**1.1.4 Latest treatments developed against endometriosis**

Recently, with the better understanding on the pathogenesis and progression toward endometriosis, novel medications on using molecular targets are developed for treatment of endometriosis. The advantages of such agents hold a higher efficacy and sensitivity on treating the disease, while minimizing evidence of side effects experienced by the patients.

#### **1.1.4.1 Anti-angiogenesis inhibitors**

One of the main etiologies of endometriosis is believe to be resulted from implantation of retrograde shed endometrium during menstruation (Sampson, 1927). The properties of the endometrium have the capacity to adhere, attach, and implant ectopically (Koks *et al.*, 1999; Maas *et al.*, 2001). Based on the anatomical surrounding, endometriotic lesions are found to be larger in size with the availability to rich blood supply. This suggesting that angiogenesis is prerequisite for the development of endometriosis.

The use of angiostatic agents may provide a new therapeutic option to inhibit this pathological process. The aim is to mainly control two processes involved in angiogenesis: endothelial cell growth and endothelial cell adhesion. Angiogenic cytokines are elevated in the peritoneal fluid in patients with endometriosis (Nisolle *et al.*, 1993). Anti-angiogenesis therapies have been shown effective in suppressing the development in endometriotic lesion in mice (Nap *et al.*, 2004). Common angiostatic compounds, such as anti-human vascular endothelial growth factor-A (anti-hVEGF), TNP-470, endostatin, and anginex, significantly decreased microvessel density and inhibited the established endometriosis lesions (Dabrosin *et al.*, 2002; Nap *et al.*, 2004; Yagyu *et al.*, 2005). By far, the only clinical trial conducted with an anti-angiogenesis therapy on treating endometriosis-associated pain was thalidomide (Scarpellini *et al.*, 2002). Although the result showed promising pain relief in the patients, however, thalidomide is a potential teratogen (Khoury *et al.*, 1987). Thus, women wanting pregnancy is prohibited.

#### **1.1.4.2 Anti-oxidant therapy**

Although the actual etiology of endometriosis remains unknown, it is widely accepted that retrograde menstruation is associated with endometriosis. However, it is unclear on why only a portion of women with retrograde menstruation develops endometriosis, while others do not. Studies proposed this might be due to the presence of elements such as macrophages, iron or environmental contaminants disrupting the balance between ROS and antioxidants in the peritoneal fluid of some women, leading to oxidative stress and endometriosis (Arumugam *et al.*, 1995; Donnez *et al.*, 2002; Murphy *et al.*, 1998). Likewise, the cyclical changes in the endometrium are accompanied by changes in the expression of various antioxidant enzymes in the endometrium (Gurdol *et al.*, 1997).

Patients with endometriosis have shown the increase in generation of ROS by peritoneal fluid macrophages, with increased lipid peroxidation (Halme *et al.*, 1983). The diminished peritoneal fluid antioxidants (Murphy *et al.*, 1998), elevated oxidized lipoproteins, lysophosphatidyl choline (Murphy *et al.*, 1998), and other markers of lipid peroxidation

Green Tea for Endometriosis 283

As surgical and hormonal treatment of endometriosis have unpleasant side effects and high rates of relapse, many patients began to explore more natural and traditional remedies. In China, treatment of endometriosis using Chinese herbal medicine is routine to alleviate pain, promote fertility, and prevent relapse. Study showed post-surgical administration of Chinese herbal medicine may have comparable benefits to western medicines but with fewer side effects (Flower *et al.*, 2009). In this study, it showed oral intake of traditional Chinese medicine have a better overall treatment effect than Danazol. Also, it is more effective in relieving dysmenorrheal and shrinking adnexal masses. Likewise, acupuncture is a new techniques employed to relieve the infertility associated with endometriosis in women (Mo *et al.*, 1993). However, due to the limited amount intervention studies reported, more rigorous researches are required to accurately assess the type, dose and potential role

Angiogenesis is the physiological process involving the growth of new blood vessels from pre-existing vessels. It is a sequence of events that is fundamental to a broad array of physiological processes occurring in our body, including embryogenesis, development, the menstrual cycle and wound healing. Yet, it is also linked to many pathological situations such as cancer, chronic inflammation, ischemic diseases and endometriosis development (Griffioen *et al.*, 2000). In general, the turnover of capillary endothelial cells is extremely slow in physiological angiogenesis. However, in the normal endometrium and in tumors, the turnover rate is altered to a more rapid state in promoting angiogenesis. Angiogenesis involve activation of angiogenic factors, dissolution of basement membranes by proteases derived from vascular endothelial cells, migration and proliferation of the endothelial cells, and capillary tube formation. And various angiogenic factors are needed to regulate each

