Insulin-like growth factor 1 promotes cord blood T cell maturation and inhibits its spontaneous and phytohemagglutinin-induced apoptosis through different mechanisms

Targeting Insulin-Like Growth Factor-I in Management of Neurological Disorders

The degradation of neurons marks as the pathological reason for onset of most of the neurological diseases although the functional deficiencies and symptoms may vary. Insulin-like growth factor-I (IGF-I) boosts regeneration of both motor and sensory neurons and thus presents as a potential treatment in management of neurological disorders. IGF-I is a pleiotropic agent which stimulates the survival and outgrowth of neurons accompanied by their motility as well as myelination by glial cells. This hormone has been found to possess neuroprotective properties which is in association with its antioxidant and mitochondrial protection activity. Studying and exploring the signaling pathways which mediate pleotropic responses intracellularly have elucidated significant therapeutic approach in treatment and management of neurological disorders by IGF-I. The current review highlights the role of IGF-I in management of major neurological disorders such as depression, Parkinson's disease, and Alzheimer's disease and also covers the mechanisms involved in the process.

Serum IGF-1 in patients with rheumatoid arthritis: correlation with disease activity

Objective

Insulin-like growth factor (IGF)-1 participates in modulating immunity and inflammation. Its bioactivity is controlled by six IGF-binding proteins (IGFBP-1 to IGFBP-6). In particular, the IGFBP-3 level is reportedly linked to the disease activity of rheumatoid arthritis (RA), consistent with our previous study. Therefore, the present study aimed to reproduce the previous results.

Results

The serum IGFBP-3 level was not significantly different among the three groups according to disease activity based on the DAS28-ESR/CRP (p > 0.05) but was significantly different between the low- and high-disease-activity groups based on the DAS28-CRP (p = 0.036). Meanwhile, the interleukin-6 (IL-6) level moderately correlated with DAS28-CRP (Spearman’s rho = 0.583, p < 0.001).

Changes in the transcriptional activity of the entero-insular axis genes in streptozotocin-induced diabetes and after the administration of TNF-α non-selective blockers

OBJECTIVE

The aim of the present study was to investigate the transcriptional activity of the GLP-1R, DPP-4, SGLT-1, INSR, and IGF-1R genes in GALT cells of rats with streptozotocin-induced diabetes in both untreated and treated with pentoxifylline, as a non-specific blocker of TNF-α.

METHODS

The expression of GLP-1R, DPP-4, SGLT-1, INSR, and IGF-1R genes in GALT cells of rats was studied by real time quantitative polymerase chain reaction.

RESULTS

It was shown that the development of diabetes was accompanied by the decrease of GLP-1R and an increase of DPP-4 genes expression in rat ileum. The administration of pentoxifyl-line to diabetic animals led to an increase in the transcriptional activity of GLP-1R on the 4th week and decrease in transcriptional activity of DPP-4 on the 2nd and 4th weeks of the experiment. An increase in the normalized expression of SGLT-1 on the 4th week of the experimental diabetes was also noted, while the administration of pentoxifylline to diabetic animals did not lead to significant changes in this index. The transcriptional activity of the INSR and IGF-1R genes was reduced in diabetic rats and the administration of the non-specific TNF-α blocker - pentoxifylline led to a significant increase only for INSR gene in animals on the 4th week of the experimental diabetes.

CONCLUSIONS

The expression of incretins, glucose transporters, and pro-inflammatory cytokines (e.g. TNF-α) in immune cells may be used as markers of several autoimmune pathologies progression such as type 1 diabetes due to their effect on the balance of pro- and anti-inflammatory factors.

Effect of the Tc13Tul antigen from Trypanosoma cruzi on splenocytes from naïve mice

Trypanosoma cruzi, the etiological agent of Chagas disease, releases factors, including antigens from the trans-sialidase (TS) superfamily, which modulate the host immune responses. Tc13 antigens belong to group IV of TSs and are characterized by C-terminal EPKSA repeats. Here, we studied the effect of the Tc13 antigen from the Tulahuén strain, Tc13Tul, on primary cultures of splenocytes from naïve BALB/c mice. Recombinant Tc13Tul increased the percentage of viable cells and induced B (CD19+) lymphocyte proliferation. Tc13Tul stimulation also induced secretion of non-specific IgM and interferon-γ (IFN-γ). The same effects were induced by Tc13Tul on splenocytes from naïve C3H/HeJ mice. In vivo administration of Tc13Tul to naïve BALB/c mice increased non-specific IgG in sera. In addition, in vitro cultured splenocytes from Tc13Tul-inoculated mice secreted a higher basal level of non-specific IgM than controls and the in vitro Tc13Tul stimulation of these cells showed an enhanced effect on IgM and IFN-γ secretion. Our results indicate that Tc13Tul may participate in the early immunity in T. cruzi infection by favouring immune system evasion through B-cell activation and non-specific Ig secretion. In contrast, as IFN-γ is an important factor involved in T. cruzi resistance, this may be considered a Tc13Tul effect in favour of the host.

Associations between IGF1, IGFBP2 and TGFß3 Genes Polymorphisms and Growth Performance of Broiler Chicken Lines

Marker-assisted selection based on fast and accurate molecular analysis of individual genes is considered an acceptable tool in the speed-up of the genetic improvement of production performance in chickens. The objective of this study was to detect the single nucleotide polymorphisms (SNPs) in the IGF1, IGFBP2 and TGFß3 genes, and to investigate their associations with growth performance (body weight (BW) and average daily gain (ADG) at 14, 21, 28, 35 and 42 days of age) and carcass traits in broilers. Performance (carcass) data (weight before slaughter; weights of the trunk, giblets, abdominal fat, breast muscle and thigh muscle; slaughter value and slaughter percentage), as well as blood samples for DNA extraction and SNP analysis, were obtained from 97 chickens belonging to two different lines (Hubbard F15 and Cobb E) equally divided between the two sexes. The genotypes were detected using polymerase chain reaction- restriction fragment length polymorphism (PCR-RFLP) methods with specific primers and restrictase for each gene. The statistical analysis discovered significant associations (p < 0.05) between the TGFβ3 SNP and the following parameters: BW at 21, 28 and 35 days, trunk weight and slaughter value. Association analysis of BWs (at 21, 28 and 35 days) and SNPs was always significant for codominant, dominant and overdominant genetic models, showing a possible path for genomic selection in these chicken lines. Slaughter value was significant for codominant, recessive and overdominant patterns, whereas other carcass traits were not influenced by SNPs. Based on the results of this study, we suggested that the TGFβ3 gene could be used as a candidate gene marker for chicken growth traits in the Hubbard F15 and Cobb E population selection programs, whereas for carcass traits further investigation is needed.

