Aquaporin 3 promotes human extravillous trophoblast migration and invasion

PROBLEM

Does aquaporin 3 (AQP3) affect the migration and invasion of human extravillous trophoblast (HTR8/Svneo) cells?

METHOD OF STUDY

A lentivirus infection system was used to construct stable cell lines with either AQP3 knockdown or overexpression. RT-PCR and western blotting were used to verify the efficiencies of AQP3 knockdown or overexpression in HTR8/Svneo cells at mRNA and protein levels, respectively. Cell Counting Kit-8 and flow cytometry assays were used to detect the influence of AQP3 knockdown or overexpression on proliferation and apoptosis of HTR8/Svneo cells. In addition, wound healing and Transwell invasion assays were used to detect the effects of AQP3 knockdown or overexpression on migration and invasion capabilities of HTR8/Svneo cells. An Agilent gene chip was used to screen for significant differentially expressed genes after AQP3 knockdown. Finally, mechanisms by which AQP3 influences the migration and invasion of HTR8/Svneo cells were explored using bioinformatic analysis.

RESULTS

Compared with controls, migration and invasion capabilities of HTR8/Svneo cells were significantly reduced after AQP3 knockdown, and significantly increased after AQP3 overexpression. Subsequent bioinformatic analysis of gene chip expression profiles indicated downregulation of genes related to adhesion such as PDGF-B, as well as signaling pathways (such as PIK3/AKT, NF-κB, and TNF) after AQP3 knockdown.

CONCLUSIONS

AQP3 could significantly promote migration and invasion capabilities of human extravillous trophoblasts, it may mediate embryo invasion and adhesion to endometrium by regulating PDGF-B, PIK3/AKT signaling pathways, although this requires further verification.

Overexpression of AQP3 Modifies the Cell Cycle and the Proliferation Rate of Mammalian Cells in Culture

Abnormal AQP3 overexpression in tumor cells of different origins has been reported and a role for this enhanced AQP3 expression in cell proliferation and tumor processess has been indicated. To further understand the role AQP3 plays in cell proliferation we explore the effect that stable over expression of AQP3 produces over the proliferation rate and cell cycle of mammalian cells. The cell cycle was analyzed by flow cytometry with propidium iodide (PI) and the cell proliferation rate measured through cell counting and BrdU staining. Cells with overexpression of AQP3 (AQP3-o) showed higher proliferation rate and larger percentage of cells in phases S and G2/M, than wild type cells (wt). Evaluation of the cell response against arresting the cell cycle with Nocodazole showed that AQP3-o exhibited a less modified cell cycle pattern and lower Annexin V specific staining than wt, consistently with a higher resistance to apoptosis of AQP3-overexpressing cells. The cell volume and complexity were also larger in AQP3-o compared to wt cells. After transcriptomic analysis, RT-qPCR was performed to highlight key molecules implicated in cell proliferation which expression may be altered by overexpression of AQP3 and the comparative analysis between both type of cells showed significant changes in the expression of Zeb2, Jun, JunB, NF-kβ, Cxcl9, Cxcl10, TNF, and TNF receptors. We conclude that the role of AQP3 in cell proliferation seems to be connected to increments in the cell cycle turnover and changes in the expression levels of relevant genes for this process. Larger expression of AQP3 may confer to the cell a more tumor like phenotype and contributes to explain the presence of this protein in many different tumors.

Aquaporin 3 Expression Predicts Survival in Patients with HER2-positive Early Breast Cancer

BACKGROUND/AIM

Recent studies have revealed aquaporins (AQPs) as targets for novel anti-tumor therapy since they are likely to play a role in carcinogenesis, tumor progression and invasion. Accordingly, we analyzed the prognostic impact of AQP3 expression and polymorphisms in a number of patients with early breast cancer (EBC).

MATERIALS AND METHODS

AQP3 expression was investigated on the basis of the immunohistochemistry of tissue microarray specimens from 447 EBC patients who underwent surgery between 2003 and 2008. We scored the staining intensity (0 through 3) and percentage of positive tumor cells (0 through 4); the staining score was defined as sum of these scores used to categorize the AQP3 expression as negative (0 through 2), weak (3 through 5) or strong (6 or more). For AQP3 polymorphisms, seven single nucleotide polymorphisms (SNPs) (rs10813981, rs34391490, rs2228332, rs2227285, rs591810, rs17553719 and rs3860987) were selected using in silico analysis and genotyped using the Sequenom MassARRAY.

