Whole Exome Sequencing of Adult and Pediatric Cohorts of the Rare Vascular Disorder Systemic Capillary Leak Syndrome

Abstract: The extent to which genetic abnormalities contribute to SCLS is unknown. The authors identified pediatric and adult cohorts with characteristic clinical courses and sought to identify a possible genetic contribution to SCLS through the application of Whole Exome Sequencing (WES). On the basis of 9 adult and 8 pediatric SCLS patients and available unaffected first-degree relatives, they did not identify a uniform germline exomic genetic etiology for SCLS. However, WES did identify several candidate genes for future research.

Narrative review: the systemic capillary leak syndrome

Abstract: The systemic capillary leak syndrome (SCLS) is a rare disease of reversible plasma extravasation and vascular collapse accompanied by hemoconcentration and hypoalbuminemia. Its cause is unknown, although it is believed to be a manifestation of transient endothelial dysfunction due to endothelial contraction, apoptosis, injury, or a combination of these. Fewer than 150 cases of SCLS have been reported, but the condition is probably underrecognized because of its nonspecific symptoms and signs and high mortality rate. Patients experience shock and massive edema, often after a nonspecific prodrome of weakness, fatigue, and myalgias, and are at risk for ischemia-induced organ failure, rhabdomyolysis and muscle compartment syndromes, and venous thromboembolism. Shock and edema reverse almost as quickly as they begin, at which time patients are at risk for death from flash pulmonary edema during rapid fluid remobilization. Diagnosis is made clinically and by exclusion of other diseases that cause similar symptoms and signs, most notably sepsis, anaphylaxis, and angioedema. Acute episodes are treated with vasopressor therapy and judicious fluid replacement, possibly with colloid solutions for their osmotic effects, to prevent the sequelae of underperfusion. Prognosis is uncertain, but patients who survive an initial severe SCLS episode are estimated to have a 10-year survival rate greater than 70%. Much remains to be learned about SCLS, and clinicians should consider the diagnosis in patients with unexplained edema, increased hematocrit, and hypotension.

Idiopathic Systemic Capillary Leak Syndrome (Clarkson's Disease): The Mayo Clinic Experience

Abstract: Of the 34 patients whose records were reviewed, 25 fulfilled all diagnostic criteria for SCLS. The median age at diagnosis of SCLS was 44 years. Median follow-up of surviving patients was 4.9 years, and median time to diagnosis from symptom onset was 1.1 years (interquartile range, 0.5-4.1 years). Flulike illness or myalgia was reported by 14 patients (56%) at onset of an acute attack of SCLS, and rhabdomyolysis developed in 9 patients (36%). Patients with a greater decrease in albumin level had a higher likelihood of developing rhabdomyolysis (P=.03). Monoclonal gammopathy, predominantly of the IgG-kappa type, was found in 19 patients (76%). The progression rate to multiple myeloma was 0.7% per person-year of follow-up. The overall response rate to the different therapies was 76%, and 24% of patients sustained durable (>2 years) complete remission. The estimated 5-year overall survival rate was 76% (95% confidence interval, 59%-97%). In conclusion, SCLS, a rare disease that occurs in those of middle age, is usually diagnosed after a considerable delay from onset of symptoms. The degree of albumin decrement during an attack correlates with development of rhabdomyolysis. A reduction in the frequency and/or the severity of attacks was seen in nearly three-fourths of patients who were offered empiric therapies. The rate of progression to multiple myeloma appears to be comparable to that of monoclonal gammopathy of undetermined significance.