Immunoregulatory effect of human β-defensin 1 on neonatal cord blood monocyte-derived dendritic cells and T cells

The relationship between breastfeeding and infant health has been well elucidated in past decades. Our previous study has shown that human β-defensin 1 (hBD-1) in human breast milk plays a protective role in reducing the incidence of upper respiratory infection in infants younger than 6 months. In the present study, we aim to reveal the mechanism underlying the protective role of hBD-1 by focusing on its immunoregulatory function in neonates. Cord blood (CB) from newborns' umbilical cords, which can simulate many of the neonatal symptoms, was used to study the immunomodulatory role of hBD-1 in neonates in vitro. Our results showed that hBD-1 promotes the GM-CSF- and IL-4-driven differentiation of neonatal umbilical CB monocytes to immature dendritic cells (DCs) and the final maturation of CB monocyte-derived DCs (moDCs) induced by LPS but not inflammatory cytokine production. In addition, hBD-1 inhibits apoptosis in neonatal moDCs through CCR6, which might be a possible mechanism of the hBD-1-induced phenotypes in moDCs. Furthermore, we found that hBD-1 promotes the proliferation and activation, but not the maturation, of neonatal CB CD4 + T cells. These results extend the immunoregulatory effects of hBD-1 and provide a potential mechanism for the protective role of hBD-1 in early infants, which will inform the development of infant nutrition, novel vaccines and anti-infective strategies in the future.

T Cell Transcriptomes from Paroxysmal Nocturnal Hemoglobinuria Patients Reveal Novel Signaling Pathways

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare acquired disorder originating from hematopoietic stem cells and is a life-threating disease characterized by intravascular hemolysis, bone marrow (BM) failure, and venous thrombosis. The etiology of PNH is a somatic mutation in the phosphatidylinositol glycan class A gene (PIG-A) on the X chromosome, which blocks synthesis of the glycolipid moiety and causes deficiency in GPI-anchored proteins. PNH is closely related to aplastic anemia, in which T cells mediate destruction of BM. To identify aberrant molecular mechanisms involved in immune targeting of hematopoietic stem cells in BM, we applied RNA-seq to examine the transcriptome of T cell subsets (CD4⁺ naive, CD4⁺ memory, CD8⁺ naive, and CD8⁺ memory) from PNH patients and healthy control subjects. Differentially expressed gene analysis in four different T cell subsets from PNH and healthy control subjects showed distinct transcriptional profiles, depending on the T cell subsets. By pathway analysis, we identified novel signaling pathways in T cell subsets from PNH, including increased gene expression involved in TNFR, IGF1, NOTCH, AP-1, and ATF2 pathways. Dysregulation of several candidate genes (JUN, TNFAIP3, TOB1, GIMAP4, GIMAP6, TRMT112, NR4A2, CD69, and TNFSF8) was validated by quantitative real-time RT-PCR and flow cytometry. We have demonstrated molecular signatures associated with positive and negative regulators in T cells, suggesting novel pathophysiologic mechanisms in PNH. These pathways may be targets for new strategies to modulate T cell immune responses in BM failure.

Insulin-Like Growth Factor-1 Deficiency and Cirrhosis Establishment

Cirrhosis represents the final stage of chronic liver damage, which can be due to different factors such as alcohol, metabolic syndrome with liver steatosis, autoimmune diseases, drugs, toxins, and viral infection, among others. Nowadays, cirrhosis is an important health problem and it is an increasing cause of morbidity and mortality, being the 14th most common cause of death worldwide. The physiopathological pathways that lead to fibrosis and finally cirrhosis partly depend on the etiology. Nevertheless, some common features are shared in this complex mechanism. Recently, it has been demonstrated that cirrhosis is a dynamic process that can be altered in order to delay or revert fibrosis. In addition, when cirrhosis has been established, insulin-like growth factor-1 (IGF-1) deficiency or reduced availability is a common condition, independently of the etiology of chronic liver damage that leads to cirrhosis. IGF-1 deprivation seriously contributes to the progressive malnutrition of cirrhotic patient, increasing the vulnerability of the liver to establish an inflammatory and oxidative microenvironment with mitochondrial dysfunction. In this context, IGF-1 deficiency in cirrhotic patients can justify some of the common characteristics of these individuals. Several studies in animals and humans have been done in order to test the replacement of IGF-1 as a possible therapeutic option, with promising results.

Micronucleus, cell-free DNA, and plasma glycan composition in the newborns of healthy and diabetic mothers

Diabetes is associated with certain environmental exposures, heritable factors, and metabolic conditions of intrauterine development due to diabetes in the mother. We evaluated genomic damage, cell-free DNA, N-glycosylation of umbilical cord plasma proteins (PG), and nuclear division index (NDI) as possible prognostic biomarkers of health risk in the newborns of mothers with treated pregestational diabetes (NBDM; 22 mothers), compared these parameters with those from newborns of healthy mothers (NBHM; 89 mothers), and associated the results with the mothers' lifestyle in both groups, based on a detailed questionnaire. Genomic damage was estimated by the in vitro micronucleus (MN) assay. NDI was detected on MN slides. Glycans were analyzed by ultra-performance liquid chromatography that separates the plasma N-glycome into 46 glycan peaks. Cell-free DNA was analyzed by real-time PCR. For the association between biomarkers and individual characteristics, generalized linear/nonlinear analysis was performed. No significant difference was found between NBHM and NBDM for cell-free DNA levels. There was no association between cell-free DNA levels and lifestyle. MN frequency was significantly higher in NBDM than in NBHM (median, 0.6 vs. 0.3%, p<0.001). MN frequency and NDI were significantly associated with residence (urban vs. rural). PG differed significantly between NBHM and NBDM (p<0.001). A significant association was found between PG and increase of MN frequency (p<0.001). As both MN frequency and altered N-glycosylation are associated with cancer risk, our study indicates need for further investigations.

Leukocyte IGF-1 receptor expression during muscle recovery

INTRODUCTION

The insulin-like growth factor 1 (IGF-1) system plays a central role in anabolic cellular processes. Recently, a regulatory role of IGF-1 in the immune response for muscle repair has been suggested, but how it modulates the inflammatory process is largely unknown. We evaluated changes in leukocyte expression of IGF-1 receptors (IGF-1R) during recovery from resistance exercise to determine whether changes in the potential for IGF-1 interactions with leukocytes may mediate the role of IGF-1 in muscle repair.

METHODS

Twenty resistance-trained men (18-35 yr) performed resistance exercise followed by cold water immersion (CWI) or control treatment (CON) on three consecutive days. Blood was sampled at baseline (PRE), immediately (IP), 30 min (30P), 24 h (24H), and 48 h after (48H) exercise. Circulating IGF-1 was assayed, and IGF-1 receptor expression (CD221) on gated circulating leukocytes (monocytes, granulocytes, and lymphocytes) was measured by flow cytometry. Time and treatment effects were analyzed with ANCOVA.

RESULTS

Circulating IGF-1 significantly increased from PRE to IP as a result of resistance exercise, but no differences between CON and CWI were observed. Mean fluorescence intensity of CD221 on monocytes and granulocytes and percent of CD221+ granulocytes significantly increased at 30P (P < 0.000) and returned to preexercise levels by 24H. No treatment effects on monocytes or granulocytes were observed. On lymphocytes, mean fluorescence intensity of CD221+ significantly increased from PRE to 30P in CWI.

