Aquaporin 5 increases keratinocyte-derived chemokine expression and NF-κB activity through ERK activation

Aquaporin-5 Dynamic Regulation

Aquaporin-5 (AQP5), belonging to the aquaporins (AQPs) family of transmembrane water channels, facilitates osmotically driven water flux across biological membranes and the movement of hydrogen peroxide and CO₂. Various mechanisms have been shown to dynamically regulate AQP5 expression, trafficking, and function. Besides fulfilling its primary water permeability function, AQP5 has been shown to regulate downstream effectors playing roles in various cellular processes. This review provides a comprehensive overview of the current knowledge of the upstream and downstream effectors of AQP5 to gain an in-depth understanding of the physiological and pathophysiological processes involving AQP5.

Spontaneous Intracranial Hypotension Manifesting Orthostatic Headache Worsened by Playing the Saxophone and Treated by Japanese Herbal Kampo Medicine Goreisan

We present a 15-year-old Japanese girl with no previous medical history who presented with a gradually worsening series of orthostatic headaches. We diagnosed spontaneous intracranial hypotension, worsened by playing the saxophone and its Valsalva maneuver effect. She was treated with Japanese herbal Kampo medicine Goreisan 7.5 g/day in three divided doses, and her symptoms gradually improved. Her headache has never recurred for a year when she played the saxophone. Our case’s headache may have been further exacerbated by cerebrospinal fluid (CSF) leakage due to CSF pressure increase by Valsalva maneuvers while playing the saxophone. Our case suggested that the Japanese herbal Kampo medicine Goreisan can facilitate the glymphatic system and adjust the CSF pressure appropriately.

Different expressions of aquaporin water channels and macrophages infiltration in human cervix remodeling during pregnancy

Despite aquaporin water channels (AQPs) play a critical role in maintaining water homeostasis in female reproductive tract and prompt a gradual increase in water content in cervical edema as pregnancy progressed, their relationship with macrophage infiltration and collagen content in human cervical remodeling need to be further investigated. This is the first study to examine the expression and localization of AQP3, AQP4, AQP5, AQP8 and macrophages simultaneously in human cervical ripening. The immunoreactivity of these AQPs was 2.6 to 6-fold higher on gestational weeks 26 (GD26W) than that on GD6W and GD15W, but AQP4 expression on GD39W dropped a similar extent on GD15W, other AQPs continued to rise on GD39W. The AQP3, AQP4 and AQP5 intensity seemed more abundant in cervical stroma than in the perivascular area on GD26W; the distribution of AQP3, AQP5 and AQP8 in cervical stroma was equivalent to that in the perivascular area on GD39W. Macrophage numbers were 1.7-fold higher in subepithelium region and 3.0-fold higher in center area on GD26W than that on GD15W; such numbers remained elevated on GD39W. The electron micrographs showed that cervical extensibility increased significantly on GD26W and GD39W accompanied with increased macrophage infiltration, cervical water content and much more space among collagen fibers. These findings suggest that the upregulation of AQPs expression in human cervix is closely related to enhanced macrophage infiltration during pregnancy; there may be a positive feedback mechanism between them to lead the increase of water content and the degradation of collagen.

Medication Overuse Headache Successfully Treated by Three Types of Japanese Herbal Kampo Medicine

Medication overuse headache (MOH) usually resolves after the overuse is stopped and starting prophylactic medications. However, it can be challenging to prescribe common prophylactic medications when patients have a history of side effects. As an alternative therapy, traditional Japanese herbal kampo medicine can be used. We herein report a case of a MOH woman with a history of side effects by such common prophylactic medications. A 50-year-old woman presented with a severe migraine attack. She had suffered from migraines for 10 years. She had taken loxoprofen and sumatriptan every day for over eight years. As prophylactic medications, lomerizine, valproic acid, and amitriptyline had been prescribed in the past, but they were discontinued due to side effects. Therefore, she could continue only propranolol as prophylactic medication. She had severe pulsatile headaches and nausea every day. We diagnosed triptan- and non-steroidal anti-inflammatory drug-overuse headache (the International Classification of Headache Disorders 3rd edition code 8.2.2 and 8.2.3.2) and chronic migraine (code 1.3). She was admitted and stopped loxoprofen and sumatriptan. We prescribed three types of Japanese herbal kampo medicines - kakkonto (TJ-1), goreisan (TJ-17), and goshuyuto (TJ-31). Her headache was relieved on day 5, and she was discharged on day 7. In the 40 days after discharge, she had only three times mild headaches with a numeric rating scale (NRS) of 2/10. She did not need any triptans nor anti-inflammatory drugs. We herein presented the MOH woman who was successfully treated using three types of kampo medicine. We should pay attention to their side effects, but kampo medicine may be useful for MOH treatment as acute and prophylactic medications for primary headaches.

