HSP27 concentrations are lower in patients with type 1 diabetes and correlate with large nerve fiber dysfunction

Downregulation of HSPB1 and MGST1 Promotes Ferroptosis and Impacts Immune Infiltration in Diabetic Cardiomyopathy

Diabetic cardiomyopathy (DCM) is a leading cause of death in diabetic patients. Current therapies do not adequately resolve this problem and focus only on the optimal level of blood glucose for patients. Ferroptosis plays an important role in diabetes mellitus and cardiovascular diseases. However, the role of ferroptosis in DCM remains unclear. Differentially expressed ferroptosis-related genes (DE-FRGs) were identified by intersection of the GSE26887 dataset and the Ferroptosis Database. The associations between the DE-FRGs and immune cells in DCM, estimated via the CIBERSORTx algorithm, were analysed. Flow cytometry (FCM) was used to evaluate the infiltration of immune cells in myocardial tissues. The expression of DE-FRGs, glutathione peroxidase 4 and solute carrier family 7 member 11 was examined via real-time quantitative PCR and Western blotting. Three DE-FRGs were identified: heat shock protein family B (small) member 1 (HSPB1), microsomal glutathione S-transferase 1 (MGST1) and solute carrier family 40 member 1 (SLC40A1), which are closely linked to immune cells in DCM. In vivo, the levels of CD8 + T cells, B cells and regulatory T (Treg) cells were significantly decreased in the DCM group, whereas the levels of CD4 + T cells, M1 cells, M2 cells and monocytes were increased. Diabetes significantly decreased HSPB1 and MGST1 levels and increased ferroptosis compared with the Normal group. Furthermore, the ferroptosis inhibitor ferrostatin-1 (Fer-1) alleviated high-fat diet (HFD)-induced cardiomyocyte injury and rescued ferroptosis. These findings suggest that the ferroptosis-related genes HSPB1 and MGST1 are closely related to immune cell infiltration and may be therapeutic targets for DCM.

Lactoferrin-derived peptide PXL01 impacts nerve regeneration after sciatic nerve reconstruction in healthy and diabetic rats

Introduction

Although advanced surgical techniques are available, satisfactory functional outcomes after peripheral nerve injuries are uncommon. Hence, immune-modulating factors such as PXL01, a lactoferrin-derived peptide that improves axonal outgrowth in injured human digital nerves, have gained attention. We previously reported a short-term immunosuppressive effect of PXL01 after the repair of transected rat sciatic nerves, but it had no effect on nerve regeneration. Here, we investigated the potential of PXL01 to improve nerve regeneration in healthy rats and in a rat model of type 2 diabetes (Goto-Kakizaki [GK] rats).

Methods

A 10-mm sciatic nerve defect was created in healthy (n = 14) and diabetic GK rats (n = 14) and reconstructed using nerve autografts. Immediately after surgery, PXL01 or sodium chloride (control, placebo) (n = 7 for each treatment) was administered around the autograft. On day 8, immunohistochemical staining of the sciatic nerve and dorsal root ganglia (DRGs) was performed to analyze axonal outgrowth (neurofilament staining); inflammation (CD68 and CD206 macrophage staining in nerve); Schwann cell and sensory neuron activation (transcription factor ATF3 staining in nerve and DRGs) and apoptosis (cleaved caspase 3 staining in nerve); and neuroprotection (heat shock protein [HSP27] staining in nerve and DRGs).

Results

PXL01 had no impact on the macrophage response in the autografts but increased axonal outgrowth and HSP27 expression in the DRGs of healthy and diabetic rats, despite a lower number of activated Schwann cells in the autograft. Diabetes affected axonal outgrowth, Schwann cell and macrophage responses, and HSP27 expression. These effects were observed in the sciatic nerve as well as the DRG.

Discussion

Application of PXL01, despite having no impact on macrophages, may improve axonal outgrowth and affects Schwann cell activation in autograft-reconstructed sciatic nerves, as well as conveys neuroprotection (HSP27 expression) in the DRGs of healthy and diabetic GK rats. Diabetes influenced nerve regeneration in such autografts. Therefore, PXL01 is a promising candidate to improve nerve regeneration.

