The role of pro-inflammatory cytokines in cancer treatment-induced alimentary tract mucositis: pathobiology, animal models and cytotoxic drugs

Alimentary tract (AT) mucositis can be a major problem for patients undergoing cancer treatment. It has significant clinical and economic consequences and is a major factor that can compromise the provision of optimal treatment for patients. The pathobiology of AT mucositis is complex and the exact mechanisms that underlie its development still need to be fully elucidated. Current opinion considers that there is a prominent interplay between all of the compartments of the mucosa involving, at a molecular level, the activation of transcription factors, particularly nuclear factor-kappaB, and the subsequent upregulation of pro-inflammatory cytokines and inflammatory mediators. The purpose of this review is to examine the literature relating to what is currently known about the pathobiology of AT mucositis, particularly with respect to the involvement of pro-inflammatory cytokines, as well as currently used animal models and the role of specific cytotoxic chemotherapy agents in the development of AT mucositis.

Gastrointestinal microflora and mucins may play a critical role in the development of 5-Fluorouracil-induced gastrointestinal mucositis

5-Fluorouracil (5-FU) is a commonly used chemotherapy agent in clinical oncology practice. Two of its major side effects are mucositis and diarrhoea. The structure of mucins offers mucosal protection, and allows maintenance of intestinal flora by providing attachment sites and preventing bacterial overgrowth and/or penetration. The aim of this study was to investigate changes in mucin secretion and microflora following treatment with 5-FU. Female DA rats were given a single 150 mg/ kg i.p. dose of 5-FU. Rats were killed at various time points after treatment. Control rats received no treatment. Jejunum, colon and faecal samples were collected. Standard microbiological culture techniques were used to identify bacteria, and real-time PCR was used to quantify bacteria in faecal samples. Goblet cells and cavitated goblet cells (having undergone mucus exocytosis) were also counted. Statistical analysis was carried out using Kruskal-Wallis test, a non-parametric method of testing equality of group medians. Following treatment with 5-FU, we showed decreases in Clostridium spp., Lactobacillus spp. and Streptococcus spp., and an increase in Escherichia spp. in the jejunum. In the colon, 5-FU caused decreases in Enterococcus spp., Lactobacillus spp. and Streptococcus spp. Real-time PCR of faecal samples showed decreasing trends in Lactobacillus spp. and Bacteroides spp., and an increasing trend in E. coli. Significant increases (P < 0.05) were seen in Clostridium spp. and Staphylococcus spp. at 24 h. Goblet cell numbers decreased significantly in the jejunum from 24-72 h, with a significant increase in the percentage of cavitated goblet cells. In conclusion, 5-FU treatment causes significant changes in intestinal flora and mucin secretion in rats. These changes could result in systemic effects and, in particular, may contribute to the development of chemotherapy-induced mucositis.

Characterisation of mucosal changes in the alimentary tract following administration of irinotecan: implications for the pathobiology of mucositis

PURPOSE

The pathobiology of alimentary tract (AT) mucositis is complex and there is limited information about the events which lead to the mucosal damage that occurs during cancer treatment. Various transcription factors and proinflammatory cytokines are thought to play important roles in pathogenesis of mucositis. The aim of this study was to determine the expression of nuclear factor-kappaB (NF-kappaB), tumor necrosis factor (TNF) and interleukins-1beta (IL-1beta) and -6 (IL-6) in the AT following the administration of the chemotherapeutic agent irinotecan.

METHODS

Eighty-one female dark Agouti rats were assigned to either control or experimental groups according to a specific time point. Following administration of irinotecan, rats were monitored for the development of diarrhoea. The rats were killed at times ranging from 30 min to 72 h after administration of irinotecan. Oral mucosa, jejunum and colon were collected and standard immunohistochemical techniques were used to identify NF-kappaB, TNF, IL-1beta and IL-6 within the tissues. Sections were also stained with haematoxylin and eosin for histological examination.

