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Correlation between early changes of serum lipids and clinical severity in patients with wasp stings

Open AccessPublished:September 12, 2022DOI:https://doi.org/10.1016/j.jacl.2022.09.003

      Highlights

      • Patients with wasp stings experience a significant reduction in blood lipid levels.
      • Hemolysis and inflammatory responses might lead to hypolipidemia.
      • Early blood lipid levels have a relationship with the clinical severity of wasp stings.
      • Lipid metabolism might be a new target for future treatment of wasp stings.

      BACKGROUND

      Wasp stings are a serious problem worldwide, and patients in severe cases may experience multi-organ failure. However, the mechanism of hypolipidemia in patients with wasp stings is unknown.

      OBJECTIVE

      To investigate the relationship between early changes in lipid levels and clinical severity and the possible underlying mechanisms.

      METHODS

      A retrospective analysis of 212 patients (mild: 77; moderate: 50; severe: 85) with wasp stings was conducted. Clinical data, including lipid test results within 24 h of admission, were analysed. A total of 1060 healthy age- and gender-matched controls were used.

      RESULTS

      Patients with wasp stings had lower lipid levels than healthy controls (P<0.01). Lipid levels decreased with disease severity, except for triglycerides (P<0.05). The number of stings, degree of organ failure, need for mechanical ventilation and extracorporeal blood purification, and mortality were higher in the severe group than in the mild and moderate groups (P<0.01). A decrease in lipid levels was accompanied by an increase in inflammatory indicators. In the severe group, a reduction in lipid levels was associated with ventilator application and blood purification, independent of survival status.

      CONCLUSIONS

      Patients with wasp stings experience a reduction in lipid levels, which is related to the severity of clinical manifestations. Early lipid levels may serve as a simple indicator for the severity of wasp stings, and targeting lipid metabolism may be a novel treatment.

      Keywords

      Introduction

      Wasps, bees, and ants belong to the insect order Hymenoptera. Wasp stings are a significant public health problem worldwide.
      • Bilò M.B.
      • Pravettoni V.
      • Bignardi D.
      • et al.
      Hymenoptera venom allergy: management of children and adults in clinical practice.
      In the United States, nearly 220,000 emergency department visits and 60 deaths occur annually due to hymenopteran stings.
      • Forrester J.A.
      • Weiser T.G.
      • Forrester J.D.
      An update on fatalities due to venomous and nonvenomous animals in the United States (2008-2015) [published correction appears in wilderness environ med. 2018 Apr 4;:].
      A study from 1994 to 2016 indicated that a total of 1691 fatalities were due to hornet, wasp and bee stings in 32 European countries.
      • Feás X.
      • Vidal C.
      • Remesar S.
      What we know about sting-related deaths? Human fatalities caused by hornet, wasp and bee stings in Europe (1994-2016).
      In China, wasp stings have occurred more frequently in recent years, and the mortality of wasp stings can reach 6% or more.
      • Liu Y.
      • Shu H.
      • Long Y.
      • et al.
      Development and internal validation of a wasp sting severity score to assess severity and indicate blood purification in persons with Asian wasp stings.
      Wasp venom, a mixture of various components, mainly includes histamine phospholipase A2 (PLA2), melittin, hyaluronidase, mastoparans and serotonin.
      • Liu Y.
      • Shu H.
      • Long Y.
      • et al.
      Development and internal validation of a wasp sting severity score to assess severity and indicate blood purification in persons with Asian wasp stings.
      From a clinical perspective, patients with wasp stings may have several clinical manifestations. Allergic reaction and toxic effects are common after wasp stings. Allergic reaction occurs in several minutes or even hours after the sting with skin symptoms of itching, erythema and edema, and severe cases can cause anaphylactic shock or even death.
      • Bilò M.B.
      • Pravettoni V.
      • Bignardi D.
      • et al.
      Hymenoptera venom allergy: management of children and adults in clinical practice.
      Toxic effects include rhabdomyolysis, intravascular hemolysis, coagulation disorders, liver damage and acute renal failure, which usually occur after multiple stings in hours to days.
      • Bilò M.B.
      • Pravettoni V.
      • Bignardi D.
      • et al.
      Hymenoptera venom allergy: management of children and adults in clinical practice.
      ,
      • Chen P.
      • Yao W.
      • Gong R.
      • et al.
      Early intervention (≤6h) reduces the degree of multiple organ dysfunction with wasps sting patients [published online ahead of print, 2021 Sep 21].
      ,
      • Yao W.
      • Sun Y.
      • Sun Y.
      • et al.
      A preliminary report of the relationship between gene polymorphism of IL-8 and its receptors and systemic inflammatory response syndrome caused by wasp stings.
      ,
      • Sun Y.
      • Yang J.
      • Sun Y.
      • et al.
      Interleukin-6 gene polymorphism and the risk of systemic inflammatory response syndrome caused by wasp sting injury.
      After multiple simultaneous stings, patients can experience severe toxic effects and develop multiple organ dysfunction syndrome. Anti-allergic treatment and supportive treatment, including fluid resuscitation therapy, maintenance of haemodynamic stability, extracorporeal blood purification and mechanical ventilation, are important. Chen et al. found that the degree of organ damage in patients with early intervention treatment (≤6 h) was reduced compared that with >6 h intervention time.
      • Chen P.
      • Yao W.
      • Gong R.
      • et al.
      Early intervention (≤6h) reduces the degree of multiple organ dysfunction with wasps sting patients [published online ahead of print, 2021 Sep 21].
      Thus, timely initiation of therapy can avoid deterioration.
      Patients with wasp stings can develop a significant systemic inflammatory response resembling sepsis.
      • Wijerathne B.T.
      • Rathnayake G.K.
      • Agampodi S.B.
      Hornet stings presenting to a primary care hospital in Anuradhapura district, Sri Lanka.
      The predictors of poor outcomes in sepsis have been linked to abnormalities in lipid metabolism.
      • Feng Q.
      • Wei W.Q.
      • Chaugai S.
      • et al.
      Association between low-density lipoprotein cholesterol levels and risk for sepsis among patients admitted to the hospital with infection.
      Lipid supplementation could be used as a potential treatment option for patients who suffer from sepsis,
      • Lee S.H.
      • Park M.S.
      • Park B.H.
      • et al.
      Prognostic implications of serum lipid metabolism over time during Sepsis.
      which might be a new therapeutic modality in wasp stings. The majority of current research on wasp stings have focused on allergy management and therapies of multi-organ function damage. Few have elucidated lipid level alterations in patients with wasp stings, and the clinical severity implications of lipid level changes remain unclear. Based on the similarities in the pathophysiology of severe wasp stings and sepsis, the goal of this study was to investigate the relationship between lipid level changes and clinical severity and to provide speculative discussion.

