Salmon calcitonin and cGMP production by human kidney: studies in vivo and in vitro

Urine markers do not predict biopsy findings or presence of bladder ulcers in interstitial cystitis/painful bladder syndrome

PURPOSE

We tested for associations between urine markers, bladder biopsy features and bladder ulcers in interstitial cystitis/painful bladder syndrome.

MATERIALS AND METHODS

Subjects were 72 patients with interstitial cystitis/painful bladder syndrome undergoing bladder distention and biopsy. Urine was collected before the procedure. Urine marker levels were correlated with biopsy and cystoscopic findings. Patients with no previous interstitial cystitis/painful bladder syndrome treatments (47) were analyzed separately from previously treated patients (25).

RESULTS

For untreated patients urine interleukin-6 and cyclic guanosine monophosphate were associated with urothelial epidermal growth factor receptor staining (for interleukin-6 r = 0.29; 95% CI 0.07, 0.51; p = 0.01 and for cyclic guanosine monophosphate r = 0.34; 95% CI 0.13, 0.55; p = 0.002). Urine interleukin-8 was negatively associated with urothelial heparin-binding epidermal growth factor-like growth factor staining (r = -0.34; 95% CI -0.55, -0.12; p = 0.002) and positively associated with lamina propria mast cell count (r = 0.29; 95% CI 0.06, 0.52; p = 0.01). The latter association also was seen in treated patients (r = 0.46; 95% CI 0.20, 0.73; p <0.001). None of the urine markers was significantly different for ulcer vs nonulcer groups. All of the patients with ulcer had extensive inflammation on bladder biopsy including severe mononuclear cell infiltration, moderate or strong interleukin-6 staining in the urothelium and lamina propria, and leukocyte common antigen staining in more than 10% of the lamina propria. However, these features also were seen in 24% to 76% of the patients without ulcer.

CONCLUSIONS

Overall urine markers did not associate robustly with biopsy findings. The strongest association was a positive association between urine interleukin-8 levels and bladder mast cell count. Patients with ulcer consistently had bladder inflammation but the cystoscopic finding of ulcers was not a sensitive indicator of inflammation on bladder biopsy.

Intranasal salcatonin (salmon calcitonin). A review of its pharmacological properties and role in the management of postmenopausal osteoporosis

Osteoporosis is a common problem among postmenopausal women and is associated with significant morbidity, mortality and costs primarily resulting from osteoporotic fractures. Salcatonin (salmon calcitonin) inhibits osteoclastic bone resorption and is approximately 40 to 50 times more potent than human calcitonin. In most randomised trials in which intranasal salcatonin (usually 50 to 200 IU/day plus oral calcium supplements) was administered for 1 to 5 years to postmenopausal women for prevention of osteoporosis, bone mineral density or content of the lumbar spine increased by approximately 1 to 3% from baseline. In contrast, postmenopausal women receiving only oral calcium supplements typically had reductions in bone mineral density or content of about 3 to 6%. The difference between treatment groups was statistically significant in essentially all studies. Although changes in bone mineral density or content were broadly similar in studies of postmenopausal women with established osteoporosis to those in postmenopausal women receiving therapy for prevention of the disease, studies in women with established osteoporosis did not usually demonstrate statistically significant differences between treatment groups. Also in postmenopausal women with established osteoporosis, intranasal salcatonin reduced pain and/or analgesic consumption in some trials and, in a limited number of studies of relatively short duration (i.e. < or = 2 years), the incidence of osteoporotic fractures. A large multicentre 5-year study with adequate statistical power to confirm the effect of intranasal salcatonin on reducing osteoporotic fracture rates in postmenopausal women is currently under way. The intranasal formulation of salcatonin offers a more convenient and better tolerated alternative to the parenteral formulation of the drug which is administered by regular subcutaneous or intramuscular injections. Adverse events associated with the intranasal formulation are generally mild and transient, usually involving local reactions such as nasal discomfort, rhinorrhoea or rhinitis. Thus, for postmenopausal women unable or unwilling to tolerate long term hormone replacement therapy, intranasal salcatonin is an attractive alternative for the management of osteoporosis.

