitochondrial dysfunction, and disruption of the structural and functional integrity of synaptic connections, which eventually leads to neuronal loss. These features are shared with other neurodegenerative diseases (NDs). Currently, several inhibitors against negative regulators of HSF1, as well as HSF1 activators, are developed and hold promise to prevent neurodegeneration in HD and other NDs.

CONCLUSION

Understanding the role of HSF1 during protein aggregation and neurodegeneration in HD may help to develop therapeutic strategies that could be effective across different NDs.

New insights into the role and therapeutic potential of HSP70 in diabetes

Emerging evidence indicates that HSP70 represents a key mechanism in the pathophysiology of β-cell dysfunction, insulin resistance, and various diabetic complications, including micro- and macro-vascular alterations, as well as impaired hemostasis. Hyperglycemia, a hallmark of both types of diabetes, increases the circulating levels of HSP70 (eHSP70), but there is still divergence about whether diabetes up- or down-regulates the intracellular fraction of this protein (iHSP70). Here, we consider that iHSP70 levels reduce in diabetic arterial structures and that the vascular system is in direct contact with all other systems in the body suggesting that a systemic response might also be happening for iHSP70, which is characterized by decreased levels of HSP70 in the vasculature. Furthermore, although many pathways have been proposed to explain HSP70's functions in diabetes, and organs/tissues/cells-specific variations occur, the membrane-bound receptor of the innate immune system, Toll-like receptor 4, and its downstream signal transduction pathways appear to be a constant, not only when we explore the actions of eHSP70, but also when we assess the contributions of iHSP70. In this review, we focus on discussing the multiple roles of HSP70 across organs/tissues/cells affected by hyperglycemia to further explore the possibility of targeting this protein with pharmacological and non-pharmacological approaches in the context of diabetes.

Inclusion Body Myositis: Update on Pathogenesis and Treatment

Inclusion body myositis is the most common acquired myopathy after the age of 50. It is characterized by progressive asymmetric weakness predominantly affecting the quadriceps and/or finger flexors. Loss of ambulation and dysphagia are major complications of the disease. Inclusion body myositis can be associated with cytosolic 5'-nucleotidase 1A antibodies. Muscle biopsy usually shows inflammatory cells surrounding and invading non-necrotic muscle fibers, rimmed vacuoles, congophilic inclusions, and protein aggregates. Disease pathogenesis remains poorly understood and consists of an interplay between inflammatory and degenerative pathways. Antigen-driven, clonally restricted, cytotoxic T cells represent a main feature of the inflammatory component, whereas abnormal protein homeostasis with protein misfolding, aggregation, and dysfunctional protein disposal is the hallmark of the degenerative component. Inclusion body myositis remains refractory to treatment. Better understanding of the disease pathogenesis led to the identification of novel therapeutic targets, addressing both the inflammatory and degenerative pathways.

Nitric oxide-heat shock protein axis in menopausal hot flushes: neglected metabolic issues of chronic inflammatory diseases associated with deranged heat shock response

BACKGROUND

Although some unequivocal underlying mechanisms of menopausal hot flushes have been demonstrated in animal models, the paucity of similar approaches in humans impedes further mechanistic outcomes. Human studies might show some as yet unexpected physiological mechanisms of metabolic adaptation that permeate the phase of decreased oestrogen levels in both symptomatic and asymptomatic women. This is particularly relevant because both the severity and time span of hot flushes are associated with increased risk of chronic inflammatory disease. On the other hand, oestrogen induces the expression of heat shock proteins of the 70 kDa family (HSP70), which are anti-inflammatory and cytoprotective protein chaperones, whose expression is modulated by different types of physiologically stressful situations, including heat stress and exercise. Therefore, lower HSP70 expression secondary to oestrogen deficiency increases cardiovascular risk and predisposes the patient to senescence-associated secretory phenotype (SASP) that culminates in chronic inflammatory diseases, such as obesities, type 2 diabetes, neuromuscular and neurodegenerative diseases.

OBJECTIVE AND RATIONALE

This review focuses on HSP70 and its accompanying heat shock response (HSR), which is an anti-inflammatory and antisenescent pathway whose intracellular triggering is also oestrogen-dependent via nitric oxide (NO) production. The main goal of the manuscript was to show that the vasomotor symptoms that accompany hot flushes may be a disguised clue for important neuroendocrine alterations linking oestrogen deficiency to the anti-inflammatory HSR.

SEARCH METHODS

Results from our own group and recent evidence on hypothalamic control of central temperature guided a search on PubMed and Google Scholar websites.

OUTCOMES

Oestrogen elicits rapid production of the vasodilatory gas NO, a powerful activator of HSP70 expression. Whence, part of the protective effects of oestrogen over cardiovascular and neuroendocrine systems is tied to its capacity of inducing the NO-elicited HSR. The hypothalamic areas involved in thermoregulation (infundibular nucleus in humans and arcuate nucleus in other mammals) and whose neurons are known to have their function altered after long-term oestrogen ablation, particularly kisspeptin-neurokinin B-dynorphin neurons, (KNDy) are the same that drive neuroprotective expression of HSP70 and, in many cases, this response is via NO even in the absence of oestrogen. From thence, it is not illogical that hot flushes might be related to an evolutionary adaptation to re-equip the NO-HSP70 axis during the downfall of circulating oestrogen.

