great read on the underlying pathogenesis of atherosclerosis. There is so much falsehood out there as it relates to the physiology behind atherosclerosis. This reviews the biochemistry.
mitochondrial dysfunction has a central role in the pathogenesis of Alzheimer's, Parkinson's and Huntington's diseases and amyotrophic lateral sclerosis
mitochondrial dysfunction has a central role in the pathogenesis of Alzheimer's, Parkinson's and Huntington's diseases and amyotrophic lateral sclerosis
Approximately 2 billion people suffer from Tuberculosis each year. Tuberculosis or simply TB is an infectious and highly contagious disease of the body especially lungs. It spreads mainly via Mycobacterium tuberculosis which is a tough and highly resistant microbe.
Tuberculosis is a serious, infectious and often fatal disease of the lungs. It can also affect other parts of the body. But the most common type of Tuberculosis is pulmonary Tuberculosis. It is more common in women than in men. The causative agent is a Gram-positive bacterium (Mycobacterium tuberculosis).
It is well known that obesity increases CRP. However, in this meta-analysis, CRP elevation in women with PCOS was found to be independent from obesity and as they concluded: "...chronic low-grade inflammation that may underpin the pathogenesis of this disorder".
Hard to show causation here, but volume of environmental toxicants associated with shortening of Telomeres. Mechanism? Increased free radical induced mitochondrial disruption resulting in relocation of the Telomerase enzyme from the mitochondria to the nuclei. This has been shown to occur in cancer pathogenesis.
In rat model, Estradiol shown to increase inflammation in lateral lobes of the prostate. Androgens, Testosterone > DHT, shown to inhibit this inflammatory response.
Much has been debated about the effects of androgens on prostate growth. However, growing evidence is emerging that prostatic aromatase activity is responsible. This study finds that high aromatase activity and thus Testosterone to Estradiol conversion in the prostate stroma is responsible for the pathogenesis of BPH.
Reduced SOD activity might be responsible for excessive accumulation of superoxide anions leading to increased free radical mediated injury. Increased free radical production has been shown to be responsible for chromosomal damage leading to mutagenecity, cell proliferation and carcinogenesis. SOD activity showed marked improvement after mastectomy indicating the lowering of oxidative stress.
The increased production of reactive oxygen species causes oxidative stress leading to cell proliferation and hence increased inflammatory conditions
Superoxide dismutase is an important antioxidant enzyme which decomposes the harmful superoxide anions into hydrogen peroxide thus protects the body from the action of free radicals
Females suffering from breast cancer had significantly decreased Superoxide dismutase (SOD) and reduced glutathione (GSH) levels in comparison to normal females
ADA seems to be a promising marker of inflammation in breast cancer thereby suggesting that it can be used as a diagnostic tool to detect the stage of breast cancer along with cytopathological studies
In conclusion, our study confirmed the role of oxidative stress in the pathogenesis of breast cancer.
Another potent antioxidant molecule is reduced glutathione. It acts as reductant which converts hydrogen peroxide into water and reduces lipid peroxidation products into their corresponding alcohols and thus mediates protective action.
In the present study, significantly low SOD activity has been observed in female patients suffering from carcinoma breast both pre as well as post operative in comparison to healthy females.
We observed significantly decreased SOD activity and GSH levels in patients belonging to clinical stage 4 as compared to those having stages 1, 2 or 3 of breast cancer.
Increased ADA activity in breast cancer patients has also been reported
The compromised antioxidant defence system produces the oxidative stress which in turn creates the inflammatory response shown by concomitant increased adenosine deaminase (ADA) activity in female patients.
Experimental and epidemiological evidences implicate the involvement of oxygen derived free radical in the pathogenesis of breast cancer.
Antioxidant status was highly depressed in advanced stages of breast cancer as compared to initial stage.
In the present study, significantly low GSH levels were observed in female patients of carcinoma breast as compared to normal females
Walia et al. (1995) reported increased ADA activity in breast cancer patients as compared to age matched normal subjects.