RESULTS

Irinotecan caused mild to moderate diarrhoea in a proportion of the rats that received the drug. Altered histological features of all tissues from rats administered irinotecan were observed which included epithelial atrophy in the oral mucosa, reduction of villus height and crypt length in the jejunum and a reduction in crypt length in the colon. Tissue staining for NF-kappaB, TNF and IL-1beta and IL-6 peaked at between 2 and 12 h in the tissues examined.

CONCLUSIONS

This is the first study to demonstrate histological and immunohistochemical evidence of changes occurring concurrently in different sites of the AT following chemotherapy. The results of the study provide further evidence for the role of NF-kappaB and associated pro-inflammatory cytokines in the pathobiology of AT mucositis. The presence of these factors in tissues from different sites of the AT also suggests that there may be a common pathway along the entire AT causing mucositis following irinotecan administration.

VSL#3 probiotic treatment reduces chemotherapy-induced diarrhea and weight loss

BACKGROUND

One of the most common toxicities of cancer treatment is diarrhea. Probiotics have been shown effective at preventing diarrhea in inflammatory bowel disease and may prove useful in the oncology setting.

AIM

The primary aim of this study was to investigate the probiotic mixture, VSL#3, for amelioration of chemotherapy-induced diarrhea (CID).

METHODS

This experiment was carried out in a clinically relevant model of CID. VSL#3 was administered to female DA rats in one of three schedules. Irinotecan was used to induce mucositis and diarrhea, with rats monitored for seven days to record incidence of weight-loss and diarrhea. At study completion, intestines were collected to investigate histological and proliferative changes, apoptosis levels and mucin composition.

RESULTS

VSL#3 reduced weight loss following irinotecan when administered before and after chemotherapy. Moderate and severe diarrhea was also prevented in these rats. This was associated with a significant increase in crypt proliferation combined with an inhibition of apoptosis in both the small and large intestines. VSL#3 also prevented irinotecan-induced increases in goblet cells within jejunal crypts.

CONCLUSIONS

VSL#3 is effective at preventing severe diarrhea following chemotherapy with irinotecan and therefore has potential to be used clinically by cancer patients.

Systematic review of agents for the management of gastrointestinal mucositis in cancer patients

PURPOSE

The aim of this study was to review the available literature and define clinical practice guidelines for the use of agents for the prevention and treatment of gastrointestinal mucositis.

METHODS

A systematic review was conducted by the Mucositis Study Group of the Multinational Association of Supportive Care in Cancer/International Society of Oral Oncology (MASCC/ISOO). The body of evidence for each intervention, in each cancer treatment setting, was assigned an evidence level. Based on the evidence level, one of the following three guideline determinations was possible: recommendation, suggestion, and no guideline possible.

RESULTS

A total of 251 clinical studies across 29 interventions were examined. Panel members were able to make one new evidence-based negative recommendation; two new evidence-based suggestions, and one evidence-based change from previous guidelines. Firstly, the panel recommends against the use of misoprostol suppositories for the prevention of acute radiation-induced proctitis. Secondly, the panel suggests probiotic treatment containing Lactobacillus spp., may be beneficial for prevention of chemotherapy and radiotherapy-induced diarrhea in patients with malignancies of the pelvic region. Thirdly, the panel suggests the use of hyperbaric oxygen as an effective means in treating radiation-induced proctitis. Finally, new evidence has emerged which is in conflict with our previous guideline surrounding the use of systemic glutamine, meaning that the panel is unable to form a guideline. No guideline was possible for any other agent, due to inadequate and/or conflicting evidence.

CONCLUSIONS

This updated review of the literature has allowed new recommendations and suggestions for clinical practice to be reached. This highlights the importance of regular updates.