RESULTS

A total of 180 (40.3%) patients were identified as AQP3-positive (staining score >2), including 86 (19.2%) cases of strong expression (stating score >5). In a univariate analysis, AQP3 expression was significantly associated with survival for the patients with HER2-over-expressing EBC. Moreover, a multivariate survival analysis revealed that AQP3 expression was an independent prognostic marker of disease-free survival (DFS): hazard ratio (HR)=3.137, 95% confidence interval (CI)=1.079-9.125, p=0.036; distant DFS (DDFS): HR=2.784, 95%CI=0.921-8.414, p=0.070, for the HER2-over-expressing EBC patients. Meanwhile, none of selected AQP3 polymorphisms were related to AQP3 expression in tumor tissue or survival in the current study.

CONCLUSION

AQP3 expression in tumor tissue may be considered as a potential prognostic marker in patients with HER2-over-expressing EBC after curative surgery.

Reciprocity in the developmental regulation of aquaporins 1, 3 and 5 during pregnancy and lactation in the rat

Milk secretion involves significant flux of water, driven largely by synthesis of lactose within the Golgi apparatus. It has not been determined whether this flux is simply a passive consequence of the osmotic potential between cytosol and Golgi, or whether it involves regulated flow. Aquaporins (AQPs) are membrane water channels that regulate water flux. AQP1, AQP3 and AQP5 have previously been detected in mammary tissue, but evidence of developmental regulation (altered expression according to the developmental and physiological state of the mammary gland) is lacking and their cellular/subcellular location is not well understood. In this paper we present evidence of developmental regulation of all three of these AQPs. Further, there was evidence of reciprocity since expression of the rather abundant AQP3 and less abundant AQP1 increased significantly from pregnancy into lactation, whereas expression of the least abundant AQP5 decreased. It would be tempting to suggest that AQP3 and AQP1 are involved in the secretion of water into milk. Paradoxically, however, it was AQP5 that demonstrated most evidence of expression located at the apical (secretory) membrane. The possibility is discussed that AQP5 is synthesized during pregnancy as a stable protein that functions to regulate water secretion during lactation. AQP3 was identified primarily at the basal and lateral membranes of the secretory cells, suggesting a possible involvement in regulated uptake of water and glycerol. AQP1 was identified primarily at the capillary and secretory cell cytoplasmic level and may again be more concerned with uptake and hence milk synthesis, rather than secretion. The fact that expression was developmentally regulated supports, but does not prove, a regulatory involvement of AQPs in water flux through the milk secretory cell.

Loss of aquaporin 3 protein expression constitutes an independent prognostic factor for progression-free survival: an immunohistochemical study on stage pT1 urothelial bladder cancer

BACKGROUND

Treatment of patients with stage pT1 urothelial bladder cancer (UBC) continues to be a challenge due to its unpredictable clinical course. Reliable molecular markers that help to determine appropriate individual treatment are still lacking. Loss of aquaporin (AQP) 3 protein expression has previously been shown in muscle-invasive UBC. The aim of the present study was to investigate the prognostic value of AQP3 protein expression with regard to the prognosis of stage pT1 UBC.

METHOD

AQP 3 protein expression was investigated by immunohistochemistry in specimens of 87 stage T1 UBC patients, who were diagnosed by transurethral resection of the bladder (TURB) and subsequent second resection at a high-volume urological centre between 2002 and 2009. Patients underwent adjuvant instillation therapy with Bacillus Calmette-Guérin (BCG). Loss of AQP3 protein expression was defined as complete absence of the protein within the whole tumour. Expression status was correlated retrospectively with clinicopathological and follow-up data (median: 31 months). Multivariate Cox regression analysis was used to assess the value of AQP3 tumour expression with regard to recurrence-free (RFS), progression-free (PFS) and cancer-specific survival (CSS). RFS, PFS and CSS were calculated by Kaplan-Meier analysis and Log rank test.

RESULTS

59% of patients were shown to exhibit AQP3-positive tumours, whereas 41% of tumours did not express the marker. Loss of AQP3 protein expression was associated with a statistically significantly worse PFS (20% vs. 72%, p=0.020). This finding was confirmed by multivariate Cox regression analysis (HR 7.58, CI 1.29 - 44.68; p=0.025).

CONCLUSIONS

Loss of AQP3 protein expression in pT1 UBC appears to play a key role in disease progression and is associated with worse PFS. Considering its potential prognostic value, assessment of AQP3 protein expression could be used to help stratify the behavior of patients with pT1 UBC.

