Renal tubular acidosis, glomerulonephritis and immunologic factors in Sjögren's syndrome

Comprehensive analysis of clinical and laboratory features of 440 published cases of Sjögren's syndrome and renal tubular acidosis

AIM

To describe the clinical and laboratory features of Sjögren's syndrome (SS) with renal tubular acidosis (RTA) from published literature.

METHODS

A systematic search of indexed publications in all languages till December 2021 identified cases of SS with RTA (SS-RTA) and were included if either antibody (anti-SSA/anti-SSB) or salivary gland histopathology were positive.

RESULTS

There were 440 cases of SS-RTA (63.9% from Asia, 95.5% women). The median (range) age was 37 (6-78) years. Only 7.7% had a previous diagnosis of SS. Oral or ocular sicca symptoms were present in 63.7%. Positive ocular tests, oral tests, anti-SSA, anti-SSB and salivary gland histopathology were reported in 256/331 (77.3%), 123/128 (96%), 382/407 (93.9%), 298/379 (78.6%), and 246/268 (91.8%), respectively. Hypokalemic paralysis (HP) was the presenting feature in 63.6%; 25% had multiple episodes of HP and 8.4% had respiratory paralysis. Type 1, type 2, combined type 1 & 2, and type 4 RTA was seen in 388, 8, 38, and 3 patients, respectively. Proximal dysfunction and RTA complications were infrequently evaluated. Fanconi syndrome, nephrogenic diabetes insipidus, proteinuria, and low estimated glomerular filtration rate were found in 45, 21, 178, and 157, respectively. Nephrocalcinosis, renal stones, and osteomalacia were reported in 92, 79, and 72, respectively. Tubulointerstitial nephritis was found in 142 out of 152 renal biopsies.

CONCLUSION

SS-RTA is an early manifestation of SS characterized by younger age and subclinical sicca symptoms. Although evaluated less frequently, oral sicca signs and salivary gland biopsy have a high positive yield. HP is the most common presentation. RTA is mostly distal; proximal dysfunction and complications were infrequently assessed.

Development and validation of a nomogram for renal involvement in primary Sjögren syndrome patients: A retrospective analysis

OBJECTIVE

To establish and validate a nomogram for individualized prediction of renal involvement in pSS patients.

METHODS

A total of 1293 patients with pSS from the First Affiliated Hospital of Wenzhou Medical University between January 2008 and January 2020 were recruited and analyzed retrospectively. The patients were randomly divided into development set (70%, n = 910) and validation set (30%, n = 383). The univariable and multivariate logistic regression were performed to analyze the risk factors of renal involvement in pSS. Based on the regression β coefficients derived from multivariate logistic analysis, an individualized nomogram prediction model was developed and subsequently evaluated by AUC and calibration plot.

RESULTS

Multivariate logistic analysis showed that hypertension, anemia, albumin, uric acid, anti-Ro52, hematuria, and ChisholmMason grade were independent risk factors of renal involvement in pSS. The AUC were 0.797 and 0.750, respectively, in development set and validation set. The calibration plot showed nomogram had a strong concordance performance between the prediction probability and the actual probability.

CONCLUSION

The individualized nomogram for pSS patients those who had renal involvement could be used by clinicians to predict the risk of pSS patients developing into renal involvement and improve early screening and intervention.

Renal Involvement in Primary Sjogren's Syndrome: A Case Series of Three Cases with Various Clinicopathological Presentations

Sjogren's syndrome is a prevalent and underdiagnosed systemic disease that primarily affects epithelial tissue. It may affect renal function, either as an epithelial disease causing tubulointerstitial nephritis (TIN) or as an immune complex-mediated glomerulopathy. These lesions may cause a variety of clinical features, both overt and occult. The epithelial disease is mediated by B and T cells. The prevalence of renal involvement in primary Sjogren's syndrome has been reported to range approximately from 10% to 30%. Patients with renal involvement in primary Sjogren's syndrome may have renal manifestations, such as renal tubular acidosis (RTA) Type I, TIN, diabetes insipidus, nephrolithiasis, and Fanconi syndrome. Distal RTA was reported more commonly than proximal RTA, which can present as acute hypokalemic paralysis. We present three cases of primary Sjogren's syndrome with significant renal involvement and various clinicopathological presentations.

Distal Renal Tubular Acidosis: ERKNet/ESPN Clinical Practice Points

Distal renal tubular acidosis (dRTA) is characterised by an impaired ability of the distal tubule to excrete acid, leading to metabolic acidosis. Associated complications include bone disease, growth failure, urolithiasis and hypokalaemia. Due to its rarity, there is a limited evidence to guide diagnosis and management, however, available data strongly suggest that metabolic control of the acidosis by alkali supplementation can halt or revert almost all complications. Despite this, cohort studies show that adequate metabolic control is present in only about half of patients, highlighting problems with treatment provision or adherence. With these clinical practice points the authors, part of the working groups tubulopathies in the European Rare Kidney Disease Reference network (ERKnet) and inherited kidney diseases of the European Society for Paediatric Nephrology (ESPN) aim to provide guidance for the management of patients with dRTA to facilitate adequate treatment and establish an initial best practice standard against which treatment of patients can be audited.

