Advances
in Scleroderma Research, 2002
By Carol Feghali, Ph.D., Research Assistant Professor of
Medicine, University of Pittsburgh (originally published in
"Scleroderma Voice," 2003 #1)
Editor's note: This is a long article. You can skip
directly to the sections that interest you, by clicking on
these links:
The annual meeting of the American College of Rheumatology
(ACR) was held in New Orleans, Louisiana, October 25–29,
2002. The research presented on systemic sclerosis (SSc) during
the meeting included clinical studies, epidemiological studies,
and basic research.
Reproduction in SSc
 |
| Figure
1. Fetal Microchimerism. Fetal cells
enter the mother's blood via the placenta. If the fetus
is a male, the fetal cells are identified by the Y chromosome. |
The detection of chimeric cells in patients with SSc has
resulted in extensive studies examining the role of pregnancies
in the disease.
Fetal microchimerism refers to the presence of fetal cells
which have persisted for many years in the blood and tissues
of patients with SSc (Figure
1). For example, the male Y-chromosome can be identified
in the blood of women with SSc who have had male children.
Fetal Cells Identified as T Lymphocytes
Investigators in Philadelphia, Penn., reported that fetal
cells can be detected in both clinically affected and unaffected
skin of patients with SSc. These cells were found to be T
lymphocytes, which are a type of white blood cell (WBC) believed
to be important in the development of SSc.
Fetal Cells Present in Women Who Have Never Been Pregnant
Investigators in Seattle, WA, have also detected male fetal
cells in the blood of SSc and healthy women who have never
had sons and those who have never had children, miscarriages,
or abortions. The researchers suggest that the male cells
may have been transferred to these women from their mothers
during pregnancy after their mothers had a son, since all
had one or more older brothers.
Speculation that Reproduction Is a Risk Factor for SSc
Thus there are many possible sources of chimeric cells. The
presence of these fetal cells and the increased occurrence
of SSc in women, especially during childbearing years, have
led to the speculation that reproduction may be one of the
risk factors for the development of SSc.
Brazil Study Suggests Pregnancy Not a Factor
A reproductive study from Brazil examined pregnancy factors,
including the number of pregnancies and the number of abortions
in 118 patients with SSc and 72 patients with rheumatoid arthritis
(RA) using a questionnaire. Their results indicate that pregnancy
does not result in an increased risk or a protective effect
for RA or for either limited cutaneous or diffuse cutaneous
SSc.
Important to Control Mother’s Blood Pressure During
Pregnancy
Pregnancies in SSc usually result in the birth of healthy
infants.
For SSc patients with kidney failure, pregnancy can be complicated.
An investigator in Washington, D.C., examined the outcome
of pregnancy in 10 patients with SSc affecting the kidney,
five of whom remained on angiotensin converting enzyme (ACE)
inhibitors for control of blood pressure during their pregnancy,
and five of whom discontinued this type of drug.
All five patients who continued taking ACE inhibitors during
pregnancy gave birth to healthy infants.
Among the five taken off ACE inhibitors during pregnancy,
there were three healthy infants, two small infants, and one
stillbirth.
The latter five patients received other medications for blood
pressure control.
Patients with the worst pregnancy outcome were those whose
blood pressure was not well controlled with other medications.
Swedish Data Inconclusive on Possible Relationship Between
Pregnancy and SSc
Reproductive history of SSc patients in a Swedish population-based
registry was examined by investigators from Durham, NC, and
Stockholm, Sweden.
The registry included a hospital inpatient listing covering
the period from 1964 to 1999 and a national fertility listing
covering the years since 1925.
Twenty-four percent of SSc patients in the registry never
had children (nulliparous). Nulliparity was associated with
an increased risk for SSc.
One of the drawbacks of these data is that information on
spontaneous and induced abortions was not available.
Another possible interpretation is that pregnancy may have
a protective effect in scleroderma, which is the opposite
of the theory proposed above by microchimerism investigators.
Alternatively, patients with SSc may have some degree of
infertility after their diagnosis, although this was not found
to be the case in a study presented last year involving 214
women with SSc from the Pittsburgh database. In this previous
study, women with SSc did not have reduced fertility compared
to those with rheumatoid arthritis (RA) or healthy control
women.
