Acute Kidney Injury Associated with Severe Leptospirosis: Fatal Re-Emerging Disease in Latin America

Round 1

Reviewer 1 Report

Article titled " Acute kidney injury associated with severe leptospirosis: fatal re-emerging disease in Latin-America" addressed the leptospirosis in south America  

Authors described the organism causing infection and different manifestation of disease.

Comments:

Title: as all articles which used for the current written manuscript is from three countries in south America region, I recommend authors to address the name of the countries in title instead of Latin-America.

Body of article:

Article is well organized and it has good writing until the page five. From page six there are mistakes and writing issues that have to be correct.  

for examples:

Line 226: “(Jarisch reaction). Herxheimer) “

Lines 229-231: “Furthermore, it contributes to the clinical recovery of critically ill patients and the significant reduction in mortality in cases of severe complicated leptospirosis and associated multiple organ failure “

Lines 249-252 “In patients with severe ARDS in conditions of refractory hypoxemia, successful cases have been described with the use of extracorporeal membrane oxygenation therapy [85–87] in patients with severe leptospirosis and multiple organ dysfunction.

Lines 281, 327, and 331: please do not used symbols for numbers less than ten

Moderate corrections are needed. 

Author Response

Best regard

Our team is grateful for the review carried out, which was an opportunity, and improve the quality of the manuscript. The above describes the adjustments made for each suggestion made.

1. Title: as all articles which used for the current written manuscript is from three countries in south America region, I recommend authors to address the name of the countries in title instead of Latin-America.

• We consider that we can maintain the expression Latin America in the title, because in the literature search and selection, all Latin American countries were included under what is described in the methods section.

     2. Line 226: “(Jarisch reaction). Herxheimer) “

• Jarisch–Herxheimer reaction

     3. Lines 229-231: “Furthermore, it contributes to the clinical recovery of critically ill patients and the significant reduction in mortality in cases of severe complicated leptospirosis and associated multiple organ failure “

• In addition, it favors clinical recovery and a significant reduction in mortality in critically ill patients.

     4. Lines 249-252 “In patients with severe ARDS in conditions of refractory hypoxemia, successful cases have been described with the use of extracorporeal membrane oxygenation therapy [85–87] in patients with severe leptospirosis and multiple organ dysfunction..

• In patients with severe ARDS in conditions of refractory hypoxemia and multiple organ dysfunction, successful cases have been described with the use of extracorporeal membrane oxygenation therapy.

    5. Lines 281, 327, and 331: please do not used symbols for numbers less than ten

• The percentage value of line 281 is removed. 327 and 331 no symbols are evident. However, the symbols on line 329 are adjusted.

Reviewer 2 Report

In the manuscript “Acute kidney injury associated with severe leptospirosis: re-emerging fatal disease in Latin America”, Osorio-Rodríguez et al. aimed to highlight AKI due to Leptospirosis, presenting a review of the clinical aspects in addition to describing the scientific, clinical and therapeutic evidence of acute kidney injury attributed to Leptospira spp. and emphasize its relevance in patients with severe leptospirosis in Latin America.

The authors address a topic of great impact to the region, however there are some points that must be considered before the manuscript is accepted for publication.

Leptospirosis is a peculiar model of human AKI that results from the peculiar pathophysiological phenomena involved in this bacterial zoonosis. If some aspects linked to bacteria were exposed in the text, there is other stronger scientific evidence consolidated in the literature that was not considered and should not fail to be included.

Major Issues:

1)      Renal histopathological studies of human AKI due to leptospirosis show two pathological patterns that can occur together or separately: tubulointerstitial nephritis and/or acute tubular necrosis. The assumptions for the pathophysiological basis of tubulointerstitial nephritis are related to the Lip32 outer membrane fraction, as explained in detail in the manuscript. However, there are cytotoxicity phenomena present in leptospirosis that are potentially ubiquitous, not exclusively limited to renal tissue and that are related to another component of the leptospiral outer membrane, the GLP fraction. In renal tubular epithelium, this form of cytotoxicity induces acute tubular necrosis and compromises the entire tubular transport system along the nephron, being notably related to hypokalemia and other peculiar hydro electrolyte disorders.