[Renal involvement in Sjögren's syndrome]

Primary Sjögren syndrome is an autoimmune disorder characterized by lymphoplasmacytic infiltration of the exocrine (salivary and lachrymal) glands resulting in sicca symptoms (dryness). Systemic complications can occur in primary Sjögren syndrome, but renal involvement is rare, affecting<10% patients. The most frequent form of nephropathy in primary Sjögren syndrome is tubulointerstitial nephritis, where infiltration of the kidney by plasma cells is a key feature and shows similarity to the lymphoplasmacytic infiltration of the salivary glands. Electrolyte disturbances may occur in primary Sjögren syndrome, such as renal distal tubular acidosis, diabetes insipidus, Gitelman syndrome, or Fanconi syndrome. Glomerular involvement is less frequently detected in patients with primary Sjögren syndrome, but can take the form of membranoproliferative glomerulonephritis secondary to cryoglobulinaemia. The renal prognosis in patients with primary Sjögren syndrome and TIN or glomerular disease is usually good, but the risk of chronic kidney disease remains significant for some patients. Appropriate screening must be performed at least once a year in patients with systemic primary Sjögren syndrome in order to facilitate the early detection of renal complications. In this Review, we discuss the epidemiology, pathophysiology, differential diagnosis, and treatment of renal disease in primary Sjögren syndrome.

Hypokalemic Paralysis due to Primary Sjögren Syndrome: Case Report and Review of the Literature

Tubulointerstitial nephritis (TIN) is the main renal involvement associated with primary Sjögren syndrome (pSS). TIN can manifest as distal renal tubular acidosis (RTA), nephrogenic diabetes insipidus, proximal tubular dysfunction, and others. We present a 31-year-old female with hypokalemic paralysis due to distal RTA (dRTA). She received symptomatic treatment and hydroxychloroquine with a good response. There is insufficient information on whether to perform a kidney biopsy in these patients or not. The evidence suggests that there is an inflammatory background and therefore a potential serious affection to these patients, such as hypokalemic paralysis. We found 52 cases of hypokalemic paralysis due to dRTA in pSS patients. The majority of those patients were treated only with symptomatic medication. Patients who received corticosteroids had stable evolution even though they did not have another symptomatology. With such heterogeneous information, prospective studies are needed to assess the value of adding corticosteroids as a standardized treatment of this manifestation.

Hypokalemic Paralysis: A Hidden Card of Several Autoimmune Diseases

Acute hypokalemic paralysis is a rare and potentially fatal condition, with few related causes, one of which highlights distal renal tubular acidosis (dRTA). Distal renal tubular acidosis is a rare complication of several autoimmune diseases such as systemic lupus erythematosus, Sjögren's syndrome, and Hashimoto thyroiditis. We report a case of a lupic patient who presented rapidly progressive quadriparesis in the context of active renal disease. Research revealed severe refractory hypokalemia, metabolic acidosis, and alkaline urine suggestive of dRTA. We diagnosed Sjögren's syndrome based on sicca symptoms, an abnormal salivary glands' nuclear scan and the presence of anti-Ro/SSA and anti-La/SSB. In addition, the finding of thyroid peroxidase, thyroglobulin antibodies, and hypothyroidism led us to the diagnosis of Hashimoto thyroiditis. Due to the active renal involvement on the context of systemic lupus erythematosus and Sjögren's syndrome, the patient received immunosuppression with rituximab, resulting in a progressive and complete improvement.

Systemic manifestations of primary Sjögren's syndrome in the NOD.B10Sn-H2b/J mouse model

Animal models that recapitulate human disease are crucial for the study of Sjögren's Syndrome (SS). While several SS mouse models exist, there are few primary SS (pSS) models that mimic systemic disease manifestations seen in humans. Similar to pSS patients, NOD.B10Sn-H2^b/J (NOD.B10) mice develop exocrine gland disease and anti-nuclear autoantibodies. However, the disease kinetics and spectrum of extra-glandular disease remain poorly characterized in this model. Our objective was to characterize local and systemic SS manifestations in depth in NOD.B10 female mice at early and late disease time points. To this end, sera, exocrine tissue, lung, and kidney were analyzed. NOD.B10 mice have robust lymphocytic infiltration of salivary and lacrimal tissue. In addition, they exhibit significant renal and pulmonary inflammation. We identified numerous autoantibodies, including those directed against salivary proteins. In conclusion, the NOD.B10 model recapitulates both local and systemic pSS disease and represents an excellent model for translational studies.

Tubulointerstitial nephritis in primary Sjögren syndrome: clinical manifestations and response to treatment

BACKGROUND

Primary Sjögren syndrome (pSS) is a common autoimmune condition which primarily affects epithelial tissue, often including the kidney causing either tubulointerstitial nephritis (TIN) or more rarely, an immune complex related glomerulonephritis.

METHODS

We describe the clinical, biochemical and histological characteristics of 12 patients with pSS related TIN and their response to treatment with antiproliferative agents. All 12 patients were investigated and treated at the UCL Centre for Nephrology in London.

RESULTS

All patients had TIN demonstrated via needle biopsy; immunophenotyping showed that the interstitial infiltrate was predominantly a CD4+ T-cell infiltrate. Urinary acidification testing demonstrated distal renal tubular acidosis in 8 patients. Proximal tubular dysfunction was present in 5 patients. All but 1 patient were treated with antiproliferative agents and most also with a reducing course of steroids. In the treated patients, there was a significant improvement in the serum creatinine and measured GFR.

CONCLUSION

Patients with pSS TIN have significant renal impairment and other functional tubular defects. There is a mononuclear lymphocytic infiltrate on renal biopsy and this appears to be mainly a CD4+ T-cell infiltrate. Treatment with mycophenolate (and corticosteroids) improves the renal function in patients with pSS TIN.