These free radicals are able to cause damage to membrane, mitochondria and macromolecules including proteins, lipids and DNA and actively take part in cell proliferation. This cascade in turn generates the inflammatory response and causes the progression of the disease.
increased oxidative stress gives rise to inflammation which could further aggravates the disease
Breast carcinoma involves a cascade of events that are highly inflammatory.
Marked oxidative stress in stage 4 of breast cancer indicated advancement of the disease, hence checking oxidative stress at initial stage could be helpful for controlling the progression of the disease.
They concluded that ADA is a better probable parameter for detection of breast cancer
Adenosine deaminase enzyme (ADA) catalyzes the conversion of adenosine to inosine which finally gets converted to uric acid
serum ADA activity tends to increase with advancing age,
Prevalence of oxidative stress gives rise to inflammation.
Study finds a reduction in SuperOxide Dismutase and Glutathione Perioxidase in advancing breast cancer. Cancer is a high oxidative stress disease that results in inflammation, mitochondrial dysfunction and proliferation. Adenosine Deaminase (ADA) is proposed to be another biomarker to assess tumor stage.
Cisplatin and 5-FU or CAP (cisplatin, doxorubicin, and cyclophosphamide) regimens can be used for combination chemotherapy
patients with advanced salivary gland malignancy treated with the CAP regimen achieved partial response (PR) or stable disease (SD) rates of 67% (8 out of 12 patients)
Agents commonly given as monotherapy for treating ACC are cisplatin, mitoxantrone, epirubicin, vinorelbine, paclitaxel, and gemcitabine. However, few of these agents have shown efficacy
single agent mitoxantrone or vinorelbine were recommended as reasonable choices
ACC is subdivided into 3 histological groups based on solid components of the tumor including cribriform, tubular, and solid
Cribriform and tubular ACCs usually exhibit a more indolent course, whereas the solid subtype is associated with worse prognosis
ACC consists of two different cell types: inner luminal epithelial cells and outer myoepithelial cells
epithelial cells express c-kit, cox-2 and Bcl-2
myoepithelial cells express EGFR and MYB
a balanced translocation of the v-myb avian myeloblastosis viral oncogene homolog-nuclear factor I/B (MYB-NFIB) is considered to be a signature molecular event of ACC oncogenesis
As a transcription factor, MYB is known to modulate multiple genetic downstream targets involved in oncogenesis, such as cox-2, c-kit, Bcl-2 and BclX
Various signaling cascades are essential for cancer cells to survive and grow. The PI3K/Akt/mTOR pathway is one of them
This pathway regulates cell survival and growth and is upregulated in many cancers
Mutations in genes associated with DNA repair are frequently found in familial cancer syndromes, such as hereditary breast-ovarian cancer syndrome (HBOC), hereditary non-polyposis colorectal cancer (HNPCC, also called Lynch syndrome) and Li-Fraumeni syndrome [30, 31]. These mutations were also reported in non-hereditary cancers
70% of ACC samples (58 of 84) were found to have genetic alterations in the MYB/MYC pathway, indicating that changes in this pathway are crucial in ACC pathogenesis
The second most frequently mutated pathway was involved in chromatin remodeling (epigenetic modification), a pathway that includes multiple histone related proteins, and was altered in 44% of samples
C-kit
VEGF, iNOS and NF-κB were noted to be highly expressed in ACC cells as compared to normal salivary gland cells
members of the SOX family, such as SOX 4 and SOX10, are overexpressed in ACC
FABP7 (Fatty acid binding protein 7) and AQP1 (Aquaporin 1) tend to be overexpressed in ACC cell lines
considerable variability in HER2 overexpression ranging from 0–58% in patients with ACC
the study with cetuximab and concurrent chemoradiation or chemotherapy showed the highest ORR (total 43%, 9.5% CR and 33% PR), but this regimen was only given to the EGFR positive patients
Cancer immunotherapy can be classified into 3 major groups. Active immunization using anti-tumor vaccines to induce and recruit T cells, passive immunization based on monoclonal antibodies, and adoptive cell transfer to expand tumor-reactive autologous T cells ex vivo and then reintroduce these cells into the same individual
LAK cells showed cytotoxicity against ACC cells
cytokine-induced cell apoptosis and the cytotoxic effect of the LAK cells contributed to tumor regression
molecular finding of the MYB-NFIB fusion gene has the greatest potential to target what appears to be a fundamental event in disease pathogenesis
Activation of the innate immune system controls macronutrient metabolism
the innate immune response is the first line of defense against invading pathogens, wherein highly conserved pathogen-associated molecular patterns (PAMPs) are recognized by cognate pattern recognition receptors (PRRs
many studies have supported the idea that cytokine signaling directly promotes insulin resistance
innate immune system may be causally linked to obesity
adipose tissue contains a substantial population of macrophages, and macrophage-driven adipose inflammation contributes significantly to the pathogenesis of obesity
Collectively, activation of the innate immune system is strongly associated with ASCVD, insulin resistance, and obesity, and recent evidence suggests that much of this association can be traced to a unique family of PRRs known as TLRs
TLRs are a family of type I transmembrane receptors, currently thought to comprise at least 13 members in mammals, that specifically recognize a variety of microbial PAMPs and trigger host cellular responses
Free SFAs have indeed been demonstrated to elicit TLR4-dependent and TLR2-dependent responses in several cell types.