WIDER IMPLICATIONS

Understanding of HSR could shed light on yet uncovered mechanisms of menopause-associated diseases as well as on possible manipulation of HSR in menopausal women through physiological, pharmacological, nutraceutical and prebiotic interventions. Moreover, decreased HSR indices (that can be clinically determined with ease) in perimenopause could be of prognostic value in predicting the moment and appropriateness of starting a HRT.

Heat Shock Proteins and Autophagy Pathways in Neuroprotection: from Molecular Bases to Pharmacological Interventions

Neurodegenerative diseases (NDDs) such as Alzheimer's disease, Parkinson's disease and Huntington's disease (HD), amyotrophic lateral sclerosis, and prion diseases are all characterized by the accumulation of protein aggregates (amyloids) into inclusions and/or plaques. The ubiquitous presence of amyloids in NDDs suggests the involvement of disturbed protein homeostasis (proteostasis) in the underlying pathomechanisms. This review summarizes specific mechanisms that maintain proteostasis, including molecular chaperons, the ubiquitin-proteasome system (UPS), endoplasmic reticulum associated degradation (ERAD), and different autophagic pathways (chaperon mediated-, micro-, and macro-autophagy). The role of heat shock proteins (Hsps) in cellular quality control and degradation of pathogenic proteins is reviewed. Finally, putative therapeutic strategies for efficient removal of cytotoxic proteins from neurons and design of new therapeutic targets against the progression of NDDs are discussed.

Heat Shock Proteins and Diabetes

Diabetes is a chronic disease, and its prevalence continues to rise and can increase the risk for the progression of microvascular (such as nephropathy, retinopathy and neuropathy) and also macrovascular complications. Diabetes is a condition in which the oxidative stress and inflammation rise. Heat shock proteins (HSPs) are a highly conserved family of proteins that are expressed by all cells exposed to environmental stress, and they have diverse functions. In patients with diabetes, the expression and levels of HSPs decrease, but these chaperones can aid in improving some complications of diabetes, such as oxidative stress and inflammation. (The suppression of some HSPs is associated with a generalized increase in tissue inflammation.) In this review, we summarize the current understanding of HSPs in diabetes as well as their complications, and we also highlight their potential role as therapeutic targets in diabetes.

Plasma membranes as heat stress sensors: from lipid-controlled molecular switches to therapeutic applications

The classic heat shock (stress) response (HSR) was originally attributed to protein denaturation. However, heat shock protein (Hsp) induction occurs in many circumstances where no protein denaturation is observed. Recently considerable evidence has been accumulated to the favor of the "Membrane Sensor Hypothesis" which predicts that the level of Hsps can be changed as a result of alterations to the plasma membrane. This is especially pertinent to mild heat shock, such as occurs in fever. In this condition the sensitivity of many transient receptor potential (TRP) channels is particularly notable. Small temperature stresses can modulate TRP gating significantly and this is influenced by lipids. In addition, stress hormones often modify plasma membrane structure and function and thus initiate a cascade of events, which may affect HSR. The major transactivator heat shock factor-1 integrates the signals originating from the plasma membrane and orchestrates the expression of individual heat shock genes. We describe how these observations can be tested at the molecular level, for example, with the use of membrane perturbers and through computational calculations. An important fact which now starts to be addressed is that membranes are not homogeneous nor do all cells react identically. Lipidomics and cell profiling are beginning to address the above two points. Finally, we observe that a deregulated HSR is found in a large number of important diseases where more detailed knowledge of the molecular mechanisms involved may offer timely opportunities for clinical interventions and new, innovative drug treatments. This article is part of a Special Issue entitled: Membrane Structure and Function: Relevance in the Cell's Physiology, Pathology and Therapy.

Pyridoxal 5' phosphate protects islets against streptozotocin-induced beta-cell dysfunction--in vitro and in vivo

Administration of pyridoxal 5' phosphate (PLP) has demonstrated beneficial effects in the management of diabetes, albeit the mechanism(s) are not clearly understood. The present study addressed the islet-cell function(s) in streptozotocin (STZ)-induced diabetic mice both in vitro and in vivo. Primary islet cells primed with or without PLP (5 mmol/L) were treated with STZ (2 mmol/L) and were measured for cell viability, insulin secretion, free radicals and mRNA of Insulin and Pdx1. The specificity of PLP's response on insulin secretion was assessed with amino oxy acetic acid (AOAA)-PLP inhibitor. In vivo, the STZ (200 mg/kg b.w)-treated diabetic mice received 10 mmol/L PLP intraperitoneally a day before (PLP + STZ) or after (STZ + PLP) with three more doses once every 48 h. On 7, 14 and 21 d of STZ treatment, physiological parameters, islet morphology, insulin:glucagon, insulin:HSP104, and mRNA of Insulin, Glut2, Pdx1 and Reg1 were determined. In vitro, PLP protected islets against STZ-induced changes in viability, insulin secretion, prevented increase in free radical levels and normalized mRNA of Insulin and Pdx1. Further, AOAA inhibited PLP-induced insulin secretion in islets. In vivo, PLP treatment normalized STZ-induced changes in physiological parameters, circulating levels of PLP and insulin. Also, islet morphology, insulin:glucagon, insulin:HSP104 and mRNA levels of Insulin, Pdx1 and Glut2 were restored by 21 d. Although PLP treatment (pre- and post-STZ) prevented development of frank diabetes, STZ + PLP mice showed transient hyperglycemia, and increased mRNA for Reg1. The data suggest the cytoprotective vis-à-vis insulinotrophic effects of PLP against STZ-induced beta-cell dysfunction and underline its prophylactic use in the management of diabetes.

