Angiotensin converting enzyme inhibition blocks interstitial hyaluronan dissipation in the neonatal rat kidney via hyaluronan synthase 2 and hyaluronidase 1

A functional renin-angiotensin system (RAS) is required for normal kidney development. Neonatal inhibition of the RAS in rats results in long-term pathological renal phenotype and causes hyaluronan (HA), which is involved in morphogenesis and inflammation, to accumulate. To elucidate the mechanisms, intrarenal HA content was followed during neonatal completion of nephrogenesis with or without angiotensin converting enzyme inhibition (ACEI) together with mRNA expression of hyaluronan synthases (HAS), hyaluronidases (Hyal), urinary hyaluronidase activity and cortical lymphatic vessels, which facilitate the drainage of HA from the tissue. In 6-8days old control rats cortical HA content was high and reduced by 93% on days 10-21, reaching adult low levels. Medullary HA content was high on days 6-8 and then reduced by 85% to 12-fold above cortical levels at day 21. In neonatally ACEI-treated rats the reduction in HA was abolished. Temporal expression of HAS2 corresponded with the reduction in HA content in the normal kidney. In ACEI-treated animals cortical HAS2 remained twice the expression of controls. Medullary Hyal1 increased in controls but decreased in ACEI-treated animals. Urine hyaluronidase activity decreased with time in control animals while in ACEI-treated animals it was initially 50% lower and did not change over time. Cells expressing the lymphatic endothelial mucoprotein podoplanin in ACEI-treated animals were increased 18-fold compared to controls suggesting compensation. In conclusion, the high renal HA content is rapidly reduced due to reduced HAS2 and increased Hyal1 mRNA expressions. Normal angiotensin II function is crucial for inducing these changes. Due to the extreme water-attracting and pro-inflammatory properties of HA, accumulation in the neonatally ACEI-treated kidneys may partly explain the pathological renal phenotype of the adult kidney, which include reduced urinary concentration ability and tubulointerstitial inflammation.

Hormonal regulation of renomedullary hyaluronan

AIM

Hyaluronan (HA) is involved in renomedullary water handling through its water-binding capacity. This study addressed the effect of hormones involved in regulating fluid-electrolyte homeostasis on renomedullary HA content in vivo and in vitro.

METHODS

The kidneys from rats treated with L-NAME, indomethacin, vasopressin (AVP) or methylprednisolone (MP) during euvolaemia or water loading were analysed for HA by RIA, ELISA and histochemical staining. HA was measured in renomedullary interstitial cells treated with AVP, angiotensin II (Ang II) or a combination of AVP and Ang II.

RESULTS

Baseline renal cortical and medullary HA content was unaffected by 2 h of intravenous treatment with L-NAME (NOS inhibitor) or indomethacin (cyclo-oxygenase inhibitor), whereas AVP reduced medullary HA by 33%. During 2 h of acute water loading, diuresis was accompanied by an increase in renomedullary HA (+45%), but cortical HA was unaffected. In both L-NAME- and indomethacin-treated animals, the water loading-induced increase in renomedullary HA was absent, indicating involvement of NO and prostaglandins. After 7 days of MP treatment, medullary HA was reduced by 40%, but the water loading-induced elevation in HA remained. In cultured renomedullary interstitial cells, AVP reduced the HA content in the supernatant by 63%, and simultaneous treatment with Ang II reduced the HA content even further (95%).

CONCLUSION

AVP reduces HA content, and NO and prostaglandins are needed for the increase in HA during water loading.

Renal hyaluronan content during experimental uncontrolled diabetes in rats

With diabetes mellitus, the ability of the kidneys to maintain fluid balance is affected. Hyperglycaemia increases production of hyaluronan in cultured kidney cells implying that diabetes promotes induction of hyaluronan in the kidney. The aim of the present study was to determine if the interstitial matrix component hyaluronan is differently distributed within the kidney in diabetic rats compared to non-diabetic rats. Furthermore, to test if diabetic rats are able to respond with diuresis upon a hypotonic fluid load. The normal heterogeneous intrarenal distribution of hyaluronan was confirmed in non-diabetic control rats, with 60-fold more in the papilla than in the cortex. In diabetic animals, the cortical hyaluronan was unaffected but the papillary hyaluronan content was 3-fold higher than in non-diabetic rats. This increase correlated with a more than three-fold induction of the papillary hyaluronan-synthase 2 mRNA expression. In non-diabetic animals, 2 h water loading increased papillary hyaluronan (+93%) and diuresis (17-fold). In diabetic animals, baseline diuresis was 8-fold higher than in non-diabetic animals, which correlated with hyperglycaemia, glucosuria and proteinuria. Water loading in diabetic animals did not further increase papillary hyaluronan or diuresis: the urine flow rate decreased. To conclude, papillary hyaluronan is elevated in diabetic rats, which coincides with induction of hyaluronan-synthase 2 mRNA, hyperglycaemia, glucosuria, proteinuria and overt diuresis. The inability to respond to a water load with further diuresis may be related to the already elevated papillary hyaluronan and the inability to change hyaluronan during water loading.

Antibody responses to xenogenic antigens?a study in the mouse-to-rat system

Antibodies play a crucial role in the rejection of an organ that has been transplanted between different animal species, i.e. xenotransplantation. In previous work, we have induced a state of humoral tolerance where mouse-to-rat heart grafts continued to beat under ciclosporine A monotherapy. Initially, a combined treatment with ciclosporine A and 15-deoxyspergualin was given. This state of tolerance could not be reproduced when the vascularised heart graft was replaced with a free tissue graft or xenogeneic blood transfusions. To gain further insight into the humoral response against mouse antigens, we studied the antibody production in naive rats and rats challenged with heart transplants, heart cells, mononuclear cells (MNC) and erythrocytes from mice. Rats not challenged with any mouse cells or organs had a moderate amount of antibodies targeted against mouse MNC as well as rosette-forming cells in the spleen targeted against mouse erythrocytes. A challenge with either mouse MNC or erythrocytes lead to immunisation with antibodies of both IgM and IgG subtype directed against both MNC and erythrocytes. Antibody titres against mouse erythrocytes in animals challenged with MNC were not detectable until day 7, whereas antibody titres against mouse MNC in animals challenged with erythrocytes were detected on day 1. Immunisation with mouse erythrocytes raised the titre of rosette-forming cells in the spleen compared with naive rats (P < 0.05). Our data indicate that different xenogeneic antigens in the mouse-to-rat system are shared between heart cells, MNC and erythrocytes; however, the immunisation patterns differ regarding the time when antibodies are first detected.