Identification of a keratinocarcinoma cell line expressing AQP3

BACKGROUND INFORMATION

AQP3 (aquaporin 3) in the skin is important for skin moisture as demonstrated by the studies of AQP3-null mice, which have accelerated skin drying. Prevention of dry skin is important not only from a cosmetic but also from a clinical point of view. Primary keratinocyte cultures are cumbersome for screening substances that modulate AQP3 expression.

RESULTS

A human keratocarcinoma cell line was found to express AQP3 mRNA and protein, which responded to hypertonic stimulation with sorbitol, suggesting that the AQP3 expression is normally regulated in this cell line. This cell line also expressed the type 1 keratinocyte transglutaminase gene. The AQP3 expression was unaffected by all-trans-retinoic acid up to 10(-6) M. Similarly, the retinoic acid did not increase the AQP3 expression up to 1% concentration in rat skin.

CONCLUSION

This cell line is useful for the screening of candidate substances that modulate AQP3 expression.

Overexpression of the natural antisense hypoxia-inducible factor-1alpha transcript is associated with malignant pheochromocytoma/paraganglioma

Paragangliomas (PGLs) have widely different metastastic potentials. Two different types of PGLs can be defined by expression profiling. Cluster 1 PGLs exhibit VHL and/or succinate dehydrogenase (SDH) mutations and a pseudohypoxic phenotype. RET and neurofibromatosis type 1 (NF1) mutations occur in cluster 2 tumors characterized by deregulation of the RAS/RAF/MAP kinase signaling cascade. Sporadic PGLs can exhibit either profile. During sustained hypoxia, a natural antisense transcript of hypoxia-inducible factor 1 (aHIF) is expressed. The role of aHIF in the metastatic potential of PGL has not yet been investigated. The aim was to test the hypothesis that genotype-specific overexpression of aHIF is associated with an increased metastatic potential. Tumor samples were collected from 87 patients with PGL. Quantitative PCR was performed for aHIF, vascular endothelial growth factor (VEGF), aquaporin 3, cytochrome b561, p57Kip2, slit homolog 3, and SDHC. Expression was related to mutation status, benign versus malignant tumors, and metastasis-free survival. We found that both aHIF and VEGF were overexpressed in cluster 1 PGLs and in metastatic tumors. In contrast, slit homolog 3, p57Kip2, cytochrome b561, and SDHC showed overexpression in non-metastatic tumors, whereas no such difference was observed for aquaporin 3. Patients with higher expression levels of aHIF and VEGF had a significantly decreased metastasis-free survival. Higher expression levels of SDHC are correlated with an increased metastasis-free survival. In conclusion, we not only demonstrate a higher expression of VEGF in cluster 1 PGL, fitting a profile of pseudohypoxia and angiogenesis, but also of aHIF. Moreover, overexpression of aHIF and VEGF marks a higher metastatic potential in PGL.

Roles of aquaporin-3 water channels in volume-regulatory water flow in a human epithelial cell line

Membrane water transport is an essential event not only in the osmotic cell volume change but also in the subsequent cell volume regulation. Here we investigated the route of water transport involved in the regulatory volume decrease (RVD) that occurs after osmotic swelling in human epithelial Intestine 407 cells. The diffusion water permeability coefficient (Pd) measured by NMR under isotonic conditions was much smaller than the osmotic water permeability coefficient (Pf) measured under an osmotic gradient. Temperature dependence of Pf showed the Arrhenius activation energy (Ea) of a low value (1.6 kcal/mol). These results indicate an involvement of a facilitated diffusion mechanism in osmotic water transport. A mercurial water channel blocker (HgCl(2)) diminished the Pf value. A non-mercurial sulfhydryl reagent (MMTS) was also effective. These blockers of water channels suppressed the RVD. RT-PCR and immunocytochemistry demonstrated predominant expression of AQP3 water channel in this cell line. Downregulation of AQP3 expression induced by treatment with antisense oligodeoxynucleotides was found to suppress the RVD response. Thus, it is concluded that AQP3 water channels serve as an essential pathway for volume-regulatory water transport in, human epithelial cells.