CONCLUSIONS

Changes in IGF-1 and its receptor on monocytes and granulocytes seem to be part of the mechanism that facilitates recovery from resistance exercise during earlier stages of muscle recovery. In addition, CWI seems to alter IGF-mediated responses on slower-acting lymphocytes, suggesting that its effects may be seen in later stages of muscle repair.

Cytokine-induced killer cells induce apoptosis and inhibit the Akt/nuclear factor-κB signaling pathway in cisplatin-resistant human glioma U87MG cells

Despite advances in the development of treatment methods, glioma remains among the cancer types with a high rate of mortality. Therefore, significant efforts are made to develop novel strategies for the treatment of glioma. Ineffective, long-term cancer chemotherapy can lead to multidrug resistance (MDR), which is one of the most common reasons for the failure of chemotherapy. The present study investigated the effects of cytokine‑induced killer cells (CIK) on reversing MDR in cisplatin-resistant U87MG cells (U87MG/DDP). Mononuclear cells were isolated from the peripheral blood of healthy individuals and cultured in vitro in the presence of a combination of cytokines to generate CIK for the treatment of U87MG/DDP. An MTS assay, flow cytometric analysis of apoptosis, ELISA, western blotting and reverse transcription quantitative polymerase chain reaction were used to investigate the MDR-reversing effects of CIK as well as the underlying mechanisms. The results showed that cisplatin sensitivity and the apoptotic rate following cisplatin treatment were increased, P‑glycoprotein expression was decreased and the intracellular rhodamine‑123 content was increased in U87MG/DDP co‑cultured with CIK. In addition, the present study also identified increased mRNA and protein expression levels of MDR gene 1 (MDR1), MDR‑associated protein 1 (MRP1), B-cell lymphoma 2, Survivin and glutathione S-transferase‑π, while the phosphorylation of AKT and the transcriptional activity of nuclear factor‑κB in CIK co‑cultured U87MG/DDP was decreased. These results indicated that pre‑treatment with CIK reversed the MDR of U87MG/DDP, and that CIK‑induced apoptosis of U87MG/DDP was associated with the inhibition of Akt/NF‑κB. These findings suggested that treatment with CIK may be an effective method to enhance the sensitivity of patients with glioma to chemotherapy.

Lymphocyte GH-axis hormones in immunity

The production and utilization of common ligands and their receptors by cells of the immune and neuroendocrine systems constitutes a biochemical information circuit between and within the immune and neuroendocrine systems. The sharing of ligands and receptors allows the immune system to serve as the sixth sense notifying the nervous system of the presence of foreign entities. Within this framework, it is also clear that immune cell functions can be altered by neuroendocrine hormones and that cells of the immune system have the ability to produce neuroendocrine hormones. This review summarizes a part of this knowledge with particular emphasis on growth hormone (GH). The past two decades have uncovered a lot of detail about the actions of GH, acting through its receptor, at the molecular and cellular level and its influence on the immune system. The production and action of immune cell-derived GH is less well developed although its important role in immunity is also slowly emerging. Here we discuss the production of GH, GH-releasing hormone (GHRH) and insulin-like growth factor-1 (IGF-1) and their cognate receptors on cells of the immune system and their influence via endocrine/autocrine/paracrine and intracrine pathways on immune function. The intracellular mechanisms of action of immune cell-derived GH are still largely unexplored, and it is anticipated that further work in this particular area will establish an important role for this source of GH in normal physiology and in pathologic situations.

Vγ9Vδ2-T lymphocytes have impaired antiviral function in small-for-gestational-age and preterm neonates

Preterm and small-for-gestational-age (SGA) neonates are vulnerable groups that are susceptible to various microbial infections. Vγ9Vδ2-T cells are critical components of the host immune system and have been demonstrated to play an important role in the defense against viral infection in adults. However, the characteristics of Vγ9Vδ2-T cells in children, especially the preterm and SGA populations, are poorly understood. Here, we examined the frequency and antiviral function of Vγ9Vδ2-T cells in neonates, including preterm, SGA and full-term babies. When compared to adults, neonates had a significantly lower percentage of Vγ9Vδ2-T cells in the blood. Upon influenza virus stimulation, neonatal Vγ9Vδ2-T cells, especially from preterm and SGA babies, showed markedly decreased and delayed antiviral cytokine responses than those of adults. In addition, the antiviral responses of neonatal Vγ9Vδ2-T cells were positively correlated with gestational age and birth weight. Finally, a weaker expansion of Vγ9Vδ2-T cells by isopentenyl pyrophosphate (IPP) was shown in neonates than the expansion in adults. Our data suggest that the depressed antiviral activity and decreased frequency of Vγ9Vδ2-T cells may likely account for the high susceptibility to microbial infection in neonates, particularly in preterm and SGA babies. Improving Vγ9Vδ2-T-cell function of neonates may provide a new way to defend against virus infection.

Human conditions of insulin-like growth factor-I (IGF-I) deficiency

Insulin-like growth factor I (IGF-I) is a polypeptide hormone produced mainly by the liver in response to the endocrine GH stimulus, but it is also secreted by multiple tissues for autocrine/paracrine purposes. IGF-I is partly responsible for systemic GH activities although it possesses a wide number of own properties (anabolic, antioxidant, anti-inflammatory and cytoprotective actions). IGF-I is a closely regulated hormone. Consequently, its logical therapeutical applications seems to be limited to restore physiological circulating levels in order to recover the clinical consequences of IGF-I deficiency, conditions where, despite continuous discrepancies, IGF-I treatment has never been related to oncogenesis. Currently the best characterized conditions of IGF-I deficiency are Laron Syndrome, in children; liver cirrhosis, in adults; aging including age-related-cardiovascular and neurological diseases; and more recently, intrauterine growth restriction. The aim of this review is to summarize the increasing list of roles of IGF-I, both in physiological and pathological conditions, underlying that its potential therapeutical options seem to be limited to those proven states of local or systemic IGF-I deficiency as a replacement treatment, rather than increasing its level upper the normal range.

IGFBP7 participates in the reciprocal interaction between acute lymphoblastic leukemia and BM stromal cells and in leukemia resistance to asparaginase

The interaction of acute lymphoblastic leukemia (ALL) blasts with bone marrow (BM) stromal cells (BMSCs) has a positive impact on ALL resistance to chemotherapy. We investigated the modulation of a series of putative asparaginase-resistance/sensitivity genes in B-precursor ALL cells upon coculture with BMSCs. Coculture with stromal cells resulted in increased insulin-like growth factor (IGF)-binding protein 7 (IGFBP7) expression by ALL cells. Assays with IGFBP7 knockdown ALL and stromal cell lines, or with addition of recombinant rIGFBP7 (rIGFBP7) to the culture medium, showed that IGFBP7 acts as a positive regulator of ALL and stromal cells growth, and significantly enhances in-vitro resistance of ALL to asparaginase. In these assays, IGFBP7 function occurred mainly in an insulin- and stromal-dependent manner. ALL cells were found to contribute substantially to extracellular IGFBP7 levels in the conditioned coculture medium. Diagnostic BM plasma from children with ALL had higher levels of IGFBP7 than controls. IGFBP7, in an insulin/IGF-dependent manner, enhanced asparagine synthetase expression and asparagine secretion by BMSCs, thus providing a stromal-dependent mechanism by which IGFBP7 protects ALL cells against asparaginase in this coculture system. Importantly, higher IGFBP7 mRNA levels were associated with lower leukemia-free survival (Cox regression model, P=0.003) in precursor B-cell Ph(-) ALL patients (n=147) treated with a contemporary polychemotherapy protocol.