Down-regulation of HSPB1 and MGST1 promote ferroptosis and impact immune infiltration in diabetic cardiomyopathy

Diabetic cardiomyopathy (DCM) is a leading cause of death in diabetic patients. Current therapies do not adequately resolve this problem and focus only on the optimal level of blood glucose for patients. Ferroptosis plays an important role in diabetes mellitus and cardiovascular diseases. However, the role of ferroptosis in DCM remains unclear. Differentially expressed ferroptosis-related genes (DE-FRGs) were identified by intersecting GSE26887 dataset and the Ferroptosis Database (FerrDb). The associations between the DE-FRGs and immune cells in DCM, estimated by CIBERSORTx algorithm, were analyzed. Using ow cytometry (FCM) to evaluated the infiltration of immune cells of myocardial tissues. The expression of DE-FRGs, Glutathione peroxidase 4 (GPX4) and Solute carrier family 7 member 11 (SLC7A11) were examined by real-time quantitative PCR and western blotting. 3 DE-FRGs were identified, which are Heat shock protein family B (small) member 1 (HSPB1), Microsomal glutathione S-transferase 1 (MGST1) and solute carrier family 40 member 1 (SLC40A1) respectively, and they were closely linked to immune cells in DCM. In vivo, the levels of CD8 + T cells, B cells and Treg cells were significantly decreased in the DCM group, while the levels of CD4 + T cells, M1 cells, M2 cells and monocytes were increased. Diabetes significantly decreased HSPB1 and MGST1 levels and increased ferroptosis compared to normal group. Furthermore, ferroptosis inhibitor ferrostatin-1 (Fer-1) alleviated high-fat diet (HFD)-induced cadiomyocyte injury and rescued the ferroptosis. This study suggests that ferroptosis related gene HSPB1 and MGST1 are closely related to immune cell infiltration, which may become therapeutic targets for DCM.

Promising predictors of diabetic peripheral neuropathy in children and adolescents with type 1 diabetes mellitus

BACKGROUND

Diabetic peripheral neuropathy (DPN) in children and adolescents with type 1 diabetes mellitus (T1DM) is a growing issue, with controversial data in the terms of prevalence and evaluation timelines. Currently, there are no clear standards for its early detection. Therefore, our aim was to assess the contribution of the Michigan neuropathy screening instrument (MNSI), lipid profile, serum neuron specific enolase (NSE), and serum heat shock protein 27 (HSP 27) to the prediction of DPN in children and adolescents with T1DM.

METHODS

In this case-control study, fifty children diagnosed with T1DM for at least five years were enrolled and evaluated through complete neurological examination, MNSI, and nerve conduction study (NCS). Additionally, HbA1c, lipid profile, serum NSE, and serum HSP 27 levels were measured for patients and controls.

RESULTS

The prevalence of DPN in our study was 24% by NCS, and electrophysiological changes showed a statistically significant lower conduction velocity for the posterior tibial and sural nerves, as well as a prolonged latency period for the common peroneal and sural nerves in neuropathic patients. In these patients, older age, earlier age of diabetes onset, longer disease duration, higher total cholesterol, triglycerides, low density lipoprotein cholesterol, HbA1c, serum NSE, and HSP27 levels were observed. The MNSI examination score ≥ 1.5 cutoff point had an area under the curve (AUC) of 0.955, with 75% sensitivity and 94.74% specificity, according to receiver operating characteristic curve analysis. However, the questionnaire's cutoff point of ≥ 5 had an AUC of 0.720, 75% sensitivity, and 63% specificity, with improved overall instrument performance when combining both scores. Regarding blood biomarkers, serum NSE had greater sensitivity and specificity in discriminating neuropathic patients than HSP27 (92% and 74% versus 75% and 71%, respectively). Regression analysis revealed a substantial dependency for MNSI and serum NSE in predicting DPN in patients.

CONCLUSIONS

Despite limited research in pediatrics, MNSI and serum NSE are promising predictive tools for DPN in children and adolescents with T1DM, even when they are asymptomatic. Poor glycemic control and lipid profile changes may play a critical role in the development of DPN in these patients, despite conflicting results in various studies.

PXL01 alters macrophage response with no effect on axonal outgrowth or Schwann cell response after nerve repair in rats

Background: Adjunctive pharmacological treatment may improve nerve regeneration. We investigated nerve regeneration processes of PXL01 - a lactoferrin-derived peptide - after repair of the sciatic nerve in healthy Wistar rats.Materials & methods: PXL01, sodium hyaluronate (carrier) or sodium chloride was administered around the repair. After 6 days axonal outgrowth, Schwann cell response, pan- (CD68) and pro-healing (CD206) macrophages in sciatic nerve, sensory neuronal response in dorsal root ganglia (DRG) and expression of heat shock protein 27 (HSP27) in sciatic nerves and DRGs were analyzed.Results: Despite a lower number of pan-macrophages, other investigated variables in sciatic nerves or DRGs did not differ between the treatment groups.Conclusion: PLX01 applied locally inhibits inflammation through pan-macrophages in repaired sciatic nerves without any impact on nerve regeneration or pro-healing macrophages.