Renal involvement in primary Sjögren syndrome

Primary Sjögren syndrome (pSS) is an autoimmune disorder characterized by lymphoplasmacytic infiltration of the exocrine (salivary and lachrymal) glands that results in sicca symptoms (dryness of the eyes and mouth). Systemic complications can occur in pSS, but renal involvement is rare, affecting <10% patients. The most frequent form of nephropathy in pSS is tubulointerstitial nephritis (TIN), in which infiltration of the kidney by plasma cells is a key feature and shows similarity to the lymphoplasmacytic infiltration of the salivary glands. Electrolyte disturbances may occur in pSS, such as renal distal tubular acidosis, diabetes insipidus, Gitelman syndrome or Fanconi syndrome. Glomerular involvement is less frequently detected in patients with pSS, but usually takes the form of membranoproliferative glomerulonephritis secondary to cryoglobulinaemia. The renal prognosis in patients with pSS and TIN or glomerular disease is usually favourable, but the risk of chronic kidney disease remains high in patients with TIN. Appropriate screening must be performed at least once a year in patients with systemic pSS in order to facilitate the early detection of renal complications. In this Review we discuss the epidemiology, pathophysiology, differential diagnosis and treatment of renal disease in pSS.

Renal involvement in primary Sjögren's syndrome

SS is a prevalent and underdiagnosed systemic disease that primarily affects epithelial tissue. It may affect renal function either as epithelial disease causing tubulointerstitial nephritis or as an immune complex-mediated glomerulopathy. These lesions may cause a variety of clinical features, both overt and occult. The epithelial disease is mediated by B and T cells, notably the Th17 subtype. We review the prevalence of renal SS, its presentation, likely pathogenesis and treatment.

Sjögren's, Renal Tubular Acidosis And Osteomalacia - An Asian Indian Series

Objective:

To study the profile of Renal Tubular Acidosis (RTA) in Asian Indian patients with Primary Sjögren's Syndrome (pSS).

Methods:

The Electronic medical records of patients with a diagnosis of pSS seen between 2003 and 2010 at our tertiary care teaching hospital were screened for RTA. Clinical features, immunological profile, acid-base balance and electrolyte status, 25-hydroxyvitamin D (25(OH) D3) levels, histopathological changes in minor salivary gland biopsy samples and radiological findings were retrieved. RTA was diagnosed in cases of hyperchloremic metabolic acidosis with urinary pH values higher than 5.5. Those with known features suggestive of RTA including hypokalemic paralysis, hyperchloremia and nephrocalcinosis without acidosis were defined as incomplete RTA.

Results:

Of the 380 patients with clinically suspected pSS, 25 had RTA. The median age was 32 (18-60) years. Nineteen patients had complete RTA. Six had incomplete RTA. Only 10 patients (40%) had symptoms related to RTA at presentation. Sixteen patients (64%) had present or past history of hypokalemic paralysis. Pseudofractures were seen in 7 patients and an additional 2 had subclinical radiological osteomalacia. Majority of the patients (61.2%) had a normal 25(OH) D3 level. Those with osteomalacia had significantly lower serum phosphate, blood ph and higher alkaline phosphatase. Serum calcium and 25(OH) D3 levels were not significantly different between patients with osteomalacia and those without.

Conclusion:

Most patients were asymptomatic for RTA inspite of clinically overt and elicitable features. Skeletal manifestation was a common finding in patients with Sjögren and RTA, despite normal levels of 25 (OH) D3 in a majority.

Renal tubular acidosis in Sjögren's syndrome: a case series

BACKGROUND

The exact frequency of distal and proximal renal tubular acidosis (RTA) in Sjögren's syndrome is unknown. Other features of Sjögren's syndrome like polyuria, glomerular manifestations, familial occurrence and pregnancy are not widely reported. The aim was to prospectively study the clinical features and outcome of distal and proximal RTA in Sjögren's syndrome and also report on other renal manifestations of Sjögren's syndrome.

METHODS

The present study is a prospective consecutive case series of patients who presented with a history suggestive of RTA and Sjögren's syndrome. All patients were followed for 1 year. The diagnosis of RTA was by fractional excretion of bicarbonate. The diagnosis of Sjögren's syndrome was according to the American-European classification system [modified by Tzioufas and Voulgarelis: Best Pract Res Clin Rheumatol 2007;21:989-1010].

RESULTS

The total number of RTA patients diagnosed during this period was 149. Sjögren's syndrome accounted for 34.8% (52 of 149) of RTA patients. The important symptoms and laboratory parameters were oral and ocular symptoms in 23 (44.2%), dental caries in 12 (23%), body pains in 47 (90.3%), mean serum pH 7.202 ± 0.03, mean serum bicarbonate, 14.03 ± 1.66 mmol/l, and mean urine pH, 7.125 ± 0.54. There were 30 (57.6%) patients with distal RTA and 22 (42.3%) patients with proximal RTA.

CONCLUSIONS

The clinical implication of the present study is that RTA is a common feature of Sjögren's syndrome. It may be missed if the presentation is not due to oral and ocular symptoms. The present study is also the only one with a 1-year follow-up.

Clinically significant renal involvement in primary Sjögren's syndrome: clinical presentation and outcome

OBJECTIVE

To estimate the prevalence and investigate the clinical features and the outcome of clinically significant renal involvement in a large cohort of patients with primary Sjögren's syndrome (SS).

METHODS

Among 715 patients who met the American-European Consensus Group criteria for primary SS, those with clinically significant renal involvement were identified and their clinical and immunologic features were recorded. The prognosis in patients with primary SS with renal involvement was assessed by the clinical appearance of any of the following major outcomes: death, hemodialysis, chronic renal failure (CRF), and lymphoma. Kaplan-Meier analysis was applied to compare death rates between patients without and those with renal involvement.