Endogenous SFAs released from adipocytes activate cocultured macrophages via TLR4 [18], indicating the potential for cellular crosstalk in adipose tissue. Collectively, there is a growing body of evidence that SFAs promote, whereas long chain PUFA antagonize, TLR4-dependent and TLR2-dependent signaling in multiple cell models
In an elegant study, Shi et al. [16] demonstrated that SFAs activate TLR4-dependent signaling in both macrophages and adipocytes, and mice lacking TLR4 are protected against insulin resistance driven by intravenous lipid infusion
In addition to effects in macrophages and adipocytes, SFAs can activate TLR4 in the hypothalamus, which triggers a central inflammatory response that results in resistance to anorexigenic signals
endogenous SFAs can indeed promote innate immunity and inflammatory disease
This finding strongly supports the work of Hwang and coworkers [19–22] demonstrating that ω-3 PUFAs can effectively counteract SFA-induced TLR4 activation in cultured macrophages and dendritic cells.
Testosterone has beneficial
effects on several cardiovascular risk factors, which include cholesterol, endothelial dysfunction and inflammation
In clinical studies, acute and chronic testosterone administration increases coronary artery diameter and flow, improves
cardiac ischaemia and symptoms in men with chronic stable angina and reduces peripheral vascular resistance in chronic heart
failure.
testosterone is an L-calcium channel blocker and induces potassium
channel activation in vascular smooth muscle cells
Animal studies have consistently demonstrated that testosterone is atheroprotective,
whereas testosterone deficiency promotes the early stages of atherogenesis
there is no compelling evidence that testosterone replacement to levels within the normal healthy range contributes
adversely to the pathogenesis of CVD (Carson & Rosano 2011) or prostate cancer (Morgentaler & Schulman 2009)
bidirectional effect between decreased testosterone
concentrations and disease pathology exists as concomitant cardiovascular risk factors (including inflammation, obesity and
insulin resistance) are known to reduce testosterone levels and that testosterone confers beneficial effects on these cardiovascular
risk factors
Achieving a normal physiological testosterone concentration through the administration
of testosterone replacement therapy (TRT) has been shown to improve risk factors for atherosclerosis including reducing central
adiposity and insulin resistance and improving lipid profiles (in particular, lowering cholesterol), clotting and inflammatory
profiles and vascular function
It is well known that impaired erectile function and CVD are closely
related in that ED can be the first clinical manifestation of atherosclerosis often preceding a cardiovascular event by 3–5
years
no decrease in the response (i.e. no tachyphylaxis) of testosterone and that patient benefit persists in the long term.
