Lasting effects of an impairment of Th1-like immune response in γ-irradiated mice: A resemblance between irradiated mice and aged mice

Radiotherapy Improves the Disability in Patients with Secondary Progressive Multiple Sclerosis

Background

Multiple sclerosis (MS) as a complex neurological abnormality is marked with loss of myelin and axons due to chronic inflammatory and autoimmune responses. The modulatory properties of the low dose radiation (LDR) on inflammatory and immune responses have well known.

Objective

The current research aimed to assess the impacts of LDR on the disability in patients suffering from MS.

Material and Methods

This experimental pilot study was done on 10 patients with secondary progressive multiple sclerosis (SPMS). After magnetic resonance imaging, the SPMS patients were treated by LDR at a daily dose of 2 Gray for 5 consecutive days (totally 10 Gray dose) using a linear accelerator. The extent of the disability was evaluated one week after the completion of radiotherapy using expanded disability status scale (EDSS).

Results

After receiving radiotherapy, the patients had a feeling of wellbeing of some sort. The mean of EDSS was significantly reduced after radiotherapy compared with before irradiation (7.4±0.45 vs 6.35±1.18; P<0.017). EDSS more decreased in younger SPMS patients (P=0.0001), and in the women after LDR (P=0.027).

Conclusion

Radiotherapy can reduce fatigue and EDSS in patients with SPMS. The age and gender of patients may influence the LDR efficacy.

Delayed effects of radiation in adipose tissue reflect progenitor damage and not cellular senescence

The pathogenesis of many age-related diseases is linked to cellular senescence, a state of inflammation-inducing, irreversible cell cycle arrest. The consequences and mechanisms of age-associated cellular senescence are often studied using in vivo models of radiation exposure. However, it is unknown whether radiation induces persistent senescence, like that observed in ageing. We performed analogous studies in mice and monkeys, where young mice and rhesus macaques received sub-lethal doses of ionizing radiation and were observed for ~ 15% of their expected lifespan. Assessments of 8-hydroxy-2' -deoxyguanosine (8-OHdG), senescence-associated beta-galactosidase (SAβ-gal), and p16Ink4a and p21 were performed on mitotic and post-mitotic tissues - liver and adipose tissue - 6 months and 3 years post-exposure for the mice and monkeys, respectively. No elevations in 8-OHdG, SA-βgal staining, or p16 Ink4a or p21 gene or protein expression were found in mouse and monkey liver or adipose tissue compared to control animals. Despite no evidence of senescence, progenitor cell dysfunction persisted after radiation exposure, as indicated by lower in situ CD34+ adipose cells (p = 0.03), and deficient adipose stromal vascular cell proliferation (p < 0.05) and differentiation (p = 0.04) ex vivo. Our investigation cautions that employing radiation to study senescence-related processes should be limited to the acute post-exposure period and that stem cell damage likely underpins the dysfunction associated with delayed effects of radiation.

The role of radiotherapy-related autophagy genes in the prognosis and immune infiltration in lung adenocarcinoma

Background

There is a close relationship between radiotherapy and autophagy in tumors, but the prognostic role of radiotherapy-related autophagy genes (RRAGs) in lung adenocarcinoma (LUAD) remains unclear.

Methods

Data used in the current study were extracted from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. Weighted gene co-expression network analysis (WGCNA) was executed to recognize module genes associated with radiotherapy. The differentially expressed genes (DEGs) between different radiotherapy response groups were filtered via edgeR package. The differentially expressed radiotherapy-related autophagy genes (DERRAGs) were obtained by overlapping the module genes, DEGs, and autophagy genes (ATGs). Then, prognostic autophagy genes were selected by Cox analyses, and a risk model and nomogram were subsequently built. Gene Set Enrichment Analysis (GSEA) and single-sample Gene Set Enrichment Analysis (ssGSEA) were performed to investigate potential mechanisms through which prognostic autophagy signatures regulate LUAD. Radiotherapy-resistant cell lines (A549IR and PC9IR) were established after exposure to hypo-fractionated irradiation. Ultimately, mRNA expression was validated by quantitative real-time PCR (qRT-PCR), and relative protein levels were measured in different cell lines by western blot.