Alpha-lipoic acid does not alter stress protein response to acute exercise in diabetic brain

Heat shock proteins (HSPs) are molecular chaperones which may act protective in cerebrovascular insults and peripheral diabetic neuropathy. We hypothesized that alpha-lipoic acid (LA), a natural thiol antioxidant, may enhance brain HSP response in diabetes. Rats with or without streptozotocin-induced diabetes were treated with LA or saline for 8 weeks. Half of the rats were subjected to exhaustive exercise to investigate HSP induction, and the brain tissue was analyzed. Diabetes increased constitutive HSC70 mRNA, and decreased HSP90 and glucose-regulated protein 75 (GRP75) mRNA without affecting protein levels. Exercise increased HSP90 protein and mRNA, and also GRP75 and heme oxygenase-1 (HO-1) mRNA only in non-diabetic animals. LA had no significant effect on brain HSPs, although LA increased HSC70 and HO-1 mRNA in diabetic animals and decreased HSC70 mRNA in non-diabetic animals. Eukaryotic translation elongation factor-2, essential for protein synthesis, was decreased by diabetes and suggesting a mechanism for the impaired HSP response related to translocation of the nascent chain during protein synthesis. LA supplementation does not offset the adverse effects of diabetes on brain HSP mRNA expression. Diabetes may impair HSP translation through elongation factors related to nascent chain translocation and subsequent responses to acute stress.

Inhibiting heat-shock protein 90 reverses sensory hypoalgesia in diabetic mice

Increasing the expression of Hsp70 (heat-shock protein 70) can inhibit sensory neuron degeneration after axotomy. Since the onset of DPN (diabetic peripheral neuropathy) is associated with the gradual decline of sensory neuron function, we evaluated whether increasing Hsp70 was sufficient to improve several indices of neuronal function. Hsp90 is the master regulator of the heat-shock response and its inhibition can up-regulate Hsp70. KU-32 (N-{7-[(2R,3R,4S,5R)-3,4-dihydroxy-5-methoxy-6,6-dimethyl-tetrahydro-2H-pyran-2-yloxy]-8-methyl-2-oxo-2H-chromen-3-yl}acetamide) was developed as a novel, novobiocin-based, C-terminal inhibitor of Hsp90 whose ability to increase Hsp70 expression is linked to the presence of an acetamide substitution of the prenylated benzamide moiety of novobiocin. KU-32 protected against glucose-induced death of embryonic DRG (dorsal root ganglia) neurons cultured for 3 days in vitro. Similarly, KU-32 significantly decreased neuregulin 1-induced degeneration of myelinated Schwann cell DRG neuron co-cultures prepared from WT (wild-type) mice. This protection was lost if the co-cultures were prepared from Hsp70.1 and Hsp70.3 KO (knockout) mice. KU-32 is readily bioavailable and was administered once a week for 6 weeks at a dose of 20 mg/kg to WT and Hsp70 KO mice that had been rendered diabetic with streptozotocin for 12 weeks. After 12 weeks of diabetes, both WT and Hsp70 KO mice developed deficits in NCV (nerve conduction velocity) and a sensory hypoalgesia. Although KU-32 did not improve glucose levels, HbA1c (glycated haemoglobin) or insulin levels, it reversed the NCV and sensory deficits in WT but not Hsp70 KO mice. These studies provide the first evidence that targeting molecular chaperones reverses the sensory hypoalgesia associated with DPN.

The phenylic hydroxyl group is essential for the induction of stress response by sodium salicylate

We have shown that sodium salicylate (SA) activates the heat shock promoter and induces the expression of heat shock proteins (Hsps) with a concomitant increase in the thermotolerance of cells. To identify the functional groups of SA necessary for the induction of Hsps, we evaluated the effect of various derivatives of SA using a mammalian cell line containing a reporter gene downstream of an hsp105 promoter. Among the derivatives, the compounds in which the carboxyl group of SA was substituted activated the hsp105 promoter at 37 degrees C as SA did, but the compounds in which the hydroxyl group was substituted did not. Thus, the phenylic hydroxyl group but not the carboxyl group of SA seemed to be necessary for a stress-induced response. In addition, the orientation of two functional groups on the benzene ring of SA derivatives was also important for the induction of a response. Among these compounds, salicylalcohol which strongly induced the expression of Hsps suppressed the protein aggregation and apoptosis caused by an expanded polyglutamine tract in a cellular model of polyglutamine disease. These findings may aid in the development of novel effective Hsp-inducers.