An ankle sprain with long-term swelling and pain successfully treated with the traditional Japanese herbal medicine Jidabokuippo: A case report

In this report, we present a case in which long-term swelling and pain because of an ankle sprain were successfully treated with the traditional Japanese herbal (Kampo) medicine Jidabokuippo. Jidabokuippo was created in Japan and has been used to treat swelling and pain associated with trauma. A 44-year-old woman sprained her right ankle and received the standard treatments including icing and immobilization for three weeks. However, the swelling, redness, and pain of her ankle continued for two months after the treatments. After initiating Jidabokuippo, her pain and swelling were promptly improved. This suggests that Jidabokuippo is a potentially promising pharmacotherapy for patients with ankle sprain which has not recovered smoothly. It is said that Jidabokuippo can be prescribed simply referring to pain and swelling of the affected areas; therefore, it should be considered as a treatment for trauma patients with long-term swelling and pain.

Aquaporins in lung health and disease: Emerging roles, regulation, and clinical implications

Aquaporins (AQPs) aka water channels are a family of conserved transmembrane proteins (~30 kDa monomers) expressed in various organ systems. Of the 13 AQPs (AQP0 through AQP12) in the human body, four (AQPs 1, 3, 4, and 5) are expressed in the respiratory system. These channels are conventionally known for mediating transcellular fluid movements. Certain AQPs (aquaglyceroporins) have the capability to transport glycerol and potentially other solutes. There is an emerging body of literature unveiling the non-conventional roles of AQPs such as in cell proliferation and migration, gas permeation, signal potentiation, etc. Initial gene knock-out studies established a physiological role for lung AQPs, particularly AQP5, in maintaining homeostasis, by mediating fluid secretion from submucosal glands onto the airway surface liquid (ASL) lining. Subsequent studies have highlighted the functional significance of AQPs, particularly AQP1 and AQP5 in lung pathophysiology and diseases, including but not limited to chronic and acute lung injury, chronic obstructive pulmonary disease (COPD), other inflammatory lung conditions, and lung cancer. AQP1 has been suggested as a potential prognostic marker for malignant mesothelioma. Recent efforts are directed toward exploiting AQPs as targets for diagnosis, prevention, intervention, and/or treatment of various lung conditions. Emerging information on regulatory pathways and directed mechanistic research are posited to unravel novel strategies for these clinical implications. Future considerations should focus on development of AQP inhibitors, blockers, and modulators for therapeutic needs, and better understanding the role of lung-specific AQPs in inter-individual susceptibility to chronic lung diseases such as COPD and cancer.

AQP5 regulates the proliferation and differentiation of epidermal stem cells in skin aging

The epidermis, the outermost layer of the skin, is the first barrier that comes into contact with the external environment. It plays an important role in resisting the invasion of harmful substances and microbial infections. The skin changes with age and external environmental factors. This study aimed to investigate epidermal stem cells during the process of aging. This study enrolled 9 volunteers with benign pigmented nevus for clinical dermatologic surgery. The phenotypes associated with skin aging changes such as skin wrinkles and elasticity of the unexposed/healthy parts near benign pigmented skin were measured, and epidermal stem cells from this region were isolated for transcriptome sequencing. The results showed that epidermal stem cells could be obtained by magnetic activated cell sorting (MACS) with high purity. Results of the transcriptome sequencing revealed that aquaporin (AQP)5 significantly decreased in the epidermal stem cells with age, and further functional experiments revealed that AQP5 could promote the proliferation and dedifferentiation of HaCaT, but did not influence cell apoptosis. In summary, AQP5 regulated the proliferation and differentiation of epidermal stem cells in skin aging, and it may play an important role in the balance of proliferation and differentiation. However, further studies are needed to determine the mechanism by which AQP5 regulates the proliferation and differentiation of epidermal skin cells in aging.