Results

A total of 11 DERRAGs were identified in LUAD. After Cox analyses, SHC1, NAPSA, and AURKA were filtered as prognostic signatures in LUAD. Then, the risk score model was constructed using the prognostic signatures, which had a good performance in predicting the prognosis, as evidenced by receiver operating characteristics curves. Furthermore, Cox regression analyses demonstrated that risk score was deemed as an independent prognostic factor in LUAD. Moreover, GSEA and ssGSEA results revealed that prognostic RRAGs may regulate LUAD by modulating the immune microenvironment and affecting cell proliferation. The colony formation assay showed that the radiosensitivity of radiation-resistant cell lines was lower than that of primary cells. The western blot assay found that the levels of autophagy were elevated in the radiotherapy-resistant cell lines. Moreover, the expression of DERRAGs (SHC1, AURKA) was higher in the radiotherapy-resistant cells than in primary cells.

Conclusion

Our study explored the role of RRAGs in the prognosis of LUAD and identified three biomarkers. The findings enhanced the understanding of the relationship between radiotherapy, autophagy, and prognosis in LUAD and provided potential therapeutic targets for LUAD patients.

Depletion of NK Cells Resistant to Ionizing Radiation Increases Mutations in Mice After Whole-body Irradiation

BACKGROUND

Ionizing radiation is a very powerful genetic mutagenic agent. Although immune cells are very sensitive to radiation, their sensitivity varies between different types of immune cell. We hypothesized that radiation-resistant immune cells survive after irradiation and then play a role in removing mutant cells.

MATERIALS AND METHODS

Splenic lymphocytes and mice were irradiated with γ-rays. Cell populations were analyzed using flow cytometry after dyeing with antibodies and expression of B-cell lymphoma 2 (BCL2) was measured by western blot analysis. To deplete natural killer (NK) cells, anti-asialo GM1 antiserum was used. Micronuclei in polychromatic erythrocytes were measured by May-Grunwald/Giemsa staining. H-2Kb loss variant in T-cells induced by irradiation of B6C3F1 mice were detected by flow cytometry.

RESULTS

When splenic lymphocytes were irradiated in vitro, B cells notably died, while NK cells did not. In vivo, on the third day after whole-body irradiation, the total number of lymphocytes in the spleen decreased rapidly, but the proportion of NK cells was approximately three times higher than that of the normal control group. In addition, it was confirmed that high expression of BCL2 in NK cells was maintained after irradiation, whereas that of B-cells was not. Removal of NK cells by injection with anti-asialo GM1 antiserum immediately after irradiation increased the micronuclei of polychromatic erythrocytes in the bone marrow and the variant fraction with H-2kb loss in the spleen.

CONCLUSION

These results provide important evidence that radioresistant NK cells apparently survive by escaping apoptosis in the early stages after irradiation, and work to eliminate mutant cells resulting from γ-ray irradiation. Future studies are needed to reveal why NK cells are resistant to radiation and the in-depth mechanisms involved in the elimination of radiation-induced mutant cells.

Effects of diabetes on the development of radiation pneumonitis

Radiation pneumonia (RP) is a common adverse reaction to radiation therapy in patients with chest tumors. Recent studies have shown that diabetes mellitus (DM), which can cause systemic multisystem damage, specifically targets lungs, and the incidence of RP in patients with a history of diabetes is higher than that in other patients with tumors who have undergone radiotherapy. DM is an important risk factor for RP in tumor patients undergoing RT, and patients with DM should be treated with caution. This article reviews research on the clinical aspects, as well as the mechanism, of the effects of diabetes on RP and suggests future research needed to reduce RP.

Effects of low dose radiation on immune cells subsets and cytokines in mice

Whole-body exposure to low-dose radiation due to diagnostic imaging procedures, occupational hazards and radiation accidents is a source of concern. In this study, we analyzed the effects of single and long-term low-dose irradiation on the immune system. Male Balb/c mice received a single whole-body dose of irradiation (0.01, 0.05, 0.2, 0.5 or 1 Gy). For long-term irradiation, mice were irradiated 10 times (total dose of 0.2, 0.5 or 1 Gy) over a period of 6 weeks. Two days after single or long-term irradiation, the numbers of splenic macrophages, natural killer cells and dendritic cells were reduced, and the spleen organ coefficient was decreased. At 2 Days after long-term low-dose irradiation, the number of white blood cells in the peripheral blood of the mice decreased. Between 7 and 14 Days after long-term low-dose irradiation, the number of immune cells in the thymus and spleen began to increase and then stabilized. Th1/Th2 cytokines and reactive oxygen species-related proteins first decreased and then increased to a plateau. Our results show a significant difference in the effects of single and long-term low-dose irradiation on the immune system.