Bimoclomol ameliorates mercuric chloride nephrotoxicity through recruitment of stress proteins

Bimoclomol (BIM), is a stress proteins coinducer, that acts synergistically with a mild stressor to activate cytoprotective stress proteins. BIM has been successfully utilized in animal models for the treatment of various nervous, cardiac and cerebrovascular diseases. Mercuric chloride (HgCl(2)) induces acute renal failure in rats by a single dosage. The present in vivo study was conducted to assess the efficacy of BIM against acute HgCl(2) nephrotoxicity. At different times after BIM and/or HgCl(2) exposure we evaluated renal morphology and the localization/abundance of three stress proteins (HSP72, GRP75, HSP60) by electron microscopy, immunohistochemistry and Western blot analysis. BIM delivery to rats 6h before mercury, ameliorated damage to renal ultrastructure, with recovery of tubular and mitochondrial membranes 24h after mercury treatment. In rats pretreated with BIM prior to HgCl(2) exposure, HSP72 was significantly overexpressed in proximal tubules in a time-dependent manner. In contrast, the amounts of GRP75 and HSP60 after BIM pretreatment were comparable to the group treated with mercury alone, but these stress proteins had translocated to the nuclei at 14 and 24h, respectively. These novel findings suggest that BIM mitigates HgCl(2) nephrotoxicity in rats through the early recruitment of stress proteins in midcortical proximal tubules that are the main renal mercury-targets.

Induction of heat shock proteins may combat insulin resistance

The molecular mechanism responsible for obesity-associated insulin resistance has been partially clarified: increased fatty acid levels in muscle fibers promote diacylglycerol synthesis, which activates certain isoforms of protein kinase C (PKC). This in turn triggers a kinase cascade which activates both IkappaB kinase-beta (IKK-beta) and c-Jun N-terminal kinase (JNK), each of which can phosphorylate a key serine residue in IRS-1, rendering it a poor substrate for the activated insulin receptor. Heat shock proteins Hsp27 and Hsp72 have the potential to prevent the activation of IKK-beta and JNK, respectively; this suggests that induction of heat shock proteins may blunt the adverse impact of fat overexposure on insulin function. Indeed, bimoclomol--a heat shock protein co-inducer being developed for treatment of diabetic neuropathy--and lipoic acid--suspected to be a heat shock protein inducer--have each demonstrated favorable effects on the insulin sensitivity of obese rodents, and parenteral lipoic acid is reported to improve the insulin sensitivity of type 2 diabetics. Moreover, there is reason to believe that heat shock protein induction may have a favorable impact on the microvascular complications of diabetes, and on the increased risk for macrovascular disease associated with diabetes and insulin resistance syndrome. Heat shock protein induction may also have potential for preventing or treating neurodegenerative disorders, controlling inflammation, and possibly even slowing the aging process. The possible complementarity of bimoclomol and lipoic acid for heat shock protein induction should be assessed, and further efforts to identify well-tolerated agents active in this regard are warranted.

Heat shock proteins: new keys to the development of cytoprotective therapies

All cells, from bacterial to human, have a common, intricate response to stress that protects them from injury. Heat shock proteins (Hsps), also known as stress proteins and molecular chaperones, play a central role in protecting cellular homeostatic processes from environmental and physiologic insult by preserving the structure of normal proteins and repairing or removing damaged ones. An understanding of the interplay between Hsps and cell stress tolerance will provide new tools for treatment and drug design that maximise preservation or restoration of health. For example, the increased vulnerability of tissues to injury in some conditions, such as ageing, diabetes mellitus and menopause, or with the use of certain drugs,, such as some antihypertensive medications, is associated with an impaired Hsp response. Additionally, diseases that are associated with tissue oxidation, free radical formation, disorders of protein folding, or inflammation, may be improved therapeutically by elevated expression of Hsps. The accumulation of Hsps, whether induced physiologically, pharmacologically, genetically, or by direct administration of the proteins, is known to protect the organism from a great variety of pathological conditions, including myocardial infarction, stroke, sepsis, viral infection, trauma, neurodegenerative diseases, retinal damage, congestive heart failure, arthritis, sunburn, colitis, gastric ulcer, diabetic complications and transplanted organ failure. Conversely, lowering Hsps in cancer tissues can amplify the effectiveness of chemo- or radiotherapy. Treatments and agents that induce Hsps include hyperthermia, heavy metals (zinc and tin), salicylates, dexamethasone, cocaine, nicotine, alcohol, alpha-adrenergic agonists, PPAR-gamma agonists, bimoclomol, geldanamycin, geranylgeranylacetone and cyclopentenone prostanoids. Compounds that suppress Hsps include quercetin (a bioflavinoid), 15-deoxyspergualin (an immunosuppressive agent) and retinoic acid. Researchers who are cognisant of the Hsp-related effects of these and other agents will be able to use them to develop new therapeutic paradigms.

Paeoniflorin, a novel heat shock protein-inducing compound

Heat shock proteins (HSPs) are induced by various physical, chemical, and biological stresses. HSPs are known to function as molecular chaperones, and they not only regulate various processes of protein biogenesis but also function as lifeguards against proteotoxic stresses. Because it is very useful to discover nontoxic chaperone-inducing compounds, we searched for them in herbal medicines. Some herbal medicines had positive effects on the induction of HSPs (Hsp70, Hsp40, and Hsp27) in cultured mammalian cells. We next examined 2 major constituents of these herbal medicines, glycyrrhizin and paeoniflorin, with previously defined chemical structures. Glycyrrhizin had an enhancing effect on the HSP induction by heat shock but could not induce HSPs by itself. In contrast, paeoniflorin had not only an enhancing effect but also an inducing effect by itself on HSP expression. Thus, paeoniflorin might be termed a chaperone inducer and glycyrrhizin a chaperone coinducer. Treatment of cells with paeoniflorin but not glycyrrhizin resulted in enhanced phosphorylation and acquisition of the deoxyribonucleic acid-binding ability of heat shock transcription factor 1 (HSF1), as well as the formation of characteristic HSF1 granules in the nucleus, suggesting that the induction of HSPs by paeoniflorin is mediated by the activation of HSF1. Also, thermotolerance was induced by treatment with paeoniflorin but not glycyrrhizin. Paeoniflorin had no toxic effect at concentrations as high as 80 microg/ mL (166.4 microM). To our knowledge, this is the first report on the induction of HSPs by herbal medicines.