      Materials and methods

      Study design and patients

      Between June 1, 2018 and December 1, 2021, a total of 231 patients with wasp stings were hospitalised at the Department of Emergency Medicine, Taihe Hospital, Shiyan City, Hubei Province. The inclusion and exclusion criteria are as follows: Inclusion criteria: (1) patients were diagnosed with wasp stings, (2) age 18–80 years old and (3) complete clinical data. Exclusion criteria: (1) other cases of sting; (2) incomplete data; and (3) prior history of haematologic disorders, chronic liver and kidney insufficiency, immune deficiency or hyperlipidemia. A total of 212 patients were selected for the present study. A total of 1060 control patients were selected from the Physical Examination Center of Taihe Hospital, with matched age and gender at a ratio of 1 to 5. Wasp stings were diagnosed based on the clinical history and physical examination findings. Based on the severity of clinical manifestations and Expert Consensus Statement on the Standardized Diagnosis and Treatment of Wasp Sting in China
      Chinese Society Of Toxicology Poisoning And Treatment Of Specialized Committee
      Hubei emergency medicine committee of Chinese Medical Association, Hubei provincial poisoning and occupational disease union, Yang X, Xiao m.
      (hereafter referred to as the ‘expert consensus’), the severity of wasp stings can be classified into mild, moderate and severe. Severity rating: (1) Mild: The number of sting skin lesions is generally less than 10, with occurrence of local allergic reaction only and no organ function involvement. (2) Moderate: The number of sting skin lesions is generally between 10 and 30. Allergic reactions are graded as Ⅰ–Ⅱ, and only one organ system is involved. The Sequential Organ Failure assessment (SOFA) score is greater than or equal to Ⅱ, and the early appearance of soy sauce- or tea-coloured urine is found. (3) Severe: The number of sting skin lesions is generally more than 30. The allergic reaction is graded as Ⅲ–Ⅳ, or at least two organ systems are involved. The SOFA score of each organ system is greater than or equal to II. Twenty-four hours within the onset of wasp stings was defined as the early stage. A CONSORT flow diagram is shown in Fig. 1. The study was approved by the Ethics Committee of Shiyan Taihe Hospital.
      Fig 1
      Fig. 1A CONSORT flow diagram for inclusion of the wasp stings patients in this study.

