Myometrial immune cells contribute to term parturition, preterm labour and post-partum involution in mice

This study aimed to determine the mechanism of uterine activation during labour, both term (TL) and preterm (PTL). We hypothesized that the peripheral leucocytes are recruited to uterine tissues by locally produced cytokines where they contribute to the initiation of parturition. Mouse uteri were collected (i) during gestation, TL and post-partum (PP), (ii) during PTL initiated by intrauterine infusion of LPS (125 μg) or (iii) injection of the progesterone receptor antagonist RU486 and analysed for multiple cytokine expression levels by real-time polymerase chain reaction (RT-PCR) and 23-plex Cytokine assay or enzymatically dispersed for assessment of immune cell populations. Markers of myeloid cell differentiation (Gr1, Neu7/4 and F4/80) were evaluated by FACS to define tissue macrophages (Macs), monocytes (M) and neutrophils (N) and by immunohistochemistry to detect tissue Macs and N. Our results indicate that: (1) Macs were elevated in mouse myometrium before TL (P < 0.05) followed by an increase in M and N; these changes were accompanied by an increase in multiple pro-inflammatory cytokines/chemokines genes. The expression of corresponding proteins increased PP. (2) TL and RU486-PTL models showed similar gene/protein expression profiles, (3) LPS-PTL was characterized by strong pro-inflammatory response and massive influx of N in myometrial tissues showing a pattern different from TL and RU486-PTL, (4) The PP period appears similar in all three models, with elevated myometrial cytokine levels and high infiltration of immune cells. We concluded that leucocytes infiltrate myometrium around the time of parturition implicating their potential role in labour activation (both term and preterm) and major role in PP uterine involution.

Physiologic uterine inflammation and labor onset: integration of endocrine and mechanical signals

The mechanisms underlying the preparation of the uterus for labor are not fully understood. Our previous studies have shown that during pregnancy, the uterine muscle (myometrium) undergoes dramatic phenotypic modulation culminating in term labor. The current review will discuss the cellular mechanisms involved in the regulation of myometrial activity and its modulation by endocrine signals and by mechanical stimulation of the uterus by the growing fetus. In particular, the contribution of uterine inflammation to the onset of labor will be described. We provide evidence that increased production of cytokines/chemokines in pregnant myometrium is associated with uterine occupancy and regulated by progesterone, suggesting the integration of mechanical and endocrine signals. Myometrial cells can actively participate in the inflammatory process in the uterus through the release of multiple proinflammatory cytokines and chemokines, providing a strong signal for activation of immune cells, their subsequent infiltration into pregnant uterus, and the initiation of labor.

Periovulatory leukocyte infiltration in the rat ovary

Ovulation is preceded by intraovarian inflammatory reactions that occur in response to the preovulatory gonadotropin surge. As a main inflammatory event, leukocytes infiltrate the ovary and release proteolytic enzymes that degrade the extracellular matrix weakening the follicular wall, a required step for follicle rupture. This study aimed to quantitatively measure the infiltrating leukocytes, determine their cell types, and localize infiltration sites in the periovulatory rat ovary. Cycling adult and gonadotropin-stimulated immature rats were used as animal models. Ovaries were collected at five different stages of estrous cycle in the adult rats (diestrus, 1700 h; proestrus, 1500 h; proestrus, 2400 h; estrus, 0600 h; and metestrus, 1700 h) and at five different time points after superovulation induction in the immature rats (pregnant mare's serum gonadotrophin, 0 h; pregnant mare's serum gonadotrophin, 48 h; human chorionic gonadotropin, 6 h; human chorionic gonadotropin, 12 h; and human chorionic gonadotropin, 24 h). The ovaries were either dissociated into a single cell suspension for flow cytometric analysis or fixed for immunohistochemical localization of the leukocytes. Similar numbers of leukocytes were seen throughout the estrous cycle (approximately 500,000/ovary), except proestrus 2400 when 2-fold higher numbers of leukocytes were found (approximately 1.1 million/ovary). A similar trend of periovulatory rise of leukocyte numbers was seen in the superovulation-induced immature rat model, recapitulating a dramatic increase in leukocyte numbers upon gonadotropin stimulation. Both macrophage/granulocytes and lymphocytes were among the infiltrating leukocytes and were localized in the theca and interstitial tissues, where platelet-endothelial cell adhesion molecule-1 and intercellular adhesion molecule-1 may play roles in the transmigration of leukocytes, because their expressions correlates spatiotemporally with the infiltrating leukocytes. In addition, a strong inverse relationship between leukocyte numbers in the ovary and spleen, as well as significant reduction of leukocyte infiltration in the splenectomized rats, were seen, indicating that the spleen may serve as an immediate supplier of leukocytes to the periovulatory ovary.