RESULTS

Thirty-five patients with primary SS (4.9%) had clinically significant renal involvement, representing a total followup time after renal diagnosis of 252.2 person-years. Thirteen patients (37.1%) had interstitial nephritis alone, 17 patients (48.6%) had glomerulonephritis (GN) alone, and 5 patients (14.3%) had both entities. Nine patients died (25.7%), 11 developed CRF (including 4 requiring chronic hemodialysis) (31.4%), and 9 developed lymphoma (25.7%). The overall 5-year survival rate was 85%. Kaplan-Meier analysis showed statistically significant reduced survival for patients with primary SS with renal involvement compared to those without renal involvement (P < 0.0001 by log rank test), with GN patients displaying increased mortality. Eight of 9 reported deaths (89%) and 8 of 9 lymphomas (89%) were observed among patients with GN.

CONCLUSION

The long-term prognosis varies for patients with primary SS who have clinically significant renal involvement. Patients with interstitial nephritis display a favorable prognosis, while patients with GN are at high risk of developing lymphoma and have poor survival.

Relation of sensory peripheral neuropathy in Sjögren syndrome to anti-Ro/SSA

BACKGROUND

Sjögren syndrome is a common, chronic autoimmune disease that typically produces inflammation and poor function of the salivary and lacrimal glands. Other organs can be affected, including the nervous system. Sensory peripheral neuropathy is a common manifestation of the disease.

METHODS

Eight-eight patients attending a dry eyes-dry mouth clinic were diagnosed to have primary Sjögren syndrome and underwent a neurological examination. Anti-Ro (or SSA) and anti-La (or SSB) were determined using immunodiffusion as well as Inno-Lia and BioPlex ANA screen. Serum vitamin B(12) levels were determined using an enzyme-linked microtiter plate assay.

RESULTS

Twenty-seven (31%) of the 88 patients had peripheral neuropathy as defined by loss of light touch, proprioception, or vibratory sensation. Anti-Ro and anti-La were found by immunodiffusion in 12 patients, and 8 of these 12 had neuropathy (χ(2) = 8.46, P = 0.0036, odds ratio = 6.0 compared to those without precipitating anti-Ro and anti-La). Of the 27 patients with only anti-Ro by immunodiffusion, 13 (48.1%) had neuropathy (χ(2) = 5.587, P = 0.018, compared to those without anti-Ro). There was no relationship of the other, more sensitive measures of anti-Ro and anti-La to neuropathy. In addition, we found no association of serum vitamin B(12) levels to neuropathy among these patients with Sjögren syndrome.

CONCLUSIONS

Sensory peripheral neuropathy is common among patients with Sjögren syndrome and is associated with the presence of anti-Ro and anti-La when determined by immunodiffusion.

Hypokalemic periodic paralysis in Sjogren's syndrome secondary to distal renal tubular acidosis

We report a 53-year-old Turkish female presented with progressive weakness and mild dyspnea. Laboratory results demonstrated severe hypokalemia with hyperchloremic metabolic acidosis. The urinary anion gap was positive in the presence of acidemia, thus she was diagnosed with hypokalemic paralysis from a severe distal renal tubular acidosis (RTA). Immunologic work-up showed a strongly positive ANA of 1:3,200 and positive antibodies to SSA and SSB. Schirmer's test was abnormal. Autoimmune and other tests revealed Sjögren syndrome as the underlying cause of the distal renal tubular acidosis. Renal involvement in Sjogren's syndrome (SS) is not uncommon and may precede sicca complaints. The pathology in most cases is a tubulointerstitial nephritis causing among other things, distal RTA, and, rarely, hypokalemic paralysis. Treatment consists of potassium repletion, alkali therapy, and corticosteroids. Primary SS could be a differential in women with acute weakness and hypokalemia.

Non-Randall proliferative glomerulonephritis with humps and monotypic IgG deposits in primary Sjögren's syndrome: a first case report

Renal involvement is frequent in patients suffering from primary Sjögren's syndrome (pSS). Tubulointerstitial infiltration is the most common renal lesion, while glomerular involvement is rare. We report the case of a 50-year-old woman with pSS who developed renal failure due to an unusual proliferative glomerulonephritis with humps and monotypic IgG1-kappa deposits. Searches for cryoglobulinaemia, anti-double-stranded DNA and anti-neutrophil cytoplasmic antibodies were negative. Serum protein electrophoresis and immunofixation revealed no monoclonal immunoglobulin. Extensive work-up excluded associated infectious, collagen or lymphoproliferative disease. This case adds to the spectrum of pSS-related glomerular disease which is reviewed in depth.

Pathogenetic mechanisms in the initiation and perpetuation of Sjögren's syndrome

Sjögren's syndrome (SS), a chronic autoimmune disorder, particularly compromises the function of exocrine glands. The involvement of these glands is characterized by focal, mononuclear cell infiltrates that surround the ducts and replace the secretory units. The pathogenetic mechanisms of this autoimmune exocrinopathy have not been fully elucidated. Immunologically-activated or apoptotic glandular epithelial cells that expose autoantigens in genetically predisposed individuals might drive autoimmune-mediated tissue injury. Alterations in several immune mediators, such as upregulation of type I interferon-regulated genes, abnormal expression of B-cell-activating factor and activation of the interleukin-23-type 17 T-helper cell pathway, have been reported. Extension of the pathological process that affects the exocrine glands into periepithelial and extraepithelial tissue can cause a considerable percentage of patients to exhibit systemic findings that involve the lungs, liver or kidneys. These manifestations develop as a result of lymphocytic invasion or an immune-complex-mediated process, or both, and present as skin vasculitis coupled with peripheral neuropathy or glomerulonephritis (or both). Patients with systemic extraepithelial manifestations display low serum levels of the complement component C4 and mixed type II cryoglobulins, and show an increased risk of developing non-Hodgkin lymphoma, thereby reflecting an overall worse prognosis with higher mortality rates than those without extraepithelial manifestations.