The effect of treatment with BRX-220, a co-inducer of heat shock proteins, on sensory fibers of the rat following peripheral nerve injury

In this study, we examined the effect BRX-220, a co-inducer of heat shock proteins, in injury-induced peripheral neuropathy. Following sciatic nerve injury in adult rats and treatment with BRX-220, the following features of the sensory system were studied: (a) expression of calcitonin gene-related peptide (CGRP); (b) binding of isolectin B4 (IB4) in dorsal root ganglia (DRG) and spinal cord; (c) stimulation-evoked release of substance P (SP) in an in vitro spinal cord preparation and (d) nociceptive responses of partially denervated rats. BRX-220 partially reverses axotomy-induced changes in the sensory system. In vehicle-treated rats there is a decrease in IB4 binding and CGRP expression in injured neurones, while in BRX-220-treated rats these markers were better preserved. Thus, 7.0 +/- 0.6% of injured DRG neurones bound IB4 in vehicle-treated rats compared to 14.4 +/- 0.9% in BRX-220-treated animals. Similarly, 4.5 +/- 0.5% of DRG neurones expressed CGRP in the vehicle-treated group, whereas 9.0 +/- 0.3% were positive in the BRX-220-treated group. BRX-220 also partially restored SP release from spinal cord sections to electrical stimulation of primary sensory neurones. Behavioural tests carried out on partially denervated animals showed that BRX-220 treatment did not prevent the emergence of mechanical or thermal hyperalgesia. However, oral treatment for 4 weeks lead to reduced pain-related behaviour suggesting either slowly developing analgesic actions or enhancement of recovery processes. Thus, the morphological improvement seen in sensory neurone markers was accompanied by restored functional activity. Therefore, treatment with BRX-220 promotes restoration of morphological and functional properties in the sensory system following peripheral nerve injury.

Bimoclomol, a heat shock protein co-inducer, acts by the prolonged activation of heat shock factor-1

The novel hydroxylamine derivative, bimoclomol, has been shown previously to act as a co-inducer of several heat shock proteins (Hsp-s), enhancing the amount of these proteins produced following a heat shock compared to heat shock alone. Here we show that the co-inducing effect of bimoclomol on Hsp expression is mediated via the prolonged activation of the heat shock transcription factor (HSF-1). Bimoclomol effects are abolished in cells from mice lacking HSF-1. Moreover, bimoclomol binds to HSF-1 and induces a prolonged binding of HSF-1 to the respective DNA elements. Since HSF-1 does not bind to DNA in the absence of stress, the bimoclomol-induced extension of HSF-1/DNA interaction may contribute to the chaperone co-induction of bimoclomol observed previously. These findings indicate that bimoclomol may be of value in targeting HSF-1 so as to induce up-regulation of protective Hsp-s in a non-stressful manner and for therapeutic benefit.

Heat shock protein coinducers with no effect on protein denaturation specifically modulate the membrane lipid phase

The hydroxylamine derivative bimoclomol (BM) has been shown to activate natural cytoprotective homeostatic responses by enhancing the capability of cells to cope with various pathophysiological conditions. It exerts its effect in synergy with low levels of stress to induce the synthesis of members of major stress protein families. We show here that the presence of BM does not influence protein denaturation in the cells. BM and its derivatives selectively interact with acidic lipids and modulate their thermal and dynamic properties. BM acts as a membrane fluidizer at normal temperature, but it is a highly efficient membrane stabilizer, inhibiting the bilayer-nonbilayer phase transitions during severe heat shock. We suggest that BM and the related compounds modify those domains of membrane lipids where the thermally or chemically induced perturbation of lipid phase is sensed and transduced into a cellular signal, leading to enhanced activation of heat shock genes. BM may be a prototype for clinically safe membrane-interacting drug candidates that rebalance the level and composition of heat shock proteins.

Enantioselective plasma protein binding of bimoclomol

The binding of bimoclomol enantiomers to human plasma, its components, as well as to plasma from monkey, dog, rat, and mouse was investigated by ultrafiltration and equilibrium dialysis. The considerably stronger binding of the (-)-(S)-enantiomer found in human plasma is due to the alpha(1)-acid glycoprotein (AAG) component. The binding parameters for AAG (n(R)K(R) = 1.3 x 10(4) M(-1) and n(S)K(S) = 1.0 x 10(5) M(-1)) revealed high enantioselectivity, while the binding to human serum albumin was found to be weak (nK = 5 x 10(3) M(-1)) and not stereoselective. (-)-(S)-Bimoclomol was extensively displaced in the presence of specific marker ligands for the "FIS" subfraction of human AAG. Comparative binding studies indicated considerable differences between plasma of the five species investigated.