      Methods

      Data collection

      Our team conducted a retrospective analysis of available medical records. Disagreements were resolved through arbitration with a third person. Demographic information, underlying diseases, clinical information, results of the first laboratory examination, treatment, follow-up examinations and outcome of the research subjects were obtained from the records and participants. Laboratory data included lipid tests (triglycerides [TG], total cholesterol [TC], high-density lipoprotein cholesterol [HDL-C], low-density lipoprotein cholesterol [LDL-C], apolipoprotein A1 [Apo-A1] and apolipoprotein B [Apo-B]), routine blood tests, liver and kidney function, and inflammatory markers such as interleukin-6 (IL-6) and C-reactive protein (CRP). Additionally, the Acute Physiology and Chronic Health Evaluation II (APACHE II) score, SOFA score and mortality at 28 days were determined. The control group consisted of age- and gender-matched normal healthy subjects who underwent lipid tests at our hospital between June 1, 2018 and December 1, 2021.

      Laboratory examination

      Blood samples were randomly collected within 24 h of admission and in non-fasting condition. Drugs that could affect test results, such as fat milk and propofol, were not given at the time of the initial blood collection. The peripheral blood was measured by an automatic blood cell analyser (Mindray BC‐5800, Shenzhen, China). Kidney and liver function parameters and blood lipids were tested using the Automatic Biochemistry Analyzer (7600, Hitachi).  Procalcitonin, IL-6 and serum amyloid-A (SAA) were tested using NOVIZAN QD-S1200 according to the manufacturer's chemiluminescent immunoassay reagents (Nanjing NOVIZAN Biotechnology Company, China). An automatic coagulation analyser was used to detect the coagulation function indicators (Sysmex CS5100, Japan). Lactate was analysed with the COBAS b 123 autoanalyzer (Roche, Basel, Switzerland).

      Statistical analysis

      SPSS 22.0 (IBM, Armonk, NY) was used for statistical analysis. Continuous variables were depicted using medians with interquartile ranges. The normal distribution test was performed on all data, and the non-parametric test was used for data that did not meet the criteria for normal distribution. The Mann–Whitney test or Kruskal–Wallis test was used to analyse all continuous variables because of their non-normal distributions. Categorical variables were expressed as number (%) and compared using Fisher's exact test or Chi-square test. Pearson's correlation test was used for correlation analysis.

      Results

      Lipid characteristics of patients with wasp stings

      All 212 patients diagnosed with wasp stings and tested for blood lipid levels were included in this study. Compared with controls, patients showed significantly lower levels of TC (median, 2.81 vs 4.45 mmol/L, P<0.01), TG (median, 0.62 vs 1.12 mmol/L, P<0.01), HDL-C (median, 0.87 vs 1.36 mmol/L, P<0.01), LDL-C (median, 1.55 vs 2.64 mmol/L, P<0.01), Apo-A1 (median, 0.90 vs 1.26 mmol/L, P<0.01) and Apo-B (median, 0.52 vs 0.98 mmol/L, P<0.01) (Fig. 2).
      Fig 2
      Fig. 2Patients with wasp stings show hypolipidemia compared with the control group. Mann Whitney U test was used to compare differences between groups. TC, total cholesterol; TG, triglycerides; HDL-C, high-density lipoprotein cholesterol; LDL-C, low-density lipoprotein cholesterol; Apo-A1, apolipoprotein A1; Apo-B, apolipoprotein B.