Monotherapy with the vitamin D3 analogue MC1288 does not result in prolonged kidney allograft survival in rhesus monkeys

The active form of vitamin D3, 1,25(OH)2D3, has pronounced immunoregulatory properties and is a potential treatment of immune-based disorders. However, the central role of this hormone in calcium and bone metabolism complicates its long-term use as an immunomodulator. Some newly developed vitamin D3-derived analogues, such as MC1288, have an improved immunoregulatory potential and prolong allograft survival in rodent models. Such compounds might be a valuable component of immunosuppressive treatment regimen in transplantation and autoimmunity. The rhesus monkey provides a useful model for the preclinical validation of new therapeutic strategies for transplantation. The present study shows that MC1288 inhibits both proliferation and interferon-gamma production by rhesus peripheral blood mononuclear cells in a mixed lymphocyte reaction. We have tested the maximum tolerated dose of MC1288 in a rhesus monkey model of kidney transplantation. The observed effects on serum calcium and parathyroid hormone confirm the in vivo activity of MC1288. However, as a monotherapy, MC1288 did not cause prolongation of the kidney allograft survival in rhesus monkeys.

Macrophage uptake of ultra-small iron oxide particles for magnetic resonance imaging in experimental acute cardiac transplant rejection

PURPOSE

To discriminate between acutely rejecting and non-rejecting transplanted hearts using a blood pool contrast agent and T2* magnetic resonance imaging (MRI) in a clinical 1.5T scanner.

MATERIAL AND METHODS

Allogeneic and syngeneic heterotopic heart transplantations were performed in rats. One allogeneic and one syngeneic group each received either the ultra-small iron oxide particle (USPIO), at two different doses, or no contrast agent at all. MRI was performed on postoperative day 6. Immediately after the MR scanning, contrast agent was injected and a further MRI was done 24 h later. Change in T2* was calculated.

RESULTS

No significant difference in change in T2* could be seen between rejecting and non-rejecting grafts in either of the doses, or in the control groups. There was a difference between the allogeneic group that received the higher contrast agent dose and the allogeneic group that did not receive any contrast agent at all.

CONCLUSION

In our rat model, measurements of T2* after myocardial macrophage uptake of AMI-227 in a clinical 1.5T scanner were not useful for the diagnosis of acute rejection.

Effects of commonly used immunosuppressants on graft-derived fibroblasts

In acute rejection of transplanted organs intragraft fibroblasts increase their production of hyaluronan. Hyaluronan has strong water binding capacity and an increased tissue content of hyaluronan thus contributes to the development of interstitial oedema. The present study examined the effects of commonly used immunosuppressants (prednisolone, cyclosporin, tacrolimus, mycophenolic acid and sirolimus) on fibroblast proliferation, hyaluronan production and cell surface receptor expression. Fibroblasts isolated from rejecting tissue and from normal, non-transplanted tissue were studied in parallel. All substances investigated, except tacrolimus, were found to affect fibroblasts in one way or another. The most striking effect was the almost total inhibition of fibroblast proliferation in the presence of mycophenolic acid. Cyclosporin reduced the proliferation by about 50% and prednisolone had an inhibiting effect on hyaluronan production (50% reduction). These effects were observed on fibroblasts isolated from rat cardiac allografts undergoing rejection as well as on fibroblasts obtained from normal heart tissue. In contrast, sirolimus was found to stimulate the proliferation of fibroblasts from rejecting tissue (100% increase), but not that of normal fibroblasts. The majority of the fibroblasts expressed the hyaluronan receptor CD44, with a more intense expression in cultures of fibroblasts derived at rejection. None of the immunosuppressants affected the staining pattern (number of positive cells or intensity). The inhibitory effects of prednisolone, cyclosporin and mycophenolic acid on fibroblasts may contribute to the overall beneficial effects of these drugs when used for prevention or treatment of rejection.

Pretransplant xenogeneic blood transfusions reduce the humoral response in a mouse-to-rat heart transplantation model

A mouse heart transplanted to a rat is rejected promptly 3 days after transplantation, independent of whether cyclosporin A (CyA) is used as an immunosuppressant or not. Adding a short course of deoxyspergualin (DSG) initially, in addition to continuous CyA treatment, results in long-term graft survival and permits retransplantation during CyA monotherapy. In this paper, we have explored the possibility of substituting the initial heart transplant with blood transfusions. Lymphocyte-enriched blood transfusions combined with CyA and an initial course of DSG proved to lower or eliminate the haemagglutinating antibody titre normally seen in acute vascular xenorejection. The therapy, however, did not prolong the mean survival of the cardiac xenograft, but the same treatment protocol could result in either hyperacute rejection or prolonged survival of up to 11 days. In conclusion, this and earlier studies propose that a humoral unresponsiveness can be induced if the recipient vascular circulation is exposed to a xenoantigen in a mouse-to-rat combination.

Synthesis and biological evaluation of technetium(III) mixed-ligand complexes with high affinity for the cerebral 5-HT(1A) receptor and the alpha1-adrenergic receptor

Tc(III) and Re(III) complexes [M(NS(3))(CNR)] (M = Re, 99mTc, NS(3) = 2,2',2"-nitrilotris(ethanethiol), CNR = functionalized isocyanide bearing a derivative of WAY 100635) have been synthesized and characterized. Re was used as Tc surrogate for chemical characterization and in vitro receptor-binding studies. For two representatives subnanomolar affinities for the 5-HT(1A) as well as for the alpha1-adrenergic receptor were reached. Biodistribution studies in rats of the 99mTc complexes showed brain uptakes between 0.3 and 0.5% ID/organ (5 min p.i.). In vitro autoradiography of one 99mTc representative in sections of post mortem human brain indicate its accumulation in 5-HT(1A) receptor-rich brain regions. However, addition of the specific 5-HT(1A) receptor agonist 8-OH-DPAT as well as the alpha1-adrenoceptor antagonist prazosin could not substantially block this tracer accumulation. A preliminary SPET study in a monkey showed negligible brain uptake.