free testosterone
levels within the physiological range, has been shown to result in a marked increase in both flow- and nitroglycerin-mediated
brachial artery vasodilation in men with CAD
Clinical studies, however, have revealed either small reductions of 2–3 mm in diastolic pressure or no significant effects
when testosterone is replaced within normal physiological limits in humans
Endothelium-independent mechanisms of testosterone
are considered to occur primarily via the inhibition of voltage-operated Ca2+ channels (VOCCs) and/or activation of K+ channels (KCs) on smooth muscle cells (SMCs)
Testosterone shares the same molecular binding site as nifedipine
Testosterone increases the expression of endothelial nitric oxide synthase (eNOS)
and enhances nitric oxide (NO) production
Testosterone also inhibited
the Ca2+ influx response to PGF2α
one of the major actions of testosterone is on NO and its signalling pathways
In addition to direct effects on NOS expression, testosterone may also affect phosphodiesterase type 5 (PDE5 (PDE5A)) gene expression, an enzyme controlling the degradation of cGMP, which acts as a vasodilatory second messenger
the significance of the action of testosterone on VSMC apoptosis and proliferation in atherosclerosis is difficult
to delineate and may be dependent upon the stage of plaque development
Several human studies have shown that carotid IMT (CIMT) and aortic calcification negatively correlate
with serum testosterone
t long-term testosterone treatment reduced CIMT in men with low testosterone levels
and angina
neither intracellular nor membrane-associated
ARs are required for the rapid vasodilator effect
acute responses appear to be AR independent, long-term AR-mediated effects on the vasculature have also been described,
primarily in the context of vascular tone regulation via the modulation of gene transcription
Testosterone and DHT increased the expression of eNOS in HUVECs
oestrogens have been shown to activate eNOS and stimulate NO production in an ERα-dependent manner
Several studies, however, have demonstrated that the vasodilatory actions of testosterone are not reduced by aromatase
inhibition
non-aromatisable DHT elicited similar vasodilation to testosterone treatment in arterial smooth muscle
increased endothelial NOS (eNOS) expression and phosphorylation were observed in testosterone- and DHT-treated
human umbilical vein endothelial cells
Androgen deprivation leads to a reduction in neuronal NOS expression associated with a decrease of intracavernosal pressure
in penile arteries during erection, an effect that is promptly reversed by androgen replacement therapy
Observational evidence suggests that several pro-inflammatory cytokines (including interleukin 1β (IL1β), IL6, tumour necrosis
factor α (TNFα), and highly sensitive CRP) and serum testosterone levels are inversely associated in patients with CAD, T2DM
and/or hypogonadism
patients with the
highest IL1β concentrations had lower endogenous testosterone levels
TRT has been reported to significantly
reduce TNFα and elevate the circulating anti-inflammatory IL10 in hypogonadal men with CVD
testosterone treatment to normalise levels in hypogonadal men with the MetS
resulted in a significant reduction in the circulating CRP, IL1β and TNFα, with a trend towards lower IL6 compared with placebo
parenteral testosterone undecanoate, CRP decreased significantly in hypogonadal elderly
men
Higher levels of serum adiponectin have been shown to lower cardiovascular risk
Research suggests that the expression of VCAM-1, as induced by pro-inflammatory cytokines such as TNFα or interferon γ (IFNγ
(IFNG)) in endothelial cells, can be attenuated by treatment with testosterone
Testosterone also inhibits the production of pro-inflammatory cytokines such as IL6, IL1β and TNFα in a range of cell types
including human endothelial cells
decreased inflammatory response to TNFα and lipopolysaccharide (LPS) in
human endothelial cells when treated with DHT
The key to unravelling the link between testosterone
and its role in atherosclerosis may lay in the understanding of testosterone signalling and the cross-talk between receptors
and intracellular events that result in pro- and/or anti-inflammatory actions in athero-sensitive cells.