Irinotecan-induced mucositis manifesting as diarrhoea corresponds with an amended intestinal flora and mucin profile

Chemotherapy-induced diarrhoea is a major oncological problem, caused by the cytotoxic effects of cancer chemotherapy. Irinotecan is linked with severe mucositis and diarrhoea, the mechanisms of which remain poorly understood. Bacterial beta-glucuronidase is thought to be involved in the metabolism of irinotecan, implicating the intestinal flora. Intestinal mucins may also be implicated in the development of chemotherapy-induced diarrhoea. Rats were treated with 200 mg/kg of irinotecan and killed at 96, 120 and 144 h. The rats were monitored for diarrhoea. Pathology and immunohistochemical staining was performed. The samples were cultured and faecal DNA was analysed using real-time polymerase chain reaction. Severe diarrhoea was observed from 72 to 96 h. A decrease in body mass was also observed after treatment. Significant changes in goblet cell numbers (both complete and cavitated cells) were observed in the small and large intestines. Changes in MUC gene expression were observed in the small intestine only. Modifications were observed to the intestinal flora profile, especially Escherichia coli, and an increase in the expression of beta-glucuronidase was detected. In conclusion, irinotecan-induced diarrhoea may be caused by an increase in some beta-glucuronidase-producing bacteria, especially E. coli, exacerbating the toxicity of active metabolites. Accelerated mucous secretion and mucin release may also contribute to the delayed onset of diarrhoea.

Pro-inflammatory cytokines play a key role in the development of radiotherapy-induced gastrointestinal mucositis

Background

Mucositis is a toxic side effect of anti-cancer treatments and is a major focus in cancer research. Pro-inflammatory cytokines have previously been implicated in the pathophysiology of chemotherapy-induced gastrointestinal mucositis. However, whether they play a key role in the development of radiotherapy-induced gastrointestinal mucositis is still unknown. Therefore, the aim of the present study was to characterise the expression of pro-inflammatory cytokines in the gastrointestinal tract using a rat model of fractionated radiotherapy-induced toxicity.

Methods

Thirty six female Dark Agouti rats were randomly assigned into groups and received 2.5 Gys abdominal radiotherapy three times a week over six weeks. Real time PCR was conducted to determine the relative change in mRNA expression of pro-inflammatory cytokines IL-1β, IL-6 and TNF in the jejunum and colon. Protein expression of IL-1β, IL-6 and TNF in the intestinal epithelium was investigated using qualitative immunohistochemistry.

Results

Radiotherapy-induced sub-acute damage was associated with significantly upregulated IL-1β, IL-6 and TNF mRNA levels in the jejunum and colon. The majority of pro-inflammatory cytokine protein expression in the jejunum and colon exhibited minimal change following fractionated radiotherapy.

Conclusions

Pro-inflammatory cytokines play a key role in radiotherapy-induced gastrointestinal mucositis in the sub-acute onset setting.

Biomarkers of chemotherapy-induced diarrhoea: a clinical study of intestinal microbiome alterations, inflammation and circulating matrix metalloproteinases

PURPOSE

A common side effect of chemotherapy treatment is diarrhoea. Unfortunately, the underlying mechanisms of chemotherapy-induced diarrhoea (CD) are poorly understood. We aimed to determine if faecal microbes of CD patients were displaced, if faecal calprotectin increased during CD and if there were alterations in circulating matrix metalloproteinases, nuclear factor kappa B (NF-κB), IL-1β and TNF.

PATIENTS AND METHODS

Twenty-six cancer patients receiving chemotherapy were enrolled and requested to provide stool samples and blood samples at various times during their chemotherapy cycle. Stool samples were analysed using conventional culture techniques and qRT-PCR. ELISA kits determined faecal calprotectin levels, levels of circulating matrix metalloproteinases and circulating NF-κB, IL-1β and TNF.

RESULTS

The majority of patients with CD showed decreases in Lactobacillus spp., Bifidobacterium spp., Bacteroides spp. and Enterococcus spp. Increases were observed in Escherichia coli and Staphylococcus spp. Methanogenic archaea were also quantified, with all patients except one showing a decrease. Faecal calprotectin levels were increased in 81.25 % of patients with CD. Circulating MMP-3 and MMP-9 significantly increased following chemotherapy. Circulating levels of NF-κB, IL-1β and TNF were increased following chemotherapy, although this did not reach significance.

CONCLUSIONS

We demonstrated that CD is associated with marked changes in intestinal microflora, methanogenic archaea, matrix metalloproteinase and serum levels of NF-κB, IL-1β and TNF. These changes may result in diminished bacterial functions within the gut, altering gut function and initiating intestinal damage, resulting in the onset of diarrhoea. More importantly, these changes may provide clinicians with a possible new target for biomarkers of toxicity.

