*5.1. Energy E*ffi*ciency*

### 5.1.1. Fuel Economy Standard for Light Duty Vehicles (LDV)

Implementation of fuel economy standards for new LDVs that foster the improvement of LDV energy efficiency by increasing fuel economy by 5% yearly departing from year 3 to 7, generating a 35% increase in relation to the reference year where the LDVs have a fuel efficiency of 12 km/lt. An additional average investment cost of 918 USD is assumed per improved vehicle throughout the first five years [41]. This additional cost was calculated, according to this author, by estimating the global cost for manufacturers to comply with this standard which resulted in a value of 4526 MUSD, which was divided by the number of vehicles sold during those first 5 years of this measure summing up 4.9 million LDV according to [36]. In subsequent years, an average annual performance growth of 2.3% is assumed as an inertial improvement due to the manufacturer´s new infrastructure installed to

comply with this standard and which was amortized as mentioned in the first 5 years of LDV sales, so that new LDVs from the sixth year on, no longer have an extra unit cost. Finally, the maintenance (M) costs are considered to be similar to those of existing LDVs in the BLS.

### 5.1.2. Fuel Economy Standard for Heavy Duty Vehicles-Freight (HDV-F)

This measure encourages the implementation of a performance standard that increases the fuel economy of HDV-F by 20% by the fifth year of operation of the regulations, assuming an annual increase of 4% in the fuel economy departing from year 4 to 8. An additional average investment cost of 378 USD per improved vehicle is assumed throughout the mentioned five years, emulating the USA draft fuel economy standard for heavy duty vehicles class 2B-8 according to [42]. This additional cost was calculated, according to [36] by estimating the global cost for manufacturers to comply with this standard which resulted in a value of 160 MUSD, which was divided by the number of vehicles sold during those 5 years of this measure summing up 423,155. An average annual performance increase of 2.5% after the eighth year is assumed as an inertial improvement due to the manufacturer´s new infrastructure installed to comply with this standard and which was amortized in the 5 years mentioned of HDV-F sales, so that new HDV-F from the eighth year on, no longer have an extra unit cost. Finally, the maintenance costs are like those of used vehicles in the BLS.


**2. Interleukin 10 (IL-10)**

IL-10 is an important regulatory cytokine with a potent anti-inflammatory effect. In humans, it is encoded by the IL10 gene [2]. It presents polymorphisms (SNPs), most of them within the promoter regions, and has been proposed as responsible for the altered function, by dysregulating their expression. Several groups report associations between polymorphism and cancer risk [3–7]. It is a helical cytokine and exists in solution predominantly as a homodimer, composed of two polypeptide chains of 160 amino acids, each with a molecular weight of 20,6419 kD [8].

IL-10 was initially thought to be produced only by T helper (Th2) cells but is now known to be made by a variety of cell types [9]. It is primarily produced by monocytes upon PD-1 triggering in these cells and, to a lesser extent, lymphocytes type 2 T helper cells (TH2), mast cells, CD4+CD25+Foxp3+ regulatory T cells, and in a specific subset of activated T cells and B cells (**Figure 1**) [10]. IL-10 expression is minimal in unstimulated tissues and seems to require triggering [11].

Cytokine signals are generated through a receptor complex consisting of two IL-10 receptor-1 and two IL-10 receptor-2 proteins. After IL-10 binding, it induces STAT3 signaling via the phosphorylation of the cytoplasmic tails of IL-10 receptor 1 + IL-10 receptor 2 by JAK1 and Tyk2, respectively (**Figure 2**) [12, 13].

IL-10 expression is regulated at the transcriptional and posttranscriptional levels. Extensive IL-10 locus remodeling in monocytes upon the stimulation of Toll-like receptor (TLR) or Fc receptor pathways was described. Induction involves ERK1/2, p38, and NF-κB signaling and transcriptional activation via promoter binding of

#### **Figure 1.**

*IL-10R homodimers bind to form in a tetrameric heterodimer after IL-10 binds to its receptor α. It downstream signaling through STAT3 until target genes.*

**27**

*IL10 as Cancer Biomarker*

**Figure 2.**

*cytokine by blocking its expression*.