testosterone
functions through the AR to modulate adhesion molecule expression
pre-treatment with DHT reduced the cytokine-stimulated inflammatory response
DHT inhibited NFκB activation
DHT could inhibit an LPS-induced upregulation of MCP1
Both NFκB and
AR act at the transcriptional level and have been experimentally found to be antagonistic to each other
As the AR and NFκB are mutual antagonists, their interaction and influence on functions can be bidirectional, with inflammatory
agents that activate NFκB interfering with normal androgen signalling as well as the AR interrupting NFκB inflammatory transcription
prolonged exposure of vascular cells to the inflammatory activation of NFκB associated with atherosclerosis
may reduce or alter any potentially protective effects of testosterone
DHT and IFNγ also modulate each other's signalling through interaction at the transcriptional
level, suggesting that androgens down-regulate IFN-induced genes
(Simoncini et al. 2000a,b). Norata et al. (2010) suggest that part of the testosterone-mediated atheroprotective effects could depend on ER activation mediated by the testosterone/DHT
3β-derivative, 3β-Adiol
TNFα-induced induction of ICAM-1, VCAM-1 and E-selectin as well as MCP1 and IL6 was significantly
reduced by a pre-incubation with 3β-Adiol in HUVECs
3β-Adiol also reduced LPS-induced gene expression
of IL6, TNFα, cyclooxygenase 2 (COX2 (PTGS2)), CD40, CX3CR1, plasminogen activator inhibitor-1, MMP9, resistin, pentraxin-3 and MCP1 in the monocytic cell line U937 (Norata et al. 2010)
This study suggests that testosterone metabolites, other than those generated through aromatisation, could exert anti-inflammatory
effects that are mediated by ER activation.
The authors suggest that DHT differentially
effects COX2 levels under physiological and pathophysiological conditions in human coronary artery smooth muscle cells and
via AR-dependent and -independent mechanisms influenced by the physiological state of the cell
There are, however, a number of systematic meta-analyses of clinical trials of TRT that have not demonstrated
an increased risk of adverse cardiovascular events or mortality
The TOM trial, which was designed to investigate the effect of TRT on frailty in elderly men, was terminated prematurely
as a result of an increased incidence of cardiovascular-related events after 6 months in the treatment arm
trials of TRT in men with either chronic stable angina or chronic cardiac failure have also found no increase
in either cardiovascular events or mortality in studies up to 12 months
Evidence may therefore suggest that low testosterone levels and testosterone levels above the normal range have an adverse
effect on CVD, whereas testosterone levels titrated to within the mid- to upper-normal range have at least a neutral effect
or, taking into account the knowledge of the beneficial effects of testosterone on a series of cardiovascular risk factors,
there may possibly be a cardioprotective action
The effect of testosterone on human vascular function is a complex issue and may be dependent upon the underlying androgen
and/or disease status.
the majority of studies suggest that testosterone may display both acute and
chronic vasodilatory effects upon various vascular beds at both physiological and supraphysiological concentrations and via
endothelium-dependent and -independent mechanisms
E2 and the inflammatory adipocytokines tumour necrosis factor α (TNFα) and interleukin 6 (IL6) inhibit hypothalamic production
of GNRH and subsequent release of LH and FSH from the pituitary
Leptin, an adipose-derived hormone with a well-known role
in regulation of body weight and food intake, also induces LH release under normal conditions via stimulation of hypothalamic
GNRH neurons
In human obesity, whereby adipocytes are producing elevated amounts of leptin, the hypothalamic–pituitary axis becomes
leptin resistant
there is evidence from animal studies
that leptin resistance, inflammation and oestrogens inhibit neuronal release of kisspeptin
Beyond hypothalamic action, leptin also directly inhibits the stimulatory action of gonadotrophins on the Leydig cells
of the testis to decrease testosterone production; therefore, elevated leptin levels in obesity may further diminish androgen
status
increasing insulin resistance assessed by glucose tolerence test and hypoglycemic clamp was shown to be associated
with a decrease in Leydig cell testosterone secretion in men
ADT for the treatment of prostatic carcinoma in some large epidemiological studies has been shown to be associated with an
increased risk of developing MetS and T2DM
Non-diabetic men undergoing androgen ablation show increased occurrence of new-onset diabetes and demonstrate elevated
insulin levels and worsening glycaemic control
Prostate cancer patients with pre-existing T2DM show a further deterioration of insulin resistance and worsening of diabetic
control following ADT
The response to testosterone replacement of insulin sensitivity is in part dependent on the androgen receptor (AR)
Low levels of testosterone have been associated with an atherogenic lipoprotein profile, characterised by high LDL and triglyceride
levels
a positive correlation between serum testosterone and HDL has been reported in both healthy and diabetic
men
up to 70% of the body's insulin sensitivity is accounted for by muscle
Testosterone deficiency is associated with a decrease in lean body mass
relative muscle mass is inversely associated
with insulin resistance and pre-diabetes
GLUT4 and IRS1 were up-regulated in cultured adipocytes and skeletal
muscle cells following testosterone treatment at low dose and short-time incubations
local conversion of testosterone to
DHT and activation of AR may be important for glucose uptake
inverse correlation between testosterone levels and adverse mitochondrial function
orchidectomy of male Wistar rats and associated testosterone deficiency induced increased absorption of glucose
from the intestine
(Kelley & Mandarino 2000). Frederiksen et al. (2012a) recently demonstrated that testosterone may influence components of metabolic flexibility as 6 months of transdermal testosterone
treatment in aging men with low–normal bioavailable testosterone levels increased lipid oxidation and decreased glucose oxidation
during the fasting state.