Upregulation of heat shock proteins rescues motoneurones from axotomy-induced cell death in neonatal rats

Heat shock proteins (hsps) are induced in a variety of cells following periods of stress, where they promote cell survival. In this study, we examined the effect of upregulating hsp expression by treatment with BRX-220, a co-inducer of hsps, on the survival of injured motoneurones. Following sciatic nerve crush at birth, rat pups were treated daily with BRX-220. The expression of hsp70 and hsp90, motoneurone survival, and muscle function was examined at various intervals later and the number of functional motor units was assessed by in vivo isometric tension recordings. Fourteen days after injury, significantly more motoneurones survived in the BRX-220-treated group (39 +/- 2.8%) compared to the saline-treated group (21 +/- 1.7%). Moreover, in the BRX-220-treated group no further loss of motoneurones occurred, so that at 10 weeks 42 +/- 2.1% of motoneurones survived compared to 15 +/- 0.6% in the untreated group. There were also more functional motor units in the hindlimb muscles of BRX-220-treated animals. In addition, treatment with BRX-220 resulted in a significant increase in the expression of hsp70 and hsp90 in glia and neurones. Thus, treatment with BRX-220, a co-inducer of hsps, protects motoneurones from axotomy-induced cell death.

Effect of BRX-220 against peripheral neuropathy and insulin resistance in diabetic rat models

Bimoclomol (BML), a symptomatic antidiabetic agent, has been developed by Biorex R & D Co. to treat diabetic neuropathy and retinopathy. BRX-220, an orally active member of the BRX family, has been developed to treat diabetic complications and insulin resistance (IR) as a follow-up compound. The effect of BRX-220 on peripheral neuropathy was examined in rats with diabetes (type 1) induced by administration of a beta-cell toxin, streptozotocin (STZ, 45 mg/kg iv). Nerve functions were evaluated by electrophysiological measurements of muscle motor and sensory nerve conduction velocities (MNCV and SNCV, respectively). MNCV and SNCV decreased in diabetic rats by 25% (p < 0.001). A 1-month preventive treatment with BRX-220 (2.5, 5, 10, and 20 mg/kg po) dose-dependently improved diabetes-related deficits in MNCV (51.3%, 71.3%, 86.1%, and 91.3%) and SNCV (48.9%, 68.5%, 86.1%, and 93.2%). Insulin sensitivity was measured using the insulin tolerance test (ITT), both in STZ diabetic and in Zucker diabetic fatty (ZDF) rats (model of type 2 diabetes). Severe IR was detected in STZ diabetic and ZDF rats. This resistance was significantly (p < 0.05) reduced by BRX-220 treatment.

Comparison of the extrapancreatic action of BRX-220 and pioglitazone in the high-fat diet-induced insulin resistance

A new Biorex molecule, BRX-220, has been shown to be effective in animal models of diabetic neuro- and retinopathy. Recent in vitro studies showed that it might also have an insulin-sensitizing action. Therefore, the effect of BRX-220 on insulin sensitivity was compared with the action of pioglitazone (PGZ) in high fat (HF) diet-induced insulin resistance (IR) of rats.

METHODS

Male Wistar rats were fed for 3 weeks a standard chow (PD) or the HF (70-cal%) diet. The HF-fed rats were also given daily BRX-220 (20 mg/kg BW) or PGZ (6 mg/kg BW) by gavage. In vivo insulin action was assessed by the euglycemic hyperinsulinemic clamp. Glucose, insulin, FFA, triglyceride (TG), and glycerol levels in blood were also measured, as well as tissue TG content.

RESULTS

Increased levels of fed TG in circulation after HF diet (PD: 2.0+/-0.2 vs. HF: 5.0+/-0.8 mmol/L) were partially corrected by BRX-220 (HF + BRX: 3.8+/-0.3) and normalized by PGZ (HF + PGZ: 2.6+/-0.3). Both molecules prevented the increase in fed serum FFA levels after HF diet (PD: 0.5+/-0.06; HF: 1.8+/-0.2 mmol/L), with a more pronounced effect of PGZ (HF + BRX: 1.2+/-0.1; HF + PGZ: 0.7+/-0.06). Tissue TG levels increased significantly in response to HF feeding in both liver (HF: 16+/-3.0; PD: 6.4+/-1.1 micromol/g) and skeletal muscle (HF: 7.7+/-1.2; PD: 2.4+/-0.4). This increase was completely normalized by both agents in the liver (HF + BRX: 8.8+/-0.8; HF + PGZ: 8.8+/-1.0), and only partially in the skeletal muscles. HF diet-induced in vivo IR (PD: 25.4+/-0.5; HF: 15.7+/-0.5 mg/kg/min) was significantly reduced by BRX-220 (HF + BRX: 18.7+/-0.3) and PGZ (HF + PGZ: 22.8+/-0.4) treatment.

CONCLUSIONS

(1) Subchronic administration of BRX-220 leads to an improvement of in vivo insulin action. (2) This insulin-sensitizing effect is, however, not as pronounced as that of PGZ. (3) It is accompanied by a decrease of circulating TG and FFA levels in the postprandial state and (4) by lower TG content in liver and skeletal muscle.