*DOI: http://dx.doi.org/10.5772/intechopen.90806*

the transcription factors NF-κB and AP-1; other regulation as a complex of multiple transcriptional factors has been described, such as GATA-3, E4BP4, MAF, and Blimp [14, 15]. These reports are allowing the possibility that transcriptional regulatory machinery could be specific to certain cell types [16, 17]. In addition, the regulation of IL-10 production depending on the TLR2 or TLR4-stimulated in BM-derived macrophages presents different stability profiles for the IL10 mRNA [18].

*After antigenic stimulus on cells from innate and adaptive system, the IL-10 is expressed from these cells. To avoid severe danger from pro-inflammatory cytokines and reactive radicals, IL-10 acts as anti-inflammatory*

It has the ability to inhibit activation and effector function of T cells, monocytes, and macrophages. It regulates the growth and differentiation of several cells such as B cells, NK cells, cytotoxic, and helper T cells, as well as mast cells, granulocytes,

Discovered in 1991, IL-10 was initially reported to suppress cytokine secretion, antigen presentation, and CD4+ T cell activation. IL-10 is crucial for controlling these T-cell responses, as IFNγ [19–22]. Further investigations have shown that IL-10 predominantly inhibits the synthesis of the pro-inflammatory cytokines IL-1, IL12, tumor necrosis factor (TNFα), and gamma Interferon (IFNγ) by stimulated monocytes/macrophages [23–25]. IL-10 is crucial for controlling these T-cell

The pivotal role of autocrine IL-10 and the interaction with CD28 in the induction of T cell are to initiate peripheral tolerance as an immunoregulatory mecha-

In addition, several effects have been reported: it downregulates the expression of Th1 cytokines, MHC class II antigens, dendritic cells, and co-stimulatory mol-

Biphasic effects have been reported on B cells. It prevents apoptosis in germinal B cells but induces apoptosis on B-chronic lymphocytic leukemia cells, enhances proliferation induced by CD40L, and promotes differentiation of B cells to become

IL-10 appears to have considerable importance in the development of human cancer and its immune escape. These have suggested that it could serve as a biomarker for prognostic diseases or as a target for treatment. Two factors should be considered: high levels of this cytokine in the system, and genetic polymorphisms.

dendritic cells, keratinocytes, and endothelial cells (**Figure 1**).

responses, as IFNγ-secreting and blocking proliferation [22, 26–28].

plasma cells secreting IgM, IgG, and IgA immunoglobulins [30–34].

nism controlling antigen-specific T cell responses [21].

ecules on macrophages [29].

#### **Figure 2.**

*Translational Research in Cancer*

**2. Interleukin 10 (IL-10)**

20,6419 kD [8].

IL-10 is an important regulatory cytokine with a potent anti-inflammatory effect. In humans, it is encoded by the IL10 gene [2]. It presents polymorphisms (SNPs), most of them within the promoter regions, and has been proposed as responsible for the altered function, by dysregulating their expression. Several groups report associations between polymorphism and cancer risk [3–7]. It is a helical cytokine and exists in solution predominantly as a homodimer, composed of two polypeptide chains of 160 amino acids, each with a molecular weight of

IL-10 was initially thought to be produced only by T helper (Th2) cells but is now known to be made by a variety of cell types [9]. It is primarily produced by monocytes upon PD-1 triggering in these cells and, to a lesser extent, lymphocytes type 2 T helper cells (TH2), mast cells, CD4+CD25+Foxp3+ regulatory T cells, and in a specific subset of activated T cells and B cells (**Figure 1**) [10]. IL-10 expression

Cytokine signals are generated through a receptor complex consisting of two IL-10 receptor-1 and two IL-10 receptor-2 proteins. After IL-10 binding, it induces STAT3 signaling via the phosphorylation of the cytoplasmic tails of IL-10 receptor 1

IL-10 expression is regulated at the transcriptional and posttranscriptional levels. Extensive IL-10 locus remodeling in monocytes upon the stimulation of Toll-like receptor (TLR) or Fc receptor pathways was described. Induction involves ERK1/2, p38, and NF-κB signaling and transcriptional activation via promoter binding of

*IL-10R homodimers bind to form in a tetrameric heterodimer after IL-10 binds to its receptor α. It downstream*

is minimal in unstimulated tissues and seems to require triggering [11].

+ IL-10 receptor 2 by JAK1 and Tyk2, respectively (**Figure 2**) [12, 13].