Tubulointerstitial immune complex nephritis in a patient with systemic lupus erythematosus: role of peritubular capillaritis with immune complex deposits in the pathogenesis of the tubulointerstitial nephritis

Class IV-G (A/C) diffuse lupus nephritis and tubulointerstitial (TI) nephritis in a 31-year old woman was studied by light, immunofluorescence (IF), and electron microscopy (EM), to determine the pathogenesis of the TI lesions. The light microscopic findings showed peritubular capillaritis in the interstitium, with ruptures in the capillary structure, lysis of the surrounding tubular basement membrane (TBM), extravasated red blood cells (RBCs), the infiltration of neutrophils and mononuclear cells, and edema. The IF study revealed IgG, IgA, IgM, C1q, C3, and C4 depositions along the TBM, on the capillary walls, and in the interstitium proper. The EM study disclosed the deposition of immune complexes in the TBM, the capillary wall, and the interstitium proper. Based on these findings, the TI nephritis in this patient was considered to be due to peritubular capillaritis secondary to the immune complex depositions in the capillary wall of the interstitium.

The spectrum of renal tubular acidosis in paediatric Sjögren syndrome

OBJECTIVES

Renal tubular acidosis (RTA) is a well-recognized extraglandular complication of adult Sjögren syndrome (SS) but has been reported only rarely in paediatric SS. We wished to describe the natural history of RTA in paediatric SS.

METHODS

We performed a chart and literature review. Inclusion criteria were primary or secondary SS with onset before 18 yr of age, complicated by RTA before 18 yr of age.

RESULTS

Twelve cases were identified: two from chart review and 10 from the literature. RTA was mostly associated with primary SS. RTA was detected at the onset of SS or up to 9 yr later. The clinical spectrum ranged from nearly silent to life-threatening, with plasma pH and serum potassium as low as 7.0 and 1.2 mEq/l, respectively. Hypokalaemia was present in 92%. Half the patients presented with profound weakness or paralysis, most likely from hypokalaemia. Proximal, distal and mixed RTA were detected, reflecting a diffuse 'tubulopathy' from interstitial nephritis, which was the predominant histopathological finding. Diabetes insipidus was the most frequent renal comorbidity. The RTA stabilized in 82% of the cases and resolved in one case. Only one patient had long-term unstable RTA.

CONCLUSIONS

RTA is an under-recognized complication of paediatric SS. It can be life-threatening in the acute phase but generally has a good long-term renal outcome. SS should be considered in the older child with otherwise unexplained RTA. Likewise, RTA should be excluded in children and adolescents with SS who develop weakness, fatigue or growth failure. Early recognition would reduce long-term complications such as growth failure.

A dual role for interferon-gamma in the pathogenesis of Sjogren's syndrome-like autoimmune exocrinopathy in the nonobese diabetic mouse

Sjogren's syndrome-like autoimmune exocrinopathy (AEC) in the nonobese diabetic (NOD) mouse progresses from a preimmune phase to an immune phase, resulting in dry mouth and/or dry eyes. In the present study, the impact of the prototypical T-helper type 1 cytokine, interferon-gamma (IFN-gamma), on the onset of AEC was investigated using both the IFN-gamma and the IFN-gamma receptor gene knockout mice, NOD.IFN-gamma(-/-) and NOD.IFN-gammaR(-/-), respectively. Neither the NOD.IFN-gamma(-/-) nor the NOD.IFN-gammaR(-/-) mice exhibited increased acinar cell apoptosis and abnormal salivary protein expression, typically observed in parental NOD mice prior to disease. Without these preimmune phase abnormalities, NOD.IFN-gamma(-/-) and NOD.IFN-gammaR(-/-) mice showed no subsequent autoimmune responses against the salivary glands at 20 weeks. Interestingly, real-time polymerase chain reaction and electrophoretic gel mobility shift assays suggested that IFN-gamma and STAT1, as well as the transcriptional activity of STAT1 in NOD glands, were increased at birth. Unlike the neonatal submandibular glands of NOD or NOD-scid mice that show abnormal glandular morphogenesis at birth, the submandibular glands of the newly constructed congenic strain, NOD-scid.IFN-gamma(-/-), were found to be normal. Taken together, IFN-gamma appears to play a critical role not only during the later immune phase of AEC, but also the early preimmune phase, independent of effector functions of immune cells. How exactly IFN-gamma functions during this period remains speculative.

Subclinical renal tubular acidosis in patients with primary and secondary Sjögren's syndrome: a possible marker of disease progression

Abstract To clarify the prevalence of subclinical renal tubular acidosis (RTA) and its association with clinical and laboratory parameters in primary and secondary Sjögren's syndrome (SS), an acid-loading test was conducted. Subclinical RTA was found in 32% of patients with SS. The prevalence of subclinical RTA in primary and secondary SS was about the same (31.6% and 33.3%, respectively). Significant longer duration of illness, more severely decreased salivary excretion, decreased lymphocyte number, higher serum levels of IgG and IgA, and higher frequency of anti-SS-A (Ro) and SS-B (La) antibodies were found in patients with subclinical RTA. These results suggested that subclinical RTA may be a characteristic manifestation both in primary and secondary SS, along with the progression of immunologic dysfunction, when the illness seemed to be indolent.

Clinical and morphological features of kidney involvement in primary Sjögren's syndrome

BACKGROUND

Primary Sjögren's syndrome is a connective tissue disorder affecting primarily the lacrimal and salivary glands, resulting in xerophtalmia and xerostomia. Extraglandular manifestations are frequent and may include renal involvement.

METHODS

We studied the prevalence and nature of kidney involvement in 60 Italian patients with primary Sjögren's syndrome, diagnosed according to the European classification criteria. The following renal laboratory tests were performed in all patients: electrolytes in serum and in 24-h urine, creatinine in serum and in 24-h urine, venous pH and HCO(3)(-), urinalysis, urine culture, urinary osmolality and urine pH. A water deprivation test was performed in patients with morning urine osmolalities below the reference values adjusted for age. An oral ammonium chloride loading test was performed in patients with urine pH above 5.5 from morning samples. Renal biopsy was performed in patients with renal involvement.