The Dynamics of Nerve Degeneration and Regeneration in a Healthy Milieu and in Diabetes

Appropriate animal models, mimicking conditions of both health and disease, are needed to understand not only the biology and the physiology of neurons and other cells under normal conditions but also under stress conditions, like nerve injuries and neuropathy. In such conditions, understanding how genes and different factors are activated through the well-orchestrated programs in neurons and other related cells is crucial. Knowledge about key players associated with nerve regeneration intended for axonal outgrowth, migration of Schwann cells with respect to suitable substrates, invasion of macrophages, appropriate conditioning of extracellular matrix, activation of fibroblasts, formation of endothelial cells and blood vessels, and activation of other players in healthy and diabetic conditions is relevant. Appropriate physical and chemical attractions and repulsions are needed for an optimal and directed regeneration and are investigated in various nerve injury and repair/reconstruction models using healthy and diabetic rat models with relevant blood glucose levels. Understanding dynamic processes constantly occurring in neuropathies, like diabetic neuropathy, with concomitant degeneration and regeneration, requires advanced technology and bioinformatics for an integrated view of the behavior of different cell types based on genomics, transcriptomics, proteomics, and imaging at different visualization levels. Single-cell-transcriptional profile analysis of different cells may reveal any heterogeneity among key players in peripheral nerves in health and disease.

Quantification of heat shock proteins in the posterior interosseous nerve among subjects with type 1 and type 2 diabetes compared to healthy controls

Introduction

Diabetic peripheral neuropathy (DPN) is a common complication of both type 1 (T1D) and type 2 diabetes (T2D). No cure for DPN is available, but several potential targets have been proposed for treatment. Heat shock proteins (HSPs) are known to respond to both hyper- and hypoglycemia. DPN can be diagnosed using electrophysiology and studied using peripheral nerve biopsies.

Aim

This study aimed to analyze the presence and patterns of HSPs in peripheral nerve biopsies from subjects with T1D, T2D, and healthy controls.

Methods

Posterior interosseous nerves (PIN) from a total of 56 subjects with T1D (n = 9), with T2D (n = 24), and without diabetes (i.e., healthy controls, n = 23) were harvested under local anesthesia and prepared for quantitative mass spectrometry analysis. Protein intensities were associated with electrophysiology data of the ulnar nerve and morphometry of the same PIN, and differences in protein intensities between groups were analyzed.

Results

In total, 32 different HSPs were identified and quantified in the nerve specimens. No statistically significant differences were observed regarding protein intensities between groups. Furthermore, protein intensities did not correlate with amplitude or conduction velocity in the ulnar nerve or with the myelinated nerve fiber density of PIN.

Conclusion

Quantitative proteomics can be used to study HSPs in nerve biopsies, but no clear differences in protein quantities were observed between groups in this cohort.

Exposure to hand-held vibrating tools and biomarkers of nerve injury in plasma: a population-based, observational study

OBJECTIVES

To analyse potential biomarkers for vibration-induced nerve damage in a population-based, observational study.

DESIGN

Prospective cohort study.

SETTING

Malmö Diet Cancer Study (MDCS), Malmö, Sweden.

PARTICIPANTS

In a subcohort of 3898 individuals (recruited 1991-1996) from MDCS (baseline examination in 28 449 individuals; collection of fasting blood samples in a cardiovascular subcohort of MDCS of 5540 subjects), neuropathy-relevant plasma biomarkers were analysed during follow-up after filling out questionnaires, including a question whether work involved hand-held vibrating tools, graded as 'not at all', 'some' or 'much'.

PRIMARY OUTCOME MEASURES

The neuropathy-relevant plasma biomarkers vascular endothelial growth factor (VEGF)-A, VEGF-D, VEGF receptor 2, galanin, galectin-3, HSP27, ß-nerve growth factor, caspase-3, caspase-8, transforming growth factor-α and tumour necrosis factor were analysed. Data were analysed by conventional statistics (Kruskal-Wallis test; post hoc test Mann-Whitney U test; Bonferroni correction for multiple testing) and in a subanalysis for galanin using two linear regression models (unadjusted and adjusted).

