Expression of transforming growth factor beta1/Sma- and Mad-related proteins in rat with chronic pancreatitis induced by dibutyltin dichloride

Adipose‑derived mesenchymal stem cells ameliorate dibutyltin dichloride‑induced chronic pancreatitis by inhibiting the PI3K/AKT/mTOR signaling pathway

Adipose-derived mesenchymal stem cells (ASCs) play a positive role in tissue injury repair and regeneration. The aim of this study was to determine whether ASCs could ameliorate chronic pancreatitis (CP) induced by the injection of dibutyltin dichloride (DBTC) and to elucidate its potential mechanisms. Furthermore, this study also explored whether there was a significant difference if the ASCs were injected via the inferior vena cava or the left gastric artery. CP was induced in rats by a single intravenous administration of DBTC, and the accumulation of collagen and apoptotic rates of pancreatic acinar cells were analyzed. According to the results, ASCs markedly reduced DBTC-induced pancreatic damage and collagen deposition in the rat model of CP. Moreover, ASCs significantly decreased pancreatic cell apoptosis by regulating the expression levels of caspase-3, BAX and Bcl-2. These effects were observed regardless of whether the injection was in the inferior vena cava or the left gastric artery. It was also found that the expression levels of phosphorylated PI3K, AKT and mTOR in pancreatic tissues of the DBTC-induced CP model group were significantly increased, while the expression levels of phosphorylated PI3K, AKT and mTOR in the two treatment groups were markedly decreased. ASCs noticeably suppressed the PI3K/AKT/mTOR pathway in the pancreatic tissue of DBTC-induced CP. This study indicated that ASCs protect against pancreatic fibrosis by modulating the PI3K/AKT/mTOR pathway, and have the potential to be a new strategy for the treatment of CP in the future.

Transforming growth factor-β in pancreatic diseases: Mechanisms and therapeutic potential

Pancreatic diseases, such as acute pancreatitis, chronic pancreatitis, and pancreatic cancer, are common gastrointestinal diseases resulting in the development of local and systemic complications with a high risk of death. Numerous studies have examined pancreatic diseases over the past few decades; however, the pathogenesis remains unclear, and there is a lack of effective treatment options. Recently, emerging evidence has suggested that transforming growth factor beta (TGF-β) exerts controversial functions in apoptosis, inflammatory responses, and carcinogenesis, indicating its complex role in the pathogenesis of pancreas-associated disease. Therefore, a further understanding of relevant TGF-β signalling will provide new ideas and potential therapeutic targets for preventing disease progression. This is the first systematic review of recent data from animal and human clinical studies focusing on TGF-β signalling in pancreas damage and diseases. This information may aid in the development of therapeutic agents for regulating TGF-β in this pathology to prevent or treat pancreatic diseases.

Neuronal Transforming Growth Factor beta Signaling via SMAD3 Contributes to Pain in Animal Models of Chronic Pancreatitis

BACKGROUND & AIMS

Chronic pancreatitis (CP) is characterized by pancreatic inflammation and fibrosis, associated with increased pancreatic expression of transforming growth factor beta (TGFB). It is not clear how these might contribute to pain. We investigated whether TGFB signaling via SMAD induces sensitization of pancreatic sensory neurons to increase nociception.

METHODS

CP was induced in Sprague-Dawley rats by infusion of trinitrobenzene sulfonic acid; some rats were given intrathecal infusions of TGFB1. CP was induced in control mice by administration of cerulein; we also studied β1glo/Ptf1acre-ER mice, which on induction overexpress TGFB1 in pancreatic acinar cells, and TGFBr1^{f/f-CGRPcreER} mice, which have inducible disruption of TGFBr1 in calcitonin gene-related peptide-positive neurons. Dominant negative forms of human TGFBR2 and SMAD3 were overexpressed from viral vectors in rat pancreas. Some rats were given the SMAD3 inhibitors SIS3 or halofuginone. After induction of CP, mice were analyzed for pain in behavior tests or electrophysiologic studies of sensory neurons. Pancreatic nociceptor excitability was examined by patch-clamp techniques and nociception was measured by Von Frey Filament tests for referred somatic hyperalgesia and behavioral responses to pancreatic electrical stimulation. Pancreata were collected from mice and rats and analyzed histologically and by enzyme-linked immunosorbent assay and immunohistochemistry.

RESULTS

Overexpression of TGFB in pancreatic acinar cells of mice and infusion of TGFB1 into rats resulted in sensory neuron hyperexcitability, SMAD3 activation, and increased nociception. This was accompanied by a reduction in the transient A-type current in pancreas-specific sensory neurons in rats, a characteristic of nociceptive sensitization in animal models of CP. Conversely, pancreata from TGFBr1^{f/f-CGRPcreER} mice, rats with pancreatic expression of dominant negative forms of human TGFBR2 or SMAD3, and rats given small molecule inhibitors of SMAD3 had attenuated neuronal sensitization and pain behavior following induction of CP. In contrast to findings from peripheral administration of TGFB1, intrathecal infusion of TGFB1 reduced hyperalgesia in rats with CP.

CONCLUSIONS

In pancreata of mice and rats, TGFB promotes peripheral nociceptive sensitization via a direct effect on primary sensory neurons mediated by intra-neuronal SMAD3. This is distinct from the central nervous system, where TGFB reduces nociception. These results provide an explanation for the link between fibrosis and pain in patients with CP. This signaling pathway might be targeted therapeutically to reduce pain in patients with CP.

