Expression of functional neurokinin-1 receptors in regenerative glands during gastric wound healing in rodents

Marked Effects of Tachykinin in Myositis Both in the Experimental Side and Contralaterally: Studies on NK-1 Receptor Expressions in an Animal Model

Muscle injury and inflammation (myositis) in a rabbit model of an unilateral muscle overuse were examined. It is unknown if the tachykinin system has a functional role in this situation. In this study, therefore, the neurokinin-1 receptor (NK-1R) expression patterns were evaluated. White blood cells, nerve fascicles, fine nerve fibers, and blood vessel walls in myositis areas showed NK-1R immunoreaction. NK-1R mRNA reactions were observable for white blood cells and blood vessel walls of these areas. NK-1R immunoreaction and NK-1R mRNA reactions were also seen for muscle fibers showing degenerative and regenerative features. There were almost no NK-1R immunoreactions in normal muscle tissue. Interestingly, marked NK-1R expressions were seen for myositis areas of both the experimental side and the contralateral nonexperimental side. EIA analyses showed that the concentration of substance P in the muscle tissue was clearly increased bilaterally at the experimental end stage, as compared to the situation for normal muscle tissue. These observations show that the tachykinin system is very much involved in the processes that occur in muscle injury/myositis. The effects can be related to proinflammatory effects and/or tissue repair. The fact that there are also marked NK-1R expressions contralaterally indicate that the tachykinin system has crossover effects.

Morphine-induced early delays in wound closure: involvement of sensory neuropeptides and modification of neurokinin receptor expression

Dose-limiting side effects of centrally acting opioid drugs have led to the use of topical opioids to reduce the pain associated with chronic cutaneous wounds. However, previous studies indicate that topical morphine application impairs wound healing. This study was designed to elucidate the mechanisms by which morphine delays wound closure. Rats were depleted of sensory neuropeptides by treatment with capsaicin, and full-thickness 4-mm diameter wounds were excised from the intrascapular region. Wounds were treated topically twice daily with 5mM morphine sulfate, 1mM substance P, 1mM neurokinin A, or 5mM morphine combined with 1mM substance P or neurokinin A and wound areas assessed. During closure, wound tissue was taken 1, 3, 5, and 8 days post-wounding from control and morphine-treated rats and immunostained for neurokinin receptors and markers for macrophages, myofibroblasts, and vasculature. Results obtained from capsaicin-treated animals demonstrated a significant delay in the early stages of wound contraction that was reversed by neuropeptide application. Treatment of capsaicin-treated rats with topical morphine did not further delay wound closure, suggesting that topical opioids impair wound closure via the inhibition of peripheral neuropeptide release into the healing wound. Morphine application altered neurokinin-1 and neurokinin-2 receptor expression in inflammatory and parenchymal cells essential for wound healing in a cell-specific manner, demonstrating a direct effect of morphine on neurokinin receptor regulation within an array of cells involved in wound healing. These data provide evidence indicating a potentially detrimental effect of topical morphine application on the dynamic wound healing process.

Observations favouring the occurrence of local production and marked effects of bombesin/gastrin-releasing peptide in the synovial tissue of the human knee joint--comparisons with substance P and the NK-1 receptor

We have previously shown that levels of the neuropeptides substance P (SP) and bombesin/gastrin-releasing peptide (BN/GRP) in blood and synovial fluid correlate with levels of pro-inflammatory cytokines in patients with rheumatoid arthritis (RA). It is well-established that SP is present in nerve endings in the synovium whilst the source of BN/GRP in human joints is completely unknown. Nor is it known whether GRP-receptors (GRP-R) are present in human synovial tissue. This study aimed to investigate the expression pattern of SP, BN/GRP and their receptors (NK-1R and GRP-R) in synovial tissue. Synovial tissue specimens from patients with RA or osteoarthritis (OA) were processed for immunohistochemistry, in situ hybridisation and ELISA. The results show the presence of BN/GRP, but not SP, in cells in the synovial tissue at both the protein and mRNA level. We did not find immunoreactive BN/GRP in nerve structures. NK-1R and GRP-R were also expressed at both protein and mRNA levels in cells associated with blood vessels and cells in the interstitial tissue. ELISA analyses revealed both SP and BN/GRP to be present in synovial tissue extracts and that synovial levels of SP were higher in RA patients than those with OA. Our results indicate that BN/GRP is produced by non-neuronal cells in the synovial tissue. Furthermore, both BN/GRP and SP may exert their effects on the synovial tissue through the respective receptors. These results suggest that BN/GRP and SP may modulate inflammation and vascular events, and possibly healing processes in the synovium. Finally, nerves should not be considered as the source of BN/GRP in synovial tissue although this peptide is presumably intimately involved functionally in synovial tissue, a previously unrecognised fact.