Autoantibody Disease Markers
 |
| Figure
2. Antigen-Antibody Recognition.
An antibody recognizes a specific antigen (antibody generator)
and binds to it. |
Autoantibodies are antibodies generated against self-proteins,
also known as antigens (Figure 2).
In most cases, these antigens are proteins found in the nucleus
of normal cells.
Autoantibodies have been detected in the blood of patients
with SSc and other connective tissue diseases (CTDs) such
as systemic lupus erythematosus (SLE), polymyositis/dermatomyositis
(PM/DM), and Sjögren’s Syndrome (SS). Some of these
antibodies are strongly associated with SSc (that is, they
seldom occur in other diseases), e.g. anti-topoisomerase I,
anti-RNA polymerase, anti-Th/To, anti-RNP, and anti-centromere,
and sometimes these antibodies are associated with a higher
risk for a particular internal organ involvement.
For example, SSc patients with autoantibodies against topoisomerase
I (Scl-70), a protein whose normal function is to unwind DNA
prior to cell division, have a high frequency (60-70%) of
lung fibrosis. The presence of anti-RNA polymerase antibodies
is correlated with the complication of “renal crisis.”
Korean Researchers Identify New Autoantibody
Researchers in Korea recently identified a new autoantibody
in the blood of patients with SSc which recognizes a protein
known as DNA binding protein B (Dbp B).
This antibody was not specific to SSc since it was detected
in the blood of 40% of SSc patients and 7% of healthy controls
and individuals with other CTDs.
The antibody was found in a larger proportion of patients
with diffuse cutaneous SSc (55%) than with limited cutaneous
SSc (24%).
|
| Researchers have found
several autoantibodies and other disease markers that
correlate with the severity and type of scleroderma. Some
of these findings suggest new directions for treatment. |
Japanese Researchers Detect Anti-Wa Antibody
Another rare antibody was described by researchers in Japan
and called anti-Wa antibody. It was detected in the blood
of patients with SSc, RA, and also other CTDs, but most frequently
in SSc patients.
Centromere Regions Found to Be Different in SSc Patients
Antibodies against centromeres in the nucleus of cells are
identified in the blood of some patients with SSc, especially
those with limited skin thickening, but also in persons with
SS, SLE, and certain cancers.
Two different groups of investigators, one in Oklahoma City,
Okla., and one in Baltimore, Md., have found that specific
regions in the centromere that are recognized by these antibodies
are different in SSc patients than in those with other autoimmune
diseases.
Australian Researchers Find SSc Antibody That May Inhibit
Colon Contraction
A research group in Adelaide, Australia, examined the blood
of SSc patients and healthy controls for the presence of antibodies
that may prevent intestinal muscle contraction and thus contribute
to intestinal malfunction.
When added to the colon (large intestine) of a mouse that
had been stimulated to contract, the antibody from 7 of 9
SSc patients prevented the contraction of mouse colon.
Non-Antibody Disease Markers
Several additional markers of disease severity and internal
organ involvement were described.
Type I Collagen in Blood of SSc Patients Correlates with
Skin and Lung Involvement
Increased production of molecules accumulating around tissue
cells, such as collagen, results in the thickening of skin
and internal organs in patients with SSc.
Research conducted in Paris, France, showed that fragments
of the most common type of collagen (type I) are increased
in the blood of patients with SSc and correlate with the severity
of skin and lung involvement.
CD44 May Mark Less Severe Fibrosis
Studies from Kanazawa, Japan, suggest that another molecule,
cluster of differentiation 44 (CD44), is increased in the
blood of SSc patients with limited compared with diffuse skin
fibrosis.
In addition, patients with lung fibrosis had lower levels
of CD44 in their blood than patients without lung involvement.
Thus CD44 may be a marker of less severe fibrosis in SSc.
CD44 promotes the rolling of WBCs along blood vessels. Its
absence may reduce the ability of WBCs to escape from blood
vessels and to initiate the inflammation that precedes fibrosis.