Renal vascular inflammation induced by Western diet in ApoE-null mice quantified by (19)F NMR of VCAM-1 targeted nanobeacons

We have designed multifunctional nanoparticulate reporter bioprobes capable of targeting vascular cell adhesion molecule 1 (VCAM-1), which is up-regulated in numerous inflammatory processes. These perfluorocarbon-cored nanoparticles emit a unique (19)F magnetic resonance (MR) signature, providing the potential to localize and quantify VCAM-1 expression in early atherosclerosis. Nanoparticle-VCAM-1 targeting specificity was confirmed by in vitro binding and competition studies. ApoE-null and control C57-BL6 mice (n = 6/group), fed a Western diet for 35 weeks, were injected i.v. with targeted or non-targeted nanoparticles. After two hours, kidneys were excised and prepared for analysis. ApoE-null kidneys exhibited increased VCAM-1-targeted nanoparticle content over healthy controls by (19)F MR spectroscopy (36.5+8.8 vs. 9.3+2.2 x 10(8)/g, P < .05), which correlated with increased VCAM-1 staining (2.5 +/- 1.3% vs. 0.9 +/- 0.3%, P < .05); their relative biodistributions were confirmed by fluorescence microscopy and MR imaging. These molecular imaging agents offer new approaches for detection, quantification, and longitudinal evaluation of early inflammation utilising (19)F MR spectroscopy and imaging.

FROM THE CLINICAL EDITOR

Multifunctional nanoparticulate reporter bioprobes capable of targeting vascular cell adhesion molecule 1 (VCAM-1) are reported in this paper. These perfluorocarbon-cored nanoparticles offer new approaches for detection, quantification, and longitudinal evaluation of early inflammation utilising 19F MR spectroscopy and imaging.

Molecular evidence of injury and inflammation in normal and fibrotic renal allografts one year posttransplant

INTRODUCTION

Factors contributing to kidney transplant fibrosis remain incompletely understood, particularly in the absence of acute complications.

METHODS

Baseline and 1-year surveillance biopsies from 15 uncomplicated living donor kidney transplants were subjected to microarray and quantitative reverse transcription polymerase chain reaction (qRT-PCR) analyses to examine changes in gene expression patterns over time. Biopsy pairs were purposefully selected from allografts with no history of acute complications and were divided into those that were histologically normal (n=7) and those that had developed subclinical interstitial fibrosis (n=8) at 1 year.

RESULTS

Compared with the paired baseline specimens, expression levels of 3578 probesets were found altered in all the 1-year biopsies studied. A large proportion of the up-regulated genes in this transplant-associated profile were functionally linked with inflammation, immunity, or response to injury. These included components of inflammation-related signaling pathways (integrin, interferon, and Toll-like receptor) as well as individual mediators of inflammatory and immune responses. An additional 2884 probesets demonstrated altered expression in fibrotic grafts only at 1 year. The gene products in this fibrosis-associated profile also were predominantly linked with inflammation and immune function, suggesting exaggerated inflammatory activity within the fibrotic grafts. qRT-PCR analyses confirmed the predicted expression patterns for selected transcripts from the microarray profiles.