Hydrating skin by stimulating biosynthesis of aquaporins

Aquaporins (AQPs) are proteins that facilitate the transport of water across cell membranes. AQP3 expression is related to the expressions of other epidermal proteins involved in water maintenance (ie, CD44, claudin-1, and filaggrin). The expressions of AQP3 water channels are strongly affected by age and chronic sun exposure, and a defective osmotic equilibrium could occur in the epidermis, which would account for the skin dryness observed in older people and skin areas most exposed to sunlight. We investigated active ingredients that are able to increase AQP3 levels in order to improve hydration in human skin keratinocytes. We selected an ethanolic/water (70/30 v/v) extract of Ajuga turkestanica, a plant from Central Asia, as the hydrating agent. After 17 days of treatment every 2 days with this extract (2.5 microg/mL) in vitro, AQP3 expression measured at the protein level in human reconstructed epidermis was significantly increased. Water transport through both aquaporins and aquaglyceroporins and glycerol transport through aquaglyceroporins alone are important to skin hydration. The distribution and the variability of aquaporins in human skin cells suggest that these channels may have important roles in skin physiology. AQPs appear to be key protein targets to improve the resistance and quality of the skin surface as well as to improve aging and sun exposure-induced dryness as shown by their roles in 1) hydrating the living layers of the epidermis where the keratinocyte differentiation takes place and 2) barrier formation and recovery.

Differential expression of aquaporin 3 in Triturus italicus from larval to adult epidermal conversion

By using immunohistochemical techniques applied to confocal microscopy, the presence of aquaporin 3 water channel in the epidermis of Triturus italicus (Amphibia, Urodela) has been shown. We analysed the expression of aquaporin 3 (AQP3) during the larval, pre-metamorphic and adult phases; we also showed the localization of the water-channel protein AQP3 in free-swimming conditions and during aestivation in parallel with histological analysis of the skin, focusing on the possible relationship between protein expression and terrestrial habitats. Our results indicate that aquaporin is produced as the epidermis modifies during the functional maturation phase starting at the climax. Moreover, our data suggest an increase in enzyme expression in aestivating newts emphasizing the putative functional importance of differential expression related to a distinct phase of the biological cycle.

EGFR-mediated expression of aquaporin-3 is involved in human skin fibroblast migration

AQP3 (aquaporin-3), known as an integral membrane channel in epidermal keratinocytes, facilitates water and glycerol movement into and out of the skin. Here, we demonstrate that AQP3 is also expressed in cultured human skin fibroblasts, which under normal wound healing processes migrate from surrounding tissues to close the wound. EGF (epidermal growth factor), which induced fibroblast migration, also induced AQP3 expression in a time- and dose-dependent manner. CuSO4 and NiCl2, previously known as AQP3 water transport inhibitors, as well as two other bivalent heavy metals Mn2+ and Co2+, inhibited EGF-induced cell migration in human skin fibroblasts. AQP3 knockdown by small interfering RNA inhibited EGF-induced AQP3 expression and cell migration. Furthermore, an EGFR (EGF receptor) kinase inhibitor, PD153035, blocked EGF-induced AQP3 expression and cell migration. MEK [MAPK (mitogen-activated protein kinase)/ERK (extracellular-signal-regulated kinase) kinase]/ERK inhibitor U0126 and PI3K (phosphoinositide 3-kinase) inhibitor LY294002 also inhibited EGF-induced AQP3 expression and cell migration. Collectively, our findings show for the first time that AQP3 is expressed in human skin fibroblasts and that EGF induces AQP3 expression via EGFR, PI3K and ERK signal transduction pathways. We have provided evidence for a novel role of AQP3 in human skin fibroblast cell migration, which occurs during normal wound healing.

Expression of aquaporin-3 improves the permeability to water and cryoprotectants of immature oocytes in the medaka (Oryzias latipes)

The permeability of the plasma membrane plays a crucial role in the successful cryopreservation of oocytes and embryos. Several efforts have been made to facilitate the movement of water and cryoprotectants across the plasma membrane of fish oocytes/embryos because of their large size. Aquaporin-3 is a water/solute channel that can also transport various cryoprotectants. In this study, we tried to improve the permeability of immature medaka (Oryzias latipes) oocytes to water and cryoprotectants by artificially expressing aquaporin-3. The oocytes were injected with aquaporin-3 cRNA and cultured for 6-7 h. Then, hydraulic conductivity (L(P)) and cryoprotectant permeability (P(S)) were determined from volume changes in a hypertonic sucrose solution and various cryoprotectant solutions, respectively, at 25 degrees C. The L(P) value of the cRNA-injected oocytes was 0.22+/-0.04 microm/min/atm, nearly twice larger than that of intact or water-injected oocytes (0.14+/-0.02 and 0.14+/-0.03 microm/min/atm, respectively). P(S) values of intact oocytes for ethylene glycol, propylene glycol, and DMSO were 1.36+/-0.34, 1.97+/-0.20, and 1.17+/-0.52 x 10(-3) cm/min, respectively. The permeability to glycerol could not be calculated because oocytes remained shrunken in the glycerol solution. On the other hand, cRNA-injected oocytes had significantly higher P(S) values (glycerol, 2.20+/-1.29; ethylene glycol, 2.98+/-0.36; propylene glycol, 3.93+/-1.70; DMSO, 3.11+/-0.74 x 10(-3) cm/min) than intact oocytes. When cRNA-injected oocytes were cultured for 12-14 h, 51% matured to the metaphase II stage, and 43% of the matured oocytes were fertilized and hatched following in vitro fertilization and 14 days of culture. Thus, the permeability of medaka oocytes to water and cryoprotectants was improved by the artificial expression of aquaporin-3, and the oocytes retained the ability to develop to term.