Renal cortical accumulation of hyaluronan in adult rats exposed neonatally to angiotensin-converting enzyme inhibition

Neonatal inhibition of the renin-angiotensin system [angiotensin-converting enzyme (ACE) inhibition] in the rat results in long-term abnormal renal morphology and function, including interstitial inflammation and fibrosis. Hyaluronan (hyaluronic acid, HA) has pathological implications in inflammatory diseases and renal ischaemia-reperfusion injury. The present study aimed at determining if renal cortical HA in the adult rat is correlated to the abnormal morphology and function in rats treated neonatally with the ACE inhibitor enalapril. In adult control rats (23 weeks old), the cortical HA content was very low [about 5 microg g(-1) dry weight (d.w.)] and about 1% of the papillary HA content. In rats treated neonatally with enalapril (days 3-13), the cortical HA level was 15 times that in control rats already at 21 days after birth, and it persisted at this level during adulthood (at 23 weeks). At 13 weeks the enalapril-treated animals showed markedly reduced ability (-53%) to concentrate urine during 24-h thirst provocation. At 21 days as well as at 23 weeks the enalapril-treated kidneys displayed morphological changes, such as papillary atrophy, dilation of the tubules and cellular infiltration of the cortical tissue. Histochemical staining confirmed the HA quantification assay and revealed a patchy staining for HA located in the same regions as the infiltrating cells. In conclusion, neonatal treatment with the ACE inhibitor enalapril results in renal morphological and functional abnormalities during adulthood. Cortical HA levels are already seriously elevated at day 21 and coexist with infiltrating cells. Besides the known effects of angiotensin II in development, the accumulation of HA in these kidneys may be involved in the genesis of at least the cortical abnormalities in enalapril-treated animals because of the proinflammatory effects and water-binding properties of HA.

Influence of laser irradiation on endogenous hyaluronan in rabbit iris and aqueous humor

PURPOSE

To monitor changes of endogenous hyaluronan in the iris tissue and aqueous humor after an isolated trauma to the iris by argon laser irradiation of the anterior surface of the iris.

METHODS

Iris and aqueous hyaluronan concentrations in rabbit were measured with a radiometric assay at different time points after laser irradiation.

RESULTS

Total hyaluronan content in iris tissue increased 3-fold to a peak concentration of 71-72 microg/g at 1 and 2 days after laser treatment. Aqueous hyaluronan increased to a maximum of about 1.6 microg/ml at 2 h and 12 h after laser irradiation of the iris.

CONCLUSIONS

The iris tissue responds with increased hyluronan synthesis to an isolated iris argon laser irradiation and it seems to be the most important source of aqueous hyaluronan.

Bacterial translocation from defunctionalized rat small bowel

Bacterial translocation from the intestine may cause severe infectious complications in a number of clinical situations, including the short bowel syndrome and after small bowel transplantation. The aim of the present study was to develop a simplified model for the study of bacterial translocation from a defunctionalized intestine. An ileal segment from untreated or cyclosporine-treated rats was exteriorized as a Thiry-Vella loop. After 1, 3. or 7 days, bacterial translocation and distribution of immunocompetent cells were assessed. The data obtained were compared with data from animals subjected to intestinal transplantation. Translocation to the mesenteric lymph nodes was detected in 60% of the Thiry-Vella loop animals on day 1. in 100% on day 3, and in 83% on day 7: concomitantly, the number of macrophages and T-cells in the mesenteric lymph nodes increased from day I until day 7. The degree of bacterial translocation on days 3 and 7 in animals with a Thiry-Vella loop was comparable with that observed 7 days after intestinal transplantation. Furthermore, treatment with cyclosporine A enhanced the number of translocating bacteria. In the model presented here bacterial translocation occurs from the small bowel to the mesenteric lymph nodes. The model offers possibilities to study the mechanisms and immunological phenomena associated with microbial translocation.

Renomedullary interstitial cells in culture; the osmolality and oxygen tension influence the extracellular amounts of hyaluronan and cellular expression of CD44

Our previous studies have suggested a role for renomedullary interstitial cells (RMICs) and renal medullary hyaluronan (HA) in water homeostasis. In the present study, cultured rat RMICs were used to examine the relationship of osmolality and oxygen tension on the extracellular amount of HA in the culture and to the cellular immunoreactivity to CD44, a HA binding protein. Under isotonic (330 mOsm(.)kg(-1) H(2)O), normoxic (20% O(2)) conditions, supernatant from sub-confluent RMICs contained 120+/-37 pg 10(4) cells(-1) 24 h(-1) of HA. Under hyperosmotic conditions (630 mOsm kg(-1) H(2)O), HA in the supernatant was decreased by 42% and under hypoosmotic conditions (230 mOsm kg(-1) H(2)O) it was doubled. Under hypoxic, iso-osmolar conditions (5% and 1% O(2), 330 mOsm kg(-1) H(2)O) this HA content was decreased by 56 and 48%, respectively, compared with normoxic, iso-osmolal conditions. Expression of CD44 on sub-confluent cells increased with increasing osmolality, as shown by immunostaining and flow cytometric analysis. The increases in CD44 from 330 to 630, 930 and 1230 mOsm kg(-1) H(2)O amounted to 5, 142 and 212%, respectively. Low oxygen tension (5% O(2)) decreased the intensity of CD44 immunofluorescence by 31%. Cell viability was similar at all conditions studied. In summary, these data indicate that cultured RMICs produce HA and are immunoreactive to CD44. In the supernatant of RMICs, the HA content decreases under hyperosmotic, hypoxic conditions. Conversely, CD44 immunoreactivity increases under hyperosmotic conditions. These results may explain our previous in vivo findings of a decreased renal papillary HA content during anti-diuresis and an increased content during water diuresis. The results support the concept that RMICs play an important role in renal water handling.