      Demographic and clinical characteristics of patients with wasp stings

      According to expert consensus, the 212 patients with wasp stings were divided into three groups: mild (77), moderate (50) and severe (85). The average age of patients in the severe group was 60.0 (48.0, 66.5) years; the patients in this group were significantly older than those in the mild group (48.0 (34.0, 57.5) years) and moderate group (46.5 (30.8, 57.5) years) (P<0.01) (Table 1). No differences were observed in gender and co-morbidities (hypertension, cardiovascular disease or diabetes) in all three groups (P>0.05). All patients were graded by the Ring and Messmer classification for hypersensitivity reactions.
      • Przybilla B.
      • Ruëff F.
      Hymenoptera venom allergy.
      The severe group had a significantly higher rate of grade II, III and IV allergic reactions than the other two groups (P<0.01). The severe group received significantly more stings than the other two groups (P<0.01). The major complications included liver damage, hemolysis, acute kidney injury (AKI) and acute respiratory distress syndrome (ARDS), with the severe group having the highest incidence (P<0.01). The ratios of life-support treatments, clinical severity scores (APACHE-II and SOFA), hospital length of stay and mortality among patients in each category are listed in Table 1.
      Table 1Clinical features of the patients
      CharacteristicsWasp stings patientsP
      Mild (n=77)Moderate (n=50)Severe (n=85)
      Age, years48.0(34.0,57.5)46.5(30.8,57.5)60.0(48.0,66.5)<0.01
       Male44(57.1)29(58.0)53(62.4)0.77
       Female33(42.9)21(42.0)32(37.6)
      Ring and Messmer classification
       Ⅰ57(74.03)40(80.00)29(34.12)<0.01
       Ⅱ20(25.97)10(20.00)32(37.65)
       Ⅲ0(0.00)0(0.00)20(23.53)
       Ⅳ0(0.00)0(0.00)4(4.71)
      No. of stings6.0(2.0,11.5)15.0(11.0,22.0)35.0(22.0,54.0)<0.01
      Comorbidities
       Hypertension21(27.3)17(34.0)32(37.6)0.37
        CVD13(16.9)8(16.0)20(23.5)0.45
        2-DM4(5.2)6(12.0)3(3.5)0.13
      Complications
       Liver damage20(26.0)11(22.0)53(62.4)<0.01
       Hemolysis44(57.1)27(54.0)71(83.5)<0.01
        AKI4(5.19)8(16.00)51(60.00)<0.01
        ARDS0(0.00)0(0.00)26(30.59)<0.01
      Life-support treatment
       Blood purification1(1.3)2(4.0)45(52.9)<0.01
        Ventilation0(0.0)0(0.0)24(28.2)<0.01
      Clinical severity scores
        SOFA1.0(0.0,2.0)2.0(0.0,2.0)5.0(4.0,10.0)<0.01
        APACHE-II5.0(4.0,7.0)5.0(4.0,7.0)12.0(7.0,19.0)<0.01
      HLOS (d)2.0(1.0,3.0)3.0(2.0,3.0)5.0(3.0,8.0)<0.01
      Mortality0(0.0)0(0.0)16(18.8)<0.01
      CVD, cardiovascular disease; 2-DM, type 2 diabetes mellitus; AKI, acute kidney injury (AKI); ARDS, acute respiratory distress syndrome; SOFA, Sequential Organ Failure Score; APACHE-II, Acute Physiology and Chronic Health Evaluation II;
      HLOS, hospital length of stay.
      Data were median (IQR) or n (%).

      Clinical laboratory tests

      There were significant and graded decreases in TC, HDL-C, LDL-C, Apo-A1 and Apo-B levels in all three groups (P<0.01) (Table 2). Erythrocytes, platelets, haemoglobin and lactate levels were not significantly different between the three groups. Alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin (T-bil), unconjugated bilirubin (U-bil) and lactate dehydrogenase (LDH) levels were higher in the severe group than in the other two groups (P<0.05). The patients in the severe group presented with higher levels of ALT, AST, T-bil, U-bil, blood urea nitrogen, creatinine and activated partial thromboplastin time. The severe group had the highest levels of inflammatory markers such as white blood cells (WBCs), neutrophil-to-lymphocyte ratio (NLR), IL-6, SAA and CRP among the three groups (P<0.05). Refer to Table 2.
      Table 2Main clinical laboratory profiles of wasp stings patients
      Laboratory testingReference rangesWasp stings patientsP
      Mild (n=77)Moderate (n=50)Severe (n=85)
      TC (mmol/L)2.33-5.693.14(2.65,3.56)2.78(1.42,3.22)2.51(1.50,3.18)<0.01
      TG (mmol/L)0.25-1.710.69(0.52,1.33)0.61(0.35,1.01)0.50(0.31,1.11)0.16
      HDL-C (mmol/L)0.90- 1.941.05(0.85,1.29)0.81(0.54,1.13)0.73(0.44,0.98)<0.01
      LDL-C (mmol/L)0.60-4.141.83(1.46,2.31)1.70(0.68,2.33)1.32(0.80,1.78)<0.01
      Apo-A1 (g/L)1.06-1.81.13(0.86,1.26)0.90(0.48,1.18)0.76(0.40,0.96)<0.01
      Apo-B (g/L)0.6-1.140.61(0.45,0.74)0.53(0.34,0.75)0.43(0.28,0.68)<0.05
      WBC (× 109/L)3.5–9.513.88(9.41,17.98)13.57(8.62,19.05)18.12(12.50,22.29)<0.01
      NLR10.13(5.96,18.78)13.78(8.52,20.81)19.66(12.65,25.04)<0.01
      RBC (× 1012/L)3.8-5.14.30(3.88,4.72)4.43(3.87,4.81)4.21(3.63,4.69)0.23
      Hb (g/L)115-150134.00(120.50,147.00)131.00(117.00,152.25)131.00(116.00,146.50)0.75
      PLT (× 109/L)125-350211.00(149.00,288.00)214.00(173.00,256.00)185.00(136.00,241.00)0.3
      Lac (mmol/L)0.5∼1.72.75(2.20,3.40)2.75(2.15,3.83)2.80(2.40,5.00)0.1
      T-bil (μmol/L)3.42-20.518.10(11.50,25.45)18.59(14.80,26.64)36.30(13.98,58.88)<0.01
      U-bil (μmol/L)1-17.014.20(8.78,19.80)14.38(10.95,21.56)28.92(11.20,46.75)<0.01
      ALT (U/L)5–3522.00(13.80,38.15)23.50(18.35,43.48)42.00(18.80,224.50)<0.01
      AST (U/L)8–4033.00(22.00,55.00)33.80(22.65,48.13)81.00(30.50,730.10)<0.01
      LDH (U/L)100-240228.40(172.30,307.00)251.00(206.15,317.00)362.70(245.10,1680.00)<0.01
      BUN (mmol/L)1.7-7.54.86(4.32,6.61)5.05(4.09,7.48)6.34(4.42,9.82)<0.05
      Cr (umol/L)44-12070.70(52.45,78.65)79.80(62.88,104.50)84.00(66.60,134.60)<0.01
      PT (s)9-1311.70(11.15,13.05)12.00(11.10,14.80)12.90(11.80,15.75)<0.01
      APTT (s)25-3738.70(29.20,50.85)39.16(30.82,64.28)47.70(33.75,99.50)<0.01
      IL-6 (Pg/mL)0.1–2.916.00(11.00,24.00)32.00(16.00,43.00)35.00(16.00,51.00)<0.01
      SAA (mg/L)<1021.68(6.20,27.50)21.68(5.34,30.00)25.00(21.68,40.86)<0.01
      CRP (mg/L)<44.19(1.15,7.60)5.00(2.65,15.24)5.73(1.88,18.48)<0.05
      TC, total cholesterol; TG, triglycerides; HDL-C, high-density lipoprotein cholesterol; LDL-C, low-density lipoprotein cholesterol; Apo-A1, apolipoprotein A1;Apo-B, apolipoprotein B; WBC, white blood cells; NLR, neutrophil-to-lymphocyte ratio; RBC, red blood cells; Hb, haemoglobin; PLT, platelet count; Lac, lactate levels; T-bil, total bilirubin; U-bil, unconjugated bilirubin; ALT, Alanine aminotransferase; AST, glutamic aminotransferase; LDH, lactate dehydrogenase; BUN, Urea nitrogen; Cr, creatinine; PT, Prothrombin time; APTT, activated partial thromboplastin time; IL-6, interleukin-6; SAA, amyloid-A; CRP, C-reactive protein.
      Data were median (IQR).
      Kruskal-Wallis test was used to compare variables among groups (mild, moderate, severe).