Increased expression of aquaporin 3 in atopic eczema

BACKGROUND

Dry skin in atopic eczema depends on increased water loss. The mechanisms behind this are poorly understood. The aim of this work was to identify genes that may contribute to water loss in eczema.

METHODS

Affymetrix DNA microarrays U133A were used to analyse gene expression in skin biopsies from 10 patients with atopic eczema and 10 healthy controls.

RESULTS

DNA microarray analysis showed up-regulation of 262 genes and down-regulation of 129 genes in atopic eczema. The known functions of these genes were analysed using Gene Ontology to identify genes that could contribute to increased water loss. This led to identification of aquaporin 3 (AQP3), which has a key role in hydrating healthy epidermis. Increased expression of AQP3 was found in eczema compared with healthy skin. This was confirmed with real-time polymerase chain reaction (P<0.001). In healthy skin, epidermal AQP3 immunoreactivity was weak and mainly found in the stratum basale. A gradient was formed with decreasing AQP3 staining in the lower layers of the stratum spinosum. By contrast, in acute and chronic atopic eczema strong AQP3 staining was found in both the stratum basale and the stratum spinosum.

CONCLUSIONS

Aquaporin 3 is the predominant aquaporin in human skin. Increased expression and altered cellular distribution of AQP3 is found in eczema and this may contribute to water loss.

Expression and function of aquaporins in human skin: Is aquaporin-3 just a glycerol transporter?

The aquaporins (AQPs) are a family of transmembrane proteins forming water channels. In mammals, water transport through AQPs is important in kidney and other tissues involved in water transport. Some AQPs (aquaglyceroporins) also exhibit glycerol and urea permeability. Skin is the limiting tissue of the body and within skin, the stratum corneum (SC) of the epidermis is the limiting barrier to water loss by evaporation. The aquaglyceroporin AQP3 is abundantly expressed in keratinocytes of mammalian skin epidermis. Mice lacking AQP3 have dry skin and reduced SC hydration. Interestingly, however, results suggested that impaired glycerol, rather than water transport was responsible for this phenotype. In the present work, we examined the overall expression of AQPs in cells from human skin and we reviewed data on the functional role of AQPs in skin, particularly in the epidermis. By RT-PCR on primary cell cultures, we found that up to 6 different AQPs (AQP1, 3, 5, 7, 9 and 10) may be selectively expressed in various cells from human skin. AQP1, 5 are strictly water channels. But in keratinocytes, the major cell type of the epidermis, only the aquaglyceroporins AQP3, 10 were found. To understand the role of aquaglyceroporins in skin, we examined the relevance to human skin of the conclusion, from studies on mice, that skin AQP3 is only important for glycerol transport. In particular, we find a correlation between the absence of AQP3 and intercellular edema in the epidermis in two different experimental models: eczema and hyperplastic epidermis. In conclusion, we suggest that in addition to glycerol, AQP3 may be important for water transport and hydration in human skin epidermis.

Aquaporin 3 expression in human fetal membranes and its up-regulation by cyclic adenosine monophosphate in amnion epithelial cell culture

OBJECTIVE

The cell membrane water channel protein aquaporins (AQPs) may be important in regulating the intramembranous (IM) pathway of amniotic fluid (AF) resorption. The objective of the present study was to determine whether aquaporin 3 (AQP3) is expressed in human fetal membranes and to further determine if AQP3 expression in primary human amnion cell culture is regulated by second-messenger cyclic adenosine monophosphate (cAMP).