Emerging evidence on the pathobiology of mucositis

BACKGROUND

Considerable progress has been made in our understanding of the biological basis for cancer therapy-induced mucosal barrier injury (mucositis). The last formal review of the subject by MASCC/ISOO was published in 2007; consequently, an update is timely.

METHODS

Panel members reviewed the biomedical literature on mucositis pathobiology published between January 2005 and December 2011.

RESULTS

Recent research has provided data on the contribution of tissue structure changes, inflammation and microbiome changes to the development of mucositis. Additional research has focused on targeted therapy-induced toxicity, toxicity clustering and the investigation of genetic polymorphisms in toxicity prediction. This review paper summarizes the recent evidence on these aspects of mucositis pathobiology.

CONCLUSION

The ultimate goal of mucositis researchers is to identify the most appropriate targets for therapeutic interventions and to be able to predict toxicity risk and personalize interventions to genetically suitable patients. Continuing research efforts are needed to further our understanding of mucositis pathobiology and the pharmacogenomics of toxicity.

Microbiota and their role in the pathogenesis of oral mucositis

Oral mucositis in patients undergoing cancer therapy is a significant problem. Its prevalence ranges between 20 and 100%, depending on treatment type and protocols and patient-based variables. Mucositis is self-limiting when uncomplicated by infection. Unfortunately, the incidence of developing a local or systemic infection during the course of the treatment is very high. At this stage, it is unclear which role oral microbiota play in the onset, duration, and severity of oral mucositis. Nevertheless, there is growing interest in this underexplored topic, and new studies are being undertaken to unravel their impact on the pathogenesis of mucositis.

Noncardiac vascular toxicities of vascular endothelial growth factor inhibitors in advanced cancer: a review

The introduction of molecularly targeted anticancer therapies has brought the promise of longer survival times for select patients with cancers previously considered untreatable. However, it has also brought new toxicities that require understanding and management, sometimes for long periods of time. Vascular endothelial growth factor inhibitors are associated with a broad range of adverse effects, with vascular toxicity being particularly serious. This review focuses on the current understanding of the pathophysiology and mechanisms of macrovascular toxicities (hypertension, hemorrhage, and thromboembolism), their incidence and severity, the current clinical management, and implications in the advanced cancer setting. Movement of these agents into the early disease setting will alter the impact of these toxicities. Search Strategy and Selection Criteria. Information for this review was collected by searching PubMed/Medline and American Society of Clinical Oncology abstract databases. The medical subject heading terms used included toxicity, hypertension, thromboembolism, hemorrhage, intestinal perforation, risk factors, pharmacokinetics, and metabolism, combined with free text search terms including, but not limited to, VEGF inhibitor*, bevacizumab, sunitinib, and sorafenib. Articles published in English before March 2010 were included, in addition to information from case reports and pharmaceutical agent package inserts.

Matrix metalloproteinases are possible mediators for the development of alimentary tract mucositis in the dark agouti rat

Alimentary tract (AT) mucositis is a serious and debilitating side-effect of cancer therapy primarily characterized by damage of the mucous membranes throughout the AT. It is well established that this damage is a result of up-regulation of stress response genes and pro-inflammatory cytokines. Matrix metalloproteinases (MMPs) have been shown to function in several of the pathways known to be up-regulated in mucositis and play a key role in tissue injury and inflammation in many gastrointestinal disorders. This study aims to characterize the expression of multiple MMPs including MMP-1, -2, -3, -9 and -12 and their inhibitors, tissue inhibitor of metalloproteinase (TIMP)-1 and -2, in a rat model of irinotecan-induced mucositis. Dark agouti rats were administered a single 200 mg/kg intraperitoneal dose of irinotecan and killed at 1, 6, 24, 48, 72, 96 and 144 h following treatment. Hematoxylin and eosin staining, immunohistochemistry and realtime polymerase chain reaction were used to assess histopathological damage and MMP expression in the jejunum and colon. Marked histopathological evidence of mucositis was observed in the jejunum and colon as early as six hours following irinotecan treatment. A significant alteration in both gene expression and tissue levels of MMPs and TIMPs was noted following irinotecan. The increase in MMP-2, -3, -9 and -12 levels was associated with inflammatory infiltrate and maximum tissue damage. In contrast, MMP-1 expression correlated with tissue restitution. TIMP-1 and -2 levels were significantly altered in the jejunum following irinotecan. The augmentation in the expression profiles of MMPs and their inhibitors correlated with histopathological alterations observed in the tissue following irinotecan. This prompts the consideration of MMPs as possible mediators of chemotherapy-induced mucositis.