      Relationship between lipid levels and clinical outcomes in the severe group

      Table 3 shows the relationships between TC, TG, HDL-C, LDL-C, Apo-A1 and Apo-B levels and the clinical outcomes (need for ventilator, need for extracorporeal blood purification and mortality at day 28) in the severe group. The levels of HDL-C and Apo-A1 were statistically significantly lower in patients requiring ventilation (P<0.05). Patients requiring blood purification had lower TC, HDL-C, LDL-C and Apo-A1 (P<0.01). No statistically significant association was found between lipid levels and mortality at day 28.
      Table 3Relationship between lipid levels and clinical outcomes in severe group
      LipidSevere group (n=85)Mechanical ventilationP
      No (n=61)Yes (n=24)
      TC (mmol/L)2.51(1.50,3.18)2.52(1.50,3.22)2.31(1.29,2.91)0.43
      TG (mmol/L)0.50(0.31,1.11)0.49(0.25,1.10)0.57(0.40,1.40)0.22
      HDL-C (mmol/L)0.73(0.44,0.98)0.82(0.46,1.07)0.52(0.36,0.84)<0.05
      LDL-C (mmol/L)1.32(0.80,1.78)1.37(0.75,1.81)1.31(0.85,1.50)0.71
      Apo-A1 (g/L)0.76(0.40,0.96)0.81(0.42,1.06)0.45(0.39,0.80)<0.05
      Apo-B (g/L)0.43(0.28,0.68)0.43(0.28,0.64)0.43(0.29,0.76)0.59
      LipidSevere group (n=85)Blood purificationP
      No(n=40)Yes(n=45)
      TC (mmol/L)2.51(1.50,3.18)2.70(1.85,3.71)2.05(1.09,2.69)<0.05
      TG (mmol/L)0.50(0.31,1.11)0.54(0.29,1.44)0.50(0.32,1.05)0.87
      HDL-C (mmol/L)0.73(0.44,0.98)0.92(0.60,1.13)0.57(0.37,0.83)<0.01
      LDL-C (mmol/L)1.32(0.80,1.78)1.50(1.01,2.28)1.15(0.71,1.48)<0.01
      Apo-A1 (g/L)0.76(0.40,0.96)0.88(0.56,1.17)0.58(0.39,0.82)<0.01
      Apo-B (g/L)0.43(0.28,0.68)0.55(0.32,0.69)0.34(0.25,0.61)0.05
      LipidSevere group (n=85)Vital status at day 28P
      Alive (n=69)Deceased (n=16)
      TC (mmol/L)2.51(1.50,3.18)2.51(1.33,3.10)2.66(2.04,3.78)0.14
      TG (mmol/L)0.50(0.31,1.11)0.49(0.29,1.12)0.74(0.42,1.08)0.28
      HDL-C (mmol/L)0.73(0.44,0.98)0.79(0.42,1.06)0.64(0.50,0.85)0.48
      LDL-C (mmol/L)1.32(0.80,1.78)1.32(0.72,1.76)1.48(1.10,1.97)0.37
      Apo-A1 (g/L)0.76(0.40,0.96)0.80(0.39,1.05)0.59(0.40,0.82)0.44
      Apo-B (g/L)0.43(0.28,0.68)0.43(0.26,0.64)0.44(0.33,0.74)0.33
      TC, total cholesterol; TG, triglycerides; HDL-C, high-density lipoprotein cholesterol; LDL-C; low-density lipoprotein cholesterol; Apo-A1, apolipoprotein A1; Apo-B, apolipoprotein B.
      Data were median (IQR).
      Mann‐Whitney U tests was applied.