Decreased lipid oxidation coupled with diet-induced chronic FA elevation is linked to increased accumulation of myocellular
lipid, in particular diacylglycerol and/or ceramide in myocytes
In
the Chang human adult liver cell line, insulin receptor mRNA expression was significantly increased following exposure to
testosterone
Testosterone deprivation via castration of male rats led to decreased expression of Glut4 in liver tissue, as well as adipose and muscle
oestrogen was found to increase the expression of insulin receptors in insulin-resistant HepG2 human liver cell
line
FFA decrease hepatic
insulin binding and extraction, increase hepatic gluconeogenesis and increase hepatic insulin resistance.
Only one, albeit large-scale,
population-based cross-sectional study reports an association between low serum testosterone concentrations and hepatic steatosis
in men (Völzke et al. 2010)
This suggests that testosterone may confer some of its beneficial effects on hepatic lipid metabolism via conversion to
E2 and subsequent activation of ERα.
hypogonadal men exhibiting a reduced lean body mass and an increased fat mass, abdominal or central obesity
visceral adipose tissue was inversely correlated with
bioavailable testosterone
there was no change in visceral fat mass in aged men with low testosterone levels
following 6 months of transdermal TRT, yet subcutaneous fat mass was significantly reduced in both the thigh and the abdominal
areas when analysed by MRI (Frederiksen et al. 2012b)
ADT of prostate cancer patients increased both visceral and subcutaneous abdominal fat in a 12-month prospective
observational study (Hamilton et al. 2011)
Catecholamines are the major lipolysis regulating hormones in man and
regulate adipocyte lipolysis through activation of adenylate cyclase to produce cAMP
deficiency of androgen action decreases lipolysis and is primarily
responsible for the induction of obesity (Yanase et al. 2008)
may be some regional differences in the action of testosterone on
subcutaneous and visceral adipose function
proinflammatory adipocytokines IL1, IL6 and TNFα are increased in obesity with a downstream effect that stimulates
liver production of CRP
observational evidence suggests that
IL1β, IL6, TNFα and CRP are inversely associated with serum testosterone levels in patients
TRT has been reported to significantly reduce these proinflammatory mediators
This suggests a role for AR in the metabolic actions of testosterone on fat accumulation and adipose tissue inflammatory
response
testosterone treatment may have beneficial effects on preventing the pathogenesis of obesity by inhibiting adipogenesis,
decreasing triglyceride uptake and storage, increasing lipolysis, influencing lipoprotein content and function and may directly
reduce fat mass and increase muscle mass
Early interventional
studies suggest that TRT in hypogonadal men with T2DM and/or MetS has beneficial effects on lipids, adiposity and parameters
of insulin sensitivity and glucose control
Evidence that whole-body insulin sensitivity is reduced in testosterone deficiency and increases with testosterone replacement
supports a key role of this hormone in glucose and lipid metabolism
Impaired insulin sensitivity in these three tissues is
characterised by defects in insulin-stimulated glucose transport activity, in particular into skeletal muscle, impaired insulin-mediated
inhibition of hepatic glucose production and stimulation of glycogen synthesis in liver, and a reduced ability of insulin
to inhibit lipolysis in adipose tissue