2)      Numerous experiments in the literature carried out with intact kidney cells, tubular segments or purified enzymes from various tissues, from different species, show that GLP endotoxin fraction interacts molecularly and specifically with different isoforms of the Na,K-ATPase enzyme, causing organic dysfunctions whose manifestations are highly compatible with most of the symptoms of leptospirosis. As the manuscript intends to highlight the update of the AKI attributed to Leptospira spp. the lack of this information compromises the understanding of the topic.

3)      On the other hand, the phenomena of albuminemia and lipotoxicity have been used as significant determinants for the clinical outcomes in patients with Leptospirosis, including those with critical lung injuries caused by Adult Respiratory Distress Syndrome.

4)      Line 73 – “Recovery of kidney function may take several months, however, AKI exposure from severe leptospirosis can lead to long-term end-stage kidney disease [18].” – The reference does not support this statement.

5)      Line 95 – “Leptospira spp. colonization of the kidney can cause tubulointerstitial nephritis followed by fibrosis, and if not treated in time it culminates in chronic kidney disease [25]” – This is currently a hypothesis, not an established statement.

6)      Line 100 – “This generates an ideal alkaline microenvironment for bacterial replication and to last longer in the kidney tissue [26]”. The reference does not support this statement.

7)      Line 105 – “Once the attack occurs, interleukin 34 (IL-34) is released, a cytokine that drives greater destruction of tubular cells, and migration of macrophages and fibroblasts to kidney tissue [31]”. This is an over speculation for human leptospirosis AKI.

8)      Line 110 – “also reducing the sodium/hydrogen ion exchanger and aquaporin 1 (AQP-1) in the apical and basolateral membrane [27].”  The reference does not support this statement.

9)      Line 127- “In particular, this stimulates the mediator of tubulointerstitial fibrosis (STAT3 transcription factor), which increases the secretion of transforming growth factor beta 1 (TGF-β1) and the production of type II and IV collagen that contribute to the progression of kidney disease. [38,39]”. This is an over speculation for human leptospirosis AKI.

10)   Line 131 – “After this, the residual and functional nephrons enter into a maladaptive compensation process to replace the work of the glomeruli and tubules injured by this microorganism [40]. Damaged tubular cells enter a phase of structural and functional repair. If the degree of inflammation is chronic and severe, it can favor the invasion of immune cells, abnormal migration of fibroblasts, and lead to fibrosis [40,41].” This is an over speculation for human leptospirosis AKI.

11)  To assist in the rapid diagnostic of AKI in leptospirosis, there is a portable tool (doi.org/10.1371/journal.pntd.0006285 F), which allows the diagnosis of leptospirosis in 20 minutes by finger stick at the bedside.

12)   It is also important to inform in the text that the general AKI biomarkers mentioned are not specific for leptospirosis AKI.

13) Because paradoxical hypokalemia is often present in patients with this type of AKI, the kaliuretic diuretics, prolonged dialysis methods, and CRRT mentioned in text should be used with caution.

Author Response

Best regard

Our team is grateful for the review carried out, which was an opportunity, and improve the quality of the manuscript. The above describes the adjustments made for each suggestion made.

1. Renal histopathological studies of human AKI due to leptospirosis show two pathological patterns that can occur together or separately: tubulointerstitial nephritis and/or acute tubular necrosis. The assumptions for the pathophysiological basis of tubulointerstitial nephritis are related to the Lip32 outer membrane fraction, as explained in detail in the manuscript. However, there are cytotoxicity phenomena present in leptospirosis that are potentially ubiquitous, not exclusively limited to renal tissue and that are related to another component of the leptospiral outer membrane, the GLP fraction. In renal tubular epithelium, this form of cytotoxicity induces acute tubular necrosis and compromises the entire tubular transport system along the nephron, being notably related to hypokalemia and other peculiar hydro electrolyte disorders. 