      Relationships of inflammatory factors with lipid levels

      Pearson correlation coefficients were used to assess the correlation between inflammatory factors and lipid levels. The WBC counts were negatively correlated with the levels of TC (R=-0.184; P=0.007, Fig. 3A), HDL-C (R=-0.177; P<0.001, Fig. 3D) and Apo-A1 (R=-0.241; P<0.01, Fig. 3J). The SAA levels showed an inverse correlation with HDL-C (R=-0.160; P=0.019, Fig. 3G). The CRP levels were inversely correlated with the levels of HDL-C (R=-0.195; P=0.004, Fig. 3H). NLR was negatively correlated with the levels of TC (R=-0.250; P<0.001, Fig. 3B), TG (R=-0.182; P=0.008, Fig. 3L), HDL-C (R=-0.239; P<0.001, Fig. 3E) and Apo-B (R=-0.199; P=0.004, Fig. 3I). The levels of IL-6 were found to be inversely related to those of TC (R=-0.194; P=0.005, Fig. 3C), HDL-C (R=-0.257; P<0.001, Fig. 3F) and Apo-A1 (R=-0.237; P<0.001, Fig. 3K).
      Fig 3
      Fig. 3Correlations of WBC, NLR, IL-6, SAA, CRP and levels of TC, TG, HDL-C, LDL-C, Apo-A1, Apo-B in Wasp stings patients. A Pearson correlation analysis was used. TC, total cholesterol; TG, triglycerides; HDL-C, high-density lipoprotein cholesterol; LDL-C; low-density lipoprotein cholesterol; Apo-A1, apolipoprotein A1; Apo-B, apolipoprotein B; WBC, white blood cells; NLR, neutrophil-to-lymphocyte ratio; IL-6, interleukin-6; SAA, amyloid-A; CRP, C-reactive protein.