Characterization of Forssman and other antigen/antibody systems in vascularized mouse heart to rat xenotransplantation

In the present study, the nature of hyperacute xenograft rejection was closely studied in a vascularized mouse-to-rat transplantation model. Antibodies against mouse heart, erythrocytes and lymphocytes and against the Forssman antigen were raised in the rat. Upon heterotopic heart transplantation the respective antisera were intravenously (i.v.) injected. Passive transfer of antiheart, antierythrocyte or antilymphocyte serum resulted in hyperacute rejection of the transplanted mouse heart. Subfractionation of the antiheart serum showed that the capacity to induce hyperacute rejection was carried by the immunoglobulin (Ig)G fraction. When antierythrocyte serum adsorbed with mouse erythrocytes was administered the cardiac grafts remained beating. To the contrary, antilymphocyte serum adsorbed with erythrocytes still had the capacity to induce hyperacute rejection. None of the rats that had previously been challenged with the Forssman antigen rejected their grafts hyperacutely. Subsequent investigations by electron microscopy revealed that the Forssman antigen is expressed on dendritic cells (DC) adjacent to the vessels, but not on the vascular endothelium, thus explaining the inability of the anti-Forssman serum to induce hyperacute rejection. Taken together, we have demonstrated the existence of several xenoantigens that can be targets for antibody-mediated rejection, suggesting that more than one relevant xenoantigen exists also in more distantly related combinations, such as the pig-to-human combination.

Monitoring of intragraft pressure of rejecting organs: increased tissue pressure can be reduced by hyaluronidase therapy

BACKGROUND

The present study was undertaken in order to: (a) develop a new technique for measurement of interstitial pressure, (b) study the intragraft pressure of rejecting and non-rejecting organs, and (c) study the effect of treatment with the hyaluronan-degrading enzyme hyaluronidase on intragraft pressure. Treatment with hyaluronidase has previously been demonstrated to result not only in reduction of tissue hyaluronan but also in ameliorated interstitial edema, and we suggested that the diminished edema would lead to a reduced interstitial pressure as well.

METHODS

At day 5 after syngeneic or allogeneic rat heterotopic heart transplantation, the interstitial pressure of the cardiac grafts was measured using a microtip pressure sensor. Subsequently, the allogeneically grafted animals received a continuous intravenous infusion of either hyaluronidase (total dose: 60,000 U/kg) or vehicle during 2 hr; meanwhile, the interstitial pressure was monitored.

RESULTS

The intragraft pressure measurement technique was found to give reproducible results. The interstitial pressure of the rejecting (allogeneic) grafts was considerably higher than that of the non-rejecting (syngeneic), i.e., 12.3+/-1.6 mmHg vs. 1.1+/-0.6 mmHg (P<0.001). Hyaluronidase infusion effectively reduced the interstitial pressure as compared with vehicle treatment. By 20 min, the pressure had been reduced by 28% (P<0.01 compared with vehicle treatment); after 1 hr, by 49% (P<0.001); and after 2 hr, by 68% (P<0.01).

CONCLUSIONS

By using modern technology for tissue pressure measurements, we found that the strongly increased interstitial pressure of rejecting organs can be instantly reduced by intravenous administration of the hyaluronan-degrading enzyme hyaluronidase.

Hyaluronidase can be used to reduce interstitial edema in the presence of heparin

BACKGROUND

Treatment with the hyaluronan-degrading enzyme, hyaluronidase, reduces rejection-induced interstitial edema of transplanted organs. Hyaluronidase has also been demonstrated to reduce tissue necrosis after experimentally induced myocardial infarction, but its clinical use has been limited by an observed interaction between heparin and hyaluronan. In the present work, we investigated whether it is also possible to retain the effect of the enzyme in heparinized animals.

METHODS

Day 5 after heterotopic heart transplantation, recipient rats received a 2-hour intravenous infusion of hyaluronidase, either of ovine or of bovine origin. Concomitantly, the animals received intravenous heparin, either as 2 bolus doses or as a constant infusion.

RESULTS

Both hyaluronidase preparations effective reduced the hyaluronan content as well as the water content of the rejecting cardiac grafts. The concomitant use of heparin did not hamper the positive results, neither when heparin was administered intermittently nor when it was given continuously.

CONCLUSIONS

Our results in the transplantation model clearly demonstrate that hyaluronidase can be successfully used in heparinized individuals, provided that sufficient doses of the enzyme are given.

Role of hyaluronan in acute pancreatitis

BACKGROUND

The connective tissue component hyaluronan is accumulated locally in the damaged tissue during various inflammatory conditions. Owing to the strong water-binding capacity of this glycosaminoglycan, increased tissue content of hyaluronan is paralleled by the development of interstitial edema. The aim with the current experiment was to investigate whether hyaluronan is accumulated in acute pancreatitis and if increased levels of hyaluronan can be correlated to the inflammation of the pancreatic tissue.

METHODS

Acute pancreatitis was induced in Sprague-Dawley rats by the administration of supramaximal doses of the cholecystokinin analogue caerulein. The animals were followed for 5 hours (n = 4), 24 hours (n = 6), or 48 hours (n = 5), and the pancreata were then investigated for hyaluronan and water content, hyaluronan distribution, general morphology and the presence of CD44-positive cells, macrophages, and T lymphocytes.

RESULTS

Hyaluronan accumulated in the edematous interstitium during acute pancreatitis. Twenty-four hours after the induction of pancreatitis, the hyaluronan content of the pancreata had increased by more than 100%. Simultaneously, CD44-positive cells infiltrated the tissue. However, no correlation between hyaluronan and water was seen at any time point.

CONCLUSIONS

This study shows that acute pancreatitis is associated with a strong but transient increase in interstitial hyaluronan and an infiltration of CD44-positive cells located mainly in the same region as the accumulated hyaluronan.