Effects of various radiation doses on induced T-helper cell differentiation and related cytokine secretion

Exposure to ionizing radiation often induces T helper (Th) cell differentiation, resulting in an imbalance of Th1 and Th2 cellular subtypes, which can affect the efficacy of cancer radiotherapy. The aim of this study was to analyze differential expression of Th1, Th2 and Th3/Type 1 regulatory T cell (Tr1) subtype-related genes and cytokines in mouse thymocytes after high- and low-dose systemic radiation, using functional classification gene arrays and Elisa assays, and to explore the molecular mechanisms underlying radiation's immune effects and their relationship with Th1/Th2 immunity. We found that expression of 8 genes was upregulated after LDR, while expression of 5 genes was downregulated. After HDR, 54 genes were upregulated and 3 genes were downregulated, including genes related to Th1, Th2 and Th3/Tr1 cellular subtypes, Th1/Th2-type immune response genes and transcription factor-related genes. In the foregoing results, LDR and HDR in the thymus induced opposite patterns of expression for Th1-, Th2- and Th3-type related cytokines TGF-β, C/EBP-β and TNF-α. We also found that expression of Interferon-γ (IFN-γ) and Interleukin-2 (IL-2), which have a moderating effect on immune function, was upregulated after LDR. Furthermore, the secretion of negative regulatory factors Interleukin-1β (IL-1β), Interleukin-4 (IL-4), transforming growth factor-β (TGF-β) and Interleukin-21 (IL-21) was reduced after LDR, but HDR produced the opposite effect and stimulated their expression. These findings suggest that LDR may induce a Th1-type immune response, while HDR may lead to a Th2-type immune response.

Effector/memory CD4 T cells making either Th1 or Th2 cytokines commonly co-express T-bet and GATA-3

Naïve CD4 T (NCD4T) cells post-activation undergo programming for inducible production of cytokines leading to generation of memory cells with various functions. Based on cytokine based polarization of NCD4T cells in vitro, programming for either ‘Th1’ (interferon-gamma [IFNg]) or ‘Th2’ (interleukin [IL]-4/5/13) cytokines is thought to occur via mutually exclusive expression and functioning of T-bet or GATA-3 transcription factors (TFs). However, we show that a high proportion of mouse and human memory-phenotype CD4 T (MCD4T) cells generated in vivo which expressed either Th1 or Th2 cytokines commonly co-expressed T-bet and GATA-3. While T-bet levels did not differ between IFNg-expressing and IL-4/5/13-expressing MCD4T cells, GATA-3 levels were higher in the latter. These observations were also confirmed in MCD4T cells from FVB/NJ or aged C57BL/6 or IFNg-deficient mice. While MCD4T cells from these strains showed greater Th2 commitment than those from young C57BL/6 mice, pattern of co-expression of TF was similar. Effector T cells generated in vivo following immunization also showed TF co-expression in Th1 or Th2 cytokine producing cells. We speculated that the difference in TF expression pattern of MCD4T cells generated in vivo and those generated in cytokine polarized cultures in vitro could be due to relative absence of polarizing conditions during activation in vivo. We tested this by NCD4T cell activation in non-polarizing conditions in vitro. Anti-CD3 and anti-CD28-mediated priming of polyclonal NCD4T cells in vitro without polarizing milieu generated cells that expressed either IFNg or IL-4/5/13 but not both, yet both IFNg- and IL-4/5/13-expressing cells showed upregulation of both TFs. We also tested monoclonal T cell populations activated in non-polarizing conditions. TCR-transgenic NCD4T cells primed in vitro by cognate peptide in non-polarizing conditions which expressed either IFNg or IL-4/5/13 also showed a high proportion of cells co-expressing TFs, and their cytokine commitment varied depending on genetic background or priming conditions, without altering pattern of TF co-expression. Thus, the model of mutually antagonistic differentiation programs driven by mutually exclusively expressed T-bet or GATA-3 does not completely explain natural CD4 T cell priming outcomes.

Bone marrow cell migration to the heart in a chimeric mouse model of acute chagasic disease

BACKGROUND

Chagas disease is a public health problem caused by infection with the protozoan Trypanosoma cruzi. There is currently no effective therapy for Chagas disease. Although there is some evidence for the beneficial effect of bone marrow-derived cells in chagasic disease, the mechanisms underlying their effects in the heart are unknown. Reports have suggested that bone marrow cells are recruited to the chagasic heart; however, studies using chimeric mouse models of chagasic cardiomyopathy are rare.

OBJECTIVES

The aim of this study was to investigate the migration of bone marrow cells to the heart after T. cruzi infection in a model of chagasic disease in chimeric mice.