Improvement in disability after alemtuzumab treatment of multiple sclerosis is associated with neuroprotective autoimmunity

Treatment of early relapsing-remitting multiple sclerosis with the lymphocyte-depleting humanized monoclonal antibody alemtuzumab (Campath [registered trade mark]) significantly reduced the risk of relapse and accumulation of disability compared with interferon β-1a in a phase 2 trial [Coles et al., (Alemtuzumab vs. interferon β-1a in early multiple sclerosis. N Engl J Med 2008; 359: 1786-801)]. Patients treated with alemtuzumab experienced an improvement in disability at 6 months that was sustained for at least 3 years. In contrast, those treated with interferon β-1a steadily accumulated disability. Here, by post hoc subgroup analyses of the CAMMS223 trial, we show that among participants with no clinical disease activity immediately before treatment, or any clinical or radiological disease activity on-trial, disability improved after alemtuzumab but not following interferon β-1a. This suggests that disability improvement after alemtuzumab is not solely attributable to its anti-inflammatory effect. So we hypothesized that lymphocytes, reconstituting after alemtuzumab, permit or promote brain repair. Here we show that after alemtuzumab, and only when specifically stimulated with myelin basic protein, peripheral blood mononuclear cell cultures produced increased concentrations of brain-derived neurotrophic factor, platelet-derived growth factor and ciliary neurotrophic factor. Analysis by reverse transcriptase polymerase chain reaction of cell separations showed that the increased production of ciliary neurotrophic factor and brain-derived neurotrophic factor after alemtuzumab is attributable to increased production by T cells. Media from these post-alemtuzumab peripheral blood mononuclear cell cultures promoted survival of rat neurones and increased axonal length in vitro, effects that were partially reversed by neutralizing antibodies against brain-derived nerve growth factor and ciliary neurotrophic factor. This conditioned media also enhanced oligodendrocyte precursor cell survival, maturation and myelination. Taken together, the clinical analyses and laboratory findings support the interpretation that improvement in disability after alemtuzumab may result, in part, from neuroprotection associated with increased lymphocytic delivery of neurotrophins to the central nervous system.

Insulin-like growth factor-I regulation of immune function: a potential therapeutic target in autoimmune diseases?

This topically limited review explores the relationship between the immune system and insulin-like growth factors (IGF-I and IGF-II) and the proteins through which they act, including IGF-I receptor (IGF-IR) and the IGF-I binding proteins. The IGF/IGF-IR pathway plays important and diverse roles in tissue development and function. It regulates cell cycle progression, apoptosis, and the translation of proteins. Many of the consequences ascribed to IGF-IR activation result from its association with several accessory proteins that are either identical or closely related to those involved in insulin receptor signaling. Relatively recent awareness that IGF-I and IGF-IR regulate immune function has cast this pathway in an unexpected light; it may represent an important switch governing the quality and amplitude of immune responses. IGF-I/IGF-IR signaling may also participate in the pathogenesis of autoimmune diseases, although its relationship with these processes seems complex and relatively unexplored. On the one hand, IGF-I seems to protect experimental animals from developing insulin-deficient diabetes mellitus. In contrast, activating antibodies directed at IGF-IR have been detected in patients with Graves' disease, where the receptor is overexpressed by multiple cell types. The frequency of IGF-IR+ B and T cells is substantially increased in patients with that disease. Potential involvement of IGF-I and IGF-IR in the pathogenesis of autoimmune diseases suggests that this pathway might constitute an attractive therapeutic target. IGF-IR has been targeted in efforts directed toward drug development for cancer, employing both small-molecule and monoclonal antibody approaches. These have been generally well-tolerated. Recognizing the broader role of IGF-IR in regulating both normal and pathological immune responses may offer important opportunities for therapeutic intervention in several allied diseases that have proven particularly difficult to treat.

Titanium dioxide nanoparticles cause apoptosis in BEAS-2B cells through the caspase 8/t-Bid-independent mitochondrial pathway

To understand the underlying mechanism for apoptosis induced by titanium dioxide nanoparticles (TNP), human airway epithelial cell line was cultured to investigate the relevant apoptosis pathways. Our results showed that the levels of reactive oxygen species and morphological apoptosis increased in a dose-dependent manner whereas cell viability decreased in a similar manner in response to TNP exposure in the BEAS-2B cells. The activities of caspase 3 and PARP were also increased in parallel to the morphological apoptosis. Levels of caspase 9 increased significantly whereas there were no detectable changes in caspase 8 and t-Bid in the TNP treated cells. Caspase 9 inhibition blocked the TNP-induced activation of caspase 3 significantly. The levels of bax, cytochrome C, p53 and bcl-2 also changed reflecting the activation of intrinsic apoptosis pathway. Our results provide solid evidence that apoptosis in BEAS-2B cells exposed to TNP occurred via a mitochondrial apoptosis pathway independent of caspase 8/t-Bid pathway.

Variation in the IGF-1 gene is associated with lymphocyte subset counts in neonates: the Generation R Study

OBJECTIVE

IGF-1 stimulates growth, development and function of lymphocytes. The aim of this study was to examine whether functional variants of the IGF-1 gene are associated with absolute lymphocyte subset counts in neonates.

STUDY DESIGN AND MEASUREMENTS

This study was embedded in the Generation R Study, a prospective cohort study from foetal life onwards. A polymorphism in the IGF-1 promoter region was genotyped in cord blood DNA. Lymphocytes (T, B and NK) and T lymphocyte subsets (helper, cytotoxic, naive and memory) in cord blood were immunophenotyped in 380 neonates by six-colour flow cytometry.

RESULTS

In total, 39% of the neonates were homozygous for the 192-bp allele (wild-type), 48% were heterozygous and 13% were noncarrier. No differences in absolute lymphocyte and T lymphocyte subset counts were observed between the 192-bp allele heterozygous and homozygous groups. In noncarriers, we found 15% lower T lymphocyte (P = 0.03), 22% lower B lymphocyte (P = 0.04) and 10% lower NK lymphocyte counts (P = 0.36) than in the 192-bp allele homozygous group. Analyses of T lymphocyte subsets showed 16% lower helper T lymphocyte counts (P = 0.01) in noncarriers. No significant differences were found for cytotoxic, naive and memory T lymphocyte counts. All associations were adjusted for gravidity, mode of delivery, gestational age, birth weight, gender and 1- and 5- min Apgar scores.