The Consequences of the Covid-19 Pandemic on SCLS Patients

Abstract: The authors report on the fate of 30 known SCLS patients from Europe through mid-July 2021: 90% (27) of them were receiving IVIG on a regular basis, and two-thirds (20) of them were vaccinated. Five of the ten who were unvaccinated patients experienced an episode of SCLS and 4 of them died as a result, even though none had evidence of Covid-19 pneumonia. Covid vaccination was uneventful in 18 out of the 20 patients, including 2 who were not receiving IVIG. Two patients treated with IVIG had a relapse after a second dose of mRNA vaccine, with a favorable outcome in both cases. In addition, five patients were newly diagnosed with SCLS, none of whom were receiving IVIG: 4 of them were unvaccinated and had an episode of SCLS after contracting Covid, and the 5^th one after receiving a first Covid vaccination. One of the unvaccinated four died, while the rest survived. In sum, the Covid pandemic has had serious consequences in patients with SCLS. Covid infections are associated with a high risk of SCLS episodes, and all Covid vaccines can trigger episodes. High-dose IVIG remains the only effective preventive treatment and should not be stopped during the pandemic. The risk/benefit ratio favors Covid vaccination in SCLS patients receiving IVIG.

The Clinical Picture of Severe SCLS Episodes Requiring ICU Admission

Abstract: SCLS is a very rare cause of recurrent hypovolemic shock. Few data are available on its clinical manifestations, laboratory findings, and outcomes of those patients requiring ICU admission.  This study was undertaken to describe the clinical pictures and ICU management of severe SCLS episodes.  This multicenter retrospective analysis concerned patients entered in the European Clarkson's disease (EurêClark) Registry and admitted to ICUs between May 1992 and February 2016.  Fifty-nine attacks occurring in 37 patients (male-to-female sex ratio, 1.05; mean ± SD age, 51 ± 11.4 yr) were included.  Among 34 patients (91.9%) with monoclonal immunoglobulin G gammopathy, 20 (58.8%) had kappa light chains.  ICU-admission hemoglobin and proteinemia were respectively median (interquartile range) 20.2 g/dL (17.9-22 g/dL) and 50 g/L (36.5-58.5 g/L).  IVIG was infused during 15 episodes (25.4%).  A compartment syndrome developed during 12 episodes (20.3%).  Eleven (18.6%) in-ICU deaths occurred. Bivariable analyses (the 37 patients' last episodes) retained Sequential Organ-Failure Assessment score greater than 10 (odds ratio, 12.9 [95% CI, 1.2-140]; p = 0.04) and cumulated fluid-therapy volume greater than 10.7 L (odds ratio, 16.8 [1.6-180]; p = 0.02) as independent predictors of hospital mortality.  In conclusion, high-volume fluid therapy was independently associated with poorer outcomes.  IVIG use was not associated with improved survival; hence, its use in an ICU setting should be considered prudently and needs further evaluation in future studies.

Systemic capillary leak syndrome: recognition prevents morbidity and mortality.

Abstract: The authors report on a case of SCLS in Australia involving a 61-year-old male who was properly diagnosed after his third episode, to increase awareness of the condition and to highlight the benefits of prophylactic intravenous immunoglobulin (IVIG) in this condition. The diagnosis was made by exclusion and clinically by a classic triad of hypotension, hypoalbuminaemia and haemoconcentration. There have been recent advances in understanding the pathophysiological basis for SCLS and in effective prophylaxis, and the authors and patient benefitted from said advances.

Systemic Capillary Leak Syndrome

Abstract: The different forms of SCLS include idiopathic SCLS (ISCLS) and secondary SCLS (SSCLS), which can be triggered by several conditions, including certain infections and haematological malignancies. A subgroup of patients with ISCLS have monoclonal gammopathy-associated SCLS (also known as Clarkson disease), which is an ultra-rare and extreme form of ISCLS. ISCLS can be managed effectively with monthly prophylactic immunoglobulin therapy whereas SSCLS frequently does not recur once the underlying condition resolves or the offending agent is discontinued. Thus, differentiation between ISCLS, SSCLS and other causes of oedema is crucial for quick diagnosis and positive patient outcomes. 

Successful Treatment of Systemic Capillary Leak Syndrome with Intravenous Immunoglobulins.

Abstract: The authors report on a 48-year-old woman in Spain who had her 1st episode of SCLS in 1997 and was initially put on a regimen of terbutaline and aminophylline, but went on to endure 20 additional episodes in the subsequent 3 years. She was then treated with melphalan-prednisone for a year and the frequency and intensity of her episodes diminished and even disappeared. In 2005, however, the episodes returned and in 2008 she was finally put on a regimen of IVIG (2 g/kg) every 6 weeks. She has had no more episodes since then.