CONCLUSIONS

Transcriptional profiles of histologically normal living donor renal allografts indicate that there is ongoing injury response and inflammation at 1 year compared to the immediate posttransplant period. Subclinical development of interstitial fibrosis during the first posttransplant year is associated with additional up-regulation of inflammation-related genes.

Adhesive functions of both chains of VLA-integrins are not fully conserved across the human-porcine species barrier: implications for xenotransplantation

BACKGROUND

A possible solution to the shortage of organs for transplantation would be the use of swine as source animals. As current immunosuppressive protocols cannot prevent rejection of these organs, super-selective immunosuppression or the induction of donor-specific central tolerance represent two promising approaches. Central tolerance induction involves bone marrow transplantation, and depends on intrathymic deletion of donor reactive host cells by donor antigen-presenting cells. In super-selective immunosuppression, the aim would be to block specific adhesive interactions on one species side only, leaving the other species side unaffected. As both processes depend on the interaction of adhesion molecules with their ligands, we investigated whether the beta1-integrins, which play roles in hematopoiesis as well as in rejection, can successfully interact across the swine-to-human species barrier.

METHODS

We employed static cell-to-extracellular protein and cell-to-cell adhesion assays, using different cell types and monoclonal antibody as well as peptide-fragments to analyze conservation of cross-species adhesive interactions.

RESULTS

We found that porcine and human cells interact differently with their cross-species ligands than their own and that the adhesive function of the beta1-chain does not seem to be fully conserved across the species barrier.

CONCLUSIONS

Integrin functions are not fully conserved across the pig-to-human species barrier. While the development of multi-transgenic pigs, whose integrins interact with human ligands in a more ''human-like'' manner may be necessary to facilitate tolerance induction, these facts give rise to new possibilities concerning super-selective immunosuppression.

Reduction of ICAM-1 and LFA-1-positive leukocytes in the perivascular space of arteries under mycophenolate mofetil therapy reduces rat heart transplant vasculopathy

BACKGROUND

The interaction of lymphocyte function-associated antigen-1 (LFA-1)-positive host leukocytes with intercellular adhesion molecule-1 (ICAM-1) on graft endothelium may play a key role in allograft recognition, triggering the development of transplant vasculopathy (TVP). We investigated the correlation between TVP and ICAM-1 expression and accumulation of LFA-1-positive leukocytes in the perivascular space (PVS) of arteries under different immunosuppressive drugs.

METHODS

After cardiac transplantation (Lewis to Fisher) animals were randomized 4 groups: cyclosporine (CsA), 3 mg/kg/day (n=74); mycophenolate mofetil (MMF), 40 mg/kg/day (n=96); FK 506, 0.3 mg/kg/day (n=96); and control, no therapy (n=74). Three or 4 animals from each group were harvested at intervals of 1 to 4 days within the study period of 60 days. Using immunohistochemistry, LFA-1-positive leukocytes were analyzed in intra- and epicardial arteries. ICAM-1 expression was scored histologically. TVP was assessed by digitizing morphometry and expressed as mean vascular occlusion.

RESULTS

Accumulation of LFA-1-positive leukocytes in the PVS of arteries and the myocardium correlated with expression of ICAM-1 on graft endothelium. The severity of TVP in arteries correlated with the accumulation of LFA-1-positive leukocytes in PVS. All immunosuppressive drugs significantly reduced ICAM-1 expression, LFA-1 accumulation and extent of TVP, compared with controls. In MMF-treated animals, we also found a significant reduction of ICAM-1 expression, LFA-1 accumulation and extent of TVP compared with the groups treated with CsA and FK 506 (p <0.005).

CONCLUSION

These data support an essential role of LFA-1/ICAM-1 interaction in the genesis of TVP that may be abrogated, especially by the use of MMF.

alpha4beta1-integrin blockade and cyclosporine decreases the prevalence and severity of transplant vasculopathy in a rat transplant model

BACKGROUND

Transplant vasculopathy leads to neointimal proliferation of allograft arteries, and alpha4beta1-integrin (very late antigen-4 [VLA-4]) seems to play an important role in the pathogenesis. This study evaluates the effect of a new, synthetic, VLA-4 blocker (S3429) on transplant vasculopathy in a rat cardiac transplant model.