Reduced Ability to Prevent Blood Clotting in SSc
One of the initial problems in SSc is a reduction in oxygen
level (hypoxia) in the skin and internal organs, which injures
cells. Endothelial cells (the cells which line blood vessels)
play an important role in this process.
Researchers from Toledo, Ohio, and Florence, Italy, conducted
a study on endothelial cells in small blood vessels in the
affected tissues of patients with SSc. They noted that these
cells in patients with SSc have a reduced ability to prevent
blood clotting compared with those of healthy individuals.
These results were supported by research conducted in Florence
and Ancona, Italy, in which investigators measured blood levels
of factors which cause breakdown of blood clots in SSc patients
and found some to be higher and some to be lower compared
with those in healthy controls.
These findings suggest that treatments targeting the blood
clotting system may be of benefit in SSc.
The Role of Hypoxia in SSc
To examine the role of hypoxia, investigators from Switzerland,
Italy, and Germany grew skin biopsy cells known as fibroblasts
and exposed them to low oxygen (hypoxic) conditions. Hypoxic
SSc fibroblasts had increased “expression” of a
small group of genes involved in the production of collagen.
Another group from London, U.K., reported that an enzyme
known as xanthine oxidoreductase (XOR) is increased in fibroblasts
from the skin of SSc patients. XOR can bind to collagen and,
under low oxygen conditions, can cause an increase in the
levels of reactive oxygen species, which may in turn be responsible
for the abnormally active fibroblasts in SSc.
Using Microarray Technology to Examine Gene Expression
Expression of genes was also examined by investigators in
Houston, Texas, in fibroblasts grown from the skin of a pair
of identical twins, one with SSc and the other healthy.
|
| Some investigators
are using microarray analysis to identify which genes
are "switched on" or "switched off"
in scleroderma and related diseases. |
They used “microarray analysis,” which allows identification
of genes that are “switched on” or “switched
off.” Some genes were switched on in the skin of the
patient with SSc, while others were switched off compared
to the skin of the healthy twin.
They also showed that genes were detected at abnormal levels
in both the affected and apparently unaffected skin of the
SSc patient, indicating that apparently unaffected skin cells
had begun the early stages of activation.
Investigators also used microarray technology to compare
the genes expressed in SSc skin to those expressed in the
skin of patients with a SSc-related disease known as sclero-myxedema.
Some of the genes that are switched on in sclero-myxedema
were the same as those switched on in scleroderma.
Newly Identified: Nephrogenic Fibrosing Dermopathy
Another disease related to SSc that has been identified recently
is Nephrogenic Fibrosing Dermopathy (NFD). Patients with this
disease develop skin features of SSc with involvement of deeper
tissues (fasciitis) after being on kidney dialysis.
Investigators in Philadelphia, Pa., noticed that skin specimens
from NFD patients had increased levels of proteins and cells
also found to be elevated in the skin of SSc patients.
Fibroblasts grown from the skin of NFD and SSc patients both
produced excessive amounts of collagen.
Progress in Identifying Markers for Lung Involvement
One of the ways to examine inflammation in the lung is to
do a bronchoscopy, insert some fluid into the lung, and then,
after several minutes, suck back the fluid for analysis. This
procedure is called a bronchoalveolar lavage (BAL). The number
of WBCs recovered in BAL fluid usually indicates the degree
of inflammation in the lungs.
In research work from Baltimore, Md., investigators examined
BAL fluid WBCs of patients with SSc and found that these cells
were “active” or “turned on,” which may
explain their role in lung inflammation.
In a study from Switzerland and Poland, investigators found
that the levels of two products known to promote inflammation
and fibrosis, leukotriene B4 (LTB4) and E4 (LTE4), respectively,
were increased in the BAL fluid from the lungs of 30 patients
with SSc who had lung involvement compared with 10 healthy
non-smoking controls.
The levels of LTB4 and LTE4 were highest in SSc patients
who had the most severe lung inflammation, thus suggesting
they are markers of inflammation or they may be participating
in the inflammation.
Treating SSc
Calcium deposits (calcinosis) in and under the skin are common
in SSc, especially in patients with the limited cutaneous
subtype (old term “CREST variant”).