RESULTS

Among participants, 3361 of 3898 (86%) reported no work with hand-held vibrating tools, 351 of 3898 (9%) reported some and 186 of 3898 (5%) much work. There were more men and smokers in vibration-exposed groups. Galanin levels were higher after much vibration exposure (arbitrary units 5.16±0.71) compared with no vibration exposure (5.01±0.76; p=0.015) with no other observed differences.

CONCLUSIONS

Higher plasma levels of galanin, possibly related to magnitude, frequency, acceleration and duration, as well as to severity of symptoms of vibration exposure, may be found in individuals working with hand-held vibrating tools.

Axonal transport deficits in the pathogenesis of diabetic peripheral neuropathy

Diabetic peripheral neuropathy (DPN) is a chronic and prevalent metabolic disease that gravely endangers human health and seriously affects the quality of life of hyperglycemic patients. More seriously, it can lead to amputation and neuropathic pain, imposing a severe financial burden on patients and the healthcare system. Even with strict glycemic control or pancreas transplantation, peripheral nerve damage is difficult to reverse. Most current treatment options for DPN can only treat the symptoms but not the underlying mechanism. Patients with long-term diabetes mellitus (DM) develop axonal transport dysfunction, which could be an important factor in causing or exacerbating DPN. This review explores the underlying mechanisms that may be related to axonal transport impairment and cytoskeletal changes caused by DM, and the relevance of the latter with the occurrence and progression of DPN, including nerve fiber loss, diminished nerve conduction velocity, and impaired nerve regeneration, and also predicts possible therapeutic strategies. Understanding the mechanisms of diabetic neuronal injury is essential to prevent the deterioration of DPN and to develop new therapeutic strategies. Timely and effective improvement of axonal transport impairment is particularly critical for the treatment of peripheral neuropathies.

Carpal Tunnel Syndrome and Ulnar Nerve Entrapment at the Elbow Are Not Associated With Plasma Levels of Caspase-3, Caspase-8 or HSP27

Background

Nerve compression disorders, such as carpal tunnel syndrome (CTS) and ulnar entrapment at the elbow (UNE), may be associated with apoptosis and neuroprotective mechanisms in the peripheral nerve that may be detected by biomarkers in the blood. The relationships between CTS and UNE and two biomarkers of apoptosis, i.e., caspase-3 and caspase-8, and the neuroprotective factor Heat Shock Protein 27 (HSP27) in plasma were examined in a population-based cohort.

Method

The biomarkers caspase-3, caspase-8 and HSP27 were measured in plasma at inclusion of 4,284 study participants aged 46-68 years in the population-based Malmö Diet and Cancer study (MDCS). End-point retrieval was made from national registers concerning CTS and UNE. Independent t-test was used to examine the association between caspase-3, caspase-8 and HSP27 plasma levels and incidence of CTS and UNE. Cox proportional hazards regression was used to investigate if plasma levels of caspase-3, caspase-8 and HSP27 affected time to diagnosis of CTS or UNE.

Results

During the mean follow-up time of 22 years, 189/4,284 (4%) participants were diagnosed with CTS and 42/4,284 (1%) were diagnosed with UNE. No associations were found between incident CTS or UNE and the biomarkers caspase-3, caspase-8 and HSP27 in plasma.

Conclusion

The apoptotic biomarkers caspase-3 and caspase-8 and the neuroprotective factor HSP27 in plasma, factors conceivably related to a nerve injury, are not associated with the nerve compression disorders CTS and UNE in a general population.

Injury-Induced HSP27 Expression in Peripheral Nervous Tissue Is Not Associated with Any Alteration in Axonal Outgrowth after Immediate or Delayed Nerve Repair

We investigated injury-induced heat shock protein 27 (HSP27) expression and its association to axonal outgrowth after injury and different nerve repair models in healthy Wistar and diabetic Goto-Kakizaki rats. By immunohistochemistry, expression of HSP27 in sciatic nerves and DRG and axonal outgrowth (neurofilaments) in sciatic nerves were analyzed after no, immediate, and delayed (7-day delay) nerve repairs (7- or 14-day follow-up). An increased HSP27 expression in nerves and in DRG at the uninjured side was associated with diabetes. HSP27 expression in nerves and in DRG increased substantially after the nerve injuries, being higher at the site where axons and Schwann cells interacted. Regression analysis indicated a positive influence of immediate nerve repair compared to an unrepaired injury, but a shortly delayed nerve repair had no impact on axonal outgrowth. Diabetes was associated with a decreased axonal outgrowth. The increased expression of HSP27 in sciatic nerve and DRG did not influence axonal outgrowth. Injured sciatic nerves should appropriately be repaired in healthy and diabetic rats, but a short delay does not influence axonal outgrowth. HSP27 expression in sciatic nerve or DRG, despite an increase after nerve injury with or without a repair, is not associated with any alteration in axonal outgrowth.

