Monocyte cytokine synthesis in response to extracellular cell stress proteins suggests these proteins exhibit network behaviour

Association between circulating levels of heat-shock protein 27 and aggressive periodontitis

Heat-shock protein (Hsp) 27 is a major intracellular molecular chaperone and controller of intracellular responses to inflammatory signals. In the extracellular space, recombinant Hsp27 has been described to exert anti-inflammatory activities. The aim of this study was to assess the association between circulating levels of Hsp27 and different types of periodontitis. Pro- and anti-inflammatory cytokines and the stress proteins Hsp27 and Hsp60 with proposed anti- and pro-inflammatory properties, respectively, were measured by two-site ELISA in the serum of patients with aggressive periodontitis (AgP, n = 30), chronic periodontitis (CP, n = 29) and periodontally healthy controls (H, n = 28). Furthermore, Hsp27 and Hsp60 levels were also measured longitudinally in 12 AgP patients at 6 time points up to 3 months after treatment. AgP patients had lower levels of Hsp27 compared to CP patients and healthy subjects (adjusted one-way ANOVA, p < 0.001, followed by post hoc Tukey HSD comparisons), while no differences in levels of Hsp60 or cytokines between the three groups were detected. In CP patients and H subjects, the systemic Hsp27 levels correlated with Hsp60 (r = 0.43, p < 0.001; r = 0.59, p < 0.001, respectively) and with pro-inflammatory cytokines TNF-α (r = 0.48, p < 0.001; r = 0.55, p < 0.001, respectively) and IL-6 (r = 0.44, p < 0.01). However, no such correlations were detected in AgP cases. No consistent temporal patterns of changes of Hsp27 concentration were detected across AgP patients following periodontal treatment. This study provides the first evidence that Hsp27 may be differentially expressed and regulated in AgP patients as compared with CP patients and healthy individuals.

Regulator Versus Effector Paradigm: Interleukin-10 as Indicator of the Switching Response

The interleukin-10 (IL-10) is generally considered as the most important cytokine with anti-inflammatory properties and one of the key cytokines preventing inflammation-mediated tissue damage. In this respect, IL-10 producing cells play a crucial role in the outcome of infections, allergy, autoimmune reactions, tumor development, and transplant tolerance. Based on recent findings with regard to the mentioned clinical conditions, this review attempts to shed some light on the IL-10 functions, considering this cytokine as inherent inducer of the switching immunity. While acute infections and vaccinations are associated by IL-10 enhanced during few weeks, chronic parasitoses, tumor diseases, allergen-specific immunotherapy, transplants, and use of immune-suppressor drugs show an increased IL-10 level along months or years. With regard to autoimmune pathologies, the IL-10 increase is prevalently observed during early stages, whereas the successive stages are characterized by reaching of immune equilibrium independently to disease's activity. Together, these findings indicate that IL-10 is mainly produced during transient immune conditions and the persistent IL-10-related effect is the indication/prediction (and maybe effectuation) of the switching immunity. Actual knowledge emphasizes that any manipulation of the IL-10 response for treatment purposes should be considered very cautiously due to its potential hazards to the immune system. Probably, the IL-10 as potential switcher of immunity response should be used in association with co-stimulatory immune effectors that are necessary to determine the appropriate deviation during treatment of respective pathologies. Hopefully, further findings would open new avenues to study the biology of this "master switch" cytokine and its therapeutic potential.