Minocycline Appears to Be Effective in Treating Calcinosis
|
| Minocycline
was studied as a treatment by several researchers. It
was not found effective in treating skin thickening, but
seemed to improve calcinosis and finger ulcerations. |
Researchers from Plymouth, England, examined the effect of
50 mg or 100 mg daily of the antibiotic minocycline on calcinosis
in 9 patients with limited cutaneous SSc.
Minocycline was tested because of its ability to bind to
calcium and remove it from the circulation (chelation) and
because of its antibacterial properties which help prevent
secondary infections.
Eight of the 9 patients studied showed improvement in calcinosis
and finger ulcerations related to calcinosis as early as one
month after initiation of treatment.
Deposits which decreased in size while on minocycline became
more prominent after discontinuation of treatment.
Minocycline Appears Not to Be Effective in Treating Skin
Thickening
The effect of minocycline on skin thickening was examined
by investigators from Houston, Texas, Detroit, Mich., Milwaukee,
Wis., and Farmington, Conn., in 31 patients with SSc.
Ten patients did not complete the study due to worsening
of their disease; and in those who did finish the study, there
was no beneficial effect of minocycline on skin thickening.
ECL Found Effective in Treating Soft-Tissue Calcification
A different approach was used by investigators in Tucumán,
Argentina, who used extracorporeal lithotripsy (ECL) to treat
soft tissue calcification in patients with SSc, juvenile dermatomyositis,
and calcific tendinitis of the shoulder.
ECL is a procedure commonly used to break up kidney stones
using sound waves. Each session lasted 40 minutes, and most
SSc patients received only one session.
Deposits became smaller and disappeared two weeks after the
treatment.
Benefit included resolution of pain and improvement of joint
mobility, which began at 24 hours after treatment and lasted
up to four years after the procedure. There were no adverse
effects.
Follow-Up on KPAB Treatment Implies Lasting Benefit
A treatment study of aminobenzoate potassium (KPAB) was conducted
about 10 years ago and included 146 patients with SSc; no
improvement in skin thickening was found.
The same investigators in Salt Lake City, Utah, recently
did a follow-up on the patients who had participated in the
original study to determine their current status. Their data
showed that patients who had received KPAB for at least 3
months had a lower death rate compared to patients who did
not receive KPAB.
TNFa Treatment Creates Temporary
Lupus-Like Symptoms
Drugs that block tumor necrosis alpha (TNFa),
such as Etanercept and Infliximab, are used for the treatment
of RA and other joint diseases. One of the side effects of
these drugs is the development of a lupus-like disorder.
These agents were used to treat two patients in Baltimore,
Md., who had both SSc and RA, both of whom subsequently developed
a lupus-like disease that resolved when the TNF blockers were
stopped.
Study Suggests Lung Benefit from Iloprost
Lung involvement in SSc predominantly occurs in the form
of pulmonary fibrosis (PF) or pulmonary hypertension (PHT).
The latter can be present with or without PF.
When PHT occurs without PF, it can be effectively controlled
with drugs called epoprostenoids.
Studies conducted in London, England, suggested that patients
with PHT secondary to PF also benefit from Iloprost, a related
drug treatment.
Alefacept Shows Lung Benefits
Investigators in Baltimore, Md., tested the effect of the
drug Alefacept on lung disease in SSc patients. Alefacept
prevents the activation of T lymphocytes.
Patients were treated for 12 weeks with weekly intravenous
infusions of Alefacept. After treatment, the investigators
showed that the number of blood and BAL T lymphocytes and
other inflammatory WBCs was reduced.
During the study period, lung function remained stable, neither
improving nor deteriorating. Alefacept was well tolerated.
Follow-Up on Autologous Stem Cell Transplantation Shows
Lung Disease Recurrence
|
| Patients who underwent Autologous Stem Cell
transplants had only temporary improvement in lung function. |
An experimental treatment for SSc is autologous stem cell
transplantation (ASCT). In this approach, “stem cells”
are isolated from the patient’s blood and stored.