**26**

**Figure 1.**

*signaling through STAT3 until target genes.*

*After antigenic stimulus on cells from innate and adaptive system, the IL-10 is expressed from these cells. To avoid severe danger from pro-inflammatory cytokines and reactive radicals, IL-10 acts as anti-inflammatory cytokine by blocking its expression*.

the transcription factors NF-κB and AP-1; other regulation as a complex of multiple transcriptional factors has been described, such as GATA-3, E4BP4, MAF, and Blimp [14, 15]. These reports are allowing the possibility that transcriptional regulatory machinery could be specific to certain cell types [16, 17]. In addition, the regulation of IL-10 production depending on the TLR2 or TLR4-stimulated in BM-derived macrophages presents different stability profiles for the IL10 mRNA [18].

It has the ability to inhibit activation and effector function of T cells, monocytes, and macrophages. It regulates the growth and differentiation of several cells such as B cells, NK cells, cytotoxic, and helper T cells, as well as mast cells, granulocytes, dendritic cells, keratinocytes, and endothelial cells (**Figure 1**).

Discovered in 1991, IL-10 was initially reported to suppress cytokine secretion, antigen presentation, and CD4+ T cell activation. IL-10 is crucial for controlling these T-cell responses, as IFNγ [19–22]. Further investigations have shown that IL-10 predominantly inhibits the synthesis of the pro-inflammatory cytokines IL-1, IL12, tumor necrosis factor (TNFα), and gamma Interferon (IFNγ) by stimulated monocytes/macrophages [23–25]. IL-10 is crucial for controlling these T-cell responses, as IFNγ-secreting and blocking proliferation [22, 26–28].

The pivotal role of autocrine IL-10 and the interaction with CD28 in the induction of T cell are to initiate peripheral tolerance as an immunoregulatory mechanism controlling antigen-specific T cell responses [21].

In addition, several effects have been reported: it downregulates the expression of Th1 cytokines, MHC class II antigens, dendritic cells, and co-stimulatory molecules on macrophages [29].

Biphasic effects have been reported on B cells. It prevents apoptosis in germinal B cells but induces apoptosis on B-chronic lymphocytic leukemia cells, enhances proliferation induced by CD40L, and promotes differentiation of B cells to become plasma cells secreting IgM, IgG, and IgA immunoglobulins [30–34].

IL-10 appears to have considerable importance in the development of human cancer and its immune escape. These have suggested that it could serve as a biomarker for prognostic diseases or as a target for treatment. Two factors should be considered: high levels of this cytokine in the system, and genetic polymorphisms.

#### **3. IL-10 serum levels on cancer patients**

Considering their possible role in the development and establishment of malignant cells, the first studies conducted to detect serum IL-10 levels in cancer patients, reported a higher concentration than in healthy subjects. In melanoma patients with lymph node metastases, stages III and IV showed significantly high concentration with respect to a healthy subject. *In vitro* determination performed on the supernatant of primary malignant melanoma cultures, IL-I0 mRNA, and protein was expressed. Later, in a meta-analysis that included melanoma patients, high expression of serous IL-10 leads to an adverse survival and correlated with worse outcomes in cancer patients [35–39].

On serum samples of 90 patients with gastric cancer, high IL-10 levels were associated with a worse prognosis independent of the gastric-stage patients and pancreatic cancer [40]. Similar observations were reported on another group of patients with a pancreatic and gastric cancer stage (IV). In the same study, patients with colon and renal carcinoma IL-10 levels did not significantly differ from controls [41]. *In vitro* study, supernatants of pancreatic tumors primary cultures, high concentration of IL-10 was detected [42].

Similar clinical findings on sera and tissues samples from lung cancer patients were report; samples with high levels were found on patients in stages III and IV, and less in stages II and I. The increased IL-10 levels correlate with a poor prognosis. On lung tumor tissues samples from those patients, IL10 concentration showed than the higher expression, presented lower survival rates [43].

Samples from breast cancer from patients, who underwent surgery as well as peritumoral normal breast tissue, were analyzed. Correlation between the IL-10 expressions of breast cancer tissue showed poor prognosis. No IL-10 was detected on normal tissue samples [44]. Determination of IL-10 on patients with breast cancer and early breast cancer showed that it could be usefully associated with other cytokines as biomarkers to discriminating advanced cancer, reported that IL-10 is significantly upregulated. These data could be used discerning between the two stages. [45].