Sharing the Pain [of living with SCLS]

This article from The Washington Post newspaper tells the story of how this SCLS virtual community was created, the story of its founder and, more generally, of this fantastic RareShare site.

Idiopathic Systemic Capillary Leak Syndrome in Children

Abstract: Adult subjects with systemic capillary leak syndrome (SCLS) present with acute and recurrent episodes of vascular leak manifesting as severe hypotension, hypoalbuminemia, hemoconcentration, and generalized edema. We studied clinical disease characteristics, serum cytokine profiles, and treatment modalities in a cohort of children with documented SCLS. Six children with SCLS were recruited from the United States, Australia, Canada, and Italy. Serum cytokines from SCLS subjects and a group of 10 healthy children were analyzed. Children with SCLS (aged 5-11 years old) presented with at least 1 acute, severe episode of hypotension, hypoalbuminemia, and hemoconcentration in the absence of underlying causes for these abnormalities. In contrast to what is observed in adult SCLS, identifiable infectious triggers precipitated most episodes in these children, and none of them had a monoclonal gammopathy. We found elevated levels of chemokine (C-C motif) ligand 2 (CCL2), interleukin-8, and tumor necrosis factor α in baseline SCLS sera compared with the control group. All patients are alive and well on prophylactic therapy, with 4 patients receiving intravenous or subcutaneous immunoglobulins at regular intervals. The clinical manifestations of pediatric and adult SCLS are similar, with the notable exceptions of frequent association with infections and the lack of monoclonal gammopathy. Prophylactic medication, including high dose immunoglobulins or theophylline plus verapamil, appears to be safe and efficacious therapy for SCLS in children.

PARP15 is a Susceptibility Locus for Clarkson Disease

Abstract: PARP15 is an enzyme that regulates cellular proteins; it senses single- and double-stranded DNA breaks and plays a key role in DNA repair and other cellular processes. We analyzed barrier function in PARP15-deficient vascular endothelial cells and vascular leakage in mice, and concluded that several loss-of-function PARP15 variants are associated with SCLS. PARP15 thus represents a previously unrecognized genetic susceptibility factor for SCLS.

Mechanistic Classification of SCLS.

Abstract: The authors analyzed circulating mediators of vascular permeability and proinflammatory cytokines in acute episodic sera from 14 patients with SCLS, and sera from 37 healthy control subjects. They monitored barrier function of human microvascular endothelial cells (HMVEC) after treatment with SCLS sera using transendothelial electrical resistance assays. Consistent with their previous study, the permeability factor vascular endothelial growth factor (VEGF) was increased in sera from acutely ill subjects with SCLS. An analysis of samples from one SCLS patient who has not responded to any preventive therapies (and who is a member of this Community), suggests that SCLS may have clinically varying forms, and that within the group of patients with SCLS, different cytokines may mediate the capillary leak. Therefore, quantitative molecular and humanized cell-based assays for humoral mediators of permeability should improve diagnostic specificity for SCLS and enable clinicians to screen for effective therapies.

The Mayo Clinic's summary of the diagnosis and treatment of SCLS.

During an episode of systemic capillary leak syndrome, fluids are administered intravenously to maintain the patient's blood pressure and to prevent damage to vital organs such as the kidneys, heart and brain. The amount of fluid must be carefully controlled. An attempt to normalize blood pressure through aggressive fluid administration can cause destructive swelling of the body's extremities and overload the kidneys and lungs when the body needs to eliminate the excess fluids after the episode passes.

Glucocorticoids (steroids) are often injected during an acute capillary leak syndrome attack to reduce or stop the capillary leak. This is sometimes successful. Fluid pressure in muscles may be monitored. Emergency surgery may be needed to relieve pressure and minimize damage to muscles and nerves in the arms and legs.

Once the capillary walls stop leaking and fluids start to be reabsorbed, patients are usually given diuretics to speed up elimination of the fluids before they accumulate in the lungs and other vital organs, which can be a fatal complication.