CONCLUSIONS

Our study showed associations between this IGF-1 promoter region polymorphism and absolute lymphocyte subset counts in neonates. These results should be regarded as hypothesis generating until they have been replicated in other studies.

Insulin-like growth factor I promotes cord blood T cell maturation through monocytes and inhibits their apoptosis in part through interleukin-6

Background

The functional immaturity of T cells contributes to the susceptibility of neonates to infections and the less severe graft-versus-host disease associated with cord blood (CB) transplantation. We have previously reported that insulin-like growth factor – I (IGF-I) promotes the phytohaemagglutinin (PHA)-induced CB T cell maturation and inhibits their apoptosis in mononuclear cell (MC) culture. We hypothesized that the effects of IGF-I may be mediated by accessory cells and soluble factors.

Results

This study showed that the kinetics of PHA-induced maturation in purified CD3+ T cell was delayed compared to that in CBMC. The addition of autologous CD14+ monocytes increased T cell maturation and potentiated the effect of IGF-I. The addition of IL-6 had no effect on CB T cell maturation but it reduced PHA-induced apoptosis significantly. We further demonstrated that the neutralisation of IL-6 in CBMC culture partially abrogated the anti-apoptotic effect of IGF-1 on T cells. The anti-apoptotic effect of IL-6 was not mediated via the reduction of Fas expression in T cell subsets.

Conclusion

Our results suggested that the maturation effect of IGF-1 is partially mediated by monocytes and the anti-apoptotic effect in part via IL-6. Further investigation is needed to explore the therapeutic use of IGF-I in enhancing neonatal immunity.

Lymph node architecture collapse and consequent modulation of FOXO3a pathway on memory T- and B-cells during HIV infection

Lymph nodes (LNs) represent the principal site where antigen-specific memory T- and B-cell responses are primed and differentiated into memory and effector cells. During chronic viral infections such as HIV, these lymphoid tissues undergo substantial structural changes. These changes are mostly caused by an imbalanced cytokine milieu, hyper-immune activation and collagen deposition leading to fibrotic LNs. The structural integrity of the LNs is essential to prime and maintain memory responses. Because cellular signalling events both up- and down-stream of FOXO3a are critical to the generation and the maintenance of lymphocyte memory, this review will focus on the interplay between the deregulation of the immune system caused by the virus and its impact on FOXO3a.

CD4-Positive Effector Memory T Cells Participate in Disease Expression in ANCA-Associated Vasculitis

Although the cause of ANCA-associated vasculitis (AAV) remains undetermined, the presence of lymphocytic infiltrates in inflammatory lesions of patients suggests that vascular damage is immune mediated. Studies over the past decade have implicated a role for T cells in the pathogenesis of AAV as altered T cell phenotype has been observed in this disorder. The distribution of T cell subpopulations has been analyzed most intensely in Wegener's granulomatosis (WG), where an expanded population of circulating CD4(+) effector memory T cells (CD4(+)T(EM)) was demonstrated. CD4(+)T(EM) cells play a major role in the pathogenesis of several autoimmune diseases. Specific suppression of CD4(+)T(EM) cells inhibits delayed-type hypersensitivity (DTH) and has therapeutic potential in autoimmune disease. Thus, CD4(+)T(EM) cells may act as inducers of tissue injury and participate in the development of AAV. Therapies that target CD4(+)T(EM), without impairing the activity of other lymphocyte subsets, may hold therapeutic promise for AAV.

Aberrant expression of the insulin-like growth factor-1 receptor by T cells from patients with Graves' disease may carry functional consequences for disease pathogenesis

Graves' disease (GD), an autoimmune process involving thyroid and orbital tissue, is associated with lymphocyte abnormalities including expansion of memory T cells. Insulin-like growth factor receptor-1 (IGF-1R)-bearing fibroblasts overpopulate connective tissues in GD. IGF-1R on fibroblasts, when ligated with IgGs from these patients, results in the expression of the T cell chemoattractants, IL-16 and RANTES. We now report that a disproportionately large fraction of peripheral blood T cells express IGF-1R (CD3+IGF-R+). CD3+IGF-1R+ T cells comprise 48 +/- 4% (mean +/- SE; n = 33) in patients with GD compared with 15 +/- 3% (n = 21; p < 10(-8)) in controls. This increased population of IGF-1R+ T cells results, at least in part, from an expansion of CD45RO+ T cells expressing the receptor. In contrast, the fraction of CD45RA+IGF-1R+ T cells is similar in GD and controls. T cells harvested from affected orbital tissues in GD reflect similar differences in the proportion of IGF-1R+CD3+ and IGF-1R+CD4+CD3+ cells as those found in the peripheral circulation. GD-derived peripheral T cells express durable, constitutive IGF-1R expression in culture and receptor levels are further up-regulated following CD3 complex activation. IGF-1 enhanced GD-derived T cell incorporation of BrdU (p < 0.02) and inhibited Fas-mediated apoptosis (p < 0.02). These findings suggest a potential role for IGF-1R displayed by lymphocytes in supporting the expansion of memory T cells in GD.

UC blood infection with clinical strains of Mycobacterium tuberculosis: a novel model

BACKGROUND

Use of unrelated cord blood transplantation (UCBT) is increasing, yet high rates of mortality secondary to infection remain a problem. We investigated the utility of using umbilical cord blood (UCB) as a model to study a naive cell population challenged by Mycobacterium tuberculosis.

METHODS

Mononuclear cells were isolated from nine UCB samples and infected with each of four distinct strains of M. tuberculosis. The isolates used were two highly transmissible clinical strains, the virulent laboratory strain H37Rv and a unique strain isolated from only one case (i.e. non-virulent). CFU were assessed at 3 h post-infection (day 0) and at day 7 to generate growth curves. Viability of the mononuclear cells was assessed prior to infection, 3 h post-infection and at days 3, 5 and 7 post-infection. IFN-gamma and TNF-alpha levels were determined at 24 h post-infection.

RESULTS

All three of the virulent strains demonstrated rapid growth in UCB cells that was significantly faster than the growth rate observed for the non-virulent unique isolate. There was no significant decrease in UCB cell viability after the 7-day incubation period regardless of infecting isolate. UCB cells secreted IFN-gamma in response to infection, with no significant difference related to infection with different isolates. However, there was a significant increase in the amount of TNF-alpha elicited following infection with the non-virulent isolate compared with the virulent isolates.

DISCUSSION

These results show that UCB can be used as a model to study infection, hopefully leading to new therapies for neonates and UCBT recipients.