Concordant xenotransplantation--non-vascularized pancreatic islets are more difficult to regraft than the vascularized heart

We have previously demonstrated that it is possible to perform retransplantation of a xenogeneic heart (mouse-to-rat) using cyclosporine A as monotherapy, provided that the first heart is transplanted under a short course of deoxyspergualin (DSG). If DSG is omitted, the first heart is rejected within four days and the second heart succumbs to hyperacute rejection within minutes. A mouse heart as first graft does not protect a consecutive pancreatic islet graft, although the heart continues to function after rejection of the cellular graft. One explanation for this discrepancy may be the fact that cellular grafts, as pancreatic islets, lack an endothelial lining. We have, therefore, further investigated possible differences between vascularized and non-vascularized xenografts regarding their capacity to induce unresponsiveness. The use of pancreatic islets as primary graft neither accelerated nor decelerated the speed of rejection of the vascularized heart used as secondary graft. Furthermore, hemagglutinating and cytotoxic antibody titres responded in the same manner as in naive rats transplanted with a mouse heart. Retransplantation with pancreatic islets also resulted in complete rejection of both the primary and secondary grafts. Thus, the lack of unresponsiveness cannot simply be explained by differences, between the pancreatic and cardiac tissues, in antigen expression. In addition, intraperitoneal transplantation of mouse heart cells as primary graft resulted in rejection of a secondary cardiac graft after three days. However, it cannot be totally excluded that the time of antigen exposure had an impact on these results. In conclusion, our previous and present studies suggest that the presence of an intact vascular bed, both in the first and second graft, is necessary to create a state of unresponsiveness. Because the pancreatic islets lack an endothelial lining, they do not benefit from an unresponsiveness of the immune system. Neither are they able to induce such an unresponsiveness.

An observation instrument for assessment of work technique in patient transfer tasks

The aim of the study was to construct an observation instrument for description and assessment of nursing personnel's work technique in patient transfer tasks with regard to musculoskeletal health and safety, and to evaluate the validity and reliability of the instrument. The instrument consists of 24 items arranged in three phases of a transfer: the preparation phase, the starting position and the actual performance. Observations are made from video recordings. A detailed description of the individual's work technique, including actions taken to prepare the transfer, the interaction with the patient and any assistant co-worker, and the motor performance of the nurse, is provided. An attempt was made to quantify the assessments, by calculating an overall score of the work technique with regard to the level of musculoskeletal hazard and safety. The validity and reliability of the instrument were evaluated on 35 video-recorded patient transfers from hospital wards. The validity and reliability were mostly satisfactory, both when evaluating the agreements between the observations of each item (i.e. kappa values > 0.40), and when evaluating the agreements between the overall scores (i.e. intraclass correlation coefficients 0.71-0.90). Further improvements to enhance the agreements are suggested.

Ex vivo propagation and characterization of lymphocytes from rejecting rat-kidney allografts

Today, most clinically used methods for analysis of alloreactivity in organ transplantation are based on humoral immunity. In order to study the cellular alloresponse, a rat kidney transplantation model with culturing of graft infiltrating lymphocytes was developed. Kidney transplantations between inbred rat strains were performed with the animals initially immunosuppressed with cyclosporine. In order to initiate acute cellular rejection, immunosuppression was withdrawn after 10 days. Infiltrating lymphocytes were analysed using an in vitro culture system, allowing cells to propagate from the biopsies to culture medium. The propagated cells were counted and analysed for subtype activation markers and donor-specificity using flow cytometry and a proliferation assay. Syngeneically transplanted animals and animals given constant immunosuppression upon transplantation were used as controls. During rejection, significantly more T lymphocytes were propagating from the biopsies compared to controls. A higher percentage of the propagated T lymphocytes in the rejection group expressed activation markers [CD25 and major histocompatibility complex (MHC) class II antigen] compared to spleen- and peripheral blood T lymphocytes from the same individuals. Propagated mononuclear cells from biopsies in the rejection group were proliferating and showed donor-specific reactivity whereas mononuclear spleen cells from animals in the same group did not show this donor specificity. In conclusion, we have presented a rat kidney allotransplantation model with in vitro propagation of graft-infiltrating, activated and donor-specific T lymphocytes. This technique offers a possibility to study cellular reactivity in allotransplantation.

Edema treatment during cardiac allograft rejection

BACKGROUND

Interstitial edema of rejecting organs can be correlated with the accumulation of hyaluronan in the transplant; since hyaluronan has strong water-binding capacity, treatment with the hyaluronan-degrading enzyme hyaluronidase reduces not only the hyaluronan content but also the water content of the graft. The aim of the present study was to investigate whether a further reduction of the water content would be the result if hyaluronidase was used in conjunction with classic diuretic substances.

METHODS

Five days after heterotopic heart transplantation (PVG to Wistar/Kyoto), recipient rats received hyaluronidase as a continuous intravenous infusion over 2 hours together with either a loop-diuretic (furosemide) or an osmotic diuretic (mannitol).

RESULTS

Hyaluronidase was found to reduce the hyaluronan contents of the grafts from 586+/-52 microg/g in control animals receiving vehicle infusion to 161+/-48 microg/g (p < 0.001) and the water contents from 81.3+/-0.4 x 10(-2) U to 79.7+/-0.4 x 10(-2) U (p < 0.05). Combined treatment with furosemide or mannitol did not affect the results and neither furosemide nor mannitol had any intrinsic capacity to affect the water or hyaluronan contents of the cardiac grafts.

CONCLUSION

This experiment confirms our previous findings of hyaluronidase as an effective edema-reducing drug and indicate that no additive effect is obtained by a combined therapy with diuretics and hyaluronidase.

Hyaluronidase ameliorates rejection-induced edema

Hyaluronan, a glucosaminoglycan with unique water-binding capacity, is accumulated in the interstitial edematous tissue in rejecting organs. We here investigated whether the increased tissue content of water and hyaluronan seen during allograft rejection can be prevented by treatment with the hyaluronan-degrading enzyme hyaluronidase. Heterotopic heart transplantations between PVG and Wistar/Kyoto rats were performed. Recipient rats were treated with hyaluronidase prophylactically or therapeutically, either alone or in combination with cyclosporine. Daily intravenous injections of hyaluronidase induced a significant reduction of the cardiac content of both hyaluronan and water, as evaluated on day six after transplantation. Morphological examination revealed grafts with better preserved morphology and fewer infiltrating mononuclear cells, compared to untreated controls. Hyaluronidase therapy, alone or combined with cyclosporine, resulted in prolonged graft survival times. Hyaluronidase infusion for two hours also reduced already established edema five days after transplantation. This study confirms the hypothesis that hyaluronan accumulation plays a critical role in edema formation, and that hyaluronidase therapy can be used to reduce edema after organ transplantation.