RESULTS

Sixteen patients (27%) had laboratory evidence of tubular and/or glomerular dysfunction. A variable degree of creatinine clearance reduction was found in eight patients (13%); frank distal tubular acidosis in three (5%); hypokalaemia in four (7%); and pathological proteinuria in 12 (20%). Urine concentrating capacity was defective in 10 out of 48 (21%) tested patients. Only four patients presented with overt clinical manifestations, including hypokalaemic tetraparesis (1), nephrotic syndrome (2), recurrent renal stones with flank pain and haematuria (1). In two patients, signs of renal involvement preceded the onset of sicca syndrome. Renal biopsies from nine patients showed tubulo-interstitial nephritis in six and glomerular disease in three. Patients with renal involvement had a significantly shorter disease duration compared with patients without renal abnormalities.

CONCLUSIONS

Kidney involvement is a frequent extraglandular manifestation of primary Sjögren's syndrome. It is rarely overt and may precede the onset of subjective sicca syndrome.

Retrospective cohort study of 148 patients with polyclonal gammopathy

OBJECTIVE

To quantify clinical conditions and laboratory values associated with moderate to marked polyclonal gammopathy.

PATIENTS AND METHODS

Patient characteristics, laboratory correlates, evolving disease states, and survival of all patients seen at the Mayo Clinic, Rochester, Minn, during 1991 with a polyclonal gamma globulin level of 3.0 g/dL or higher were reviewed in this retrospective cohort study.

RESULTS

One hundred forty-eight patients were identified (median age, 58 years; 59% female). In 130 patients (88%), only 1 diagnosis was identified. Liver disease was the most common single disease association in 79 (61%) of 130 patients, followed by connective tissue diseases in 28 (22%), chronic infections in 8 (6%), hematologic disorders in 6 (5%), and nonhematologic malignancies in 4 (3%). No difference in gamma globulin levels existed between groups. With a median follow-up of 67 months, 90 (63%) of 143 patients for whom follow-up was available were alive. By multivariate analysis, age, albumin concentration, disease group, and platelet count were predictive of survival. No patient developed myeloma or a clonal plasmaproliferative disorder.

CONCLUSION

Moderate to marked polyclonal gammopathy may reflect an underlying condition: liver disease, connective tissue disease, hematologic disorder, infection, or malignancy.

The occurrence of renal involvement in primary Sjögren's syndrome: a study of 78 patients

OBJECTIVE

To ascertain the occurrence of renal involvement in patients with primary Sjögren's syndrome (pSS).

METHODS

Urinary total protein excretion from 24 h urine collection, as well as urinary excretion rates of albumin, alpha-1 microglobulin (alpha1m) and IgG from overnight 8 h collections, were determined from 78 pSS patients (75 females, three males). Urine acidification capacity after oral ammonium chloride load was tested in 55 of these patients.

RESULTS

Mild proteinuria (0.15-0.42 g/24 h) was observed in 34 patients (44%). Increased urinary excretion rates of albumin (>/=20 microgram/min), alpha1m (>/=7.0 microgram/min) or IgG (>/=5.0 microgram/min) were detected in nine (12%), nine (12%) and 11 patients (14%), respectively. Latent or overt distal renal tubular acidosis (dRTA) was observed in 18 out of 55 patients with pSS (33%). These patients had a longer duration of the disease (10+/-4 vs 8+/-4 yr; P</=0.05); they also had proteinuria (67 vs 27%; P</=0.025) and hypertension (44 vs 14%; P</=0.05) more frequently, and significantly higher serum creatinine (92+/-39 vs 78+/-13 micromol/l; P</=0.025) and serum beta-2 microglobulin (beta2m) levels (3.3+/-1.6 g/l vs 2.6+/-0. 6 g/l; P</=0.025) as compared to patients with normal urine acidification capacity.

CONCLUSIONS

Inadequate renal acidification capacity, as well as mild proteinuria, were frequently found in patients with pSS. Those with dRTA had longer disease duration, a higher level of serum beta2m, and they had proteinuria and hypertension more frequently than those with normal renal acidification capacity.

Spongiotic annular erythema in SS-A/SS-B antibody negative Sjögren's syndrome

We reported four cases of Sjögren's syndrome (SjS) who manifested a new type of annular erythema that differs from the previously described annular erythema seen in anti-SS-A/SS-B antibody positive SjS in both clinical and histological findings. Characteristic histological features are the presence of spongiotic changes around the acrosyringium and perivascular lymphocytic infiltration without liquefaction degeneration or epidermal change, suggesting lupus erythematosus. No complement or immunoglobulin depositions are demonstrated along the basement membrane zone or around blood vessels. Clinically, this type of erythema usually appears on the trunk or extremities with itchy sensations, especially in summer, which contrasts with the preferential occurrence of the previously reported SjS related annular erythema on the facial skin in winter. Immunologically, all four cases lacked anti-SS-A and anti-SS-B antibodies, but possessed positive anti-microsome antibodies or thyroid tests. In three cases, metal allergy was demonstrated by patch test, which might suggest that the sweat duct is the primary target of excreted metals in this condition and that underlying SjS might play some role in the higher prevalence of metal allergy or in induction of sweat duct injury, similar to the interstitial nephritis which is now thought to be an exocrine manifestation of SjS.