METHODS

To obtain chimerical mice, wild-type (WT) C57BL6 mice were exposed to full body irradiation (7 Gy), causing bone marrow ablation. Then, bone marrow cells from green fluorescent protein (GFP)-transgenic mice were infused into the mice. Graft effectiveness was confirmed by flow cytometry. Experimental mice were divided into four groups: (i) infected chimeric (iChim) mice; (ii) infected WT (iWT) mice, both of which received 3 × 104 trypomastigotes of the Brazil strain; (iii) non-infected chimeric (Chim) mice; and (iv) non-infected WT mice.

FINDINGS

At one-month post-infection, iChim and iWT mice showed first degree atrioventricular block with decreased heart rate and treadmill exercise parameters compared to those in the non-infected groups.

MAIN CONCLUSIONS

iChim mice showed an increase in parasitaemia, myocarditis, and the presence of amastigote nests in the heart tissue compared to iWT mice. Flow cytometry analysis did not detect haematopoietic progenitor cells in the hearts of infected mice. Furthermore, GFP+ cardiomyocytes were not detected in the tissues of chimeric mice.

Polydatin alleviated radiation-induced lung injury through activation of Sirt3 and inhibition of epithelial-mesenchymal transition

Radiation-induced lung injury (RILI) is one of the most common and fatal complications of thoracic radiotherapy. It is characterized with two main features including early radiation pneumonitis and fibrosis in later phase. This study was to investigate the potential radioprotective effects of polydatin (PD), which was shown to exert anti-inflammation and anti-oxidative capacities in other diseases. In this study, we demonstrated that PD-mitigated acute inflammation and late fibrosis caused by irradiation. PD treatment inhibited TGF-β1-Smad3 signalling pathway and epithelial-mesenchymal transition. Moreover, radiation-induced imbalance of Th1/Th2 was also alleviated by PD treatment. Besides its free radical scavenging capacity, PD induced a huge increase of Sirt3 in culture cells and lung tissues. The level of Nrf2 and PGC1α in lung tissues was also elevated. In conclusion, our data showed that PD attenuated radiation-induced lung injury through inhibiting epithelial-mesenchymal transition and increased the expression of Sirt3, suggesting PD as a novel potential radioprotector for RILI.

Radiation-induced decrease of CD8+ dendritic cells contributes to Th1/Th2 shift

Exposure to ionizing radiation (IR) often reduce the helper T (Th) 1 like function, resulting in a Th1/Th2 imbalance, which could affect the efficacy of cancer radiotherapy. As the most potent antigen presenting cells, dendritic cells (DC) can be divided into several subsets with specialized function. However, there is no literature covering the changes of DC subsets and their roles in immune regulation in response to IR. In the present study, we were aimed to investigate the changes of DC subsets after IR and its relationship with Th1/Th2 immunity. We found a significant decrease of BDCA3+DC in the blood of patients treated with radiotherapy. CD8+DC, a mouse equivalent of human BDCA3+DC, was also found decreased in mice spleen, peripheral blood and lymph node tissues after irradiation. As CD8+DC mainly induce Th1 immunity, we tested the changes of Th1/Th2 response and found that IR caused a repression of Th1 immunity, indicating a possible role of CD8+DC in radiation-induced Th1/Th2 imbalance. We also found that a CD8+DC-inducing cytokine, Fms-like tyrosine kinase 3 ligand (FLT3 ligand), restored CD8+DC and reversed Th1/Th2 shift. And then we found that bone marrow cells from irradiated mice differentiated into less CD8+DC, which was also protected by FLT3 ligand. In conclusion, our data showed that IR induced a decrease of CD8+DC and Th1/Th2 shift, which was reversed by Flt3 ligand treatment, suggesting a novel mechanism for radiation-induced immunosuppression.

Interleukin-12 preserves the cutaneous physical and immunological barrier after radiation exposure

The United States continues to be a prime target for attack by terrorist organizations in which nuclear detonation and dispersal of radiological material are legitimate threats. Such attacks could have devastating consequences to large populations, in the form of radiation injury to various human organ systems. One of these at risk organs is the cutaneous system, which forms both a physical and immunological barrier to the surrounding environment and is particularly sensitive to ionizing radiation. Therefore, increased efforts to develop medical countermeasures for treatment of the deleterious effects of cutaneous radiation exposure are essential. Interleukin-12 (IL-12) was shown to elicit protective effects against radiation injury on radiosensitive systems such as the bone marrow and gastrointestinal tract. In this article, we examined if IL-12 could protect the cutaneous system from a combined radiation injury in the form of sublethal total body irradiation and beta-radiation burn (β-burn) directly to the skin. Combined radiation injury resulted in a breakdown in skin integrity as measured by transepidermal water loss, size of β-burn lesion and an exacerbated loss of surveillant cutaneous dendritic cells. Interestingly, intradermal administration of IL-12 48 h postirradiation reduced transepidermal water loss and burn size, as well as retention of cutaneous dendritic cells. Our data identify IL-12 as a potential mitigator of radiation-induced skin injury and argue for the further development of this cytokine as a radiation countermeasure.