Gold and Cobalt Oxide Nanoparticles Modified Poly-Propylene Poly-Ethylene Glycol Membranes in Poly (ε-Caprolactone) Conduits Enhance Nerve Regeneration in the Sciatic Nerve of Healthy Rats

Reconstruction of nerve defects is a clinical challenge. Autologous nerve grafts as the gold standard treatment may result in an incomplete restoration of extremity function. Biosynthetic nerve conduits are studied widely, but still have limitations. Here, we reconstructed a 10 mm sciatic nerve defect in healthy rats and analyzed nerve regeneration in poly (ε-caprolactone) (PCL) conduits longitudinally divided by gold (Au) and gold-cobalt oxide (AuCoO) nanoparticles embedded in poly-propylene poly-ethylene glycol (PPEG) membranes (AuPPEG or AuCoOPPEG) and compared it with unmodified PPEG-membrane and hollow PCL conduits. After 21 days, we detected significantly better axonal outgrowth, together with higher numbers of activated Schwann cells (ATF3-labelled) and higher HSP27 expression, in reconstructed sciatic nerve and in corresponding dorsal root ganglia (DRG) in the AuPPEG and AuCoOPPEG groups; whereas the number of apoptotic Schwann cells (cleaved caspase 3-labelled) was significantly lower. Furthermore, numbers of activated and apoptotic Schwann cells in the regenerative matrix correlated with axonal outgrowth, whereas HSP27 expression in the regenerative matrix and in DRGs did not show any correlation with axonal outgrowth. We conclude that gold and cobalt-oxide nanoparticle modified membranes in conduits improve axonal outgrowth and increase the regenerative performance of conduits after nerve reconstruction.

Recent Advances in Biomarkers and Regenerative Medicine for Diabetic Neuropathy

Diabetic neuropathy is one of the most common complications of diabetes. This complication is peripheral neuropathy with predominant sensory impairment, and its symptoms begin with hyperesthesia and pain and gradually become hypoesthesia with the loss of nerve fibers. In some cases, lower limb amputation occurs when hypoalgesia makes it impossible to be aware of trauma or mechanical stimuli. On the other hand, up to 50% of these complications are asymptomatic and tend to delay early detection. Therefore, sensitive and reliable biomarkers for diabetic neuropathy are needed for an early diagnosis of this condition. This review focuses on systemic biomarkers that may be useful at this time. It also describes research on the relationship between target gene polymorphisms and pathological conditions. Finally, we also introduce current information on regenerative therapy, which is expected to be a therapeutic approach when the pathological condition has progressed and nerve degeneration has been completed.

Heat shock protein B1 is required for the prolactin-induced cytoprotective effects on pancreatic islets

The success of islet transplantation has improved lately. Unfortunately, it is still compromised by cell loss. We have shown that prolactin (PRL) inhibits beta-cell apoptosis and up-regulates the antiapoptotic Heat Shock Protein B1 (HSPB1) in human islets. Since its function in pancreatic islets has not been studied, we explored the role of HSPB1 in PRL-induced beta-cell survival. The significant PRL-induced cytoprotection in control cells was abrogated in HSPB1 silenced cells, overexpression of HSPB1 recovered survival. PRL-mediated inhibition of cytokine-induced caspase activities and cytokine-induced decrease of BCL-2/BAX ratio was significantly reverted in knocked-down cells. Kinetics of HSPB1 and HSF1 expression were studied in primary cultures of murine and human pancreatic islets. These findings are highly relevant for the improvement of clinical islet transplantation success rate since our results demonstrated a key role for HSPB1 pointing it as a promising target for beta-cell cytoprotection through the up-regulation of an endogenous protective pathway.

Temporal trend of autonomic nerve function and HSP27, MIF and PAI-1 in type 1 diabetes

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Cardiovascular autonomic nerve function (i.e. E/I ratio) deteriorates over time in type 1 diabetes.

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HSP27, MIF and PAI-1 concentrations do not correlate with cardiovascular autonomic nerve function.

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The change in HbA1c correlates negatively with the change in E/I over time.

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Higher HbA1c is associated with worse cardiovascular autonomic nerve function.