Under normal physiological conditions, angiogenesis is well controlled by the local balance between endogenous angiogenesis stimulators and angiogenesis inhibitors, although the regulatory mechanism is still not clear. During wound healing, the expression of vascular endothelial growth factor (VEGF), one of the most potent angiogenic stimulators, is significantly upregulated to promote wound healing by restoring blood flow to the injured tissues. As wound healing resolves, the expression of VEGF is downregulated and most angiogenic capillaries regress, resulting in a residual normal vascularity (Tonnesen *et al.*, 2000). Other studies indicates that a number of endogenous angiogenic inhibitors are present in the normal retina to balance the stimulatory effect of VEGF in the regulation of angiogenesis and vascular permeability (Ma *et al.*, 2005). These studies suggest that endogenous angiogenic inhibitors can be used to balance the effect of angiogenic stimulators. Anti-angiogenic therapies have already been experimentally proven to be effective in preventing metastasis and shrinking the established experimental tumors to be formed (Camp-Sorrell, 2003). Angiogenesis therapeutic approaches can be divided into two major classes: (1) interference with the process of neovascularization and (2) directly

**1.1.4.5 Traditional Chinese medicines** 

**2. Anti-angiogenesis therapy** 

destroying immature blood vessels.

step (Table 2).

of Chinese herbal medicine in treating endometriosis.

**2.1 Properties of anti-angiogenesis therapy** 

provide further evidence of oxidative stress in the peritoneal microenvironment of endometriosis (Ho *et al.*, 1997; Szczepanska *et al.*, 2003).

Currently, a study investigated whether there would be reduced total chemokines and inflammatory cytokines in women with endometriosis (Santanam *et al.*, 2003). As patients were given 1200 IU of vitamin E and 1 g of vitamin C for a period of 2 months, this resulted in a decrease in the inflammatory markers monocyte chemotactic protein-1, regulated on activation normal T cell expressed and secreted (RANTES), and interleukin-6 in peritoneal fluid. Similar study showed these antioxidant supplements can reduce pelvic pain in women with endometriosis (Kavtaradze *et al.*, 2003).

Recently, an inhibitory drug has been used in clinical trials to determine the effect of antioxidant therapy on endometriosis (Creus *et al.*, 2008). Pentoxifylline, a phosphodiesterase inhibitor, has the capability to maintain a higher pregnancy rates in patients suffering from endometriosis. RU 486 exerts an inhibitory effect on endometrial cell growth through its antioxidant properties *in vitro*. Although antioxidants have shown to have beneficial effects in patients with endometriosis, the limited number of trials conducted questions the actual efficacy.

#### **1.1.4.3 Hormone inhibitors and modulators**

As endometriosis is an estrogen-dependent disease, the estrogen-related pathways are often the treatment used to tackle the imbalanced of estrogen in these female patients. A way is to suppress the production of estrogen by inhibiting its synthetic and regulatory pathway. Another potential way is to influence estrogen receptors minimizing estrogen-dependent gene expressions.

Since aromatase, the key enzyme in estrogen synthesis in ovary, adipose tissue or endometriotic tissue, is encoded by a single gene, the inhibition of this gene or its production may cause an effective suppression of estrogen production (Simpson *et al.*, 2002). Preliminary evidence suggests that combined treatment with luteinizing-hormone-releasing hormone analogues and aromatase inhibitors may be superior to medical treatment with luteinizing-hormone-releasing hormone analogues (Shaw, 1988).

Another type of treatment is by using tumor necrosis factor alpha (TNF-α) inhibitor. This cytokine have been found to be overproduced in women with endometriosis, and partially responsible for the influx of peritoneal macrophages to occur in women with endometriosis (Montagna *et al.*, 2008; Richter *et al.*, 2005). A study was conducted to see the therapeutic effect on blocking this cytokine with recombinant human TNF binding protein-1 (TBP-1) in a baboon model (D'Hooghe *et al.*, 2005). The result demonstrated the inhibition in the baboon, suggesting the effective in treating the manifestations of endometriosis. However, there is currently no clinical study to determine the effect in human.

