Biology Reference
In-Depth Information
pituitary GH and PRL, which share signal transduction pathways with type I CTKs,
are available right in the serum to support the IS until recovery. Clearly, GLH (GH,
PRL, and placental lactogens) are involved in the development of the IS, including
the bone marrow, thymus, and maintain naïve lymphocytes until they are primed with
antigen (e.g., maintenance of immunocompetence). GLH are involved in regeneration
of immune function after severe immunosuppressive insults to the body. Compelling
experimental and clinical evidence supports the involvement of PRL in autoimmune
disease and in cancer.
Much has been established within the first two decades. It became clear that the
nervous, endocrine, and immune systems interact continuously and integrate, coor-
dinate, and regulate all bodily functions, including host defense, from conception till
death. Hence the term neuroimmune Biology was introduced to name this field.
Meanwhile, a second form of immunity has been recognized in immunol-
ogy, which is with us from conception till death. This immunity is called INIM or
NATIM. Unlike ADIM, where clones of lymphocytes need to proliferate first in
order to mount a specific immune response, which takes 5-7 days, the cells of the
INIM system are fully differentiated and bare functional innate antigen receptors
(INIR), which recognize evolutionarily conserved and highly cross-reactive homol-
ogous epitopes (homotopes). Pathogenic microbes degenerated and cancerous cells
and even normal tissue components may express homotopes. Thus, the INIM system
is the first to defend the host with its instantaneous capacity to respond, and it is with
us for our last moment of life.
It has been discovered within the past few years that INIR is expressed in the
CNS, in glia cells but also by neurons and their dendrites. This indicates that the
CNS is an integral member of the INIM system. It is capable to recognize infection
rapidly and respond instantaneously by neurogenic inflammation and by the activa-
tion of immunological responses in order to eliminate the problem. Other organs and
cells also express TLR, such as leukocytes, the pituitary gland, the adrenal gland, the
liver, in mucosal epithelial cells, endothelial cells, in vascular smooth muscle, and in
the cornea. Therefore, the entire body participates in INIM reactions. The pituitary
produces POMC in response to LPS (TLR4 is involved), mucosal epithelial TLR
participates in inflammation and responds to pathogens, corneal TLR was found to
fight infection, and endothelial TLR was observed to play important roles in homeo-
stasis of the heart. Therefore, both the INIM and ADIM systems also fulfill impor-
tant physiological functions.
The activation of the INIM system, with or without adaptive immunity, is capable
of exerting a profound host defense response to diverse noxious agents. Clearly this
NISS, which is directed by the CNS, is capable of mobilizing the entire organism
in the interest of host defense in emergency situations (such as acute illness, APR).
NISS also performs important physiological functions, as is becoming apparent.
The regulatory network in NISS consists of
hierarchical regulatory circuits
, which
are superimposed on each other. For example, regulatory signals from the CNS are
capable of dominating the signals from lower circuits (e.g., pituitary). As we know,
pituitary hormones control hormones secreted by the adrenals, gonads, thyroid, liver,
and other tissues that secrete IGF. CTKs represent another regulatory circuit.
