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78 J. Anagnostakos and J. H. Wolf
superior mesenteric artery. This condition usually results in a narrowed mesenteric
root, which predisposes the gut to a clockwise volvulus. The splenic flexure and
pylorus often remain fixed, however. The treatment of choice has classically been
open Ladd ’ s procedure during which four steps are performed including inspection
of the entire bowel, de-torsion of volvulus counterclockwise, lysis of Ladd bands
and appendectomy. Nonviable bowel can be resected as well. Some authors have
described a laparoscopic technique for treating this disease. The procedure involves,
introducing trocars into the abdomen, running the bowel and reducing the volvulus
laparoscopically, as well as dividing Ladd’s bands with laparoscopic shears or
energy devices.
Ischemia
Patients who have suspected mesenteric ischemia are often critically ill and not
suitable for minimally invasive approaches. In select patients, however, who are
hemodynamically stable and in whom the clinical suspicion for bowel necrosis is
low, exploratory laparoscopy can be an effective diagnostic approach. Laparoscopy
can be used for a planned “second look” operation in patients after laparotomy for
acute mesenteric ischemia or non-occlusive mesenteric ischemia. Several groups
have described this as a possible bedside procedure in the intensive-care unit.
Internal Hernia
Defects in the mesentery, either congenital or iatrogenic, can lead to internal herniation of small bowel. Laparoscopy can be performed to diagnose and reduce the
hernia and repair the defect. This is appropriate in patients who have no signs of
clinical deterioration to suggest bowel necrosis. If an internal hernia arises from a
minimally invasive operation, laparoscopy can often be effective in diagnosis and
repair without requiring additional abdominal incisions.
Contraindications
Laparoscopy is not indicated in patients with hemodynamic compromise or who at
baseline have severe cardiopulmonary dysfunction, uncorrected coagulopathy, or
abdominal wall infection or evisceration. A relative contraindication is a history of
multiple major open surgeries, or of a recent abdominal operation, due to the likely
prohibitive burden of intraabdominal adhesions.
10 Diagnosing Mesenteric Diseases: Laparoscopy 79
Complementary Procedures
Intra-operative Perfusion Assessment with Fluorescence
For several of the indications mentioned above, in particular mesenteric ischemia
and internal hernia, the use of intra-operative perfusion assessments can help assess
bowel viability laparoscopically. This can be performed as an adjunctive procedure,
by administering an intravenous fluorescent agent, such as indocyanine green, and
using a specialized laparoscope that can detect the emission wavelength from the
selected fluorophore.
Preparation of the Patient
Patients should be positioned supine in the operating room and placed under
general anesthesia with endotracheal intubation. The abdomen should be prepped
and a draped in a standard fashion.
Technical Details
Abdominal Entry
One of the most important steps in laparoscopy is safely entering the abdomen
without damaging intraabdominal structures. Two commonly used techniques are a
Hasson cut-down and utilization of a Veress needle. The authors’ preference is
Hasson cut-down technique, which involves creating an incision around the
umbilicus and then dissecting down to the level of the rectus abdominus muscle
under direct visualization . Then an incision is created in the fascia, and subsequently, the peritoneum. A 12 mm trocar is inserted and the gas is connected to it
causing the abdomen to insufflate. It is important to start on low flow and then
proceed to high flow once the pressure readings reflect that one is in the peritoneal
cavity and not the preperitoneal space. The other trocars are then inserted under
direct visualization.
The second method involves utilizing a Veress needle, which is a spring-loaded
needle usually with a diameter of 2–3 mm. First, a small skin puncture is created.
The safest area for insertion is in the left upper quadrant, 3 cm below the costal
margin in the midclavicular line (Palmer’s point), to avoid inadvertent bowel
puncture. The needle is then introduced at a 90-degree angle to the contour of the
abdominal wall. The technique of insertion involves listening for three audible
clicks which represents penetration through firs the anterior rectus sheath then the
posterior sheath and the peritoneum. Confirmation of entrance into the peritoneal
cavity is confirmed by instilling saline through the top of the needle and watching
80 J. Anagnostakos and J. H. Wolf
for a positive “drop test”. This is when the plastic ball which is located at the top of
the needle drops in the plastic housing representing free flow of the saline into the
potential space of the peritoneal cavity. The gas is then connected to the needle and
once insufflation is confirmed the other trocars are placed. Many surgeons elect to
place the first trocar using the “Opti-View” technique, which introduces the scope
and troca r through each layer of the abdominal wall under direct visualization until
it is confirmed that the trocar is in the abdominal cavity.