Patients who avoid organ and limb damage in a capillary leak syndrome episode tend to recover their health after several days, once the capillary walls return to normal and the accumulated fluid is expelled from the body through urination.

Although no cure has been found for systemic capillary leak syndrome, the frequency and/or severity of episodes is often reduced by having patients take certain asthma medications: theophylline and terbutaline. Patients also may benefit from intravenous treatment with immunoglobulin or by taking thalidomide.

Patients may also be prescribed corticosteroid pills such as prednisone to be taken at the first sign of symptoms of another capillary leak.

Management of Acute Episodes of Clarkson Disease (Monoclonal Gammopathy-Associated Systemic Capillary Leak Syndrome) With Intravenous Immunoglobulins

Abstract: Monoclonal gammopathy-associated idiopathic systemic capillary leak syndrome (ISCLS, or Clarkson disease) is a rare disorder defined by transient but recurrent bouts of hypotensive shock and anasarca resulting from plasma extravasation. Although prophylactic treatment with high-dose intravenous immunoglobulins (IVIG, 1–2 g/kg/mo) prevents most disease flares, its usefulness for acute episodes of ISCLS is unclear. Here the authors report the results of a retrospective study of subjects with acute ISCLS treated at or near the onset of symptoms with IVIG -- six U.S. and European patients during nine attacks. They found that the administration of IVIG with minimal additional intravenous fluids was safe and associated with rapid clinical improvement. IVIG given close to the onset of ISCLS-related symptoms is thus associated with favorable outcomes.

The Systemic Capillary Leak Syndrome: A Case Series of 28 Patients From a European Registry.

Abstract: The article describes the clinical characteristics, laboratory findings, treatments, and outcomes of patients with SCLS who were not previously reported in the literature. These European patients with SCLS were treated and monitored from the start of 1997 until end-July 2010. Survival rates were 89% at 1 year and 73% at 5 years; instances of death were directly related to SCLS attacks in 6 cases (75% of total). Treatments of various kinds increased the chances of survival: Five years after diagnosis, survival rates were 85% in 23 patients who had received a treatment and just 20% in 5 patients who had not. The authors provide additional evidence that a prophylactic treatment with IVIG tends to reduce the frequency and severity of attacks, and may improve the survival of patients with SCLS.

Vascular Endothelial Hyperpermeability Induces The Clinical Symptoms of Clarkson Disease (The Systemic Capillary Leak Syndrome)

Abstract: The authors report clinical and molecular findings on 23 subjects, the largest SCLS case series to date. Application of episodic SCLS sera, but neither the purified immunoglobulin fraction nor sera obtained from subjects during remission, to human microvascular endothelial cells caused vascular endothelial cadherin (VE-cadherin) internalization, disruption of inter-endothelial junctions, actin stress fiber formation, and increased permeability in complementary functional assays without inducing endothelial apoptosis. Intravenous immunoglobulin (IVIG), one promising therapy for SCLS, mitigated the permeability effects of episodic sera directly. Consistent with the presence of endogenous, non-immunoglobulin, circulating permeability factor(s) constrained to SCLS episodes, we found that two such proteins, vascular endothelial growth factor (VEGF) and angiopoietin 2 (Ang2), were elevated in episodic SCLS sera but not in remission sera. Antibody-based inhibition of Ang2 counteracted permeability induced by episodic SCLS sera. Comparable experiments with anti-VEGF antibody (bevacizumab) yielded less interpretable results, likely due to endothelial toxicity of VEGF withdrawal. Our results support a model of SCLS pathogenesis in which non-immunoglobulin humoral factors such as VEGF and Ang2 contribute to transient endothelial contraction, suggesting a molecular mechanism for this highly lethal disorder.

High-dose intravenous immunoglobulins: A promising therapeutic approach for idiopathic systemic capillary leak syndrome.