A vitamin D analogue (MC 1288) has immunomodulatory properties and suppresses collagen-induced arthritis (CIA) without causing hypercalcaemia

The immunomodulatory properties of the vitamin D analogue MC 1288 (20-epi-1alpha,25-dihydroxycholecalciferol) were investigated in CIA in rats. The analogue was administered systemically at three different time points; (i) for 10 consecutive days before collagen (CII) immunization; (ii) for 10 consecutive days after CII immunization; or (iii) for 7 consecutive days from disease onset. Treatment initiated either 10 days before CII immunization or at the day of collagen immunization effectively suppressed the development of arthritis. Treatment initiated at the day of the onset of arthritis reduced the severity of joint inflammation. Significantly, doses which did not induce hypercalcaemia decreased the incidence and severity of arthritis. In vivo treatment with the 20-epi analogue of 1alpha,25-dihydroxycholecalciferol diminished the serum levels of antibodies to rat CII. Similarly, mitogen-induced proliferation of lymph node cells from rat CII-immunized animals was reduced. The experiments demonstrate that the vitamin D analogue MC 1288 has the ability to prevent, and furthermore to suppress, already established CIA by its immunomodulatory properties without inducing hypercalcaemia.

A morphological sequential study of mouse-to-rat cardiac xenografts

Long-term survival of a concordant xenograft can be achieved by using cyclosporine (CyA) and deoxyspergualin (DSG) for immunosuppression. We have demonstrated in a mouse-to-rat heterotopic heart transplantation model that DSG treatment can be stopped after 4 weeks with the grafts remaining beating. In this investigation we have sequentially characterized the morphological changes and infiltrating cells in the transplanted hearts. Graft recipients were killed 9 days, 28 days and 56 days after transplantation. At days 9 and 28, the grafts exhibited a well-preserved morphology, with infiltrating cells restricted only to the periphery. These cells stained positive for rat MHC class II antigens, the ED1-macrophage marker and the CD4 antigen, and were thus considered to be macrophages. In comparison, grafts harvested at day 56 had signs of interstitial fibrosis and some arteries showed pronounced intimal thickening. There was a moderate infiltrate of cells both in the peripheral and central parts of the graft, consisting mainly of MHC class II+/ CD4+/ED1+ macrophages. Very few T cells and NK cells were noticed. Termination of DSG after 28 days does not trigger a humoral rejection. However, the grafts exhibit morphological changes equivalent to those seen in chronic allograft rejection. In addition, the characteristics of the infiltrating cells conformed with cellular infiltrates associated with chronic allograft rejection. Hence, this model could in the future prove to be useful for studies of mechanisms involved in chronic xenograft rejection.

Tolerance induction ameliorates allograft vasculopathy in rat aortic transplants. Influence of Fas-mediated apoptosis

Based on successful induction of donor-specific unresponsiveness by alloantigenic stimulation in several animal models of acute rejection, we hypothesized that similar immune manipulations would also inhibit the evolution of chronic rejection and transplant vasculopathy. To induce immune tolerance, DA rats received a PVG heart allograft and were immunosuppressed with cyclosporine for 30 d. At day 100 the animals were challenged with a PVG aortic allograft after either 1 or 18 h of cold ischemia. 8 wk after the aortic transplantation, the grafts were investigated for morphological changes, infiltrating cells, apoptosis, and Fas-Fas ligand expression. Control allografts showed advanced transplant arteriosclerosis, whereas tolerance-induced aortic allografts displayed reduced neointimal formation, less medial atrophy, fewer apoptotic cells, and fewer Fas- and FasL-expressing cells. Prolonged ischemic storage time did not profoundly alter the morphological changes of the allografts. Fas expression was found in T cells, macrophages, vascular smooth muscle cells, and endothelial cells, whereas FasL was expressed mainly by T cells and macrophages. FasL mRNA expression was evident throughout the entire allograft wall. In conclusion, induction of allospecific tolerance can effectively prevent transplant arteriosclerosis. Cold ischemia damage does not abrogate the beneficial effect of tolerance, but creates a separate identity of mainly endothelial lesions. Furthermore, Fas-mediated apoptosis appears to be involved in the pathological lesions seen in chronic rejection.

Elevation of cyclosporin A blood levels during carvedilol treatment in renal transplant patients

In a consecutive study of 21 renal transplant patients suffering from chronic vascular rejection (CVR) we added the beta-receptor-blocking drug carvedilol to their regular medication. The purpose was to investigate possible pharmacokinetic interactions between carvedilol and cyclosporine (CsA), since carvedilol will soon be used in clinical trials in renal transplant patients with CVR. On the first day of the study the patients received 6.25 mg of carvedilol added to their daily medication. The dose was increased stepwise to 50 mg while the doses of other beta-blocking drugs were decreased. The goal was to exchange atenolol with carvedilol at a ratio of 2:1 when substituting atenolol with carvedilol. The patients' blood pressure was the final determinant of the dose of carvedilol. The trough levels of CsA were measured on days 1, 14, 30, 90 and 180. It was found that the blood levels of CsA increased when carvedilol was introduced. Thus, the doses of CsA had to be reduced in order to keep the blood levels within the therapeutic range. At 90 d, the daily doses of CsA had been reduced from 3.7 +/- 0.3 to 3.0 +/- 0.2 mg/kg BW (p < 0.001). The present results suggest an interaction between carvedilol and CsA that demands a 20% average reduction of CsA doses to maintain the CsA blood levels within the therapeutic range. However, the interaction shows a great interindividual variation, calling for careful monitoring of the CsA blood levels.

Renal accumulation and distribution of hyaluronan after ureteral obstruction

In a unilateral ureteral obstruction model, a progressive accumulation of hyaluronan (HA) was observed in the renal papilla during the first 11 days of obstruction, after which the amount of HA decreased until the last day of observation, i.e. day 22. The initial accumulation of HA in the obstructed kidney probably reflects the attempts of the kidney to maintain osmotic balance. Consequently, when filtration ceases, HA synthesis decreases and the concentration of HA falls. In the papilla of the contralateral kidney, that had not been exposed to any mechanical damage, the HA content was found to vary in a similar way to that in the obstructed kidney. The explanation for this could be that the mesenchymal cells within the papilla increase their production of HA in order to meet the requirements of increased function necessary to also shoulder the function of the damaged kidney. In short similar variations in the HA content of the renal papilla was observed in both healthy and obstructed kidneys in a unilateral ureteral obstruction model.