Oral bimoclomol elevates heat shock protein 70 and reduces myocardial infarct size in rats

Bimoclomol has been shown to increase an inducible member of the heat shock protein 70 family (HSP70) and cytoprotect in vitro. Here, we addressed whether oral pretreatment of rats with bimoclomol could elevate myocardial HSP70 and reduce infarct size in a rat model of ischemia and reperfusion. Rats were pretreated with bimoclomol at 3, 6 or 18 h or with 42 degrees thermal stress 24 h before ischemia. Infarct size was significantly decreased 6 h after oral administration of bimoclomol and 24 h after thermal stress. Left ventricles from a separate group of rats were examined for HSP70 levels. Western blots showed a significant increase in HSP70 6 h after oral administration of bimoclomol and 24 h after thermal stress. There was a significant correlation (P<0.05) between HSP70 induction and infarct size reduction, whether produced by thermal stress or oral administration of bimoclomol. Thus, bimoclomol can increase HSP70 and reduce infarct size in a rat model of ischemia and reperfusion.

Bimoclomol elevates heat shock protein 70 and cytoprotects rat neonatal cardiomyocytes

Bimoclomol is a new compound that improves cell survival under experimental stress conditions partly by increasing intracellular heat shock proteins (HSPs). HSPs, especially HSP70, play a cytoprotective role in the rat heart. Rat neonatal cardiomyocytes were used to determine the ability of bimoclomol to induce HSP70 and affect cell survival across a broad concentration range (0.01-100 microM). Bimoclomol significantly elevated HSP70 levels at concentrations ranging from 0.01 to 10 microM, depending on the time of exposure. Pretreatment with bimoclomol for 24 h significantly increased survival of cells. There was a significant correlation between the increased levels of HSP70 and the increase in cell survival as a result of the treatment with bimoclomol. In conclusion, bimoclomol improved cell survival in rat neonatal cardiomyocytes, in part, by increasing the levels of HSP70. This cytoprotection began at the relatively low concentration of 0.1 microM, which is a concentration that can be achieved clinically.

Multilateral in vivo and in vitro protective effects of the novel heat shock protein coinducer, bimoclomol: results of preclinical studies

Bimoclomol, the recently developed non-toxic heat shock protein (HSP) coinducer, was shown to display multilateral protective activities against various forms of stress or injuries at the level of the cell, tissue or organism. The compound enhanced the transcription, translation and expression of the 70 kD heat shock protein (HSP-70) in myogenic and HeLa cell lines exposed to heat stress, and increased cell survival on exposure to otherwise lethal thermal injury. Bimoclomol increased contractility of the working mammalian heart, this effect was associated with the increased intracellular calcium transients due to increased probability of opening of ryanodine receptors in the sarcoplasmic reticulum (SR). In healthy tissues these cardiac effects were evident only at relatively high concentrations of the drug, while in the ischemic myocardium bimoclomol exerted significant cardioprotective and antiarrhythmic effects at submicromolar concentrations. It decreased ischemia-induced reduction of contractility and of cardiac output, and dramatically decreased the elevation of the ST-segment during ischemia as well as the occurrence of ventricular fibrillation upon reperfusion. Bimoclomol was also active in various pathological animal models subjected to acute or chronic stress. In the spontaneously hypertensive rats chronic pretreatment with bimoclomol restored sensitivity of aortic rings to acetylcholine; this effect was accompanied by accumulation of HSP-70 in the tissues. Bimoclomol pretreatment significantly diminished the consequences of vascular disorders associated with diabetes mellitus. Diabetic neuropathy, retinopathy, and nephropathy were prevented or diminished, while wound healing was enhanced by bimoclomol. Enhancement of wound healing by bimoclomol was observed after thermal injury as well as following ultraviolet (UV) irradiation. In addition to the beneficial effects on peripheral angiopathies, bimoclomol antagonized the increase in permeability of blood-brain barrier induced by subarachnoid hemorrhager or arachidonic acid. A general and very important feature of the above effects of bimoclomol was that the drug failed to cause alterations under physiological conditions (except the enhanced calcium release from cardiac sarcoplasmic reticulum). Bimoclomol was effective only under conditions of stress. Consistent with its HSP-coinducer property, bimoclomol alone had very little effect on HSP production. Its protective activity became apparent only in the presence of cell damage. Currently, bimoclomol reached the end of the Phase II clinical trial in a group of 410 patients with diabetic complications. Results of this trial will answer the question, whether a compound with promising in vitro and in vivo preclinical findings will produce the anticipated beneficial effects in humans. In the event of a positive outcome of this trial, the indications for bimoclomol will be substantially extended.

Impact of diabetes on CNS: role of signal transduction cascade

Diabetic neuropathy is the most common secondary complication of diabetes mellitus. Several pathogenetic factors have been proposed for diabetic neuropathy. The present investigation was undertaken to study different components of signal transduction from discrete brain regions from streptozotocin-induced diabetic rats. Rats were sacrificed after 1 and 3 months of induction of diabetes, and a control group was also studied in parallel to ascertain the specificity of diabetes-associated changes. Blood glucose level and protein content of discrete brain regions were also estimated. Signal transduction cascade components like protein kinase A, protein kinase C, cAMP, phospholipase C, phospholipase A2, diacylglycerol and inositol phosphate levels were assayed in control and diabetic groups of rats. Significant attenuation in phosphoinositide metabolism along with activation of protein kinase activities were observed. These findings provide evidence to suggest a mechanism linking changes in signal transduction cascade, which is observed in 1- and 3-month diabetic rats, which ultimately leads to development of diabetic neuropathy.

