A case of malignant hypertension as a presentation of atypical hemolytic uremic syndrome

INTRODUCTION

Malignant hypertension (mHTN) damages multiple target organs, including the kidneys. mHTN has been regarded as one of the causes of secondary thrombotic microangiopathy (TMA); however, a high prevalence of complement gene abnormalities was recently reported in cohorts of mHTN.

CASE REPORT

We herein describe a 47-year-old male who presented with severe hypertension, renal failure (serum creatinine (sCr): 11.6 mg/dL), heart failure, retinal hemorrhage, hemolytic anemia, and thrombocytopenia. Renal biopsy findings were consistent with acute hypertensive nephrosclerosis. The patient was diagnosed with secondary TMA associated with mHTN. However, his previous medical history of TMA of unknown origin and family history of atypical hemolytic uremic syndrome (aHUS) suggested as aHUS presenting mHTN, and genetic testing revealed a pathogenic C3 mutation (p.I1157T). The patient required plasma exchange and hemodialysis for 2 weeks and was able to withdraw from dialysis by antihypertensive therapy without eculizumab. Renal function gradually improved to a sCr level of 2.7 mg/dL under antihypertensive therapy for 2 years after the event. There was no recurrence, and renal function was preserved throughout a 3-year follow-up.

DISCUSSION

mHTN is a common presentation of aHUS. In cases of mHTN, abnormalities in complement-related genes may be involved in the development of the disease.

Effect of Moderate Aerobic Exercise on Complement Activation Pathways in Polycystic Ovary Syndrome Women

BACKGROUND

The complement system is pivotal in host defense mechanisms, protecting against pathogenic infection by regulating inflammation and cell immunity. Complement-related protein activation occurs through three distinct pathways: classical, alternative, and lectin-dependent pathways, which are regulated by cascades of multiple proteins. Complement activation is recognized in polycystic ovary syndrome (PCOS) to be associated with obesity and insulin sensitivity. Exercise reduces insulin resistance and may help reduce obesity, and therefore, this study was undertaken to determine the effect of exercise on the activation of complement-related proteins in PCOS and control women.

SUBJECTS AND MEASUREMENTS

In this study, 10 controls and 11 PCOS subjects who were age- and weight-matched underwent an 8-week supervised exercise program at 60% maximal oxygen consumption. Weight was unchanged though insulin sensitivity was increased in PCOS subjects and controls. Fasting baseline and post-exercise samples were collected and 14 complement-related proteins belonging to classical, alternative, and lectin-dependent pathways were measured.

RESULTS

Baseline levels of complement C4b and complement C3b/iC3b were higher in PCOS (P < 0.05) compared with controls. Exercise reduced complement C1q (P < 0.05), C3 (P < 0.001), C4 (P < 0.01), factor B (P < 0.01), factor H (P < 0.01), and properdin (P < 0.05) in controls, but not in PCOS women.

CONCLUSION

Exercise induced complement changes in controls that were not seen in PCOS subjects, suggesting that these pathways remain dysregulated even in the presence of improved insulin sensitivity and not improved by moderate aerobic exercise.

CLINICAL TRIAL REGISTRATION

ISRCTN registry, ISRCTN42448814.