Abstract: The article reports the case of a 40-year-old woman with chronic SCLS treated in Berne, Switzerland, with high-dose intravenous immunoglobulins (IVIG) after a prophylactic therapy with theophylline and terbutaline (T&T) was poorly tolerated and failed to decrease the frequency and severity of the attacks. During the 5 years she was on T&T the patient suffered from about 20 similar episodes of mild to moderate shock, often requiring hospital re-admission and supportive therapy. So far, 10 months of prophylactic therapy with IVIG (2gr/kg/month) have resulted in an impressive reduction of intensity and frequency of attacks, confirming the finding of other case studies.

Intravenous Immunoglobulins Tapering and Withdrawal in SCLS

Abstract: The authors conducted a retrospective, multicenter (more than 50 hospitals in Europe) study including all adult SCLS patients with an MGUS who received at least one course of IVIG, so that made up a universe of 59 patients of mean age 51 (±13 years) followed during the January 1997 to January 2022 period. The overall cumulative probabilities of 2-, 5-, 10- and 15-years survival were 100%, 85%, 72%, 44%, respectively.  IVIG was withdrawn at least once in 18 (31%) patients (W+ group) and never in 41 (69%, W- group). The cumulative probabilities of 10-years survival in the W+ vs. W- groups were 50% and 83%, respectively. The episode relapse rate and the median number of relapses in the W+ vs. W- groups were 72% vs 58% and 2.5 vs 1, respectively.  IVIG tapering was not statistically associated with increased person-year incidence of attacks using a mixed linear model.  IVIG withdrawal, on the other hand, was associated with increased mortality and a higher rate of recurrence in SCLS patients.

IVIG in SCLS: Report and Review of Literature.

Abstract: In recent years, IVIG has become a common first-line prophylactic therapy in most patients with benefits at the dose of 2 gr/kg once a month. Here the authors report the case of a 49-year-old male patient in Italy -- he is a member of this community -- with SCLS treated successfully with a lower dose of IVIG (1 gr/kg monthly) in the maintenance phase. He presented no acute episodes in a follow-up period of 28 months. The authors describe prophylactic treatments for SCLS in the literature and compare their patient to another 18 who received IVIG in follow-up.

High-Dose Intravenous Immunoglobulins Dramatically Reverse Systemic Capillary Leak Syndrome.

Abstract: The objective of this study was to report the dramatic improvement of patients with systemic capillary leak syndrome obtained with high-dose intravenous immunoglobulins. Systemic capillary leak syndrome is a rare and life-threatening disorder characterized by hypotension that can lead to shock, weight gain, hypoalbuminemia, and elevated hematocrit secondary to unexplained episodic capillary fluid extravasation into the interstitial space. Because its cause is unknown, systemic capillary leak syndrome treatment has remained largely supportive. Intravenous immunoglobulins administration to a patient with refractory systemic capillary leak syndrome yielded dramatic improvement. The patient is still alive 11 yrs after systemic capillary leak syndrome diagnosis and receives intravenous immunoglobulins monthly. Later, based on that result, intravenous immunoglobulins were successfully given to two other patients during the acute phase of systemic capillary leak syndrome. Both are still alive 8 and 1.5 yrs after receiving intravenous immunoglobulins at the onset of each flare. In conclusion, intravenous immunoglobulins were effective against systemic capillary leak syndrome symptoms in three patients, but their exact mechanism remains unknown. Their immunomodulatory effect merits further investigation.

Immunoglobulins for Treatment of Systemic Capillary Leak Syndrome

Abstract: A 43-year-old white woman in France diagnosed with SCLS was put on the recommended combination of Theophylline plus Terbutaline, but she nevertheless had 10 episodes of severe capillary leak during 2001-mid-2007, necessitating intensive care unit admission for her last 3 episodes. She was then put on IVIG administered every 6 weeks, and this yielded a dramatic improvement such that she has had no more episodes and has returned to her normal lifestyle.