METHODS

After transplantation (Lewis to Fisher), rats were divided randomly into 6 therapy groups: Group 1, n = 14, saline solution (vehicle); Group 2, n = 14, 3 mg/kg/day cyclosporine; Group 3, n = 21, 10 mg/kg/day S3429 + 3 mg/kg/day cyclosporine; Group 4, n = 21, 5 mg/kg/day S3429 + 3 mg/kg/day cyclosporine; Group 5: n = 21, 10 mg/kg/day S3429; Group 6, n = 21, 5 mg/kg/day S3429. Cyclosporine was given continuously until rats were killed. S3429 was either given for the entire study time or was discontinued after 20 days and animals were killed at Day 80. Twenty-eighty days after grafting, we assessed vasculopathy prevalence and mean vessel occlusion in coronary arteries.

RESULTS

Cyclosporine decreased the prevalence of vasculopathy and mean vessel occlusion compared with controls. We observed a further decrease in prevalence and mean vessel occlusion with 80 days of therapy with S3429 and cyclosporine. After discontinuing S3429 therapy at Day 20, prevalence and mean vessel occlusion increased to values seen in cyclosporine-treated animals at Day 80. S3429 alone decreased mean vessel occlusion only within the first 20 days compared with controls but had no effect on the prevalence of vasculopathy.

CONCLUSION

Because of the further decrease with S3429 therapy and the dramatic increase after discontinuation of S3429 therapy, we conclude that blocking VLA-4 receptors may prevent the development of transplant vasculopathy.

Mycophenolate mofetil significantly reduces leukocyte graft infiltration after heterotopic cardiac transplantation in a rat model: comparative study with cyclosporine and FK 506

BACKGROUND

The purpose of the study was to evaluate the effects of cyclosporine (CsA), FK 506 and mycophenolate mofetil (MMF) on graft-infiltrating leukocytes (CD4, CD8, CD11a, CD18) after cardiac transplantation in rats.

METHODS

Three hundred forty animals were transplanted and randomly divided into 4 groups: CsA, 3 mg/kg/d (n = 74); MMF, 40 mg/kg/d (n = 96); FK 506, 0.3 mg/kg/d (n = 96); and a control group receiving no immunosuppressive therapy (n = 74). Three or 4 animals from each group were killed at intervals of 1 to 4 days up to Day 60. Immunohistochemistry was performed using monoclonal antibodies (MAb) against CD4, CD8, CD11a and CD18. Positively stained cells were analyzed in the perivascular space (PVS) of intra- and epicardial arteries. Statistical analysis was performed using area-under-the-curve assessment with an extended t-test.

RESULTS

CsA and FK 506 reduced the presence graft-infiltrating leukocytes (CD4, CD8, CD11a, CD18) in the PVS of intra- and epicardial arteries when compared with control animals. MMF therapy resulted in a further significant reduction in infiltrating leukocytes when compared with the 2 calcineurin inhibitors. MMF had a faster onset of action than the calcineurin inhibitors. CsA and FK 506 required 12 to 20 additional days to achieve the reducing effect of graft infiltration seen in MMF-treated animals.

CONCLUSION

MMF possesses potent infiltration-blocking properties and its application leads to a greater reduction of cellular infiltration in the course of transplant rejection when compared with calcineurin inhibitors.

Endothelial injury: cause and effect of alloimmune inflammation

This review discusses the concept that endothelial cells may facilitate inflammation, but are also targets of the inflammatory response. Endothelial cells express several molecules that promote leukocyte recruitment, and other molecules, such as MHC class I that enable endothelial injury. Circulating alloantibodies produced following transplantation may also target the endothelium for injury. It has been shown that the expression of select protective genes within endothelial cells, including anti-apoptotic genes, may provide resistance to immune-mediated injury. Thus, an understanding of the mechanisms by which endothelial cells are injured and by which endothelial cells are protected is important for our understanding of allograft rejection.