Autoantibodies and primary Sjögren's syndrome in a hypocitraturic stone population

Primary Sjögren's syndrome may be complicated by distal renal tubular acidosis (dRTA) and hypocitraturia, which are risk factors for calcium stone formation. Approached from a different perspective, in patients with urolithiasis and dRTA, autoantibodies and various autoimmune diseases are not uncommon. In search for signs of autoimmune disease, we analysed antinuclear antibodies and total levels of serum IgG in 197 hypocitraturic stone formers (67 women and 130 men). Antinuclear antibodies were present in 1.5% of the men and in 18% of the women. An isolated increase in serum IgG was found in 9% of the men and in 3% of the women. Anti-SS-A antibodies were analysed in a subgroup of 46 women and were estimated to occur in 16% of all hypocitraturic stone forming women. Four of 4 examined women, but no men, fulfilled the criteria of definite or possible primary Sjögren's syndrome. We recommend the analysis of anti-SS-A antibodies in female hypocitraturic stone formers.

Sjögren's syndrome with membranous glomerulonephritis detected by urine screening of schoolchildren

A case of Sjögren's syndrome with glomerulonephritis is presented. The patient was a 13 year old male with hematuria and proteinuria discovered by urine screening of school children. Evaluation showed no evidence of any associated connective tissue disease. Kidney biopsy was consistent with membranous glomerulonephritis. Sjögren's syndrome with membranous glomerulonephritis is rare and the patient was the youngest case in the literature.

Complications of childhood Sjögren syndrome

Sjögren syndrome (SS) is a common disorder in adults and involves both glandular and extraglandular systems. We report here four cases of childhood SS complicated by chronic thyroiditis, interstitial nephritis or sweat gland inflammation. Additionally, in one of these cases, the central nervous system was involved. All of these complications are common in adult cases.

CONCLUSION

Childhood SS is a systemic "ductilitis" or "exocrinopathy" with complications which are commonly observed in adult cases.

Glomerular filtration rate in primary Sjögren's syndrome with renal disease

Renal disease in Primary Sjögren's syndrome (SS) is often overlooked, because of a paucity of symptoms. Distal renal tubular acidosis (dRTA) and tubulointerstitial nephritis (TIN) might be present. Only a few cases of SS with decreased glomerular filtration rate (GFR) have been reported. We have studied GFR in 27 female SS-patients, mean age 62 years (37-78). GFR was measured as the single injection 51Cr-EDTA plasma clearance. Eighteen women had normal GFR (group 1), and nine (33%) had values below the lower normal limit (group 2). In group 2, dRTA was present in 8/9 urolithiasis in 6/9, previous upper urinary tract infection (UTI) in 2/9 and TIN in 5/6 patients who were kidney biopsied. Among patients with dRTA 8/18 (44%) had decreased GFR. We conclude that decreased GFR is not unusual in SS-patients with dRTA, and decreased GFR is mostly associated with TIN. Urolithiasis and UTI may contribute to decreased GFR in some individuals.

Risk factors of calcium stone formation in patients with primary Sjögren's syndrome

Distal renal tubular acidosis (dRTA), which occurs in patients with primary Sjögren's syndrome (SS), is a risk factor for the development of urolithiasis. Twenty-seven patients with SS were evaluated with respect to biochemical risk factors of calcium stone formation. Sixteen had no history of urolithiasis (group 1) whereas 11 had such a history (group 2). The stone composition was known for seven of the patients, and calcium phosphate was the major stone constituent in all of them. dRTA was present in all patients in group 2, and in 7 of the 16 patients in group 1. Hypocitraturia was common in both groups, and the urinary excretion of citrate did not differ between the two groups. There was a higher urinary excretion of calcium and urate in group 2 and this group also had a higher urine volume. The risk of forming a urine supersaturated with calcium oxalate (CaOx) expressed in terms of AP(CaOx)index(s), which is an approximate estimate of the ion-activity product of CaOx calculated for a 24-h urine volume of 1500 ml, was higher in stone formers. A similarly derived estimate of the ion-activity product of calcium phosphate, AP(CaP)index(s), was calculated for a urine pH of 7. Although AP(CaP)index(s) was not significantly higher in group 2, there was a good correlation between AP(CaP)index(s) and AP(CaOx)index(s). We conclude that the urine composition in patients with SS, dRTA and urolithiasis is similar to that of other stone-forming patients with dRTA, and recurrence preventive therapy can be designed as for these patients.

Biochemical markers of renal disease in primary Sjögren's syndrome

Primary Sjögren's syndrome (SS) is characterized by an inflammatory process in the salivary and lacrimal glands, but the kidneys may also be involved. Renal tubular functions were studied in 27 patients with SS, all females, age 37-78. Both SS-patients with and without known distal renal tubular acidosis (dRTA) were included, dRTA was found in 18/27 (67%), impaired urine concentrating ability in 13/27 (48%). Hypocitraturia was identified in 20/27 (74%) and reduced tubular reabsorption of phosphate (TRP%) in 18/27 (67%). Tubular proteinuria (alpha 1-mikroglobulin) was present in 11/24 (46%), and tubular enzymuria (NAG) in 7/24 (29%). Hypocitraturia and/or dRTA were found in all patients with any kind of abnormal renal tubular function test. All except one of the patients with dRTA not treated with sodium bicarbonate had hypocitraturia. We conclude that distal tubular dysfunction was common in our SS-patients, but a concommitant proximal dysfunction was also seen. Determination of urinary citrate represents a valuable test for detection of renal disease in SS.

Impaired sweating as an exocrine manifestation in Sjögren's syndrome

To examine the prevalence of hypohidrosis and to quantitate sweating as an exocrinopathy in Sjögren's syndrome (SS), 49 patients with SS (primary form, 38; secondary form, 11) were studied. Sweating was induced by mental stimulation such as deep breathing or hand grasping. Statistically significant reductions of sweat volume were seen in SS (P < 0.005). Patients under 50 years old showed impaired sweat function compared with normal controls (P < 0.0005). In a control study, only haemodialysis patients showed impairment of sweating and this was greater than in patients with SS aged under 50 years. These results suggest that patients with SS develop impaired sweating as an exocrine manifestation in addition to the known symptoms of xerostomia and xerophthalmus.