Oryeongsan (Goreisan) Ameliorates Experimental Autoimmune Encephalomyelitis

Objective Oryeongsan (Goreisan), a formula composed of five herbal medicines, has long been used to treat impairments of the regulation of body fluid homeostasis. Goreisan has been revealed to have anti-inflammatory actions and inhibit a water channel, the aquaporin (AQP). We herein report the therapeutic effect of Goreisan on experimental autoimmune encephalomyelitis (EAE in, an animal model of inflammatory demyelinating diseases. Materials and Methods EAE mice immunized with MOG_35-55 peptide were divided into Goreisan- and sham-treated groups. The clinical EAE score and histopathological finding of the central nervous system (CNS) were analyzed. For the proliferation assay, prepared spleen cells from immunized mice were cultured and analyzed for the [³H]-thymidine uptake and cytokine concentrations of the culture supernatant. The relative quantification of AQP4 mRNA in the CNS of EAE mice was analyzed quantitatively. Results The EAE score of the Goreisan-treated mice was significantly lower than that of the sham-treated mice. The CD4-positive cell number in the CNS of Goreisan-treated mice was lower than that of sham-treated mice. In the recall response to MOG_35-55 peptide, the cell proliferation did not differ markedly between the spleen cells from Goreisan- and sham-treated mice. Furthermore, Goreisan decreased the mRNA level of AQP4 in the spinal cord during EAE. Conclusion Goreisan prevented the disease activity of EAE by inhibiting the migration of pathogenic cells into the CNS by suppressing the AQP4 expression in the CNS. Goreisan may have a therapeutic effect on inflammatory demyelinating diseases.

Potential contribution of alveolar epithelial type I cells to pulmonary fibrosis

Pulmonary fibrosis (PF) is characterized by inflammation and fibrosis of the interstitium and destruction of alveolar histoarchitecture ultimately leading to a fatal impairment of lung function. Different concepts describe either a dominant role of inflammatory pathways or a disturbed remodeling of resident cells of the lung parenchyma during fibrogenesis. Further, a combination of both the mechanisms has been postulated. The present review emphasizes the particular involvement of alveolar epithelial type I cells in all these processes, their contribution to innate immune/inflammatory functions and maintenance of proper alveolar barrier functions. Amongst the different inflammatory and repair events the purinergic receptor P2X7, an ATP-gated cationic channel that regulates not only apoptosis, necrosis, autophagy, and NLPR3 inflammosome activation, but also the turnover of diverse tight junction (TJ) and water channel proteins, seems to be essential for the stability of alveolar barrier integrity and for the interaction with protective factors during lung injury.

Mechanism of aquaporin 4 (AQP 4) up-regulation in rat cerebral edema under hypobaric hypoxia and the preventative effect of puerarin

AIM

We aim to investigate the mechanism of aquaporin 4 (AQP 4) up-regulation during high-altitude cerebral edema (HACE) in rats under hypobaric hypoxia and preventative effect of puerarin.

METHODS

Rats were exposed to a hypobaric chamber with or without the preventative treatment of puerarin or dexamethasone. Morriz water maze was used to evaluate the spatial memory injury. HE staining and W/D ratio were used to evaluate edema injury. Rat astrocytes and microglia were co-cultured under the condition of hypoxia with the administration of p38 inhibitor, NF-κB inhibitor or puerarin. Interleukin 6 (IL-6) and tumor necrosis factor α (TNF α) of cortex and culture supernatant were measured with ELISA. AQP4, phosphorylation of MAPKs, NF-κB pathway of cortex and astrocytes were measured by Western blot.

KEY FINDINGS

Weakened spatial memory and cerebral edema were observed after hypobaric hypoxia exposure. AQP4, phosphorylation of NF-κB and MAPK signal pathway of cortex increased after hypoxia exposure and decreased with preventative treatment of puerarin. Hypoxia increased TNF-α and IL-6 levels in cortex and microglia and puerarin could prevent the increase of them. AQP4 of astrocytes increased after co-cultured with microglia when both were exposed to hypoxia. AQP4 showed a decrease after administered with p38 inhibitor, NF-κB inhibitor or puerarin.

SIGNIFICANCE

Hypoxia triggers inflammatory response, during which AQP4 of astrocytes can be up regulated through the release of TNF-α and IL-6 from microglia. Puerarin can exert a preventative effect on the increase of AQP4 through inhibiting the release of TNF-α and phosphorylation of NF-κB, MAPK pathway.

Hyperosmolarity-induced AQP5 upregulation promotes inflammation and cell death via JNK1/2 Activation in human corneal epithelial cells

Tear film hyperosmolarity and anterior ocular inflammation are two clinical signs that may be indicative of dry eye disease (DED). This condition can cause pathological and functional changes to the anterior ocular surface tissues. A contributing factor may be dysfunctional aquaporin 5 (AQP5) water channels as they are the AQP subtype that expressed in the corneal epithelium and contribute to fluid efflux needed for corneal function. We determined if described hyperosmolarity-induced increases in proinflammatory cytokine expression and cell death are mediated through AQP5 upregulation and JNK1/2 MAPK signaling activation in both primary human corneal epithelial cells (HCECs), and in a HCEC line. Real time RT-PCR identified rises in IL-1β, IL-6, IL-8, TNF-α, caspase-1, and AQP5 mRNA levels upon step increases in osmolarity up to 550 mOsm. Western blot analysis and the TUNEL assay identified corresponding rises in AQP5 and p-JNK1/2 protein expression and cell death respectively. JNK1/2 inhibition with SP600125, or siRNA AQP5 gene silencing reduced hypertonic-induced rises in proinflammatory cytokine expression and cell death. Taken together, hypertonicity-induced AQP5 upregulation leads to increases in proinflammatory cytokine expression and cell death through JNK1/2 MAPK activation. These results suggest that drug targeting AQP5 upregulation may be a therapeutic option in DED management.