Persistent inflammation and T cell exhaustion in severe sepsis in the elderly

Introduction

Sepsis is known as a complex immunological response with hyperinflammation in the acute phase followed by immunosuppression. Although aging is crucial in sepsis, the impact of aging on inflammation and immunosuppression is still unclear. The purpose of this study was to investigate the relationship between inflammation and immunosuppression in aged patients and mice after sepsis.

Methods

Fifty-five patients with severe sepsis and 30 healthy donors were prospectively enrolled, and 90-day survival was compared between elderly (≥65 years) and adult (18–64 years) septic patients with serial measurement of serum interleukin (IL)-6. Within 24 h after diagnosis of severe sepsis, peripheral blood mononuclear cells were stimulated ex vivo to measure expression of the activation maker CD25 in T cells, IL-2 levels in the supernatant, and proliferation. In the mouse study, young (6–8 weeks) and aged (20–22 months) C57/B6 mice were subjected to cecal ligation and puncture (CLP), and survival was compared after 7 days with serial measurement of serum IL-6. Expression of the negative co-stimulatory molecules, CD25, and IL-2 in CD4+ T cells was measured.

Results

The survival rate in elderly sepsis patients and aged septic mice was significantly lower than that in adult patients and young septic mice (60% vs. 93% in septic patients, 0% vs. 63% in septic mice, P < 0.05). Serum IL-6 levels in elderly sepsis patients and aged septic mice were persistently higher than those in adult patients and young septic mice. Expression of negative co-stimulatory molecules in CD4+ T cells in the spleen, lymph nodes, and peripheral blood was significantly higher in aged mice than in young mice (P < 0.01). Ex vivo stimulation decreased CD25 expression, IL-2 production, and proliferation to a greater extent in CD4+ T cells from elderly patients and aged septic mice than in those from adult patients and young septic mice. Elderly patients demonstrated increased detection of gram-negative bacteria at days 14–16 and 28–32 after sepsis (P < 0.05).

Conclusions

Persistent inflammation and T cell exhaustion may be associated with decreased survival in elderly patients and mice after sepsis.

Exacerbation of lung radiation injury by viral infection: the role of Clara cells and Clara cell secretory protein

Viral infections have been associated with exacerbation of disease in human cases of idiopathic pulmonary fibrosis. Since pulmonary fibrosis is a common outcome after irradiation to the lung, we hypothesized that viral infection after radiation exposure would exacerbate radiation-induced lung injury. Epithelial injury, a frequent outcome after infection, has been hypothesized to contribute to the pathogenesis of pulmonary fibrosis and bronchiolar epithelial Clara cells participate in epithelial repair. Therefore, it was further hypothesized that altered responses after irradiation involve the bronchiolar epithelial Clara cells. C57BL/6J or CCSP(-/-) mice were irradiated with 0 (sham), 5, 10 or 15 Gy to the whole thorax. At ten weeks post-irradiation, animals were mock infected or infected with influenza A virus and body weight and survival were monitored. Pulmonary function was assessed by whole-body plethysmography. The Clara cell markers, CCSP and Cyp2f2, were measured in the lung by qRT-PCR, and protein expression was visualized in the lung by immunofluorescence. Following pulmonary function tests, mice were sacrificed and tissues were collected for pathological analysis. In 15 Gy irradiated animals infected with influenza A virus, accelerated respiratory rates, reduced pulmonary function, and exacerbated lung pathology occurred earlier post-irradiation than previously observed after irradiation alone, suggesting infection accelerates the development of radiation injury. After irradiation alone, CCSP and Cyp2f2 mRNA levels were reduced, correlating with reductions in the number of Clara cells lining the airways. When combined with infection, these markers further declined and an apparent delay in recovery of mRNA expression was observed, suggesting that radiation injury leads to a chronic reduction in the number of Clara cells that may potentiate the epithelial injury observed after influenza A virus infection. This novel finding may have considerable therapeutic implications with respect to both thoracic tumor patients and recipients of bone marrow transplants.