Modified Xiaochaihu Decoction () Promotes Collagen Degradation and Inhibits Pancreatic Fibrosis in Chronic Pancreatitis Rats

OBJECTIVE

To investigate the effect of Modified Xiaochaihu Decoction (MXD, ) on collagen degradation in rats with chronic pancreatitis (CP).

METHODS

Rats were injected dibutyltin dichloride (DBTC, 7 mg/kg of body weight) into the right caudal vein to induce CP model. Thirty heallhy male Wistar rats were randomly divided into three groups by a random number table: the control, the model and the treatment groups. Rats of treatment group were administered MXD (10 g/kg of body weight) orally once daily starting from the day post-model establishment. Pancreatic tissues were harvested after 28-day feeding and fibrosis was evaluated by picro-sirius red staining. The contents of collagen type I and III were detected using enzymelinked immunosorbent assay (ELISA), the expression of matrix metalloproteinase 13 (MMP13) and tissue inhibitor of metalloproteinase 1 (TIMP1) was analyzed by Western blot and real-time polymerase chain reaction (PCR).

RESULTS

The fibrosis scoring of pancreatic tissues, the concentrations of collagen type I and III, the expression levels of MMP13 and TIMP1 proteins and mRNA in the model group were all increased compared with the control group (P<0.05). After treatment with MXD, the fibrosis scoring of pancreatic tissues, the concentrations of collagen type I and III, the expression levels of MMP13 proteins and mRNA in the teatment group were all decreased compared with the model group (P<0.05), but there were no significant differences in the expression levels of TIMP1 proteins and mRNA (P>0.05).

CONCLUSIONS

MXD could promote collagen degradation and reverse pancreatic fibrosis in CP rats via a mechanism involve up-regulation of MMP13 expression.

Towards a neurobiological understanding of pain in chronic pancreatitis: mechanisms and implications for treatment

We summarize the evidence for a neurobiological understanding of pain in patients with chronic pancreatitis and discuss its potential impact on prevention and treatment.

Introduction:

Chronic pancreatitis (CP) is a disease characterized by inflammation of the pancreas resulting in replacement of the normal functioning parenchyma by fibrotic connective tissue. This process leads to progressively impairment of exocrine and endocrine function and many patients develop a chronic pain syndrome.

Objectives:

We aimed to characterize the neurobiological signature of pain associated with CP and to discuss its implications for treatment strategies.

Methods:

Relevant basic and clinical articles were selected for review following an extensive search of the literature.

Results:

Pathophysiological changes in the peripheral (pancreatic gland) and central nervous system characterize the pain syndrome associated with CP; involved mechanisms can be broken down to 3 main branches: (1) peripheral sensitization, (2) pancreatic neuropathy, and (3) neuroplastic changes in the central pain pathways. Disease flares (recurrent pancreatitis) may accelerate the pathophysiological process and further sensitize the pain system, which ultimately results in an autonomous and self-perpetuating pain state that may become independent of the peripheral nociceptive drive. These findings share many similarities with those observed in neuropathic pain disorders and have important implications for treatment; adjuvant analgesics are effective in a subset of patients, and neuromodulation and neuropsychological interventions may prove useful in the future.

Conclusion:

Chronic pancreatitis is associated with abnormal processing of pain at the peripheral and central level of the pain system. This neurobiological understanding of pain has important clinical implications for treatment and prevention of pain chronification.

Modified Xiaochaihu Decoction () prevents the progression of chronic pancreatitis in rats possibly by inhibiting transforming growth factor-β1/Sma- and mad-related proteins signaling pathway

OBJECTIVE

To investigate the effect of modified Xiaochaihu Decoction (, MXD) on transforming growth factor-β1/Sma- and Mad-related proteins (TGF-β1/Smads) signaling pathway in rats with chronic pancreatitis (CP) induced by dibutyltin dichloride.

METHODS

Thirty healthy male Wistar rats were randomly divided into the normal control group, CP group and CP+MXD-treated group. CP was induced by injection of dibutyltin dichloride (DBTC, 7 mg/kg of body weight) into the right caudal vein, and the control rats were treated with vehicle. MXD was given daily by gavage at a dose of 10 g/kg of body weight, starting from the day after CP induction. After 28-day treatment, the n-benzoyl-tyrosyl para-aminobenzoic acid (NBT-PABA) test was carried out to evaluate exocrine pancreatic function. Then, rats were sacrificed, and pancreatic tissues were harvested for histological evaluation. In addition, the mRNA expression of TGF-β1, TGF-β1 type II receptor (TGFβRII), Smad3 and Smad7 was determined in pancreatic tissues by using real-time polymerase chain reaction.

RESULTS

Treatment of CP with MXD improved the PABA recovery, decreased the histological lesion, and reduced the mRNA expression of TGF-β1, TGFβRII and Smad3 (P<0.05). However, MXD had no effect on Smad7 mRNA level.

CONCLUSIONS

MXD could protect the pancreas against chronic injury and improve pancreatic exocrine function in DBTC induced rat CP model. Its mechanism may involve inhibition of the TGF-β1/Smads signaling pathway.