NFKB1 Promoter DNA from nt+402 to nt+99 Is Hypomethylated in Different Human Immune Cells

Sepsis, with a persistently high 90-day mortality of about 46%, is the third most frequent cause of death in intensive care units worldwide. Further understanding of the inflammatory signaling pathways occurring in sepsis is important for new efficient treatment options. Key regulator of the inflammatory response is the transcription factor NFκB. As we have recently shown, the -94 Ins/Del NFKB1 promoter polymorphism influences sepsis mortality. However, a molecular explanation is still missing. Thus, promoter activity might be varying depending on the NFKB1 genotype, explaining the genotype dependent mortality from sepsis, and one likely mechanism is the degree of promoter methylation. Therefore, we tested the hypothesis that NFκB mRNA expression is regulated by promoter methylation in human cell lines and primary immune cell cultures. First, we examined the methylation of the NFKB1 promoter in U937, REH and HL-60 cells. In the promoter region of nt+99/+229 methylation in all analyzed cell lines was below 1%. Following incubation with bacterial cell wall components, no significant changes in the frequency of promoter methylation in U937 and REH cells were measured and the methylation frequency was under 1%. However, NFκB1 mRNA expression was two-fold increased in U937 cells after 24 h incubation with LPS. By contrast, demethylation by 5-Aza-2′-deoxycytidine incubation enhanced NFκB1 expression significantly. In addition, we analyzed NFKB1 promoter methylation in primary cells from healthy volunteers depending on the NFKB1–94 Ins/Del genotype. Methylation in the promoter region from nt+402 to nt+99 was below 1%. Genotype dependent differences occurred in neutrophil cells, where DD-genotype was significantly more methylated compared to II genotype at nt+284/+402. Besides in the promoter region from nt-227/-8 in ID-genotypes methylation of neutrophils was significantly decreased compared to lymphocytes and in II-genotypes methylation in neutrophils was significantly decreased compared to lymphocytes and monocytes. In addition, CHART-PCR showed that the hypomethylated promoter regions are highly accessible. Therefore we assume that the demethylated regions are very important for NFKB1 promoter activity.

Aquaporin 5 Plays a Role in Estrogen-Induced Ectopic Implantation of Endometrial Stromal Cells in Endometriosis

Aquaporin 5 (AQP5) participates in the migration of endometrial cells. Elucidation of the molecular mechanisms associated with AQP5-mediated, migration of endometrial cells may contribute to a better understanding of endometriosis. Our objectives included identifying the estrogen-response element (ERE) in the promoter region of the AQP5 gene, and, investigating the effects of AQP5 on ectopic implantation of endometrial cells. Luciferase reporter assays and electrophoretic mobility shift assay (EMSA) identified the ERE-like motif in the promoter region of the AQP5 gene. After blocking and up-regulating estradiol (E₂) levels, we analysed the expression of AQP5 in endometrial stromal (ES) cells. After blocking E₂ /or phosphatidylinositol 3 kinase(PI3K), we analysed the role of AQP5 in signaling pathways. We constructed an AQP5, shRNA, lentiviral vector to knock out the AQP5 gene in ES cells. After knock-out of the AQP5 gene, we studied the role of AQP5 in cell invasion, proliferation, and the formation of ectopic endometrial implants in female mice. We identified an estrogen-response element in the promoter region of the AQP5 gene. Estradiol (E₂) increased AQP5 expression in a dose-dependent fashion, that was blocked by ICI182,780(an estrogen receptor inhibitor). E₂ activated PI3K /protein kinase B(AKT) pathway (PI3K/AKT), that, in turn, increased AQP5 expression. LY294002(PI3K inhibitor) attenuated estrogen-enhanced, AQP5 expression. Knock-out of the AQP5 gene with AQP5 shRNA lentiviral vector significantly inhibited E₂-enhanced invasion, proliferation of ES cells and formation of ectopic implants. Estrogen induces AQP5 expression by activating ERE in the promoter region of the AQP5gene, activates the PI3K/AKT pathway, and, promotes endometrial cell invasion and proliferation. These results provide new insights into some of the mechanisms that may underpin the development of deposits of ectopic endometrium.