Differential expression of chemokines and their receptors in adult and neonatal macrophages infected with human or avian influenza viruses

In 1997, avian influenza virus H5N1 was transmitted directly from chicken to human and resulted in a severe disease that had a higher mortality rate in adults than in children. The characteristic mononuclear leukocyte infiltration in the lung and the high inflammatory response in H5N1 infection prompted us to compare the chemokine responses between influenza virus–infected adult and neonatal monocyte-derived macrophages (MDMs). The effects of avian influenza virus A/Hong Kong/483/97 (H5N1) (H5N1/97), its precursor A/Quail/Hong Kong/G1/97 (H9N2) (H9N2/G1), and human influenza virus A/Hong Kong/54/98 (H1N1) (H1N1/98) were compared. Significantly higher expression of CCL2, CCL3, CCL5, and CXCL10 was induced by avian influenza viruses than by human influenza virus. Moreover, the increase in CCL3 expression in H5N1/97-infected adult MDMs was significantly higher than that in neonatal MDMs. Enhanced expression of CCR1 and CCR5 was found in avian virus–infected adult MDMs. The strong induction of chemokines and their receptors by avian influenza viruses, particularly in adult MDMs, may account for the severity of H5N1 disease

Expression of insulin-like growth factor-1 and insulin-like growth factor-1 receptors in EL4 lymphoma cells overexpressing growth hormone

Almost all of the previous studies with growth hormone (GH) have been done with exogenously supplied GH and, therefore, involve actions of the hormone through its receptor. However, the actions of endogenous or lymphocyte GH are still unclear. In a previous study, we showed that overexpression of GH (GHo) in a lymphoid cell line resulted in protection of the cells to apoptosis mediated by nitric oxide (NO). In the present study, we show that the protection from apoptosis could be transferred to control cells with culture fluids obtained from GHo cells and blocked by antibodies to the insulin-like growth factor-1 (IGF-1) or antibodies to the IGF-1-receptor (IGF-1R). Northern and Western blot analysis detected significantly higher levels of IGF-1 in cells overexpressing GH. An increase in the expression of the IGF-1R in GHo cells was also detected by Western blot analysis, (125)I-IGF-1 binding and analysis of IGF-1R promoter luciferase constructs. Transfection of GHo cells with a dominant negative IGF-1R mutant construct blocked the generation of NO and activation of Akt seen in GHo cells compared to vector alone control EL4 cells. The results suggest that one of the consequences of the overexpression of GH, in cells lacking the GH receptor, is an increase in the expression of IGF-1 and the IGF-1R which mediate the protection of EL4 lymphoma cells from apoptosis.

Increased expression of insulin-like growth factors in progressive glomerulonephritis of the MRL/lpr mouse

Glomerulonephritis is an important complication of systemic lupus erythematosus (SLE). The tissue distribution and exact role of the insulin-like growth factors (IGFs) in the development of lupus nephritis in the MRL/lpr mouse model have not been established. The present study was undertaken to evaluate the changes over time in mRNA and peptide expression of IGF-I and IGFBP-2 in the MRL/lpr mouse. Using in situ hybridization and immunocytochemistry techniques, the expression of IGF-I and IGFBP-2 in MRL/lpr mouse was examined and compared to their congenic normal MRL-++ mouse counterparts from nine to 24 weeks of age. In the MRL-++ and MRL/lpr mouse kidneys, IGF-I and IGFBP-2 mRNA expression was limited to the cortical and medullary collecting ducts, while their immunoreactivity (IR) was localized to the cortical and medullary collecting ducts, loop of Henle, glomeruli and proximal tubules. Over time, and with progression of disease, the MRL/lpr mice displayed a significant increase in IGF-I IR and a modest increase in IGFBP-2 IR within the outer cortical glomeruli, which was associated with a significant increase in glomerulosclerosis and glomerular cell proliferation and with a significant decrease in renal function. In conclusion, this overexpression of IGF-I and IGFBP-2 within the glomeruli of the MRL/lpr mouse kidney supports their potential role in the alterations in renal function and morphology that accompany lupus nephritis.

Tolerance associated with cord blood transplantation may depend on the state of host dendritic cells

Allogeneic cord blood (CB) transplantation is associated with less severe graft-versus-host disease (GvHD), thought to be due to the immaturity of CB T cells, but how T cells interact with host and donor-derived dendritic cells (DCs) to initiate GvHD has not been elucidated. We therefore investigated the responses of CB and adult blood CD4(+) T cells co-cultured with adult host DCs of different maturities. Primed by adult host DCs, CB and adult blood CD4(+) T cells underwent similar changes in the expression of CD45RA/45RO, CD25, CD40L and CTLA-4. However, CB CD4(+) T cells, when primed by either immature or Bacillus Calmette-Guerin mycobacteria-treated adult host DCs, produced lower interferon-gamma (IFN-gamma) and higher interleukin-10 (IL-10), which is a regulatory T cell-like cytokine profile, as compared with adult blood CD4(+) T cells. In contrast, lipopolysaccharide (LPS)-treated adult host DCs significantly up-regulated IFN-gamma and down-regulated IL-10 production levels from CB CD4(+) T cells to that from adult blood CD4(+) T cells. The sustained low IFN-gamma and high IL-10 production from CB CD4(+) T cells co-cultured with adult blood DCs might account for the less severe GvHD occurrence after CB transplantation, which could be reversed by LPS-treated adult blood DCs.

Functional Maturation of CD4+CD25+CTLA4+CD45RA+T Regulatory Cells in Human Neonatal T Cell Responses to Environmental Antigens/Allergens

A number of laboratories have reported cord blood T cell responses to ubiquitous environmental Ags, including allergens, by proliferation and cytokine secretion. Moreover, the magnitude of these responses has been linked with risk for subsequent expression of allergy. These findings have been widely interpreted as evidence for transplacental priming and the development of fetal T memory cells against Ags present in the maternal environment. However, we present findings below that suggest that neonatal T cell responses to allergens (and other Ags) differ markedly from those occurring in later life. Notably, in contrast to allergen-responsive adult CD4(+) T cell cultures, responding neonatal T cell cultures display high levels of apoptosis. Comparable responses were observed against a range of microbial Ags and against a parasite Ag absent from the local environment, but not against autoantigen. A notable finding was the appearance in these cultures of CD4(+)CD25(+)CTLA4(+) T cells that de novo develop MLR-suppressive activity. These cells moreover expressed CD45RA and CD38, hallmarks of recent thymic emigrants. CFSE-labeling studies indicate that the CD4(+)CD25(+) cells observed at the end of the culture period were present in the day 0 starting populations, but they were not suppressive in MLR responses. Collectively, these findings suggest that a significant component of the reactivity of human neonatal CD4(+) T cells toward nominal Ag (allergen) represents a default response by recent thymic emigrants, providing an initial burst of short-lived cellular immunity in the absence of conventional T cell memory, which is limited in intensity and duration via the parallel activation of regulatory T cells.