Presence of substance P and the neurokinin-1 receptor in tenocytes of the human Achilles tendon

Nerve signal substances, such as the tachykinin substance P (SP), may be involved in the changes that occur in response to tendinopathy (tendinosis). It is previously known that the level of SP innervation within tendon tissue is limited, but results of experimental studies have suggested that SP may have stimulatory, angiogenetic and healing effects in injured tendons. Therefore, it would be of interest to know if there is a local SP-supply in tendon tissue. In the present study, the patterns of expression of SP and its preferred receptor, the neurokinin-1 receptor (NK-1 R), in normal and tendinosis human Achilles tendons were analyzed by use of both immunohistochemistry and in situ hybridization. We found that there was expression of SP mRNA in tenocytes, and that tenocytes showed expression of NK-1 R at protein as well as mRNA levels. The observations concerning both SP and NK-1 R were most evident for tenocytes in tendinosis tendons. Our findings suggest that SP is produced in tendinosis tendons, and furthermore that SP has marked effects on the tenocytes via the NK-1 R. It cannot be excluded that the SP effects are of importance concerning the processes of reorganization and healing that occur for tendon tissue in tendinosis. In conclusion, it appears as if SPergic autocrine/paracrine effects occur in tendon tissue during the processes of tendinosis, hitherto unknown effects for human tendons.

Local targeting of malignant gliomas by the diffusible peptidic vector 1,4,7,10-tetraazacyclododecane-1-glutaric acid-4,7,10-triacetic acid-substance p

PURPOSE

Malignant glial brain tumors consistently overexpress neurokinin type 1 receptors. In classic seed-based brachytherapy, one to several rigid (125)I seeds are inserted, mainly for the treatment of small low-grade gliomas. The complex geometry of rapidly proliferating high-grade gliomas requires a diffusible system targeting tumor-associated surface structures to saturate the tumor, including its margins.

EXPERIMENTAL DESIGN

We developed a new targeting vector by conjugating the chelator 1,4,7,10-tetraazacyclododecane-1-glutaric acid-4,7,10-triacetic acid to Arg(1) of substance P, generating a radiopharmaceutical with a molecular weight of 1,806 Da and an IC(50) of 0.88 +/- 0.34 nmol/L. Cell biological studies were done with glioblastoma cell lines. neurokinin type-1 receptor (NK1R) autoradiography was done with 58 tumor biopsies. For labeling, (90)Y was mostly used. To reduce the "cross-fire effect" in critically located tumors, (177)Lut and (213)Bi were used instead. In a pilot study, we assessed feasibility, biodistribution, and early and long-term toxicity following i.t. injection of radiolabeled 1,4,7,10-tetraazacyclododecane-1-glutaric acid-4,7,10-triacetic acid substance P in 14 glioblastoma and six glioma patients of WHO grades 2 to 3.

RESULTS

Autoradiography disclosed overexpression of NK1R in 55 of 58 gliomas of WHO grades 2 to 4. Internalization of the peptidic vector was found to be specific. Clinically, the radiopharmeutical was distributed according to tumor geometry. Only transient toxicity was seen as symptomatic radiogenic edema in one patient (observation period, 7-66 months). Disease stabilization and/or improved neurologic status was observed in 13 of 20 patients. Secondary resection disclosed widespread radiation necrosis with improved demarcation.

CONCLUSIONS

Targeted radiotherapy using diffusible peptidic vectors represents an innovative strategy for local control of malignant gliomas, which will be further assessed as a neoadjuvant approach.

Role of the different isoforms of cyclooxygenase and nitric oxide synthase during gastric ulcer healing in cyclooxygenase-1 and -2 knockout mice

Traditional NSAIDs, selective cyclooxygenase (COX)-2 inhibitors, and inhibitors of nitric oxide synthase (NOS) impair the healing of preexisting gastric ulcers. However, the role of COX-1 (with or without impairment of COX-2) and the interaction between COX and NOS isoforms during healing are less clear. Thus we investigated healing and regulation of COX and NOS isoforms during ulcer healing in COX-1 and COX-2 deficiency and inhibition mouse models. In this study, female wild-type COX-1(-/-) and COX-2(-/-) mice with gastric ulcers induced by cryoprobe were treated intragastrically with vehicle, selective COX-1 (SC-560), COX-2 (celecoxib, rofecoxib, and valdedoxib), and unselective COX (piroxicam) inhibitors. Ulcer healing parameters, mRNA expression, and activity of COX and NOS were quantified. Gene disruption or inhibition of COX-1 did not impair ulcer healing. In contrast, COX-2 gene disruption and COX-2 inhibitors moderately impaired wound healing. More severe healing impairment was found in dual (SC-560 + rofecoxib) and unselective (piroxicam) COX inhibition and combined COX impairment (in COX-1(-/-) mice with COX-2 inhibition and COX-2(-/-) mice with COX-1 inhibition). In the ulcerated repair tissue, COX-2 mRNA in COX-1(-/-) mice, COX-1 mRNA in COX-2(-/-) mice, and, remarkably, NOS-2 and NOS-3 mRNA in COX-impaired mice were more upregulated than in wild-type mice. This study demonstrates that COX-2 is a key mediator in gastric wound healing. In contrast, COX-1 has no significant role in healing when COX-2 is unimpaired but becomes important when COX-2 is impaired. As counterregulatory mechanisms, mRNA of COX and NOS isoforms were increased during healing in COX-impaired mice.