      Discussion

      We conducted a retrospective analysis of the lipid profiles of patients with wasp stings within 24 h in this study. Our data showed that patients with mild wasp stings developed hypolipidemia. In addition to TG, serum TC, HDL-C, LDL-C, Apo-A1 and Apo-B levels decreased significantly as the severity of wasp sting increased, and early hypolipidemia was positively correlated with wasp sting severity. In China, Luo et al.
      • Luo C.H.
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      • et al.
      Analysis of blood lipid test results in patients with bee stings[J].
      found that patients with wasp stings had significant dyslipidemia, manifesting as hypolipidemia, but the mechanism of lipid decline and its pathophysiological significance in clinical settings have not been elucidated. Our findings shed new light on the pathophysiological evolution of lipidology in patients with wasp stings. To our knowledge, this study is the first to include clinical laboratory data on lipids from such a large patient population. This will not only provide simple and inexpensive indicators for assessing disease progression and prognosis, but will also lay the groundwork for future research on novel therapeutic targets.
      The mechanism of decreased blood lipids in patients with wasp stings is hypothesised to be related to secondary hemolysis and inflammatory responses after wasp stings. Wasp venom can cause acute intravascular hemolysis. PLA2 and melittin are the main components of wasp venom,
      • Ciron J.
      • Mathis S.
      • Iljicsov A.
      • Boucebci S.
      • Neau J.P.
      Multiple simultaneous intracranial hemorrhages due to hornet stings.
      and both act synergistically on the lipid structure of the erythrocyte membrane, causing cholesterol depletion and cell membrane rupture via hydrolysis.
      • Damianoglou A.
      • Rodger A.
      • Pridmore C.
      • et al.
      The synergistic action of melittin and phospholipase A2 with lipid membranes: development of linear dichroism for membrane-insertion kinetics.
      This is an important mechanism of hemolysis after wasp stings. Multiple stings mean a large amount of venom entering the body, and hemolysis tends to be more severe. Increased serum LDH levels and free bilirubin are regarded as key biological markers of acute hemolysis.
      • Boutboul D.
      • Touzot F.
      • Szalat R.
      Understanding therapeutic emergencies in acute hemolysis.
      In Table 2, we found that the number of stings and serum levels of LDH and free bilirubin were significantly higher in the severe group than in the mild and moderate groups, which indicated that the incidence of hemolysis was the highest in the severe group. Therefore, we hypothesised that wasp venom's direct haemolytic effect could cause lipid depletion, leading to hypolipidemia.
      Proinflammatory cytokines modulate lipid metabolism by inhibiting cholesterol efflux and transport.
      • Wei X.
      • Zeng W.
      • Su J.
      • et al.
      Hypolipidemia is associated with the severity of COVID-19.
      The inflammatory response may be another important reason for the early decline in lipids in patients with wasp stings. The allergic and toxic reactions induced by wasp venom can lead to the release of large amounts of inflammatory factors, such as IL-6 and IL-8
      • Yao W.
      • Sun Y.
      • Sun Y.
      • et al.
      A preliminary report of the relationship between gene polymorphism of IL-8 and its receptors and systemic inflammatory response syndrome caused by wasp stings.
      [7], resulting in systemic inflammatory response syndrome (SIRS)[6]. Hemolysis products such as heme, ferrous heme and oxygen free radicals contribute to and enhance the inflammatory response.
      • Schaer D.J.
      • Buehler P.W.
      • Alayash A.I.
      • Belcher J.D.
      • Vercellotti G.M.
      Hemolysis and free hemoglobin revisited: exploring hemoglobin and hemin scavengers as a novel class of therapeutic proteins.
      Patients with sepsis experience SIRS. The levels of lipids will decrease in inflammatory conditions.
      • Lee S.H.
      • Park M.S.
      • Park B.H.
      • et al.
      Prognostic implications of serum lipid metabolism over time during Sepsis.
      In critically ill patients, dyslipidemia is associated with the severity of inflammatory response and metabolic dysregulation, abnormalities in cytokine levels and severity of illness.
      • Vyroubal P.
      • Chiarla C.
      • Giovannini I.
      • et al.
      Hypocholesterolemia in clinically serious conditions–review.
      In the present study, patients with severe wasp stings showed a significant decrease in lipid levels. We found that the levels of inflammatory indicators such as IL-6, WBC, NLR, SAA and CRP were negatively correlated with lipid decline. This suggests that inflammation might be one of the contributors to lipid abnormality in patients with wasp stings.
      The abnormal leakage of lipids from capillaries may cause hypolipidemia. The severity of allergic reactions and the levels of inflammatory factors were significantly higher in the severe group than in the non-severe group, as were the rates of ARDS and ventilator use. Capillary permeability increases in the presence of allergic and non-allergic inflammatory reactions, allowing exudates to leak into the alveoli and other tissue spaces. Large amounts of lipids have been found in the exudates of intra-alveolar and other tissue spaces in autopsies from patients with SARS and COVID-19.
      • Wei X.
      • Zeng W.
      • Su J.
      • et al.
      Hypolipidemia is associated with the severity of COVID-19.
      In patients with wasp stings, severe inflammation and poor vascular permeability lead to the leakage of lipids and plasma cholesterol from the circulation into the alveoli and other tissue spaces. However, this mechanism still needs further study.
      We analysed the severe group separately to analyse the relationship between lipid profiles and clinical outcomes in patients with wasp stings. As mentioned previously, patients in the severe group underwent a severe inflammatory response. The inflammatory response causes the depletion of lipids, including TC, HDL-C and LDL-C.