Heat shock protein expression during gametogenesis and embryogenesis

When cells are subjected to various stress factors, they increase the production of a group of proteins called heat shock proteins (hsp). Heat shock proteins are highly conserved proteins present in organisms ranging from bacteria to man. Heat shock proteins enable cells to survive adverse environmental conditions by preventing protein denaturation. Thus the physiological and pathological potential of hsps is enormous and has been studied widely over the past two decades. The presence or absence of hsps influences almost every aspect of reproduction. They are among the first proteins produced during mammalian embryo development. In this report, the production of hsps in gametogenesis and early embryo development is described. It has been suggested that prolonged and asymptomatic infections trigger immunity to microbial hsp epitopes that are also expressed in man. This may be relevant for human reproduction, since many couples with fertility problems have had a previous genital tract infection. Antibodies to bacterial and human hsps are present at high titers in sera of many patients undergoing in vitro fertilization. In a mouse embryo culture model, these antibodies impaired the mouse embryo development at unique developmental stages. The gross morphology of these embryos resembled cells undergoing apoptosis. The TUNEL (terminal deoxynucleotidyl transferase-mediated X-dUTP nick end labeling) staining pattern, which is a common marker of apoptosis, revealed that embryos cultured in the presence of hsp antibodies stained TUNEL-positive more often than unexposed embryos. These data extend preexisting findings showing the detrimental effect of immune sensitization to hsps on embryo development.

Effect of bimoclomol (N-[2-hydroxy-3-(1-piperidinyl) propoxy]-3 pyridine-carboximidoyl-chloride) on iminodipropionitrile-induced central effects

Dyskinesia is frequently seen in neurological disorders affecting the basal ganglia. Iminodipropionitrile (IDPN) produces a somewhat similar motor syndrome in rodents, one that is a possible model for dyskinesia. Because in previous studies the compound (N-[2-hydroxy-3-(1-piperidinyl) propoxy]-3 pyridine-carboximidoyl-chloride) (Bimoclomol, BRLP-42) was shown to provide protection against IDPN-induced retinopathy; we investigated the effect of BRLP-42 on IDPN-induced motor changes and on IDPN-induced cerebral amino acid level changes in rats and mice. IDPN had a biphasic effect on motor activity in C57BL/6 mice: it was a depressant for 24 days and a stimulant after 30 days. Bimoclomol inhibited the motor depressant effect and enhanced the stimulatory effect of IDPN in this mouse strain. In BALB/cBy mice and Sprague Dawley rats IDPN produced persistent vertical head movements and changes in the level of glutamic acid in brain. Bimoclomol reduced the effect of IDPN on head movements and blocked the effect on cerebral glutamate; by itself it had no effect on motor activity in either species. Bimoclomol inhibited ischemia-induced [3H]norepinephrine release from rat hippocampal slices. Our findings indicate that Bimoclomol could have a beneficial effect on some dyskinesias, and on drug-induced vertical head movements.

The 90-kDa molecular chaperone family: structure, function, and clinical applications. A comprehensive review

The 90-kDa molecular chaperone family (which comprises, among other proteins, the 90-kDa heat-shock protein, hsp90 and the 94-kDa glucose-regulated protein, grp94, major molecular chaperones of the cytosol and of the endoplasmic reticulum, respectively) has become an increasingly active subject of research in the past couple of years. These ubiquitous, well-conserved proteins account for 1-2% of all cellular proteins in most cells. However, their precise function is still far from being elucidated. Their involvement in the aetiology of several autoimmune diseases, in various infections, in recognition of malignant cells, and in antigen-presentation already demonstrates the essential role they likely will play in clinical practice of the next decade. The present review summarizes our current knowledge about the cellular functions, expression, and clinical implications of the 90-kDa molecular chaperone family and some approaches for future research.

Bimoclomol protects against vascular consequences of experimental subarachnoid hemorrhage in rats

Bimoclomol (BRLP-42) is a novel antiischemic compound acting against peripheral vascular complications of diabetes mellitus (neuropathy, retinopathy, and nephropathy). In the present study the activity of bimoclomol was tested in experimental subarachnoid hemorrhage (SAH) and arachidonic acid (AA)-induced brain edema in rats to elucidate whether the compound may also have beneficial effect in cerebrovascular disturbances. For comparison, a neuroprotective AMPA antagonist, GYKI-52466, was examined. Injury caused by autologous intracranial blood injection or sodium-arachidonate was evaluated by the damage of blood-brain barrier (BBB) reflected in the extravasation of Evans blue dye into the cerebral tissue. Bimoclomol (2 x 2 mg/kg IV) markedly reduced, while GYKI-52466 (2 x 2 mg/kg IV) moderately diminished the extravasation produced by SAH (39.9%, p < 0.01 and 26.7%, p > 0.05, respectively). In the case of AA-induced brain edema, bimoclomol showed less pronounced (19.6%, p < 0.05) inhibitory action, and GYKI-52466 seemed to be more effective (34.2%, p < 0.05). These results suggest that bimoclomol may be active not only in peripheral micro- and macroangiopathy, but also in some types of cerebrovascular disorders.