Hodgkin's disease presented sera elevated IL-10 levels on range 4.5–225.6 pg/ ml, suggesting that IL-10 could be an independent prognostic factor and correlates to poor survival [46]. Lymph nodes from pediatric patients with Hodgkin's disease express high levels of IL-10 mRNA where there were associated with an unfavorable prognosis [47, 48]. For the study of sera levels in 153 patients with Non-Hodgkin's disease, IL-10 was detectable with a similar frequency in all subtypes and all clinical stages. Nevertheless, high levels correlate with poor prognosis. Patients with stage IV disease and detectable serum IL-10 had a particularly poor prognosis [49, 50]. Additional information on sera levels of IL-10 is shown in **Table 1**.

IL-10 protein or mRNA appears to be an important component of the tumor micro-environment in a range of human cancer types, as renal cell carcinoma [68]. The role of macrophages in the regulation of tumor cell proliferation, invasion, angiogenesis, or immune control does not always have a positive effect; in fact, it has shown a negative effect. The secretion of IL-10 inhibits the inflammatory response [69–72] and also has been suggested that the detection of IL-10 into and surrounding the tumor may be derived directly from the tumor cells; *in vitro* studies reveal that melanoma cells themselves are the primary origin of IL-10 in tumor specimens *in vivo* [35]. Nevertheless, Mocellin *et al*. report evidence about immunostimulating anticancer properties, suggesting IL-10 over-expression within the tumor micro-environment and it may catalyze cancer immune rejection [73].

IL-10 and IL10R were quantified in sera and surgical specimens, although no significant serum IL-10 elevation was found.  In addition to an immunohistochemistry study on human lung surgery, a positive correlation between IL-10 and IL-10 receptor expressions was related to the lung tumor diameter. Interestingly, IL-10R was mainly expressed on the surface of Foxp-3þ T-regulatory lymphocytes infiltrating the tumor [74, 75].

*Determination of IL-10 levels in serum from cancer patients.*

**4. IL10 polymorphims related to the development and prognosis**

Single nucleotide polymorphisms (SNPs) has been described on IL10 promoter, where adenine was substituted by guanine at −1082 bp (rs1800896). Thymine was replaced by cytosine at −819 bp (rs1800871) and adenine by cytosine at −592 bp (rs1800872). All of those contribute to the variation in protein expression [76]. The IL10 production have a hereditary component estimated in 75%, suggesting that

#### *IL10 as Cancer Biomarker DOI: http://dx.doi.org/10.5772/intechopen.90806*

*Translational Research in Cancer*

**3. IL-10 serum levels on cancer patients**

worse outcomes in cancer patients [35–39].

concentration of IL-10 was detected [42].

two stages. [45].

the higher expression, presented lower survival rates [43].

Considering their possible role in the development and establishment of malignant cells, the first studies conducted to detect serum IL-10 levels in cancer patients, reported a higher concentration than in healthy subjects. In melanoma patients with lymph node metastases, stages III and IV showed significantly high concentration with respect to a healthy subject. *In vitro* determination performed on the supernatant of primary malignant melanoma cultures, IL-I0 mRNA, and protein was expressed. Later, in a meta-analysis that included melanoma patients, high expression of serous IL-10 leads to an adverse survival and correlated with

On serum samples of 90 patients with gastric cancer, high IL-10 levels were associated with a worse prognosis independent of the gastric-stage patients and pancreatic cancer [40]. Similar observations were reported on another group of patients with a pancreatic and gastric cancer stage (IV). In the same study, patients with colon and renal carcinoma IL-10 levels did not significantly differ from controls [41]. *In vitro* study, supernatants of pancreatic tumors primary cultures, high

Similar clinical findings on sera and tissues samples from lung cancer patients were report; samples with high levels were found on patients in stages III and IV, and less in stages II and I. The increased IL-10 levels correlate with a poor prognosis. On lung tumor tissues samples from those patients, IL10 concentration showed than