R/- The action of LPG in AKI is described, according to the reviewer's suggestions.

2. Numerous experiments in the literature carried out with intact kidney cells, tubular segments or purified enzymes from various tissues, from different species, show that GLP endotoxin fraction interacts molecularly and specifically with different isoforms of the Na,K-ATPase enzyme, causing organic dysfunctions whose manifestations are highly compatible with most of the symptoms of leptospirosis. As the manuscript intends to highlight the update of the AKI attributed to Leptospira spp. the lack of this information compromises the understanding of the topic.

R/- The action of GPL in AKI is described, according to the reviewer's suggestions.

3. On the other hand, the phenomena of albuminemia and lipotoxicity have been used as significant determinants for the clinical outcomes in patients with Leptospirosis, including those with critical lung injuries caused by Adult Respiratory Distress Syndrome.

R/- The effect of lipotoxicity and hypoalbuminemia is described at the reviewer's suggestion.

4. Line 73 – “Recovery of kidney function may take several months, however, AKI exposure from severe leptospirosis can lead to long-term end-stage kidney disease [18].” – The reference does not support this statement.

R/- The bibliography was modified according to what was suggested by the reviewer.

5. Line 95 – “Leptospira spp. colonization of the kidney can cause tubulointerstitial nephritis followed by fibrosis, and if not treated in time it culminates in chronic kidney disease [25]” – This is currently a hypothesis, not an established statement.

R/- The statement continues and a new bibliography is added with the findings in the following works. A study found that through a multistage cross-sectional community survey and a cohort in the endemic city, an association between leptospira infection and chronic kidney disease was established (doi: 10.1371/journal.pntd.0004105). On the other hand, a case report in a young patient with severe leptospirosis and need for hemodialysis after 7 weeks of disease onset reported irreversible histopathological findings of interstitial fibrosis with tubular atrophy (doi: 10.1093/ndt/gfi014).

6. Line 100 – “This generates an ideal alkaline microenvironment for bacterial replication and to last longer in the kidney tissue [26]”. The reference does not support this statement.

R/- Phrase was withdrawn, due to not finding clinical evidence to support the hypothesis.

7. Line 105 – “Once the attack occurs, interleukin 34 (IL-34) is released, a cytokine that drives greater destruction of tubular cells, and migration of macrophages and fibroblasts to kidney tissue [31]”. This is an over speculation for human leptospirosis AKI.

R/- The sentence is modified and supported with clinical evidence.

8. Line 110 – “also reducing the sodium/hydrogen ion exchanger and aquaporin 1 (AQP-1) in the apical and basolateral membrane [27].”  The reference does not support this statement.

R/- The bibliography was modified according to what was suggested by the reviewer.

9. Line 127- “In particular, this stimulates the mediator of tubulointerstitial fibrosis (STAT3 transcription factor), which increases the secretion of transforming growth factor beta 1 (TGF-β1) and the production of type II and IV collagen that contribute to the progression of kidney disease. [38,39]”. This is an over speculation for human leptospirosis AKI.

R/- The sentence is modified and supported with clinical evidence.

10. Line 131 – “After this, the residual and functional nephrons enter into a maladaptive compensation process to replace the work of the glomeruli and tubules injured by this microorganism [40]. Damaged tubular cells enter a phase of structural and functional repair. If the degree of inflammation is chronic and severe, it can favor the invasion of immune cells, abnormal migration of fibroblasts, and lead to fibrosis [40,41].” This is an over speculation for human leptospirosis AKI.

R/-The sentence is modified and supported with clinical evidence.

11. To assist in the rapid diagnostic of AKI in leptospirosis, there is a portable tool (doi.org/10.1371/journal.pntd.0006285 F), which allows the diagnosis of leptospirosis in 20 minutes by finger stick at the bedside.