Diet-induced elevation of circulating HSP70 may trigger cell adhesion and promote the development of atherosclerosis in rats

Although accumulating evidence indicates that heat shock protein 70 (HSP70) could be secreted into plasma and its levels have been found to have an ambiguous association with atherosclerosis, our knowledge for the exact role of circulating HSP70 in the development of atherosclerosis is still limited. In the present study, we report an adhesion-promoting effect of exogenous HSP70 and evaluate the potential involvement of elevated circulating HSP70 in the development of atherosclerosis. Time-dependent elevation of plasma HSP70 was found in diet-induced atherosclerotic rats, whose effect was investigated through further in vitro experiments. In rat aortic endothelial cell (RAEC) cultures, exogenous HSP70 incubation neither produced cell injuries by itself nor had protective effects on cell injuries caused by Ox-LDL or homocysteine. However, exogenous HSP70 administration could lead to a higher adhesion rate between rat peripheral blood monocytes (PBMCs) and RAECs. This adhesion-promoting effect appeared only when PBMCs, rather than RAECs, were pretreated with HSP70 incubation. PBMCs in an HSP70 environment released more IL-6 to supernatant, which subsequently up-regulated the expression of ICAM-1 in RAECs. These results indicate that the diet-induced elevation of circulating HSP70 could trigger cell adhesion with the help of IL-6 as a mediator, which provides a novel possible mechanism for understanding the role of circulating HSP70 in the pathogenesis of atherosclerosis.

Increased percentages of regulatory T cells are associated with inflammatory and neuroendocrine responses to acute psychological stress and poorer health status in older men and women

RATIONALE

The percentage of regulatory T cells (TRegs)-a subtype of T lymphocyte that suppresses the immune response-appears to be reduced in a number of stress-related diseases. The role of the TReg in stress-disease pathways has not yet been investigated.

OBJECTIVES

The aim of the study was to investigate the association between biological responsivity to acute psychosocial stress and the percentage of TRegs in healthy older adults. The secondary purpose was to measure the associations between TReg percentage and psychological and physical well-being in the participants.

METHODS

Salivary cortisol and plasma interleukin (IL)-6 samples were obtained from 121 healthy older men and women from the Whitehall II cohort following acute psychophysiological stress testing. Three years later at a follow-up visit, we measured TReg percentages and psychological and physical well-being were recorded using the Short Form 36 Health Survey and the Center for Epidemiologic Studies Depression Scale.

RESULTS

Blunted cortisol responses (p = 0.004) and elevated IL-6 responses (p = 0.027) to acute psychophysiological stress were associated with greater TReg percentage independently of age, sex, BMI, smoking status, employment grade, time of testing, and baseline measures of cortisol and IL-6, respectively. Percentage of TRegs was associated cross-sectionally with lower physical (p = 0.043) and mental health status (p = 0.008), and higher levels of depressive symptoms (p = 0.002), independently of covariates.

CONCLUSIONS

Increased levels of TRegs may act as a defence against increased inflammation and may be a pre-indication for chronically stressed individuals on the cusp of clinical illness.

Thermostability of IFN-γ and IP-10 release assays for latent infection with Mycobacterium tuberculosis: A TBnet study

INTRODUCTION

Interferon-γ (IFN-γ) inducible protein 10kD (IP-10) and IFN-γ release assays (IGRAs) are immunodiagnostic tests aiming to identify the presence of specific cellular immune responses, interpreted as markers for latent infection with Mycobacterium tuberculosis. Incubation at higher temperatures could affect IFN-γ and IP-10 responsiveness in order to improve the performance of IP-10 release assays and IGRAs.

AIM

The aim of this study was to assess the robustness of whole blood based IP-10 release assay and IGRAs and the effect of hyper-thermic incubation (39 °C) on the diagnostic accuracy of IP-10 release assay and IGRAs.

RESULTS

We included 65 patients with confirmed pulmonary tuberculosis and 160 healthy controls from 6 European centres collaborating in the TBnet. In patients, IP-10 responses increased 1.07 (IQR 0.90-1.36) fold and IFN-γ responses decreased 0.88 (IQR 0.57-1.02) fold, with 39 °C compared to 37 °C incubation temperature. At 37 °C IGRA sensitivity was 85% and IP-10 sensitivity was 82%, whereas specificity was 97% for both tests (p > 0.8). These minor changes observed as a result of hyper-thermic incubation were not sufficient to impact IGRA and IP-10 release assay test performance.

CONCLUSION

The performance of IGRA and IP-10 release assays is robust despite variations in the incubation temperature between 37 °C and 39 °C.