A novel animal model to investigate fractionated radiotherapy-induced alimentary mucositis: the role of apoptosis, p53, nuclear factor-kappaB, COX-1, and COX-2

Radiation-induced mucositis is a common and serious side effect of radiotherapy. Molecular mechanisms of mucosal injury, however, are still poorly understood and extremely difficult to study in humans. A novel Dark Agouti rat model using fractionated radiotherapy to induce mucositis has been developed to investigate the occurrence of alimentary mucosal injury. Twenty-four Dark Agouti rats were randomly assigned to receive either fractionated radiotherapy or no radiotherapy. The irradiated rats received a fractionated course of abdominal radiotherapy at 45 Gy/18 fractions/6 weeks treating thrice weekly (i.e., at a radiation dose of 2.5 Gy per fraction). After each week of radiation, a group of irradiated rats was killed. Histomorphology and mucin distribution in the alimentary tract was investigated. The terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay was used to examine apoptosis in the colon and jejunum, and intestinal morphometry was used to assess villus length, crypt length, and mitotic crypt count. Immunohistochemistry of p53, nuclear factor-kappaB, cyclooxygenase (COX)-1, and COX-2 was also done. The fractionated radiotherapy course induced alimentary mucositis from week 1, with more severe injury seen in the small intestine. The hallmark appearance of apoptosis was present in the crypts of the small and large intestine. In the jejunum and colon, goblet cell disorganization and degeneration was obvious and crypt mitotic counts were severely depleted throughout the treatment. Expression of p53, nuclear factor-kappaB, COX-1, and COX-2 was increased in the irradiated intestinal sections. Fractionated radiation-induced alimentary mucositis has been effectively documented in the Dark Agouti rat for the first time. Further studies investigating the molecular mechanisms underlying radiation-induced mucositis are planned to ultimately achieve anti-mucotoxic-targeted therapies.

Growth factors and cytokines in the prevention and treatment of oral and gastrointestinal mucositis

GOALS OF WORK

Growth factors and cytokines may be useful in preventing chemotherapy (CT)- and radiotherapy (RT)-induced oral and gastrointestinal mucositis. Two systematic reviews of the medical literature on growth factors and cytokines for the amelioration of CT- and RT-induced mucositis throughout the alimentary tract were performed by the Mucositis Study Group of the Multinational Association of Supportive Care in Cancer/International Society for Oral Oncology. The aim of these evidence-based scientific reviews was to critically evaluate the literature and create evidence-based guidelines for the use of growth factors and cytokines in the prevention or treatment of CT- and RT-induced mucositis.

METHOD

The two reviews covered articles on clinical trials from January 1966 through May 2002 and preclinical studies from June 2002 through May 2005, respectively. The systematic review process was based on a well-established method for evaluating scientific literature.

MAIN RESULTS

The number of articles in the first review was 29. In the second review, 23 articles were evaluated, 14 preclinical and 9 clinical studies. It was concluded from the first review that there was no sufficient evidence to provide any recommendations for clinical practice guidelines regarding growth factors and cytokines. From the second review, a guideline could be presented recommending the use of recombinant human keratinocyte growth factor-1 (palifermin) to prevent oral mucositis in patients receiving high-dose CT and total body irradiation followed by stem cell transplantation for haematological malignancies. A guideline could also be provided suggesting that granulocyte macrophage colony-stimulating factor mouthwash not be used for the prevention of oral mucositis in the transplant setting with high-dose CT and autologous or allogeneic stem cell transplantation.