Stress induced neuroendocrine-immune plasticity: A role for the spleen in peripheral inflammatory disease and inflammaging?

Research over the past decade has revealed close interaction between the nervous and immune systems in regulation of peripheral inflammation linking psychosocial stress with chronic somatic disease and aging. Moreover emerging data suggests that chronic inflammations lead to a pro-inflammatory status underlying premature aging called inflammaging. In this context, the spleen can be seen as a switch board monitoring peripherally derived neuroendocrine-immune mediators in the blood and keeping up a close communication with the central stress response via its mainly sympathetic innervation. The effect aims at balanced and well-timed stress axis activation and immune adaptation in acute peripheral inflammatory events. Constant adjustment to the needs generated by environmental and endogenous challenges is provided by neuroendocrine-immune plasticity. However, maladaptive plasticity induced e.g., by chronic stress-axis activation and excessive non-neuronal derived neuroendocrine mediators may be at the heart of the observed stress sensitivity promote inflammaging under chronic inflammatory conditions. We here review the role of neurotransmitters, neuropeptides and neurotrophins as stress mediators modulating the immune response in the spleen and their potential role in inflammaging.

Age-related impaired Th1 responses to PRV vaccine in vivo in aged pigs

Murine model studies have shown that function of the immune system declines with aging, but data on aged pigs are scarce. Many physiological and pathophysiological data of pigs can be transferred to human, research in pigs is important to confirm murine data, therefore, aged pigs were chosen as an aged animal model. In this study, we demonstrated an age-related decline in Th1 responses in vivo to PRV vaccine in the pig model, and this decline in type 1 immune responses was associated with reduced PRV-specific T cell proliferation, IgG2/IgG1, and Th1 cytokines production. More importantly, these impaired Th1 responses correlated with reduced CD4(+) T cells and markedly increased CD4(+)CD8(+) T cells. Taken together, these data demonstrated that there was a decline in Th1 immune responses to PRV vaccine with aging in pigs, which may help to explain the age-related decline in vaccine efficacy and increase in morbidity and mortality of infectious diseases.

HemoHIM ameliorates the persistent down-regulation of Th1-like immune responses in fractionated γ-irradiated mice by modulating the IL-12p70-STAT4 signaling pathway

Whole body irradiated mice appear to experience a down-regulation of the helper T (Th)1-like immune response, and maintain a persistent immunological imbalance. In the current study, we evaluated the effect of HemoHIM (an herbal product made from Angelica Radix, Cnidium officinale , and Paeonia japonica cultivated in Korea) to ameliorate the immunological imbalance induce in fractionated γ-irradiated mice. The mice were exposed to γ rays twice a week (0.5 Gy fractions) for a total dose of 5 Gy, and HemoHIM was administrated orally from 1 week before the first irradiation to 1 week before the final analysis. All experiments were performed 4 and 6 months after their first exposure. HemoHIM ameliorated the Th1- and Th2-related immune responses normally occur in irradiated mice with or without dinitrophenylated keyhole limpet hemocyanin immunization. HemoHIM also restored the natural killer cell activities without changing the percentage of natural killer cells in irradiated mice. Furthermore, the administration of HemoHIM prevented the reduction in levels of interleukin-12p70 in irradiated mice. Finally, we found that HemoHIM enhanced the phosphorylation of signal transducer and activator of transcription (STAT) 4 that was reduced in irradiated mice. Our findings suggest that HemoHIM ameliorates the persistent down-regulation of Th1-like immune responses by modulating the IL-12p70/pSTAT4 signaling pathway.

Cellular Senescence - its role in cancer and the response to ionizing radiation

Cellular senescence is a normal biological process that is initiated in response to a range of intrinsic and extrinsic factors that functions to remove irreparable damage and therefore potentially harmful cells, from the proliferative pool. Senescence can therefore be thought of in beneficial terms as a tumour suppressor. In contrast to this, there is a growing body of evidence suggesting that senescence is also associated with the disruption of the tissue microenvironment and development of a pro-oncogenic environment, principally via the secretion of senescence-associated pro-inflammatory factors. The fraction of cells in a senescent state is known to increase with cellular age and from exposure to various stressors including ionising radiation therefore, the implications of the detrimental effects of the senescent phenotype are important to understand within the context of the increasing human exposure to ionising radiation. This review will discuss what is currently understood about senescence, highlighting possible associations between senescence and cancer and, how exposure to ionising radiation may modify this.