T-cell and neuronal apoptosis in HIV infection: implications for therapeutic intervention

The pathogenesis of HIV infection involves the selective loss of CD4+ T cells contributing to immune deficiency. Although loss of T cells leading to immune dysfunction in HIV infection is mediated in part by viral infection, there is a much larger effect on noninfected T cells undergoing apoptosis in response to activation stimuli. In the subset of patients with HIV dementia complex, neuronal injury, loss, and apoptosis are observed. Viral proteins, gp120 and Tat, exhibit proapoptotic activities when applied to T cell and neuronal cultures by direct and indirect mechanisms. The pathways leading to cell death involve the activation of one or more death receptor pathways (i.e., TNF-alpha, Fas, and TRAIL receptors), chemokine receptor signaling, cytokine dysregulation, caspase activation, calcium mobilization, and loss of mitochondrial membrane potential. In this review, the mechanisms involved in T-cell and neuronal apoptosis, as well as antiapoptotic pathways potentially amenable to therapeutic application, are discussed.

The fibroblast: sentinel cell and local immune modulator in tumor tissue

Development and progression of epithelial malignancies are frequently accompanied by complex phenotypic alterations of resident tissue fibroblasts. Some of these changes, such as myofibroblastic differentiation and an oncofetal extracellular matrix (ECM) expression profile, are also implicated in inflammation and tissue repair. Studies over the past decade revealed the relevance of reciprocal interactions between tumor cells and tumor-associated host fibroblasts (TAF) in the malignant process. In many tumors, a considerable fraction of the inflammatory infiltrate is located within the fibroblast- and ECM-rich stromal compartment. However, while fibroblasts are known as "sentinel cells" in various nonneoplastic diseases, where they often regulate the composition and function of recruited leucocytes, they are hardly considered active participants in the inflammatory host response in tumors. This article focuses on the functional impact of TAF on immune cells. The complex network of immune-modulating effects transduced by TAF and TAF-derived factors is highlighted, and recent reports that support the hypothesis that TAF are involved in the inflammatory response and immune suppression in tumors are reviewed. The role of TAF-dependent ECM remodeling and TAF-derived peptide growth factors, cytokines, and chemokines in the immune modulation is stressed and the idea of TAF as an important therapeutic target is emphasized.

Insulin-like growth factor I promotes maturation and inhibits apoptosis of immature cord blood monocyte-derived dendritic cells through MEK and PI 3-kinase pathways

IGF-I has profound effects on the immune system. We previously reported that IGF-I promoted cord blood (CB)-naïve T-cell maturation and now show that IGF-I promoted maturation of CB monocyte-derived dendritic cells (DC) with up-regulation of CD83, CD86, CD40, and major histocompatibility complex (MHC) class II molecules, and down-regulation of mannose receptor. Furthermore, IGF-I inhibited apoptosis of CB DC and increased the production of tumor necrosis factor alpha (TNF-alpha). These effects were blocked by specific mitogen-activated protein kinase kinase (MEK) inhibitor (PD98059) and phosphoinositol 3-kinase inhibitor (LY294002). PD98059 partially inhibited the IGF-I-induced up-regulation of MHC class II. In contrast, LY294002 was additive in the IGF-I-induced up-regulation of MHC class II. Moreover, LY294002 significantly increased the percentage of late apoptotic cells in CB. These results imply the involvement of different pathways for the differential regulation of co-stimulatory molecule expression and apoptosis. The addition of anti-TNF-alpha did not neutralize the effects of IGF-I on CB DC maturation and apoptosis. On the contrary, neutralizing TNF-alpha significantly increased the IGF-I-induced up-regulation of CD83 and CD40. We conclude that IGF-I has maturation and survival effects on CB DC. These effects are mediated through both MEK and PI 3-kinase pathways but not through the IGF-I induction of TNF-alpha production by the DC.

IGF-I stimulates IL-8 production in the promyelocytic cell line HL-60 through activation of extracellular signal-regulated protein kinase

Interleukin (IL)-8 serves as a major chemoattractant for neutrophils and has also been proposed to affect cancer progression. In the present study, we show that IGF-I stimulates IL-8 mRNA expression and IL-8 secretion in the leukemic cell line HL-60. Stimulation of IL-8 expression was completely attenuated by two inhibitors of mitogen-activated protein kinase (MAPK) kinase (MEK), which phosphorylates the MAPKs extracellular-regulated kinase (ERK)1 and ERK2, and by the c-Jun NH2-terminal kinase (JNK) inhibitor SP600125. In contrast, inhibitors of p38 MAPK and phosphatidylinositol-3 kinase (PI3K) did not abrogate the effect of IGF-I. We also show that IGF-I stimulates the activation of ERK1 and ERK2, but we could not detect any effect of IGF-I on the phosphorylation of p38, JNK(p46) or JNK(p54). Collectively, our results suggest that basal JNK activity and activation of the MEK-ERK pathway are required for upregulation of IL-8 by IGF-I in HL-60 cells.

IGF-1 down-regulates IFN-gamma R2 chain surface expression and desensitizes IFN-gamma/STAT-1 signaling in human T lymphocytes

The ability of insulin-like growth factor-1 (IGF-1) to regulate surface expression of the interferon-gamma receptor 2 (IFN-gamma R2) transducing chain and activation of IFN-gamma-induced signal transducer and activator of transcription-1 (STAT-1) in human T cells was analyzed. We show that, especially in the absence of serum (which contains IGF-1), IGF-1 down-regulated surface expression of the IFN-gamma R2 chain and inhibited both IFN-gamma-dependent STAT-1 activation and apoptosis in T-cell lines ST4, Jurkat, and Molt-4. IFN-gamma R2 down-regulation resulted from its enhanced internalization since IGF-1 completely restored the uptake of anti-IFN-gamma R2 monoclonal antibody (mAb) in serum-deprived T-cell lines. When the interaction between IGF-1 and its receptor was blocked by anti-IGF-1R mAb, enhancement of IFN-gamma R2 surface expression, STAT-1 activation, and reinstatement of IFN-gamma-induced apoptosis were observed. Enhanced expression of IFN-gamma R2 was also observed in phytohemagglutinin (PHA)-activated T lymphoblasts cultured in the presence of anti-IGF-1R mAb, whereas IGF-1 or anti-IGF-1R mAb did not modify the high IFN-gamma R2 expression in B and myeloid cell lines. Both IGF-1 and anti-IGF-1R mAb did not modify the constitutive expression of IFN-gamma R2 mRNA in T cells as well as the high IFN-gamma R1 binding chain surface expression in T, B, and myeloid cells. These data indicate that IGF-1 plays a critical role in the desensitization of IFN-gamma/STAT-1 signaling in T lymphocytes by delivering a signal for IFN-gamma R2 internalization.

Red blood cells promote survival and cell cycle progression of human peripheral blood T cells independently of CD58/LFA-3 and heme compounds

Red blood cells (RBC) are known to modulate T cell proliferation and function possibly through downregulation of oxidative stress. By examining parameters of activation, division, and cell death in vitro, we show evidence that the increase in survival afforded by RBC is due to the maintenance of the proliferative capacity of the activated T cells. We also show that the CD3+CD8+ T cell subset was preferentially expanded and rescued from apoptosis both in bulk peripheral blood lymphocyte cultures and with highly purified CD8+ T cells. The ability of RBC to induce survival of dividing T cells was not affected by blocking the CD58/CD2 interaction. Moreover, addition of hemoglobin, heme or protoporphyrin IX to cultures of activated T cells did not reproduce the effect of intact RBC. Considering that RBC circulate throughout the body, they could play a biological role in the modulation of T cell differentiation and survival in places of active cell division. Neither CD58 nor the heme compounds studied seem to play a direct relevant role in the modulation of T cell survival.