The patient is then given chemotherapy and total body irradiation,
which eliminate the immune system cells.
The stored “stem cells” are then given back to
the patient to reconstitute the immune system with new cells.
The theory is that a “normal” immune system will
result, replacing the defective immune system which might
have caused or perpetuated SSc.
A study examining lung inflammation and lung disease severity
in patients with early, severe SSc who underwent ASCT suggests
that these patients had temporary improvement in lung function.
Unfortunately, recurrence of lung disease occurred about
one year after ASCT. Three of the six patients in the study
had a relapse of their lung disease and the other three developed
new lung inflammation (alveolitis) during follow-up.
Follow-Up on Prostaglandin Treatment for Pulmonary Fibrosis
Last year’s review of advances in SSc research included
results of a study from Kawasaki, Japan, in which lipid microspheres
containing prostaglandin E1 (PGE1) were used to treat pulmonary
fibrosis (PF) in SSc patients. The results showed stabilization
of lung disease.
Prostaglandins are usually used to decrease the narrowing
of blood vessels (vasospasm) that occurs in Raynaud’s
phenomenon.
In last year’s study, PF in SSc patients receiving PGE1
progressed more slowly than in those not treated.
This year, the same investigators reported the effect of
blocking the prostaglandin E2 (PGE2) receptor in an animal
model of lung disease in which lung fibrosis develops in mice
treated with the chemotherapeutic agent bleomycin. Mice in
which the PGE receptor was blocked had less lung inflammation
than untreated mice.
Prostaglandin Treatment for Raynaud’s Needs Larger
Study
Investigators in Milan, Italy, followed blood markers in
10 SSc patients to monitor the effect of prostaglandin E1
cyclodextrin (PGE1), which was used for the treatment of severe
Raynaud’s phenomenon.
In addition to widening (dilating) blood vessels, PGE1 can
also protect vascular endothelial cells.
The study results suggest that a maintenance dose of 60 µg
once per month does not completely protect endothelial cells,
and thus more frequent injections or higher doses may be more
effective.
A study examining a larger number of patients is needed.
Mouse Model for Lung Fibrosis
 |
| Figure
3. Receptor-Ligand Interaction.
A receptor located on the surface of a cell is recognized
by a ligand (e.g. prostaglandins, TGFb). The receptor
and the ligand fit like a lock and key. When the ligand
binds the receptor, a signal is transmitted into the cell
generating a ligand/ receptor-specific reaction. |
Two difficulties in conducting research on SSc are the limited
number of human skin samples and the lack of a good animal
model for research.
One model used for lung fibrosis is obtained by delivering
bleomycin, a drug used for treating some cancers, to the lungs
of mice via the trachea.
In research presented by investigators in Chicago, Ill.,
the skin of mice was injected with bleomycin, causing WBCs
to migrate into the skin from blood vessels.
Bleomycin resulted in activation of proteins which can increase
collagen production. The effect was similar to that demonstrated
in the laboratory using transforming growth factor beta (TGFb),
which is known to be activated in a wide variety of fibrotic
conditions.
In work from London, England, and Houston, Texas, investigators
used another animal model for studying SSc. They generated
mice missing the intact receptor for TGFb. A “receptor”
is a protein found on the surface of cells which can bind
its “ligand,” such as TGFb,
and start a cascade of signals in the cell (Figure
3).
These mice develop skin and lung fibrosis, presumably because
of constant activation of TGFb-dependent
pathways by TGFb.
Endoglin Receptor Levels Tied to Skin Fibroblasts from
Diffuse Cutaneous SSc Patients
In a research study involving multiple investigators from
the U.K. and the U.S., levels of endoglin, another receptor
for TGFb found on the surface of
cells, was found to be increased in skin fibroblasts grown
in the laboratory from diffuse cutaneous SSc patients.
The increased levels of endoglin may be a mechanism by which
SSc fibroblasts try to block TGFb from promoting fibrosis.
Survival Rates for SSc Patients with Lung Transplants
In the case of severe lung involvement, one treatment option
is lung transplantation if a matching donor lung is available.