R/- In the diagnosis section, the detection methods for leptospirosis were included and the use of rapid tests was described, with their respective bibliographies.

12. It is also important to inform in the text that the general AKI biomarkers mentioned are not specific for leptospirosis AKI.

R/- It is described that the biomarkers are not specific to AKI leptospirosis.

13. Because paradoxical hypokalemia is often present in patients with this type of AKI, the kaliuretic diuretics, prolonged dialysis methods, and CRRT mentioned in text should be used with caution.

R/- The observation noted by the reviewer in our manuscript is described.

Reviewer 3 Report

This manuscript is a good review about the leprospirosis, especially the situration in Latin-America. Overall, the reviewing and writing is good. However, several minor comments and suggestions are listed in below:

1.     In Line 71, “In severe cases, these precede the abrupt drop in the glomerular filtration rate, associated with a severe hydro electrolyte imbalance [15]”. Please recheck the sentence.

2.     In Line 95-96. “ Leptospira spp. colonization of the kidney can cause tubulointerstitial nephritis followed by fibrosis, and if not treated in time it culminates in chronic kidney disease [25]”. One reference “PLoS Negl Trop Dis

. 2015 Oct 9;9(10):e0004105.” may be considered to be added in the manuscript.

3.     In Line 123-124, “Other factors that facilitate AKI are hyperbilirubinemia or myoglobinuria induced by rhabdomyolysis, release of free radicals, and increased blood viscosity obstructing the renal tubules [36].” Please confirm the description about increased blood viscosity obstruction the renal tubules ?

4.     In Line 149, “Hyponatremia is also notable in leptospirosis (frequency), however, together with hypokalemia it is characteristic of the disease [10]”. The word frequency is correct ?

5.     In the diagnosis section, the methods to diagnose leptospirosis may be reviewed. In addition, according to the study by Yang et.al., easily performed rapid immunoglobulin M serology assay is suitable as a rapid screening test for the diagnosis of leptospirosis (Shock. 2012 Jul;38(1):24-9). Because the assay is cheap and rapid, it may be suitable for early diagnosis of leptospirosis in Latin-America.

6.     The abbreviation about acute kidney injury (AKI) and chronic kidney disease (CKD) should be uniform in the manuscript.

Overall, minor revision is suggested about this manuscript.

I think overall is OK. 

Author Response

Best regard

Our team is grateful for the review carried out, which was an opportunity, and improve the quality of the manuscript. The above describes the adjustments made for each suggestion made.

1. In Line 71, “In severe cases, these precede the abrupt drop in the glomerular filtration rate, associated with a severe hydro electrolyte imbalance [15]”. Please recheck the sentence.

R/- In severe cases, there may be a drop in glomerular filtration rate, severe electrolyte imbalance [15], and the need for renal replacement therapy (RRT) by up to 31.6% [16,17].

2. In Line 95-96. “ Leptospira spp. colonization of the kidney can cause tubulointerstitial nephritis followed by fibrosis, and if not treated in time it culminates in chronic kidney disease [25]”. One reference “PLoS Negl Trop Dis 2015 Oct 9;9(10):e0004105.” may be considered to be added in the manuscript.

R/- The bibliography was modified according to what was suggested by the reviewer.

3. In Line 123-124, “Other factors that facilitate AKI are hyperbilirubinemia or myoglobinuria induced by rhabdomyolysis, release of free radicals, and increased blood viscosity obstructing the renal tubules [36].” Please confirm the description about increased blood viscosity obstruction the renal tubules ?

R/- The sentence and bibliographic reference were modified.

4. In Line 149, “Hyponatremia is also notable in leptospirosis (frequency), however, together with hypokalemia it is characteristic of the disease [10]”. The word frequency is correct ?

R/- The word frequency was removed.

5. In the diagnosis section, the methods to diagnose leptospirosis may be reviewed. In addition, according to the study by Yang et.al., easily performed rapid immunoglobulin M serology assay is suitable as a rapid screening test for the diagnosis of leptospirosis (Shock. 2012 Jul;38(1):24-9). Because the assay is cheap and rapid, it may be suitable for early diagnosis of leptospirosis in Latin-America.