Intravenous Immunoglobulins Improve Survival in Monoclonal Gammopathy-Associated SCLS

Abstract: We conducted a cohort analysis of all patients included in the European Clarkson disease registry between January 1997 and March 2016. From diagnosis to last follow-up, studied outcomes (e.g., the frequency and severity of attacks, death, and evolution toward multiple myeloma) and the type of preventive treatments administered were monitored every 6 months. Sixty-nine patients (M/F sex ratio 1:1; mean ± SD age at disease onset 52 ± 12 years) were included in the study. All patients had monoclonal gammopathy of immunoglobulin G type, with kappa light chains in 47 (68%).Twenty-four patients (35%) died after 3.3 (0.9-8) years. Fifty-seven (86%) patients received at least one preventive treatment, including intravenous immunoglobulins (IVIg) n = 48 (73.8%), theophylline n = 22 (33.8%), terbutaline n = 22 (33.8%), and thalidomide n = 5 (7.7%). In the 65 patients with follow-up, 5- and 10-year survival rates were 78% (n = 35) and 69% (n = 17), respectively. Preventive treatment with IVIg and terbutaline were the only factors significantly associated with survival in multivariate analysis. Neither the use of thalidomide nor theophylline was associated with improved survival. Five- and 10-year survival rates in patients treated with IVIg were 91% and 77%, respectively, compared to 47% and 37% in patients not treated with IVIg. Patients treated with IVIg were more likely to be free of recurrence, severe recurrence, and alive at the end of follow-up. Furthermore, all but one patient who did not experience a severe relapse were treated with IVIg. Since preventive treatment with IVIg was the strongest factor associated with survival, the use of IVIg is suggested as the first line in prevention therapy.

Idiopathic systemic capillary leak syndrome (Clarkson disease)

Abstract: The enigmatic systemic capillary leak syndrome (SCLS) named for Dr Clarkson is characterized by transient and severe but reversible hemoconcentration and hypoalbuminemia caused by leakage of fluids and macromolecules into tissues. Although less than 500 cases of SCLS have been reported in the literature since 1960, the condition is probably underdiagnosed because of a lack of awareness and a high mortality without treatment. Treatment of acute SCLS remains primarily supportive. Prophylaxis with IVIG appears promising, but this therapy is nonspecific and expensive. Mechanistic understanding of SCLS is in its infancy. As a result, clinicians today cannot predict when or how badly SCLS will flare; targeted therapies do not yet exist, and prolonged remission or cure remains elusive. Our working hypothesis invokes exaggerated microvascular endothelial responses to surges of otherwise routinely encountered inflammatory mediators. This emerging disease model lends itself to innovative patient-centered translational research in the ways highlighted above. It is our hope that detailed and personalized investigation of intraendothelial responses among individual patients with SCLS might illuminate novel genetic and molecular control mechanisms. In turn, such advances could deliver the diagnostic, prognostic, and therapeutic tools sorely needed to combat this devastating disease.

Idiopathic systemic capillary leak syndrome (Clarkson syndrome) in childhood: systematic literature review

Abstract: The authors performed a systematic review of the literature on Clarkson syndrome in subjects less than 18 years of age, and identified 24 reports, published since 1989, providing data on 32 otherwise healthy subjects, who experienced 67 well-documented episodes of SCLS. The condition affected more frequently girls (21, 66%) than boys, presented throughout childhood, and was preceded by a mostly viral illness in 75% of cases. The presence of a monoclonal gammopathy (MGUS) was never reported. Uncompensated circulatory shock, muscle compartment syndrome, acute kidney injury, pulmonary edema, and either pleural or pericardial effusion were, in decreasing order of frequency, the most common complications. Four patients died. In sum, SCLS develops not only in adulthood but also in childhood, but of potential significance is that in this age group the condition is not linked to an MGUS, and thus it could be that it does not play a pivotal pathogenic role.

High-Dose IVIG Therapy for SCLS.

Abstract: We evaluated IVIG prophylactic therapy in a cohort of 29 patients with Systemic Capillary Leak Syndrome in a longitudinal follow up study. All patients received treatments at the discretion of their primary providers and retrospectively via questionnaire recorded symptoms beginning with their first documented episode of the SCLS until May 31, 2014. Twenty-two out of 29 patients responded to the questionnaire, and 18 out of the 22 respondents received monthly prophylaxis with IVIG during the study period for a median interval of 32 months. The median annual attack frequency was 2.6/patient prior to IVIG therapy and 0/patient following initiation of IVIG prophylaxis (P = 0.001). 15 out of 18 subjects with a history of one or more acute SCLS episodes experienced no further symptoms while on IVIG therapy. In conclusion, IVIG prophylaxis is associated with a dramatic reduction in the occurrence of SCLS attacks in most patients, with minimal side effects.