Exploration of the Peritoneal Cavity and Mesentery
Port placement will depend somewhat upon the suspected location of the target
pathology. In general, the distal small bowel mesentery will be easily accessible by
triangulating from two working ports in the left abdomen. The proximal small
bowel mesentery can be explored with two ports in the right abdomen. The bowel
and mesentery should be handled with atraumatic bowel graspers. The full length of
the mesentery can be inspected by sequentially “running the bowel” with
hand-over-hand technique. If pathology is encountered, it may require biopsy or
treatment depending upon the finding.
Abdominal Closure
Upon completion of the procedure, it is important to approximate the fascia to try to
prevent incisional hernias. If the trocar is less than 10 mm, the fascia does not
usually have to approxi mated since the size of the defect is small. However, if it is
10 mm and over, the fascia must be closed. Several techniques are available to
accomplish this. One of the most commonly used techniques is to place 0 vicryl
sutures on a UR-6 needle through the fascia at the beginning of the case in a
figure-of-eight fashion and to tie it down at the completion of the case. Another
technique is to use a Carter-Thomason device. This is a device with a grasper in it
which is deployed to grab the suture and has a needle at the end which can penetrate
the fascia. Each of these methods requires some extra time however is a crucial step
in preventing post-operative complications.
Suggested Reading
1. Parajuli P, Kumar S, Gupta A, Bansal VK, Sagar S, Mishra B, Singhal M, Kumar A,
Gamangatti S, Gupta B, Sawhney C. Role of laparoscopy in patients with abdominal trauma at
level-I trauma center. Surg Laparosc Endosc Percutaneous Tech. 2018;28(1):20–5.
2. Li Y, Xiang Y, Wu N, Wu L, Yu Z, Zhang M, Wang M, Jiang J, Li Y. A comparison of
laparoscopy and laparotomy for the management of abdominal trauma: a systematic review and
meta-analysis. World J Surg. 2015;39(12):2862–71.
10 Diagnosing Mesenteric Diseases: Laparoscopy 81
3. Lin HF, Chen YD, Lin KL, Wu MC, Wu CY, Chen SC. Laparoscopy decreases the laparotomy
rate for hemodynamically stable patients with blunt hollow viscus and mesenteric injuries.
Am J Surg. 2015;210(2):326–33.
4. Garofalo A, Valle M. Laparoscopy in the management of peritoneal carcinomatosis.
Cancer J. 2009;15(3):190–5.
5. Ooms N, Matthyssens LE, Draaisma JM, de Blaauw I, Wijnen MH. Laparoscopic treatment of
intestinal malrotation in children. Eur J Pediatr Surg. 2016;26(4):376.
Immunologic Function of the Mesentery
David H. Kruchko and Eli D. Ehrenpreis
Introduction
The gastrointestinal (GI) tract has two primary roles that are critical for the
preservation of internal stability of living organisms. Aside from functions related
to digestion and absorption of nutrients, fluids and electrolytes, the GI tract also
plays a critical role in the homeostasis of the immune system. Immune homeostasis
is characterized by the identification and immune response to potentially harmful
microbes while simultaneously avoiding an immune response to non-harmful
microbes. In immunocompromised patients, failed immune responses to harmful
pathogens can result in potentially life-threatening infections. Conversely, inappropriate immune response to benign, commensural organisms and food proteins in
the GI tract can lead to the development of autoimmune conditions including
Crohn’s disease and ulcerative colitis. The delicate balance between immune tolerance and inflammatory responses secondary to inappropriate immune reactions
has been a subject of much basic science research and clinical investigation. This
research has generally been focused on the intraluminal component of the GI tract
and has largely assum ed that breeches in the mucosal barrier provide an entry site
for pathogens. Mucosal-as sociated lymphoid tissue (MA LT) consists of lymphatic
cells and epithelial lining of the intestines and other mucosa throughout the body.
As shown in Fig. 11.1, the architecture of MALT provides an intimate connection
between the mucosal barriers and immunologic cells. It also contains a variety of
cell types with specialized roles in the recogniti on and reaction to antigens and
other foreign invaders.
11
D. H. Kruchko
Department of Internal Medicine, Advocate Lutheran General Hospital, Chicago, IL, USA
E. D. Ehrenpreis (&)
Department of Medicine, Advocate Lutheran General Hospital, 1775 Dempster St, 6 South,
Park Ridge, IL 60068, USA
e-mail: e2bioconsultants@gmail.com
© Springer Nature Switzerland AG 2021
E. D. Ehrenpreis et al. (eds.), The Mesenteric Organ in Health and Disease,
https://doi.org/10.1007/978-3-030-71963-0_11
83
84 D. H. Kruchko and E. D. Ehrenpreis
IgA
Mucous
Epithelial
cell
MHC II
B cell receptor
Lymphatic system
B cell
Dendritic cell
Peyer’s
patch
B cell
M cell
Antigen
T cell
Organized
lymphoid follicles
T cell
Fig. 11.1 Mucosal-Associated Lymphoid Tissue (MALT)—Functional anatomy and interplay of
immune cells. In this figure, the important first step that M cells play in antigen update is first
demonstrated. The inner surface of the M cell encapsulates the antigen so that antigen-presenting
cells (such as dendritic cells) can present the antigens onto the cell surface using MHC II
molecules. Antigen presenting cells then migrate to nearby tissue collections (Peyer’s patches.)