METHODS

AQP3 expression in human fetal membranes of normal term pregnancy was studied by reverse transcription polymerase chain reaction (RT-PCR) and immunohistochemistry (IHC). To determine the effect of cAMP on AQP3 expression, primary human amnion cell cultures were treated in either heat-inactivated medium alone (control), or heat-inactivated medium containing: (1) SP-cAMP, a membrane-permeable and phosphodiesterase resistant cAMP agonist, or (2) forskolin, an adenylate cyclase stimulator. Total RNA was isolated and multiplex real-time RT-PCR employed for relative quantitation of AQP3 expression.

RESULTS

We detected AQP3 expression in placenta, chorion, and amnion using RT-PCR. Using IHC, we identified AQP3 protein expression in placenta syncytiotrophoblasts and cytotrophoblasts, chorion cytotrophoblasts, and amnion epithelia. In primary amnion epithelial cell culture, AQP3 mRNA significantly increased at 2 hours following forskolin or SP-cAMP, remained elevated at 10 hours following forskolin, and returned to baseline levels by 20 hours following treatment.

CONCLUSION

This study provides evidence of AQP3 expression in human fetal membranes and demonstrates that AQP3 expression in primary human amnion cell culture is up-regulated by second-messenger cAMP. As AQP3 is permeable to water, urea, and glycerol, modulation of its expression in fetal membranes may contribute to AF homeostasis.

Immunocytochemical and Phylogenetic Distribution of Aquaporins in the Frog Ventral Skin and Urinary Bladder

We recently cloned three cDNAs encoding frog aquaporin (AQP-h1, BAC07470; AQP-h2, BAC82379; and AQP-h3, BAC07471) from the ventral pelvic skin of the tree frog, Hyla japonica. The present study demonstrated that Hyla AQP-h2 was translocated from cytoplasmic pools to the apical plasma membranes of the granular cells in the bladder after antidiuretic hormone stimulation and that Hyla AQP-h2 and AQP-h3 behaved similarly in the ventral pelvic skin. Further, we found that terrestrial and tree frogs, but not aquatic and semiterrestrial-adapted frogs, absorbed water from their ventral pelvic skin by AQP-h3-like protein in concert with AQP-h2-like protein.

Regulators for Blood Glucose Level Affect Gene Expression of Aquaporin 3

Aquaporin 3 (AQP3), a membrane protein, is known to permeabilize water and other small molecules such as glycerol and urea and is localized in the bowel, skin, kidney, and erythrocytes. Since glycerol is a nutrient and serves as a source material in glycolytic metabolism, absorption of glycerol in the gastrointestinal tract may be under some control. Therefore we first investigated whether insulin regulating the glycolytic pathway took part in glycerol transport through AQP3 in the gastrointestinal tract and found that insulin significantly suppressed mRNA and protein expressions of AQP3 in Caco-2 cells. The antidiabetic drugs troglitazone and tolbutamide were also observed to suppress significantly AQP3 expression, but the biguanides metformin and buformin did not induce such suppression. Epinephrine was found to increase expression of AQP3, although glucagon showed no change of expression. Wortmannin and rapamycin were demonstrated to deactivate suppression of AQP3 expression by insulin and troglitazone, suggesting that the signal transducers, phosphoinositide 3 kinase (PI3K) and the mammalian target of rapamycin (mTOR), are involved in the signal pathway for regulating transcription of AQP3.

Effect of cyclosporin a eye drop on keratoconjunctivitis sicca and its mechanism

In this study, the effect of cyclosporin A (CsA) eye drop on keratoconjunctivitis Sicca (KCS) and its mechanism were studied. The KCS models were established by injecting Pertussis vaccine, complete Freund's adjuvant (CFA) and antigen of conjunctiva from isotype mice. Then the KCS models were treated with cyclosporin A eye drop. Changes in breaking-up time (BUT), lacrimal secretion in 30 min and diversion in 24 h were measured. The percentage of beaker cells, the lymphocytic infiltration in conjunctiva were observed. The expression levels of Aquaporin-3 (AQP3) in conjunctiva epithelial cells, beaker cells and accessory lacrimal gland were immunohistochemically detected. The results showed that there were significant differences in BUT, the percentage of beaker cells, lacrimal secretion in 30 min, the lymphocytic infiltration and the expression of AQP3 between the experimental group and an control group. It was concluded that CsA eye drop exerts marked therapeutic effect on KCS by inhibiting T lymph cells, increasing the goblet cells and AQP3 expression in conjunctiva.