Ex vivo PKH26-labelling of lymphocytes for studies of cell migration in vivo

A prerequisite for studies of cell migration is that the cells of interest can be appropriately labelled and subsequently easily traced. The use of radioisotopes or fluorescent substances that bind covalently to the cell surface, e.g. fluorescein isothiocyanate (FITC) or rhodamine isothiocyanate (RITC), have limitations such as rapid loss of the labelling, toxicity and interference with cell surface molecules. In the present work the authors labelled rat spleen lymphocytes with the fluorescent labelling molecule PKH26, which is incorporated into the lipid bilayer of cytoplasmic membranes. The labelled lymphocytes were injected intravenously into syngeneic recipients and 2 or 6 days later the lymphocytes were detected in various organs by using flow cytometry and fluorescence microscopy. As could be expected, the lymphocytes homed to lymphoid tissues, preferably the spleen, and no labelled cells were found in non-lymphoid organs such as the heart and the kidney. Membrane labelling proved to be intense, uniform and stable and PKH26 positive cells were easily detectable in fractions less than 0.2% in peripheral blood and the various tissues after 6 days of in vivo circulation. Thus, the PKH26 dye appears to be suitable for labelling cell populations used in the study of cell migration in vivo, both under normal conditions and when specific immunological processes are taking place, such as graft rejection and tumour growth.

Successful retransplantation of mouse-to-rat cardiac xenografts under immunosuppressive monotherapy with cyclosporine

The present study was undertaken to investigate whether retransplantation with a second xenograft, from the same species as the primary graft, is possible to achieve using only moderate immunosuppression. Heterotopic mouse-to-rat cardiac transplantations were performed, and the recipients were treated with 15-deoxyspergualin (DSG) and cyclosporine (CsA) at high doses for days -1 to 4 and at moderate doses for days 5 to 28. From day 29 and onward, the immunosuppressive protocol consisted of daily oral administration of CsA 10 mg/kg as monotherapy. Animals that had beating grafts when DSG treatment was stopped were retransplanted 56-154 days after the primary transplantation, either with a vascularized graft (heart) or with nonvascularized graft (pancreatic islets), under continued therapy with CsA. Six of 10 secondary cardiac xenografts functioned for more than 50 days and were harvested beating after 60-100 days. In contrast, nonimmunosuppressed or DSG-treated rats are known to reject a second cardiac mouse graft hyperacutely. The unresponsiveness was confined to cardiac tissue, as the pancreatic islets, transplanted under the kidney capsule, were totally rejected after 14 days. Long-term functioning cardiac xenografts, primary and secondary, had a well-preserved morphology, and infiltrating mononuclear cells were found just in the periphery of the grafts. A majority of these cells were macrophages expressing the ED1, but not the ED2, antigen. No deposition of IgG or complement was seen in any of the graft vessels, whereas a slight deposition of IgM was observed in some vessels of both primary and secondary grafts. In conclusion, we have demonstrated that unresponsiveness can be induced by effective immunosuppression of the recipient at the time of the initial transplantation, so that retransplantation with a second xenograft can be performed successfully under single-drug immunosuppressive therapy with CsA.

Alterations in mucosal immune cell distribution in septic rats

A reduced cell-mediated immunity in the intestinal mucosa might promote gut barrier failure and bacterial translocation in shock. This study was performed to investigate changes from the normal distribution of cellular components of the immune system within the intestine during sepsis. Intra-abdominal sepsis was induced by cecal ligation and puncture. After 24 h, the animals were killed and specimens were taken from the small bowel. Immunohistochemical stainings were performed on frozen sections using monoclonal antibodies reactive with MHC class II positive cells (OX6), the alpha/beta antigen receptor on T lymphocytes (R73), CD4+ T lymphocytes (W3/25), CD8+ T lymphocytes (OX8), and macrophages (ED1). There was a significant reduction in the number of pan T lymphocytes as well as both CD4+ and CD8+ subsets in the mucosa of the septic rats as compared with sham operated rats (p < .01). In contrast, the populations of MHC class II positive cells and macrophages increased in sepsis (p < .01). We conclude that 24 h after the induction of peritonitis, there is an altered pattern of immunocompetent cells within the intestinal mucosa.

Experimentally-induced warm renal ischemia induces cortical accumulation of hyaluronan in the kidney

An accumulation of the connective tissue component, hyaluronan (HA), is known to occur in both syngeneic and allogeneic kidney grafts during the early postoperative period. The presence of HA in the interstitial tissue of the grafts is paralleled by an increased water content, suggesting a role for HA in the development of the transplantation edema. In the present work, the kidney content and distribution of HA was studied in a model of warm renal ischemia in the rat to investigate whether renal ischemia is associated with HA accumulation. Seventy-two hours after a period of warm renal ischemia (30 or 60 min) significantly higher amounts of HA were observed in the left kidney that had been exposed to ischemia, than in the right, healthy kidney. The most pronounced increase was found to occur in the cortex (20 to 40 times), a structure where there normally is almost no presence of HA. In addition, there was a correlation between the relative water content of the kidney and the amount of HA possible to extract from the tissue. The renal accumulation of HA and water was prevented by daily intravenous administration of hyaluronidase. We conclude that renal ischemia induces an accumulation of HA that may increase the risk for the development of interstitial edema, a situation that may be circumvented by hyaluronidase treatment.

Recipient-reactive antibodies occur during development of acute graft-versus-host reaction after small bowel transplantation

After small bowel transplantation, not only rejection but also graft-versus-host reaction (GVHR) may occur. Donor T lymphocytes, transferred together with the graft, are a prerequisite for the development of GVHR. So far, however, little is known about the effector mechanisms in acute GVHR. It can be assumed that not only T lymphocytes but also other cells, i.e., B lymphocytes, monocytes/macrophages, and NK cells, together with inflammatory cytokines, are responsible for the lesions of recipient tissue. In the present study, the occurrence of recipient-reactive antibodies after semisyngeneic small bowel transplantation was investigated to elucidate the role of B lymphocytes in GVHR development. No antibodies reactive with recipient cells were detectable in serum from untreated, nontransplanted rats. Five days after transplantation, recipient-reactive antibodies started to appear in recipient serum. At the same time, a deposition of IgM antibodies became visible in the liver and native intestine, which are target organs for GVHR. No antibodies directed against either the donor strain or a third-party strain were detectable in serum. We conclude that a synthesis of antibodies against recipient tissue occurs during the development of GVHR. Whether these antibodies contribute to the disease remains unclear.