Calcitonin inhibits accumulation of cyclic AMP in stimulated peritoneal macrophages from normal rats but not from osteopetrotic (incisors-absent) littermates

Macrophages and osteoclasts derive from related cell lines. In osteopetrotic mutants the function of osteoclasts is greatly reduced compared to that in normal animals or children and macrophage function is variably affected depending upon the mutation. To further explore macrophage function in osteopetrosis we examined the regulation of cyclic AMP production in macrophages from mutants and normal littermates of the osteopetrotic stock incisors-absent (ia) in the rat. Surface stimulation by latex particles of elicited peritoneal macrophages from normal or osteopetrotic (ia) mutant rats caused an identical increase in the accumulation of cyclic AMP. This effect was inhibited in normal animals by coincubation of macrophages with calcitonin (CT) but this inhibition was either absent or less marked in macrophages from mutant littermates. In contrast to human monocytes preincubation of rat macrophages with pertussis toxin did not relieve this inhibition. This implies that rat peritoneal macrophages respond to CT by a different mechanism. These results demonstrate altered macrophage function in osteopetrotic animals and may be functionally related to the reduced CT binding previously described in ia osteoclasts. Furthermore, the coexistence of reduced function of macrophages and osteoclasts in the ia mutation suggests that macrophages and osteoclasts share a common progenitor.

Human calcitonin increases both cyclic AMP and cyclic GMP accumulation in human kidney cells

Salmon calcitonin stimulates both adenylate cyclase and guanylate cyclase systems in human kidney cortical cells but does not modify the cyclic nucleotide levels of medullary cells. In order to compare the effect of mammalian calcitonin and of calcitonin from the ultimobranchial body on cyclic nucleotides, the action of both salmon and human calcitonin was compared in intact kidney cells. The role of the regulatory unit in relation to the stimulation exerted by both calcitonins on the adenylate cyclase activity of kidney plasma membranes was also studied. Low concentrations of human calcitonin produced a significant increase of cyclic GMP accumulation in human kidney cortical cells. Higher hormone doses, active in stimulating the adenylate cyclase system, resulted in a progressive decline of the response. In kidney medullary cells human calcitonin was a more efficacious and potent stimulator of cyclic AMP than of cyclic GMP accumulation. Neither of the two calcitonins stimulated kidney cortical or medullary plasma membrane adenylate cyclase in the absence of guanylyl 5'-imidodiphosphate. However, in the presence of guanylyl 5'-imidodiphosphate, both calcitonins stimulated the cortical adenylate cyclase system. Under the same conditions, medullary adenylate cyclase activity was stimulated only by human calcitonin. These observations suggest that human calcitonin stimulates cyclic nucleotide accumulation in human kidney cortex and medulla, while salmon calcitonin is active only at the cortical level. This phenomenon could be explained on the basis of hormone-receptor binding.

Calcitonin enhances production of prostaglandins by stimulated human monocytes

Stimulated monocytes produce prostaglandins that may play a role in bone resorption. We studied the effects of salmon calcitonin (sCT) on human monocyte production of various prostaglandin metabolites. Latex particle-stimulated human monocyte production of prostaglandin E2, thromboxane A2 measured as thromboxane B2, and prostacyclin measured as 6-keto-PGF1 alpha was each increased in the presence of sCT. This effect required surface stimulation, was blocked by indomethacin, was less marked with equivalent concentrations of human calcitonin, and was not seen with parathyroid hormone. Calcitonin specifically affects prostaglandin pathways in stimulated human monocytes.

Effect of prostaglandin E2 on adenylate cyclase system in human kidney cell cultures: interactions with parathormone and arginine-vasopressin

We have used human kidney cortical and medullary cells in primary culture as an experimental model, in order to study the effect of prostaglandin E2 on the adenylate cyclase-cyclic AMP system at renal level, in comparison with that of parathormone and desamino 1-D-arginine 8-vasopressin. Prostaglandin E2 is a more potent stimulator of cyclic AMP accumulation in cortical cells than in medullary ones, the minimal effective dose being 3 nM in the cortex and 20 microM in the medulla. The maximal response was obtained with 30 microM in cortical cells and with 0.3 mM in medullary ones. The effects of combining submaximal and maximal active doses of the three hormones were always additive when tested on cortical cells. On the contrary, prostaglandin E2, at doses effective on the medullary cells adenylate cyclase system, produced an increase of cyclic AMP accumulation significantly lower than expected when incubated with submaximal and maximal amounts of desamino 1-D-arginine 8-vasopressin. Present data provide evidence for the existence of distinct receptors for parathormone, arginine-vasopressin and prostaglandin E2 at cortical level; the possible role of prostaglandin E2 in the counter-regulation of arginine-vasopressin action on medullary cells in unlikely, in view of the high prostaglandin E2 concentration which is necessary to exert this effect.