Aim

Diabetes mellitus type 1 (T1D) has numerous complications including autonomic neuropathy, i.e. dysfunction of the autonomous nervous system. This study focuses on Heat Shock Protein 27 (HSP27), Macrophage Migration Inhibitory Factor (MIF), Plasminogen Activator Inhibitor-1 (PAI-1) and HbA1c and their possible roles in effects of diabetes on the autonomic nervous system.

Methods

Patients with T1D (n = 32, 41% women) were recruited in 1985 and followed up on four occasions (1989, 1993, 1998, and 2005). Autonomic function was tested using expiration/inspiration (E/I-ratio). Blood samples, i.e. HSP27 (last three occasions), MIF, PAI-1 (last two occasions) and HbA1c (five occasions), were analyzed.

Results

Autonomic nerve function deteriorated over time during the 20-year-period, but levels of HSP27, MIF, and PAI-1 were not associated with cardiovascular autonomic neuropathy. MIF and PAI-1 were lower in T1D than in healthy controls in 2005. Increased HbA1c correlated with a decrease in E/I-ratio.

Conclusions

Neither the neuroprotective substance HSP27 nor the inflammatory substances, MIF and PAI-1 were associated with measures of cardiovascular autonomic nerve function, but a deterioration of such function was observed in relation to increasing HbA1c in T1D during a 20-year follow-up period. Improved glucose control might be associated with protection against autonomic neuropathy in T1D.

Targeting the Diabetic Chaperome to Improve Peripheral Neuropathy

The chaperome constitutes a broad family of molecular chaperones and co-chaperones that facilitate the folding, refolding, and degradation of the proteome. Heat shock protein 90 (Hsp90) promotes the folding of numerous oncoproteins to aid survival of malignant phenotypes, and small molecule inhibitors of the Hsp90 chaperone complex offer a viable approach to treat certain cancers. One therapeutic attribute of this approach is the selectivity of these molecules to target high affinity oncogenic Hsp90 complexes present in tumor cells, which are absent in nontransformed cells. This selectivity has given rise to the idea that disease may contribute to forming a stress chaperome that is functionally distinct in its ability to interact with small molecule Hsp90 modulators. Consistent with this premise, modulating Hsp90 improves clinically relevant endpoints of diabetic peripheral neuropathy but has little impact in nondiabetic nerve. The concept of targeting the "diabetic chaperome" to treat diabetes and its complications is discussed.

Extracellular Release and Signaling by Heat Shock Protein 27: Role in Modifying Vascular Inflammation

Heat shock protein 27 (HSP27) is traditionally viewed as an intracellular chaperone protein with anti-apoptotic properties. However, recent data indicate that a number of heat shock proteins, including HSP27, are also found in the extracellular space where they may signal via membrane receptors to alter gene transcription and cellular function. Therefore, there is increasing interest in better understanding how HSP27 is released from cells, its levels and composition in the extracellular space, and the cognate cell membrane receptors involved in effecting cell signaling. In this paper, the knowledge to date, as well as some emerging paradigms about the extracellular function of HSP27 is presented. Of particular interest is the role of HSP27 in attenuating atherogenesis by modifying lipid uptake and inflammation in the plaque. Moreover, the abundance of HSP27 in serum is an emerging new biomarker for ischemic events. Finally, HSP27 replacement therapy may represent a novel therapeutic opportunity for chronic inflammatory disorders, such as atherosclerosis.

Chitosan-film enhanced chitosan nerve guides for long-distance regeneration of peripheral nerves

Biosynthetic nerve grafts are developed in order to complement or replace autologous nerve grafts for peripheral nerve reconstruction. Artificial nerve guides currently approved for clinical use are not widely applied in reconstructive surgery as they still have limitations especially when it comes to critical distance repair. Here we report a comprehensive analysis of fine-tuned chitosan nerve guides (CNGs) enhanced by introduction of a longitudinal chitosan film to reconstruct critical length 15 mm sciatic nerve defects in adult healthy Wistar or diabetic Goto-Kakizaki rats. Short and long term investigations demonstrated that the CNGs enhanced by the guiding structure of the introduced chitosan film significantly improved functional and morphological results of nerve regeneration in comparison to simple hollow CNGs. Importantly, this was detectable both in healthy and in diabetic rats (short term) and the regeneration outcome almost reached the outcome after autologous nerve grafting (long term). Hollow CNGs provide properties likely leading to a wider clinical acceptance than other artificial nerve guides and their performance can be increased by simple introduction of a chitosan film with the same advantageous properties. Therefore, the chitosan film enhanced CNGs represent a new generation medical device for peripheral nerve reconstruction.