Handling shock in idiopathic systemic capillary leak syndrome (Clarkson’s disease): less is more 

Abstract: SCLS presents with recurrent potentially life-threatening episodes of hypovolemic shock associated with severe hemoconcentration and hypoproteinemia. Here the authors summarize 40 years’ experience in treating shock in Italian SCLS patients to derive a therapeutic algorithm. Records from 12 patients were informative for treatment modalities and outcome of 66 episodes of shock. Episodes are divided in 3 phases and treatment recommendations are the following: (1) prodromal symptoms-signs (growing malaise, oligo-anuria, orthostatic
dizziness) last 6-12 hours and patients should maintain rigorous bed rest. (2) The acute shock phase lasts 24-36 hours; patients should be admitted to ICU, placed on restrictive infusion of fluids favoring cautious boluses of high-molecular-weight plasma expanders when SAP < 70 mmHg; and monitored for cerebral/cardiac perfusion, myocardial edema and signs of compartment syndrome. (3) The post-acute (recovery) phase may last from 48 hours to 1 week; monitor for cardiac overload to prevent cardiac failure; in case of persistent renal failure, hemodialysis may be necessary; consider albumin infusion. Complications listed by frequency in our patients were acute renal failure, compartment syndrome and neuropathy, rhabdomyolysis, myocardial edema, pericardial-pleural-abdominal effusion, cerebral involvement, acute pulmonary edema and deep vein thrombosis.

Genome-Wide SNP Analysis of SCLS.

Abstract: Polymorphisms in genes whose functional annotations suggest involvement in cell junctions and signaling, cell adhesion, and cytoskeletal organization, correlate with our previous mechanistic studies of SCLS sera. Such annotations provide a framework for future allelic discrimination strategies to validate top-ranked SNPs discovered here, as well as novel SNPs unique to the SCLS cohort detected by exome capture sequencing. Although the findings must be corroborated in a larger cohort, they provide a springboard for discovery of underlying pathophysiological mechanisms, biomarkers, and avenues for therapy.

Comment on The Systemic Capillary Leak Syndrome.

Abstract: The authors report on 2 additional patients from the United States with SCLS in whom prophylaxis with terbutaline and theophylline failed, but who had no further episodes after the initiation of IVIG therapy. There are additional published reports of successful prophylaxis with IVIG cited, and the authors are also aware of yet another case. Given the present state of knowledge and despite the high cost, the authors strongly believe that IVIG is the optimal prophylaxis and should be the initial choice to prevent attacks in patients with SCLS.

Clinical Presentation, Management, and Prognostic Factors of Idiopathic Systemic Capillary Leak Syndrome: A Systematic Review

Abstract: A total of 133 case reports (161 patients) and 5 case series (102 patients) of idiopathic SCLS were included in a survey of articles published through end-2016. The findings include that patients had hypotension (81.4%), edema (64.6%), and previous flu-like illness (34.2%). They were often misdiagnosed as having hypovolemic shock, septic shock, polycythemia vera, or angioedema. Thirty-seven patients died (23%) mainly because of complications from SCLS (78.4%). There were significant differences in the survival rates between patients who were treated with prophylactic b2 agonists, methylxanthines, and intravenous immunoglobulins and those who were not. The estimated 1-, 5-, and 10-year survival rate of patients treated with intravenous immunoglobulins was 100%, 94%, and 94%, respectively. The results of this review suggest that prophylactic use of intravenous immunoglobulins is the most effective treatment in reducing the mortality rate of SCLS patients.