      • Vyroubal P.
      • Chiarla C.
      • Giovannini I.
      • et al.
      Hypocholesterolemia in clinically serious conditions–review.
      Apo-A1 is an important component of HDL-C, and it decreases along with HDL-C. We observed that patients requiring ventilation were associated with lower HDL-C and ApoA1. Moreover, patients requiring blood purification had lower levels of TC, HDL, LDL and Apo-A1. In the severe group, patients requiring mechanical ventilation had severe lung injury induced by allergies and inflammatory reactions. Patients requiring blood purification suffered from severe hemolysis and AKI. We found that the reduction of lipids is associated with the need for ventilator and blood purification. However, in terms of mortality at day 28, we did not find any differences in blood lipids. This may be related to some confounding factors such as age, underlying disease and complications. Due to the design limitations of this study, more detailed studies are needed to explore the relationship between specific lipids and clinical outcomes.
      During the ex vivo culturing of red blood cells (RBCs), the maintenance of RBC membrane integrity by adding cholesterol-rich lipids will reduce the incidence of hemolysis.
      • Bernecker C.
      • Köfeler H.
      • Pabst G.
      • et al.
      Cholesterol deficiency causes impaired osmotic stability of cultured red blood cells.
      Studies on wasp venom have shown that cholesterol can inhibit the haemolytic activity of melittin in a dose-dependent manner.
      • Raghuraman H.
      • Chattopadhyay A.
      Cholesterol inhibits the lytic activity of melittin in erythrocytes.
      HDL-C has pleiotropic properties such as anti-inflammatory, anti-apoptotic and antioxidant.
      • Tanaka S.
      • Couret D.
      • Tran-Dinh A.
      • et al.
      High-density lipoproteins during sepsis: from bench to bedside.
      Clinical findings have demonstrated that HDL-C levels decrease during the acute phase of inflammatory condition and especially during sepsis.
      • Cirstea M.
      • Walley K.R.
      • Russell J.A.
      • Brunham L.R.
      • Genga K.R.
      • Boyd J.H.
      Decreased high-density lipoprotein cholesterol level is an early prognostic marker for organ dysfunction and death in patients with suspected sepsis.
      In animal models of sepsis, HDL-C levels in the blood can be increased by supplementing with exogenous HDL-C or using cholesteryl ester transfer protein inhibitors, which can lower the inflammatory response and enhance survival in sepsis.
      • Trinder M.
      • Wang Y.
      • Madsen C.M.
      • et al.
      Inhibition of cholesteryl ester transfer protein preserves high-density lipoprotein cholesterol and improves survival in Sepsis.
      [
      • Barker G.
      • Leeuwenburgh C.
      • Brusko T.
      • Moldawer L.
      • Reddy S.T.
      • Guirgis F.W.
      Lipid and lipoprotein dysregulation in sepsis: clinical and mechanistic insights into chronic critical illness.
      ] The enteral or parenteral route of lipid administration to stabilise cholesterol levels could be a potential new way of treating wasp stings. An anti-inflammatory lipid injectable emulsion containing fish oil as parenteral nutrition for critically ill patients may prevent the decline of serum cholesterol levels and may be beneficial for modulating inflammation and improving patient outcomes.
      • Guirgis F.W.
      • Black L.P.
      • Rosenthal M.D.
      • et al.
      LIPid intensive drug therapy for Sepsis Pilot (LIPIDS-P): phase I/II clinical trial protocol of lipid emulsion therapy for stabilising cholesterol levels in sepsis and septic shock.
      Lipid-rich enteral nutrition can activate the vagal anti-inflammatory reflex, which can reduce inflammation and preserve intestinal integrity.
      • de Haan J.J.
      • Hadfoune M.
      • Lubbers T.
      • et al.
      Lipid-rich enteral nutrition regulates mucosal mast cell activation via the vagal anti-inflammatory reflex.
      However, few studies on enteral or parenteral nutrition with lipids for patients with wasp stings are available. Based on the anti-haemolytic effect of cholesterol and the sepsis-like effect in severe wasp stings, we boldly speculate that targeting lipid metabolism may be a potential strategy for the future treatment of wasp stings.
      This research has some limitations. Firstly, this study only focused on laboratory results within 24 h of admission, but did not analyse continuous changes. Therefore, the subsequent changes in lipids and their relationship with the prognosis remain unclear. Additional studies are needed to clarify the mechanism behind the decrease in serum lipids. Secondly, as this study was a single-centre retrospective observational study, general applicability may be lacking. Thus, a larger-scale, multicentre, prospective study is warranted, and further discussions of the pathophysiological mechanisms and clinical significance of wasp stings will be needed from the perspective of lipid metabolism.

      Conclusions

      Collectively, our study showed that the development of hypolipidemia can start in patients at the early stage of the disease, which may be related to hemolysis and inflammatory reaction. The extent of the decrease in lipid levels is related to disease severity. Early blood lipid levels can be used as inexpensive and accessible indicators of the severity of wasp stings, and we suggest that lipid metabolism might be a new target for future treatment of wasp stings.

      Contribution statement

      Z.Q. and X.Y. supervised and designed the study. Z.Q. and J.Z. contributed to the data analysis. Z.Q., M.L., J.Z., and X.Y. performed the tests and collected the data. M.L. and X.Y. contributed to the manuscript writing and data interpretation.
      Revision of the manuscript for important intellectual content: all authors.
      Final approval of the version to be published: all authors.

      Declaration of Competing Interest

      The authors declare no conflict of interest.

      Acknowledgements

      The authors declare no acknowledgements.

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