Immune independent crosstalk between lymphoma and myeloid suppressor CD14+HLA-DRlow/neg monocytes mediates chemotherapy resistance

We have previously reported a novel phenotype of myeloid suppressors in lymphoma patients characterized by a loss of HLA-DR expression on monocytes, CD14⁺HLA-DR^low/neg. These cells were directly immunosuppressive and were associated with poor clinical outcome. In this study, we found that lymphoma tumors could have more than 30% of their tumor occupied by CD14⁺ cells. This intimate spatial connection suggested substantial cell–cell communication. We examined cross talk between monocytes from healthy volunteers (normal) and lymphoma cells in co-culture to identify the mechanisms and consequences of these interactions. Normal CD14⁺HLA-DR⁺ monocytes lost their HLA-DR expression after co-culture with lymphoma cells. Lymphoma-converted CD14⁺HLA-DR^low/neg cells exhibited similar immunosuppressive functions as CD14⁺HLA-DR^low/neg monocytes from lymphoma patients. Unexpectedly monocyte additions to lymphoma cell cultures protected lymphoma from cytotoxic killing by chemotherapy drug doxorubicin (DOX). Monocyte mediated resistance to DOX killing was associated with decreased Caspase-3 activity and increased anti-apoptotic heat shock protein-27 (Hsp27) expression. Soluble Hsp27 was detected in supernatant and patient plasma. Increased Hsp27 in plasma correlated with increased proportion of CD14⁺HLA-DR^low/neg monocytes in patient blood and was associated with lack of clinical response to DOX. This is the first report to describe a non-immune function of CD14⁺HLA-DR^low/neg monocytes: enhanced lymphoma resistance to chemotherapy. It is also the first report in lymphoma of Hsp27 as a potential mediator of lymphoma and monocyte crosstalk and chemotherapy resistance. Together with previous reports of the prevalence of these myeloid suppressors in other cancers, our findings identify this pathway and these interactions as a potential novel therapeutic target.

Glutamine suppresses Hsp72 not Hsp90α and is not inducing Th1, Th2, or Th17 cytokine responses in human septic PBMCs

OBJECTIVE

L-Alanyl-glutamine (L-Ala-Gln) is a pharmaco-nutrient commonly used in nutrition regimens due to its immunomodulatory effects. In critically ill patients who are septic, L-Ala-Gln was associated with an increase in mortality. The aim of this study was to investigate whether L-Ala-Gln modulated heat shock protein (Hsp)-72, 90-α, T helper (Th)1, Th2, and Th17 cytokine expression in the peripheral blood mononuclear cells (PBMC) of patients with severe sepsis.

METHODS

Time-dose effects of L-Ala-Gln were compared with those of L-glutamine (L-Gln) and lipopolysaccharide (LPS) and to healthy controls. PBMCs were incubated with 1 or 10 μg/mL LPS, 5 or 10 mM L-Gln, and 5 or 10 mM L-Ala-Gln for different periods of time (0; 4; 24 h) when culture supernatants were harvested.

RESULTS

In both groups, basal Hsp72 increased over time (P < 0.02); Hsp90-α levels declined in controls (P < 0.02) but remained increased in septic patients (P < 0.02), not exhibiting any significant time-response trend. Both Glns suppressed Hsp72 in septic and controls at 10 mM by 4 h (P < 0.045) and Hsp90-α in the control group by 24 h (P < 0.045). LPS did not induce Hsps in either group. L-Ala-Gln did not induce any of the Th1, Th2, and Th17 cytokines in either group.

CONCLUSION

High doses of L-Gln or L-Ala-Gln do not induce any of the Th1, Th2, and Th17 cytokines in either healthy or septic human PBMCs. High Gln doses suppress Hsp72 in septic and control PBMCs. Hsp90-α time-series expression declines, contrasting the increasing trend of Hsp72 in healthy controls. Hsp90-α sustains increased levels in septic supernatants, showing a characteristic longitudinal behavior needed further elucidation.