Clinical information on 29 SSc patients who underwent lung
transplantation in Pittsburgh, Pa., and Baltimore, Md., was
compared to that of patients with idiopathic pulmonary fibrosis
(IPF), a condition in which PF is present without an underlying
connective-tissue disease (CTD).
SSc patients accounted for 4% of all lung transplant recipients.
The SSc patients ranged in age from 26 to 58 years and had
an average disease duration of 13 years. Thirteen patients
had pulmonary fibrosis (PF), 6 had pulmonary hypertension
(PHT), and 10 had both PF and PHT. Eighteen of the transplanted
SSc patients had limited or no skin thickening, and 11 had
diffuse skin thickening.
SSc patients had somewhat reduced survival at one year compared
to IPF patients, but by three years after lung transplantation,
the survival was similar (60%).
Epidemiology
Preferred Patient Support
When 25 patients in Leeds, England, were asked to respond
to a questionnaire regarding the role of the SSc nurse in
their care, 19 responded that their preferred method of support
is individual discussions with their nurse regarding their
disease, their medication, and their family.
Normal Tension Glaucoma in SSc Patients
Normal tension glaucoma (NTG) has been associated with cardiovascular
and other vascular diseases.
Investigators in Paris, France, examined the occurrence of
normal tension glaucoma in a prospective study of 44 consecutive
SSc patients—13 with diffuse cutaneous SSc and 31 with
limited cutaneous SSc—who had their disease for an average
of 10 years.
An increased frequency of NTG was found in patients with
SSc compared to 37 patients with osteoarthritis and may be
due to vascular involvement.
Cancer Risk Not Found to Be Higher for SSc Patients; Breast
and Lung Cancers Examined
Recent studies, including one of 490 patients from the Sclero-derma
Registry presented last year, have shown that cancer risk
is not increased in SSc patients.
During the 2002 ACR meeting, the features of breast and lung
cancer in patients with SSc were examined using over 2500
SSc patients from the Pittsburgh, Pa., database.
Of 57 patients who had breast cancer, 69% had diffuse cutaneous
SSc versus 31% with limited cutaneous SSc. The average age
of SSc patients with breast cancer was 57, and the cancer
diagnosis in the majority was made within three years of the
onset of SSc.
Of 52 patients who had lung cancer, 35% were men and 78%
were smokers. The average age of the patients was 61 years
and the lung cancer was diagnosed an average of 16 years after
the onset of SSc. Patients diagnosed with lung cancer had
worsening shortness of breath prior to the cancer diagnosis,
and thus increased shortness of breath in late stage SSc may
be a clue to search for lung cancer.
SSc Survival by Race
Investigators from Baltimore, Md., examined survival by race
in 1,166 SSc patients followed over a period of 11 years at
one medical center.
Women accounted for 83% of the patients. Seventy-five percent
were Caucasian, 19% were African-American, and 6% were of
other races. Patients with diffuse cutaneous SSc comprised
36% of the study group.
At three years, African-Americans had a somewhat lower survival
rate than Caucasians (78.6% vs. 82.2%).
Durometer Found Useful for Measuring Skin Thickening
The degree of skin thickening is most accurately measured
in SSc patients using the modified Rodnan skin score (MRSS).
Investigators in Boston, Mass., tested the use of a durometer
(a hand held digital measuring device) on patients with SSc
by comparing the reproducibility of four measurements at each
of nine skin sites.
The durometer was reliable and its results comparable when
used for determining skin score obtained by different physicians.
Less variability was obtained among physicians using the durometer
than using the MRSS.
Durometers may be a useful tool for determining response
to therapy in clinical trials involving multiple centers and
examining physicians.
Patient Awareness and Involvement Are Crucial for Future
Advances in Scleroderma Research
In the past year, international efforts have resulted in
numerous advances in SSc research. New potential treatments
have been reported, new animal models for SSc are being examined,
and basic research into mechanisms underlying the cause of
SSc has progressed.
Several of the new findings were feasible due to the generosity
of patients with SSc and their willingness to provide blood
samples and skin biopsies to conduct critical research to
find the cause and cure of scleroderma.
Patient awareness
and involvement is crucial for future advances in SSc research.
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