CONCLUSIONS

These systematic reviews have provided clarity and shown exciting new results. Further studies will provide new options for this debilitating side-effect of cancer therapy.

Systematic review of growth factors and cytokines for the management of oral mucositis in cancer patients and clinical practice guidelines

PURPOSE

To update the clinical practice guidelines for the use of growth factors and cytokines for the prevention and/or treatment of oral mucositis (OM).

METHODS

A systematic review was conducted by the Mucositis Study Group of the Multinational Association of Supportive Care in Cancer/International Society of Oral Oncology (MASCC/ISOO). The body of evidence for each intervention, in each cancer treatment setting, was assigned an evidence level. The findings were added to the database used to develop the 2014 MASCC/ISOO clinical practice guidelines. Based on the evidence level, the following guidelines were determined: recommendation, suggestion, and no guideline possible.

RESULTS

A total of 15 new papers were identified within the scope of this section and were merged with 51 papers that were reviewed in the previous guidelines update. Of these, 14, 5, 13, 2, and 1 were randomized controlled trials about KGF-1, G-CSF, GM-CSF, EGF, and erythropoietin, respectively. For the remaining agents there were no new RCTs. The previous recommendation for intravenous KGF-1 in patients undergoing autologous hematopoietic stem cell transplantation (HSCT) conditioned with high-dose chemotherapy and TBI-based regimens is confirmed. The previous suggestion against the use of topical GM-CSF for the prevention of OM in the setting of high-dose chemotherapy followed by autologous or allogeneic stem cell transplantation remains unchanged.

CONCLUSIONS

Of the growth factors and cytokines studied for the management of OM, the evidence supports a recommendation in favor of KGF-1 and a suggestion against GM-CSF in certain clinical settings.

Gene expression analysis of multiple gastrointestinal regions reveals activation of common cell regulatory pathways following cytotoxic chemotherapy

Gastrointestinal mucositis involves many changes at the gene level, affecting epithelial/subepithelial interactions and leading to overt damage. The regional specificity and time course of these changes, and how they relate to subsequent mucositis development however remain unknown. The aim of this study was to determine the early time course of gene expression changes along the gastrointestinal tract of the DA rat following chemotherapy. Female DA rats were treated with a single dose of 200 mg/kg irinotecan to induce mucositis, and were killed at short intervals following treatment. Small sections of stomach, jejunum and colon were harvested for analysis of genetic profiles. RNA was hybridised to high density Affymetrix oligonucleotide microarrays. Data analysis was carried out with software package, TimeCourse, freely available through Bioconductor. As early as 1 hr following chemotherapy, expression of hundreds of genes was altered, including those for transcription factors, stress response proteins and protein turnover. These genes are involved in cell proliferation, differentiation and apoptosis along with other cellular processes. At early time points, there was a significant response involving the mitogen-activated protein kinase pathway, cell cycle regulation and cytokine receptor signalling. At later time points, changes to the complement cascade became prominent. We have shown that changes in gene expression following chemotherapy occur by 1 hr, and persist for at least 72 hr after treatment. Many of these changes are highly likely to be specifically related to the subsequent development of gastrointestinal mucositis.

Radiation therapy-induced mucositis: Relationships between fractionated radiation, NF-κB, COX-1, and COX-2

Radiation therapy is one of the three major treatment modalities used in eradicating malignant tumours. When ionising radiation is used to treat abdominal tumours, severe side effects largely due to mucosal damage in the alimentary tract are common, particularly when it is combined with chemotherapy. Radiation-induced mucositis may not only limit the therapeutic doses of combined treatment but also adversely affect the quality of life of the patient. Treatment strategies to treat and prevent radiation-induced mucositis have been reviewed and published in the Clinical Practice Guidelines, 2004. However evidence supporting an effective treatment approach is tenuous, probably because the mechanistic evolution of radiation-induced mucositis is poorly understood. Several animal models have been used to examine the various effects of radiation but no single animal model has been able to effectively capture the effects of radiation on the alimentary tract at the molecular level before symptoms begin. This review will outline the events which occur following radiation exposure; from chromosomal aberrations in the mucosal cells leading to apoptotic and mitotic death, to the evolution of mucositis involving changes in gene activations and signaling. A better understanding of the mechanisms of radiation therapy-induced mucositis is necessary as it will allow for future pharmaceutical interventions to alleviate if not eliminate the debilitating side effects.