BCG promotes cord blood monocyte-derived dendritic cell maturation with nuclear Rel-B up-regulation and cytosolic I kappa B alpha and beta degradation

Mycobacterium bovis bacillus Calmette-Guerin (BCG) is given to millions of neonates in developing countries as a vaccine against Mycobacterium tuberculosis; however, little is known about the initiation of response in neonatal dendritic cells (DCs) to BCG. To address this issue, the interaction of BCG with human cord blood monocyte-derived DCs was studied. We showed that BCG could promote cord blood monocyte-derived DC maturation by up-regulation of CD80, CD83, CD86, CD40, and MHC class II molecules and down-regulation of mannose receptor. BCG was able to induce similar levels of tumor necrosis factor-alpha and IL-10 but no bioactive IL-12p70 production from cord blood DCs as from adult blood DCs. Functionally BCG-treated cord blood DCs had higher ability to induce mixed lymphocyte reaction than non-BCG-treated cord blood DCs. Both non-BCG-treated and BCG-treated cord blood DCs efficiently induced a high level of IL-10, medium level of interferon-gamma, but little IL-4 production by cord blood naïve CD4+ T cells. Heat shock protein 65, a key component of BCG, had no effect on cord blood DC maturation in terms of CD86, MHC class II, and mannose receptor up-regulation. During the BCG-induced maturation process of cord blood DCs, nuclear transcription factor Rel-B was up-regulated and cytosolic Rel-B down-regulated with cytosolic IkappaB alpha and beta degradation. These results suggest that BCG can promote cord blood monocyte-derived DC maturation, and that the mechanism is through the up-regulation of nuclear Rel-B secondary to the degradation of cytosolic IkappaB alpha and beta.

Insulin-like growth factor-I enhances lymphoid and myeloid reconstitution after allogeneic bone marrow transplantation

BACKGROUND

Prolonged immunodeficiency after allogeneic bone marrow transplantation (allo BMT) results in significant morbidity and mortality from infection. Previous studies in murine syngeneic BMT models have demonstrated that posttransplantation insulin-like growth factor (IGF)-I administration could enhance immune reconstitution.

METHODS

To analyze the effects of IGF-I on immune reconstitution and graft-versus-host disease (GVHD) after allo BMT, we used murine models for MHC-matched and -mismatched allo BMT. Young (3-month-old) recipient mice received 4 mg/kg per day of human IGF-I from days 14 to 28 by continuous subcutaneous administration.

RESULTS

IGF-I administration resulted in increased thymic precursor populations (triple negative-2 and triple negative-3) as determined on day 28 but had no effect on overall thymic cellularity. In the periphery, the numbers of donor-derived splenic CD3+ T cells were increased and these cells had an improved proliferative response to mitogen stimulation. IGF-I treatment also significantly increased the numbers of pro-, pre-, and mature B cells and myeloid cell populations in the spleens of allo BMT recipients on day 28. The administration of IGF-I in combination with interleukin 7 had a remarkable additive effect on B-cell, but not on T-cell, lymphopoiesis. Finally, we tested the effects of IGF-I administration on the development of GVHD in three different MHC-matched and -mismatched models and found no changes in GVHD morbidity and mortality.

CONCLUSION

IGF-I administration can enhance lymphoid and myeloid reconstitution after allo BMT without aggravating GVHD.

Changes of CD14 and CD1a expression in response to IL-4 and granulocyte-macrophage colony-stimulating factor are different in cord blood and adult blood monocytes

Neonates are relatively immature in their immune response; thus, to further clarify the differences of monocyte function and differentiation between neonates and adults, we investigated their CD14(+)CD4(+) and CD14(+)CD16(+) monocyte subpopulations, production of IL-1beta and tumor necrosis factor-alpha induced by lipopolysaccharide, and their CD14 and CD1a phenotypic changes in response to IL-4 and granulocyte-macrophage colony-stimulating factor. Our results showed that 1) the expression of CD14 in cord blood monocytes was significantly lower than that in adult peripheral blood monocytes; 2) both the percentages of CD14(+)CD4(+) cells and CD14(+)CD16(+) cells among CD14(+) monocytes were also significantly lower in cord blood; 3) after stimulation by lipopolysaccharide for 72 h, production of both IL-1beta and tumor necrosis factor-alpha was lower in cord blood than that in adult peripheral blood; and 4) in response to IL-4 or GM-CSF, the phenotype development of CD14 and CD1a in cord blood and adult peripheral blood was different. Down-regulation of CD14 expression in response to IL-4 and GM-CSF was slower in cord blood monocytes than that in adult peripheral blood monocytes. After 9 d of culture in the presence of IL-4 and GM-CSF, the percentage of CD1a(+) monocytes was significantly more increased in cord blood than that in adult peripheral blood. The reduced expression of CD14 and other mature phenotype markers such as CD16 and CD4 as well as the reduced IL-1beta and tumor necrosis factor-alpha production may contribute to the impaired immune response of neonates. Slower down-regulation of CD14 by IL-4 and GM-CSF suggests that differential properties of cord blood monocytes in response to cellular stress signals take a longer time than those of adult peripheral blood monocytes.

Decreased yield, phenotypic expression and function of immature monocyte-derived dendritic cells in cord blood

Dendritic cells are critical for the induction of both primary immune responses and immunological tolerance, as well as for the regulation of T-helper 1 (Th1) and 2 (Th2) immune responses. As neonates are notably deficient in Th1 response and cord blood transplantation is noted to result in less graft-versus-host disease (GvHD), we compared the phenotypic and functional characteristics of monocyte-derived dendritic cells (DCs) that favour Th1 development from cord blood and adult peripheral blood to understand the underlying mechanisms of these observations. Our results showed that: (1) after culture for 7 d with interleukin (IL)-4 and granulocyte--macrophage colony-stimulating factor (GM-CSF), cord blood monocytes generated less CD1a(+) cells than adult peripheral blood monocytes, and the CD1a+ cell percentage decreased thereafter; (2) compared with adult blood DCs, cord blood DCs had reduced intensity of expression of CD1a and MHC class II molecules, but the expression levels of CD11c and CD86 were similar; (3) the endocytotic ability of cord blood DCs was reduced compared with adult blood DCs, and this function was related to reduced mannose receptor (MR)-positive cells; (4) furthermore, the ability of cord blood DCs to stimulate CD3(+) T cells in an allogeneic mixed lymphocyte reaction was significantly lower than that of adult blood DCs. These results suggested that the dysfunction of cord blood monocytes in differentiating into professional DCs will affect the activation of naive T cells, especially Th1 development, and may be related to the susceptibility to different infections in the neonates, as well as the lower incidence of GvHD in cord blood transplantation.