Within the Peyer’s patch, there is T cell, B cell, and antigen presenting cell aggregation forming
organized lymphoid follicles. This allows for T and B cell activation which then allows for antigen
presenting cells to be loaded with the antigen and migrate throughout the lymphatic system.
Subsequent formation of antibodies such as IgA allows for secretion into the intestinal lumen
More recently, attention has focused on the mesenteric components of the
immune system and its relationship to gastrointestinal function. The mesentery can
be defined as an individual organ system by its contiguous nature and the integrated
components of the intramesenteric lymphatic, vascular, and neurological systems.
This view also defines the mesentery as an organ of the immunologic system.
The mesoderm is one of three germ layers that comprises embryonic development. The mesodermal germ layer surface is lined with mesothelial cells on both a
ventral and a dorsal side of the mesentery. The ventral aspect of the mesentery is
effectively lost during maturation at the midgut, but the dorsal aspect persists and
11 Immunologic Function of the Mesentery 85
makes up the majority of the adult mesentery. The architecture of primitive
intestinal loops is created by the embryonic mesentery and the mesothelial cells that
are created by this mesodermal origin begin to function as primitive immune cells.
Most notably, inflammatory cells such granulocytes are formed as a first line of
defense for innate immunity responses. The unique ability of the mesentery to
simultaneously be both a fixed and freely moving organ provides ideal positioning
throughout the gastrointestinal tract for environmental sampling. When an invading
foreign substance is sampled by the mesentery, it is well positioned to mediate local
responses by utilizing granulocytes and other inflammatory cells. It is also capable
of mediating systemic responses by coordination with the nearby organs that will
effectively utilize local lymph nodes to prompt an adaptive immune response. The
adaptive immune response is a component of the immune system that is composed
of more specialized cells that can travel systemically in order to respond to and
eliminate invading pathogens. Local lymph nodes are known as mesenteric lymph
nodes and are scattered throughout the mesentery, thereby playing a critical role in
sampling the commensal bacterial organisms within the GI tract as well as those
from the environment. If the organisms are recognized as invaders, the mesenteric
lymph nodes then regulate migration of B cells, T cells, natural killer (NK) cells,
and dendritic cells to the adjacent mucosa.
Innate and Adaptive Responses of the Immune System
The mesentery, like many of the body’s organs, can prompt both an innate, or a
rapid but non-specific, immune respon se, as well as an adaptive, or a slower but
more directed immune response (Fig. 11.2). Innate immunity is an important first
defense and primarily relies on epithelial and mucosal linings that develop during
embryogenesis. The physical barriers that these linings provide against pathogens
and invade rs rely on macrophage activity. Macrophages play a vital role in identifying bacterial or viral components and secrete cytokines (small molecules that
recruit inflammatory and immune cells locally) in response to foreign invaders.
Macrophages do so by using Toll-like receptors (TLRs) to identify the bacterial
lipopolysaccharide (LPS), which are specifically seen on gram-negative bacteria
found in the GI tract. TLRs are also helpful in identifying double-stranded RNA
(dsRNA) that are specific viral features. Once TLRs identify these specific characteristic bacterial and/or viral components, they secrete cytokines to request
assistance from other cells but also activate macrophage phagocytosis, or the
process of ingesting foreign molecules.
Other cells of the innate immune system include mast cells, neutrophils (or
polymorphonuclear neutrophils, PMNS), macrophages, eosinophils, basophils,
natural killer cells (NK cells; can be classified as either innate or adaptive),
gut-associated lymphoid tissue (GALT), and dendritic cells, as outlined in
Table 11.1.