Development of a rat model of oral small molecule receptor tyrosine kinase inhibitor-induced diarrhea

Orally administered small molecule receptor tyrosine kinase inhibitors (RTKIs) are increasingly common treatments for cancer, both alone and in combination with chemotherapy. However, their side effect profiles and the underlying mechanisms of such are not yet fully elucidated. Management of their most common dose limiting side effect, diarrhea, has been hampered by a lack of suitable animal models. We aimed to develop a clinically relevant rat model of RTKI-induced diarrhea that could be utilized for investigating supportive care interventions and pharmacokinetics. Albino Wistar rats were treated daily for 4 weeks with various concentrations of lapatinib to determine the optimal dose for development of diarrhea. This was then followed by an experiment with addition of paclitaxel once weekly for 4 weeks to observe effects of combination drug treatment on diarrhea. Data regarding animal tolerance to the treatment, organ weights, circulating lapatinib concentration and histopathology were collected weekly. Lapatinib caused diarrhea in rats that was dose-dependent. Diarrhea occurred without causing significant intestinal histopathology. Follow up experiments are currently underway to determine the exact pathogenesis and mechanisms of lapatinib-induced diarrhea and potential protective strategies.

Irinotecan-induced alterations in intestinal cell kinetics and extracellular matrix component expression in the Dark Agouti rat

Chemotherapy-induced mucositis is characterized by damage of mucous membranes throughout the alimentary tract (AT). Extracellular matrix (ECM) components play a vital role in maintaining mucosal barrier integrity by regulating cellular apoptosis, proliferation and differentiation of overlying epithelial cells. The aims of this study were to characterize the changes in epithelial cell kinetics and to investigate the expression of the ECM components in the gastrointestinal tract following irinotecan administration. Female dark agouti rats were treated with single 200 mg/kg dose irinotecan and killed at various time points (1, 6, 24, 48, 72, 96 and 14 h) after treatment. Ki67 immunostaining and TUNEL were used to assess proliferation and apoptosis, respectively, in the jejunum and colon. Masson trichrome staining and picro-sirius red staining were used to determine the level of collagen, and immunohistochemistry was used to further assess collagen IV, fibronectin and laminin 1 and 2 expression in these tissues. Irinotecan halved cellular proliferation in the jejunum and colon at 48 and 24 h, respectively, while apoptosis peaked at 6 h (P < 0.05). There was a substantial increase in total collagen deposits around crypts from 24 h in both regions. However, collagen IV expression decreased significantly in the crypt region in a delayed fashion (P < 0.05). Fibronectin expression decreased significantly in jejunum and colon from 6 to 24 h following treatment (P < 0.05). Irinotecan induced a significant alteration in epithelial cell kinetics in both the jejunum and colon, and this correlated with changes in ECM component expression. Changes in ECM expression may have a direct impact on the loss of mucosal layer integrity evident in chemotherapy-induced mucositis.

Chemotherapy-induced mucositis: the role of the gastrointestinal microbiome and toll-like receptors

Alimentary mucositis is a major clinical problem. Patients with mucositis are at significantly increased risk of infection and are often hospitalized for prolonged periods. More importantly, these patients often have to undergo reductions in their cytotoxic therapy, which may lead to reduced survival. Unfortunately, there are very limited therapeutic options for mucositis and no effective prevention. The human gut microbiome is receiving increased attention as a key player in the pathogenesis of alimentary mucositis with recent literature suggesting that changes in bacteria lead to mucositis. The bacteria which are found throughout the gut are tightly regulated by the toll-like receptor (TLR) family which currently has 13 known members. TLRs play a critical role in gut homeostasis and bacterial regulation. Furthermore, TLRs play a critical role in the regulation of nuclear factor kappa B, a key regulator of alimentary mucositis. However to date, no research has clearly identified a link between TLRs and alimentary mucositis. This critical literature review seeks to correct this.