CHAPTER ONE
1.0 INTRODUCTION
The prevalence nature of micro-organisms caused the human body to
develop a natural defense system against the adverse effects of these
organisms (Pick et al, 2008). A complex network of specialized
cells, glands, organs, specialized proteins and molecular messengers
make up the body defense system which is typically known as the “IMMUNE
SYSTEM”, and this immune system prevents bacteria, fungi, viruses,
parasites and any other external antibodies from over multiplying
inside the body and inflicting harm to the body system and processes
(Godfrey et al, 2006).
The immune system which is the body’s natural defense system against
invading pathogens protects the body from infection and works to
communicate an individual well being through a complex network of
interconnected cells and cytokines (Tang et al, 2009). This
system has the power to initiate a wide range of cellular responses with
the ability to directly attack an invading organism or signal cells to
begin the healing processes (Gartner and Hiatt, 2007).
Although this system is an associated host defense, an uncontrolled
immune system has the potential to trigger negative complications in the
host (Walter 2007; Kushner, 2003). Therefore, well controlled
regulation of the immune system is necessary in order to prevent
autoimmune responses from occurring (Morran et al, 2008).
In order to protect the body against foreign pathogens, the immune
system has developed throughout evolution to recognize the difference
between the ‘Self and non-self’ cells. The ability to become self –
tolerant toward the body’s own proteins and antigens is critical to
maintaining a properly functioning immune system (Bruce et al,
2010). An immune system that loses tolerance to the “Self” cells loses
ability to differentiate between “friends” and “foes” in immunological
battles (Kushner, 2003; Walter, 2007). This loss of tolerance leads the
immune system towards autoimmune responses, in which the body attacks
itself, thereby causing substantial damage to the self, even inflicting
irreversible damage (Litman et al, 2005).
The immune system is composed of two unique components or branches,
each with its own responsibilities. The innate immune system is the
body’s first-line of defense against invading pathogens. This system
recognizes common structural components of pathogens and elicits immune
response to signal the presence of pathogens and infections (Mayer,
2006). The adaptive immune system is the body’s second-line of defense
and especially targets identified pathogens. This system is antigen –
specific and generates immunological memory within the host, which
allows for more efficient pathogen clearance upon repeat exposure to the
same pathogens (Agerbeth and Gudmundson, 2011). Although, these two
immune systems are termed different branches of the immune system, they
must work together as one unified system to protect the body (Ogawa and
Calhoun, 2010).
The immune system protects the host, but it also posses the ability
to harm the host as well. Numerous autoimmune diseases have been
characterized overtime (Godfrey et al, 2006; Pick up et al, 2008; Morran et al,
2008). The result of the autoimmune system leads to alternations in the
functioning of the immune system, due to genetics, cellular
malfunctions or cell signaling functions and this in turn, leads to the
development and pathogenesis of autoimmune diseases like diabetes
mellitus (Von and Oldstone, 1997).
Diabetes mellitus is a disease characterized by the body’s inability
to accurately maintain normal blood glucose levels, leading to multiple
detrimental effects (Shoback et al, 2011). Insulin is an
important hormone in glucose metabolism. When insulin is released, it
signals cells to take up glucose. If the body is unable to produce
insulin, blood glucose level remains elevated and this is termed
hyperglycemia (Rother 2007).
Diabetes mellitus is an autoimmune disease, in which the immune
system targets and destroys the insulin – producing beta cells found in
the Islets of Langerhans in the pancreas (Delovitch and Singh, 2012).
Without insulin, individuals develop the clinical syndrome of diabetes
mellitus. Diabetes mellitus is characterized by auto-antibody production
and progressive infiltration of immune cells into the Islets of
Langerhans in the pancreas, followed by the destruction of the Islets
cells (Bardsley and Want, 2004). Studies using human and murine models
of diabetes have demonstrated that, the autoimmune destructive process
in diabetes mellitus occurs in a cell – mediated organ – specific manner
(Nepom, 1995; Yoon and Jun, 2001).
Diabetes mellitus is a chronic disease, for which there is no known
cure except in very specific situations (Janeway, 2007). Medically, the
management of diabetes mellitus concentrates on keeping the blood sugar
levels as close to normal (euglycemia) as possible, without causing
hypoglycemia (Delovitch and Singh, 2012). This can usually be
accomplished with diet, exercise and the use of appropriate medications
(insulin). Diabetes mellitus is typically managed with a combination of
regular neutral Protamine Hagedorn (NPH) insulin or Synthetic insulin
analogs (Ripson et al, 2009).
Despite the medical development to curb the increased cases of
diabetes, it in still prevalence in the society, hence, this project
work “Assessment of the defense system in diabetic rats treated with
aqueous leaves extract of Terminalia catappa”, to find out if there is a curative agent in the leave of Terminalia catappa based on the recent report of Ahmed et al,( 2005) on the leaves.
The universal role of plants in the treatment of disease is
exemplified by their employment in all major systems of medicine
irrespective of the underlying philosophical premise (Cunningham et al,
2005). There is a great wealth of knowledge concerning the medicinal,
narcotic and other properties of plants that is transmitted orally from
generation to generation by tribal societies, particularly those of
Tropical Africa, Asia, North and South America and the pacific countries
(Duke, 2002).
Ahmed et al (2005) reported that, the leaves of Terminalia catappa contain
several flavonoids, tannins, saponins, triterpiniod and phytosterols.
Due to the above chemical richness, the leaves are used in different
traditional medicines for various purposes worldwide. They also reported
the biochemical effects of administering Terminalia catappa Linn
aqueous and cold leaf extracts, orally and showed that it caused the
regeneration of the Beta cells of the Islets of Langerhans, decreased
blood sugar, serum cholesterol, triglycerides, low density lipoprotein
(LDL), creatinine, urea and alkaline phosphatase levels, while
increasing the high density lipoprotein (HDL) level in diabetes mellitus
(Nyarko and Addy, 1997). However, not much is reported about the
various blood cells involve in the body defense system.
Considering the development of diabetes mellitus to be immune system
related, it become of interest to find out what could be the possible
state of the body defense system comparatively in diabetic and
non-diabetic conditions.
The study will cover the aspect of differential white blood cell
count and serum globulin levels as a preliminary investigation on the
body defense system.