#### **1.1.4.4 Proteases**

Matrix metalloproteinases (MMPs) are a family of endopeptidases that play a role in the degradation and turnover of extracellular matrix proteins. Increased MMP activity has been described in endometriosis (Chung *et al.*, 2002; Gottschalk *et al.*, 2000). There function is believed to be integral in the ability of endometrium to invade tissue and implant successfully. Inhibition of these enzymes might be effective in inhibiting the development of endometriosis. Yet, there is no in-depth study being reported thus raising uncertainty on the value and practicality of this approach.

provide further evidence of oxidative stress in the peritoneal microenvironment of

Currently, a study investigated whether there would be reduced total chemokines and inflammatory cytokines in women with endometriosis (Santanam *et al.*, 2003). As patients were given 1200 IU of vitamin E and 1 g of vitamin C for a period of 2 months, this resulted in a decrease in the inflammatory markers monocyte chemotactic protein-1, regulated on activation normal T cell expressed and secreted (RANTES), and interleukin-6 in peritoneal fluid. Similar study showed these antioxidant supplements can reduce pelvic pain in

Recently, an inhibitory drug has been used in clinical trials to determine the effect of antioxidant therapy on endometriosis (Creus *et al.*, 2008). Pentoxifylline, a phosphodiesterase inhibitor, has the capability to maintain a higher pregnancy rates in patients suffering from endometriosis. RU 486 exerts an inhibitory effect on endometrial cell growth through its antioxidant properties *in vitro*. Although antioxidants have shown to have beneficial effects in patients with endometriosis, the limited number of trials conducted questions the actual

As endometriosis is an estrogen-dependent disease, the estrogen-related pathways are often the treatment used to tackle the imbalanced of estrogen in these female patients. A way is to suppress the production of estrogen by inhibiting its synthetic and regulatory pathway. Another potential way is to influence estrogen receptors minimizing estrogen-dependent

Since aromatase, the key enzyme in estrogen synthesis in ovary, adipose tissue or endometriotic tissue, is encoded by a single gene, the inhibition of this gene or its production may cause an effective suppression of estrogen production (Simpson *et al.*, 2002). Preliminary evidence suggests that combined treatment with luteinizing-hormone-releasing hormone analogues and aromatase inhibitors may be superior to medical treatment with

Another type of treatment is by using tumor necrosis factor alpha (TNF-α) inhibitor. This cytokine have been found to be overproduced in women with endometriosis, and partially responsible for the influx of peritoneal macrophages to occur in women with endometriosis (Montagna *et al.*, 2008; Richter *et al.*, 2005). A study was conducted to see the therapeutic effect on blocking this cytokine with recombinant human TNF binding protein-1 (TBP-1) in a baboon model (D'Hooghe *et al.*, 2005). The result demonstrated the inhibition in the baboon, suggesting the effective in treating the manifestations of endometriosis. However,

Matrix metalloproteinases (MMPs) are a family of endopeptidases that play a role in the degradation and turnover of extracellular matrix proteins. Increased MMP activity has been described in endometriosis (Chung *et al.*, 2002; Gottschalk *et al.*, 2000). There function is believed to be integral in the ability of endometrium to invade tissue and implant successfully. Inhibition of these enzymes might be effective in inhibiting the development of endometriosis. Yet, there is no in-depth study being reported thus raising uncertainty on the

luteinizing-hormone-releasing hormone analogues (Shaw, 1988).

there is currently no clinical study to determine the effect in human.

endometriosis (Ho *et al.*, 1997; Szczepanska *et al.*, 2003).

women with endometriosis (Kavtaradze *et al.*, 2003).

**1.1.4.3 Hormone inhibitors and modulators** 

efficacy.

gene expressions.

**1.1.4.4 Proteases** 

value and practicality of this approach.

### **1.1.4.5 Traditional Chinese medicines**

As surgical and hormonal treatment of endometriosis have unpleasant side effects and high rates of relapse, many patients began to explore more natural and traditional remedies. In China, treatment of endometriosis using Chinese herbal medicine is routine to alleviate pain, promote fertility, and prevent relapse. Study showed post-surgical administration of Chinese herbal medicine may have comparable benefits to western medicines but with fewer side effects (Flower *et al.*, 2009). In this study, it showed oral intake of traditional Chinese medicine have a better overall treatment effect than Danazol. Also, it is more effective in relieving dysmenorrheal and shrinking adnexal masses. Likewise, acupuncture is a new techniques employed to relieve the infertility associated with endometriosis in women (Mo *et al.*, 1993). However, due to the limited amount intervention studies reported, more rigorous researches are required to accurately assess the type, dose and potential role of Chinese herbal medicine in treating endometriosis.