86 D. H. Kruchko and E. D. Ehrenpreis
pathogen
antigen-independent
INNATE RESPONSE
(macrophages, NK, basophils,
neutrophils, eosinophils)
ANTIGEN PRESENTATION
(macrophages, dendritic cells)
antigen-dependent
ADAPTIVE RESPONSE
(T- and Th-cells, B-cells)
Fig. 11.2 Fundamental immune response outline. Activation of the immune system begins with
the antigen-independent innate immune system after exposure to a pathogen. This response can be
described as nonspecific attempts at detecting and destroying the pathogen. If this is unsuccessful,
antigen presentation occurs and serves to activate the adaptive response. As it relates to the
mesentery, this step is critical and relies on the dendritic cells. The adaptive immune system can be
described as an antigen-dependent response as it responds to and destroys pathogenic cells that
have specific antigens. It is important to note, however, that these are not disparate roles of the
immune system, but rather successive and sequential components that are interdependent on one
another
The cellular differentiation of both innate immune cells and adaptive immune
cells is demonstrated in Fig. 11.3. Mast cells provide an inflammatory response by
releasing granules and histamine to defend against pathogens and can be found in
mucous membranes connective tissues. PMNs are phagocytic, as macrophages are,
and act as the first line of defense to mount immune responses by releasing granules
and other toxic substances to bacteria and fungi. As mentioned at the beginning of
this section, macrophages have a more specific role than PMNs and can activate the
adaptive immune response via cytokine secretion as well as phagocytosing cells
infected with bacterial/viral components. Eosinophils specifically directly target
11 Immunologic Function of the Mesentery 87
Table 11.1 Immune cell types and their functions and locations
Innate immune
cells
Mast cells Inflammatory response via histamine
Neutrophils First line of defense via phagocytic
Macrophages Recognize bacterial/viral components
Eosinophils Release toxic free radicals targeted at
Basophils Release histamine like mast cells but
Natural killer
cells (innate
and/or adaptive)
Gut-associated
lymphoid tissue
Dendritic cells
(DC)
Function Location
release
mechanisms
and secrete cytokines and
phagocytose infected cells
parasites and some bacteria
target parasites like eosinophils
Destroy the entire host containing cell
instead of pathogen only
Mucosal barrier that acts as the first
line of defense
Antigen-presenting cells, responsible
for immune response initiation and
activation
Mucous membranes of
connective tissues
Found in all tissues, shortest
lifespan, recycled frequently
Peripheral blood and all tissues
Found in all tissues
Found in all tissues
Peripheral blood and all tissues
Throughout the intestinal
mucosal lining
Found both in the external
environment, e.g. epidermis,
and internal mucosal lining
parasites and secrete toxic proteins as well as free radicals to kill parasites as well as
some bacteria. Basophils similarly attack multi-cellular parasites but release histamine in a manner that is similar to mast cell histamine release. NK cells do not
attack pathogens directly but rather destroyed the host cell that contains the
pathogen.
Aside from functioning as a mucosal barrier, first line of defense, and integration
with mesenteric lymph nodes to sample and initiate responses to foreign invaders,
GALT also con tains clinically important lymphatic tissue arranged anatomically as
Peyer’s patches. Peyer’s patches are aggregated lymphoid follicles that are primarily present in the wall of the ileum. They function to monitor intestinal bacteria
to allow for the growth of commensal organisms but also to prevent the proliferation of pathogenic organisms. Dendritic cells are a form of antigen presenting cell
that are responsible for direct contact with the external environment via the inner
mucosal lining of the GI tract. Furthermore, dendritic cells effectively act as a
bridge from locations where the innate immune system is less effective, but the
adaptive immune system has yet to be activated. Dend ritic cells have an important
in the function within the mesentery. Lastly, the complement system is complex and
multifactorial, but essentially works as another bridge between the innate and
adaptive immune system and allows for removal of antigens by multiple
mechanisms.
88 D. H. Kruchko and E. D. Ehrenpreis
Multipotential hematopoietic
stem cell (hemocytoblast)
Common myeloid progenitor Common Iymphoid progenitor
Megakaryocyte
Erythrocyte Mast cell
Basophil Neutrophil Eosinophil Monocyte
Innate response cells
Myeloblast
Macrophage
Natural killer cell
(large granular
lymphocyte)
Adaptive response cells
Small lymphocyte
T lymphocyte B lymphocyte
Plasma cell
Fig. 11.3 Cell differentiation in the innate and adaptive immune response. Cell lineage of the
innate immune response cells starts with a common myeloid progenitor and then further develops
as shown above. There are many commonalities between cells in the innate immune system and all
perform nonspecific functions. Cell lineage of the adaptive immune response shows a common
lymphoid progenitor cell. The lymphoid components of these cells allow for differentiation into
either B or T cells for a more tailored immune response. Natural killer (NK) cells are listed on the
adaptive immune response side, but really they can be identified as both types of immune
responses any many texts will associate them with the innate response cells
The innate immune system can function independently for certain pathogens, but
frequently the activation of the adaptive immune system is also required to provide
a complete immunologic response. The adaptive immune system relies on lymphocytes that are activated by cytokines. Lymphocytes are made up of B and T
cells. B cells secrete antibodies or (immunoglobulins), molecules made up of
protein that bind to specific antigens that are present on pathogens. Antigens are can
either be identified in an extracellular location on a specific pathogen or they can be
found unbound and free-floating within the host circulation. The binding of antibodies and antigens prompts attack mechanisms to destroy invading pathogens.
After this antibody-antigen binding, B-cell subtypes go on to become memory cells
to prevent re-infection and/or shorten the duration of symptoms during re-infection.