Samples from breast cancer from patients, who underwent surgery as well as peritumoral normal breast tissue, were analyzed. Correlation between the IL-10 expressions of breast cancer tissue showed poor prognosis. No IL-10 was detected on normal tissue samples [44]. Determination of IL-10 on patients with breast cancer and early breast cancer showed that it could be usefully associated with other cytokines as biomarkers to discriminating advanced cancer, reported that IL-10 is significantly upregulated. These data could be used discerning between the

Hodgkin's disease presented sera elevated IL-10 levels on range 4.5–225.6 pg/ ml, suggesting that IL-10 could be an independent prognostic factor and correlates to poor survival [46]. Lymph nodes from pediatric patients with Hodgkin's disease express high levels of IL-10 mRNA where there were associated with an unfavorable prognosis [47, 48]. For the study of sera levels in 153 patients with Non-Hodgkin's disease, IL-10 was detectable with a similar frequency in all subtypes and all clinical stages. Nevertheless, high levels correlate with poor prognosis. Patients with stage IV disease and detectable serum IL-10 had a particularly poor prognosis [49, 50].

IL-10 protein or mRNA appears to be an important component of the tumor micro-environment in a range of human cancer types, as renal cell carcinoma [68]. The role of macrophages in the regulation of tumor cell proliferation, invasion, angiogenesis, or immune control does not always have a positive effect; in fact, it has shown a negative effect. The secretion of IL-10 inhibits the inflammatory response [69–72] and also has been suggested that the detection of IL-10 into and surrounding the tumor may be derived directly from the tumor cells; *in vitro* studies reveal that melanoma cells themselves are the primary origin of IL-10 in tumor specimens *in vivo* [35]. Nevertheless, Mocellin *et al*. report evidence about immunostimulating anticancer properties, suggesting IL-10 over-expression within the tumor micro-environment and it may catalyze cancer immune rejection [73]. IL-10 and IL10R were quantified in sera and surgical specimens, although no significant serum IL-10 elevation was found. On surgical lung tumor cells, IL-10

Additional information on sera levels of IL-10 is shown in **Table 1**.

**28**

#### **Table 1.**

*Determination of IL-10 levels in serum from cancer patients.*

expression was considered as a prognostic factor on nonsmall-cell lung cancer surgical specimens. In addition to an immunohistochemistry study on human lung surgery, a positive correlation between IL-10 and IL-10 receptor expressions was related to the lung tumor diameter. Interestingly, IL-10R was mainly expressed on the surface of Foxp-3þ T-regulatory lymphocytes infiltrating the tumor [74, 75].


2.2.1. Step 1. Pressure Drop Parameter Estimation

As mentioned above the pressure drop on the feed/brine side can be estimated through Darcy's law as given by Equation (5) which is written in terms of the volume flow. However, this can also be written as [21]:

$$\frac{dP}{d\mathbf{x}} = k\_{\text{fb}} \,\mu\,\,\text{v}\_{\text{f}}^{n\_{\text{f}}} \tag{20}$$

where *v*f is the feed-side fluid velocity, *µ* is the fluid viscosity, *k*fb is a friction parameter, and *n*f is a constant which is commonly assumed to be 1, although some studies have considered other values. For example, Sentilmurugan at al. also considered *n*f = 1.5 and found that changing this value only had a small effect on results [21]. In this study it is assumed *n*f = 1 and hence Equation (20) is equivalent to Equation (5).

The estimation of *b* is possible through plotting *P*o − *P*i against *L φ*sinh*φ* [(*F*i + *F*o)(cosh(*φ*) − 1)] (from Equation (16)) and fitting a linear expression should give *b* as the gradient, as suggested by Sundaramoorthy et al. [30,31].

However, this requires knowledge of the feed/brine side outlet pressure which may not be provided or possibly not measured as part of experimental studies looking at reverse osmosis desalination. In these cases the pressure drop might be estimated based on the maximum pressure drop specified by the manufacturer. For example, we might estimate that the highest flow rate tested experimentally gives a pressure drop which is 100% of the maximum:

$$b = \frac{P\_{\text{dropmax}}}{L \, F\_{\text{i,max}}} \tag{21}$$

Alternatively, if a friction factor is available the value of *b* can be readily found:

$$b = \frac{k\_{\text{fb}}\,\mu}{A\_{\text{f}}} \tag{22}$$

where *A*f is the cross sectional area of the feed channel and the viscosity is calculated for a single typical experimental inlet value.