Membranoproliferative glomerulonephritis with primary Sjögren's syndrome

Glomerular involvement in primary Sjögren's syndrome is rare and only five cases of membranoproliferative glomerulonephritis have been reported. We present a case of a 31-year-old white woman with primary Sjögren's syndrome who developed nephrotic syndrome. Evaluation showed no evidence of an associated connective tissue disease. Kidney biopsy was consistent with type I membranoproliferative glomerulonephritis. The patient's nephrotic syndrome resolved spontaneously, a course that has not been reported previously in this setting.

Renal tubular acidosis preceding systemic lupus erythematosus

A 10-year-old girl with distal renal tubular acidosis (RTA) for 4 years (adequately treated for 3 years) developed clinical features suggesting systemic lupus erythematosus (SLE) with supportive laboratory evidence. She had heavy proteinuria and a decreased creatinine clearance (CCr). Renal biopsy showed diffuse proliferative and sclerosing glomerulonephritis with severe tubulointerstitial changes. Following treatment with corticosteroids and cyclophosphamide, she had a clinical remission, an increase in CCr and recovery from systemic acidosis. It is likely that distal RTA in this patient was a manifestation of SLE.

Optic neuropathy and central nervous system disease associated with primary Sjögren's syndrome

Three cases of optic neuropathy associated with primary Sjögren's syndrome are reported. All three patients had clinical manifestations of primary Sjögren's syndrome, although two of the patients did not report sicca symptoms at initial examination. Two patients had focal neurologic signs in addition to optic neuropathy. The differentiation of this syndrome of optic neuropathy, focal neurologic signs, and Sjögren's syndrome from multiple sclerosis and antiphospholipid antibody syndrome is important for reasons of treatment and prognosis. This diagnostic differentiation was facilitated by positive tests for xerophthalmia and findings of positive minor salivary gland biopsy. High titers of antinuclear antibody, anti-SSA(Ro), and anti-SSB(La), and the absence of antiphospholipid antibodies provided additional help in the differential diagnosis. In 5 years of observation, none of the patients developed symptoms of multiple sclerosis or additional connective tissue disorders.

Renal tubular acidosis in primary Sjögren's syndrome

Renal tubular acidosis (RTA) is a frequent extraglandular manifestation of Sjögren's syndrome; however, no distinction on the incidence of this renal tubular defect between primary and secondary Sjögren's syndrome has been reported. This study was undertaken in order to define the frequency of RTA and the possible pathogenetic mechanisms in a group of 21 randomly selected primary Sjögren's syndrome patients. RTA was found in 7 (33%) patients. The incomplete type of the disorder was the most frequent. It seems that the etiology of RTA is multifactorial. Renal excretion of monoclonal proteins and the immunologically-induced interstitial inflammation are the main possible factors of this renal tubular defect.

Nephrocalcinosis in Sjögren's syndrome: a late sequela of renal tubular acidosis

Sjögren's syndrome (SS) is an autoimmune exocrinopathy that develops into systemic autoimmune disease in 25% of patients, leading to general complications, one of which is kidney involvement. It presents mainly as interstitial nephritis, disclosed by hyposthenuria, distal renal tubular acidosis (RTA) and diabetes insipidus. We here describe five cases of SS with type-1 RTA (hyperchloraemic metabolic acidosis with an anion gap and alkaline urine pH) who developed nephrolithiasis, nephrocalcinosis and renal insufficiency. Hypercalciuria due to acidosis was the main nephrocalcinosis-prone factor in four patients; four subjects displayed diminished renal concentrating capacity, and two had hypokalaemia.

A novel autoantibody reactive with carbonic anhydrase in sera from patients with systemic lupus erythematosus and Sjögren's syndrome

Carbonic anhydrase (CA) is an extremely basic zinc metalloenzyme with a wide phyletic distribution, and the enzyme is important for the regulation of acid-base status. A novel autoantibody reactive with carbonic anhydrase was demonstrated. Several different classes of CA are known in mammals. Using the immuno blotting method and and immun-dot analysis, we found this autoantibody to be reactive with CA in the sera from patients with Sjögren's syndrome (20.8%), including a patient with Sjögren's syndrome and renal tubular acidosis, and in patients with systemic lupus erythematosus (31.6%). The autoantibody varied in the extent of its cross-reactivity among human CA I (or B), human CA II (or C), bovine CA I, bovine CA II, rabbit CA, and dog CA. The titers continued to float and tended to parallel disease activity. Positive reactivity of autoantibody was observed on eccrine sweat glands and the distal tubules of the kidney by the indirect immunofluorescent method.

Renal tubular dysfunction in primary Sjögren's syndrome: clinical studies in 27 patients

Kidney involvement in Sjögren's syndrome (SS) including renal tubular disorders are well recognized but little is known about frequency and extent of such dysfunction in the general population of patients with primary SS, due to a lack of group studies. We studied 27 patients with primary SS and without other possible causes of tubular dysfunction. Increased urinary beta 2M excretion, due to proximal tubular dysfunction, was present in 26% of patients. Inadequate urine acidification after oral NH4 Cl, proving distal tubular dysfunction, was found in 12% of the patients studied. Concentrating ability, tested by thirst, was decreased in 44% of patients studied. Abnormal renal tubular tests correlated with presence of ANA (p = 0.05) but not with other clinical parameters. In conclusion demonstrable renal tubular dysfunctions occur in over half the patients with primary SS. Literature concerning this subject is discussed.