Chronic systemic capillary leak syndrome treatment with intravenous immune globulin: Case report and review of the literature 

Abstract: A rarely described chronic form of SCLS (cSCLS) presents as refractory edema, with pleural and/or pericardial effusions and hypoalbuminemia. These entities are differentiated by massive and periodic episodes of capillary leak, which can result in shock in SCLS, and chronic refractory edema in cSCLS. The etiologies of these disorders are poorly understood, but both acute and chronic forms often present with an associated monoclonal gammopathy. Flares of the SCLS have been reduced by treatment with intravenous immune globulin (IVIG). Only six cases of cSCLS have been reported, and previous treatments have included steroids, terbutaline, and theophylline. Based upon the reported responses of SCLS to IVIG, we present the case of a 54-year-old man with cSCLS where ongoing treatment with IVIG resulted in a marked and sustained improvement in the signs and symptoms of the capillary leak syndrome.

Capillary leak syndrome: etiologies, pathophysiology, and management

Abstract: In various human diseases, an increase in capillary permeability to proteins leads to the loss of protein-rich fluid from the intravascular to the interstitial space. Although sepsis is the disease most commonly associated with this phenomenon, many other diseases can lead to a “sepsis-like” syndrome with manifestations of  diffuse pitting edema, exudative serous cavity effusions, noncardiogenic pulmonary edema, hypotension, and, in some cases, hypovolemic shock with multiple-organ failure. The term capillary leak syndrome has been used to describe this constellation of disease manifestations associated with an increased capillary permeability to proteins. Diseases other than sepsis that can result in capillary leak syndrome include the idiopathic systemic capillary leak syndrome or Clarkson’s disease, engraftment syndrome, differentiation syndrome, the ovarian  hyperstimulation syndrome, hemophagocytic lymphohistiocytosis, viral hemorrhagic fevers, autoimmune diseases, snakebite envenomation, and ricin poisoning. Drugs including some interleukins, some monoclonal antibodies, and gemcitabine can also cause capillary leak syndrome. Acute kidney injury is commonly seen in all of these diseases. In addition to hypotension, cytokines are likely to be important in the pathophysiology of acute kidney injury in capillary leak syndrome. Fluid management is a critical part of the treatment of capillary leak syndrome;  hypovolemia and hypotension can cause organ injury, whereas capillary leakage of administered fluid can worsen organ edema leading to progressive organ injury. The purpose of this article is to discuss the diseases other than sepsis that produce capillary leak and review their collective pathophysiology and treatment.

A ligand-independent Tie2-activating antibody reduces vascular leakage in models of Clarkson disease

Abstract: We evaluated a monoclonal antibody (4E2) specific for the endothelial receptor tyrosine kinase Tie2 in SCLS patient-derived endothelial cells and reduced baseline and proinflammatory mediator-induced barrier dysfunction. 4E2 also reduced mortality and/or vascular leakage associated with systemic histamine challenge or influenza infection in the SJL/J mouse model of SCLS. These findings support a critical role for Tie2 dysregulation in SCLS and highlight a viable therapeutic approach to this catastrophic disorder.

A natural mouse model reveals genetic determinants of systemic capillary leak syndrome

Abstract: SCLS is a disorder of unknown etiology characterized by recurrent episodes of vascular leakage of proteins and fluids into peripheral tissues, resulting in whole-body edema and hypotensive shock. The pathologic mechanisms and genetic basis for SCLS remain elusive. Previous histological studies of skin and muscle of SCLS patients have failed to uncover gross abnormalities within the microvasculature that could account for this phenotype. Here the authors identified an inbred mouse strain, SJL, which recapitulates cardinal features of SCLS, including susceptibility to histamine- and infection-triggered vascular leak. They named this trait “Histamine hypersensitivity” (Hhs/Hhs) and mapped it to Chromosome 6. Hhs is syntenic to the genomic locus most strongly associated with SCLS in humans (3p25.3), revealing that the predisposition to develop vascular hyperpermeability has a strong genetic component conserved between humans and mice and providing a naturally occurring animal model for SCLS. Genetic analysis of Hhs may reveal orthologous candidate genes that contribute not only to SCLS, but also to normal and dysregulated mechanisms underlying vascular barrier function more generally. Future studies including assessment of expression and sequence of top Hhs candidate genes in SCLS patients and mice and their role in endothelial responses to inflammation will be essential to determine their contribution.