The effects of combined treatment with the novel vitamin D analogue MC 1288 and cyclosporine A on cardiac allograft survival

The efficacy of combined treatment with the novel vitamin D analogue MC 1288 (20-epi-1 alpha,25-dihydroxycholecalciferol) and cyclosporine A (CyA) in preventing rejection following organ transplantation was evaluated in the heterotopic cardiac allograft model. Wistar/Kyoto rats received hearts from PVG donors and were subsequently treated with MC 1288 and CyA in various dose combinations. Administration of MC 1288 0.1 microgram/kg together with CyA 5 mg/kg produced significantly prolonged graft survival times as compared with single therapy with MC 1288 0.1 microgram/kg (p < 0.01) or CyA 5 mg/kg (p < 0.001). MC 1288 and CyA were tested also in combination with the immunomodulating drug LS-2616, which, in several laboratories, is used as a model for the evaluation of new combinations of immunosuppressive drugs. LS-2616 abolishes the immunosuppressive effect of CyA and the transplanted hearts are thus rejected at the same time as grafts of untreated recipients, i.e. on day 8. The immunosuppressive effect of MC 1288 is also counteracted by LS-2616, but the effect is not absolute and the median graft survival time is 11.0 days. Combined treatment with MC 1288 and CyA in the presence of LS-2616 resulted in a median graft survival time of 14.0 days. The results obtained in our experiments indicate at least an additive effect of MC 1288 and CyA thus suggesting that in the future MC 1288, or other vitamin D analogues, might be used to control rejection, either alone, in combination with CyA or in combination with other immunosuppressive drugs with other mechanisms of action.

Simultaneous occurrence of rejection and graft-versus-host reaction after allogeneic small bowel transplantation

Small bowel transplantation may be complicated not only by rejection but also by graft-versus-host reaction (GVHR). So far, little is known about the association between these two immunological reactions, partly because of the lack of standardized, reproducible experimental models for such studies. In this work, a rat model in which GVHR and rejection occur simultaneously was established. When transplanting small bowel grafts from BN donors to Lewis recipients and thereafter treating the grafts locally with the immunomodulating substance LS-2616, a clinically visible GVHR occurred on day 6, at the same time the first signs of rejection became visible. The GVHR was confirmed by immunohistochemical staining for MHC class II-positive cells in liver and ear skin biopsy specimens. An obvious quantitative difference in the number of positive cells in both organs was observed when local treatment was compared with oral LS-2616 treatment or with findings in organs from untreated animals. We conclude that GVHR and rejection are not mutually exclusive and thus may occur simultaneously, and that this pharmacological model might facilitate further studies of the impact of GVHR on graft rejection and recipient survival.

MC 1288--a vitamin D analogue with immunosuppressive effects on heart and small bowel grafts

The vitamin D analogue MC 1288 (20-epi-1 alpha,25-dihydroxycholecalciferol) was tested here for its possible immunosuppressive properties in vivo using different rat transplantation models. MC 1288, in a dose of 0.1 microgram/kg daily, administered intraperitoneally for 10 days, was found to be effective in prolonging cardiac allograft survival. Untreated recipients rejected their grafts around day 8 while MC 1288 treatment delayed rejection until day 22 (P < 0.001). Addition of the immunostimulatory drug LS-2616 (Linomide) reduced the immunosuppressive effect of MC 1288 and rejection occurred around day 11. The immunosuppressive effect of MC 1288 on rejection following small bowel transplantation was determined by measuring the amounts of hyaluronan (HA) secreted into the intestinal lumen. On day 6 post-transplantation the amounts of intraluminal HA in untreated animals was 29.2 +/- 5.3 ng/min and cm, while in MC 1288-treated animals it was just 5.0 +/- 1.6 ng/min and cm (P < 0.01). We conclude that MC 1288 has immunosuppressive effects that may make it suitable for the prevention of graft rejection.

The immunomodulator LS-2616 (linomide) more effectively than sensitization of the donor enhances graft-versus-host reaction after small bowel transplantation

The effects of the immunomodulating substance LS-2616 (linomide) on graft-versus-host reaction (GVHR) were investigated in a semi-syngeneic small bowel transplantation model. The entire bowel of Lewis donors were transplanted heterotopically into (Lewis x BN) F1 hybrids. Both untreated animals and animals treated with LS-2616, in a daily dose of 160 mg/kg, developed a lethal GVHR. The median survival time in untreated animals was 14.5 days while in LS-2616 treated animals it was just eight days (p < 0.01). LS-2616 in combination with cyclosporin A (CyA), 15 mg/kg given orally on days 0-20, did not seem to alter the survival times compared with CyA treatment alone; 56% of the animals treated with CyA survived for more than 100 days and after combined treatment with CyA/LS-2616 there were 50% permanent survivors. Also the effect of earlier sensitization of the donor on the course of GVHR was investigated. Hearts from BN rats were transplanted heterotopically to the neck vessels of Lewis rats. The hearts were rejected on about day six; five days later the bowels were harvested and transplanted into (Lewis x BN) F1 hybrids. The median survival time in this group was 12.5 days. Taken together our results, in combination with earlier findings, suggest that, at the level of effector mechanisms, GVHR is not an exact mirror image of rejection. Also, LS-2616 appears to be a useful tool for further studies of the mechanisms of action of GVHR.

Recovery of hyaluronan during perfusion of small bowel transplantation reflects rejection

Rejection seen after small bowel transplantation (SBT) in the rat is associated with an accumulation of hyaluronan (HA) in the lamina propria of the graft. In this study the intestinal intraluminal content of this connective tissue component was measured in order to determine if HA could be used as an index of rejection following SBT. Syngeneically and semiallogeneically transplanted rats were investigated by perfusion of a 4-cm segment of the intestinal graft on days 2, 4, and 6 posttransplantation. The amounts of HA recovered during perfusion were analyzed using a radiometric assay. In rejecting grafts the recovered HA amounts increased 15 times from day 2 to day 6, although after syngeneic transplantation there was only a minor increase from day 2 to day 4 and no further increase on day 6. Thus, the recovery of HA during perfusion of transplanted small bowel grafts has the potential value to reflect rejection.