R/- In the diagnosis section, the detection methods for leptospirosis were included and the use of rapid tests was described, with their respective bibliographies.

6. The abbreviation about acute kidney injury (AKI) and chronic kidney disease (CKD) should be uniform in the manuscript.

R/-Acronyms for acute kidney injury and chronic kidney disease are adjusted.

Round 2

Reviewer 1 Report

I found your manuscript interesting 

Author Response

Our team thanks the comments, valuable review

Reviewer 2 Report

Although this new version of the manuscript is technically improved, some issues described below need to be revised before the article is suitable for publication.

Line 58 -  However, the definitive diagnosis is made by detecting Leptospira in culture  samples [6].  This statement does not correspond to clinical practice where serology and PCR are the most used tools to diagnose leptospirosis.

Line 97 -  Once Leptospira spp. enters the body, it can cause direct nephrotoxicity, altering the sodium/phosphate cotransporter in the proximal tubule, which favors the generation of ammonia and an increase in pH [10].  

suggestion for rewriting

Once Leptospira spp. enters the body, it can cause direct nephrotoxicity, altering the sodium/phosphate cotransporter in the proximal tubule, which favors the generation of ammonia and an increase in urinary pH [10].  

In Figure 1  - correction of Na/K-ATPase instead of Na/K-ATAasa

Line 104 - GLP: correction of Glycolipoprotein instead of Glycoprotein

Line 118 -  Na/K-ATPase pumps, which alters their functioning by inhibiting their  expression.

Correction: Na/K-ATPase pumps, which alters their functioning by inhibiting their activity

Line 133  - Glycolipoprotein instead of Glycoprotein (GLP) is an endotoxin with the capacity to store fatty acids …

Line 134 -  Its main characteristic is its  specificity for the Na/K-ATPase pump receptor [41], on the cytosolic surface of cell membranes through the action of its lipid component on the cell membrane (oleic acid) and the poor adsorption of the albumin toward these fatty acids [42–44]

Its main characteristic is its specificity for the Na/K-ATPase pump affinity

Line 162 - Acute interstitial nephritis is the main pathological change in patients with leptospirosis even in the absence of AKI.

Acute tubular nephritis in addition to acute interstitial nephritis are the main pathological findings.

Line 178 - However, the definitive diagnosis is made by detecting Leptospira in culture samples [6]. PCR tests remain important, but they are expensive and difficult to apply in our region [10].

This phrase already described previously is repeated in the text and should be deleted.

Line 185 -  RIFLE and AKIN stages are good markers to stratify the severity of patients with leptospirosis [64]

These criteria are not markers but scores to aid clinical decision making.

Table 1-  The table is very confusing and should be redone in order to better display the data

Ref 41 - outside the standard format of other references

Author Response

Our team thanks the comments, valuable review

• Line 58 -  However, the definitive diagnosis is made by detecting Leptospira in culture  samples [6].

The paragraph was modified according to what was suggested by the review

• Line 97 -  Once Leptospira spp. enters the body, it can cause direct nephrotoxicity, altering the sodium/phosphate cotransporter in the proximal tubule, which favors the generation of ammonia and an increase in pH [10].  -

The paragraph was modified according to what was suggested by the review

• In Figure 1  - correction of Na/K-ATPase instead of Na/K-ATAasa

- Was modified according to what was suggested by the review

• Line 104 - GLP: correction of Glycolipoprotein instead of Glycoprotein

- The paragraph was modified according to what was suggested by the review

• Line 118 -  Na/K-ATPase pumps, which alters their functioning by inhibiting their  expression.

- The paragraph was modified according to what was suggested by the review

• Line 133  - Glycolipoprotein instead of Glycoprotein (GLP) is an endotoxin with the capacity to store fatty acids …

- The paragraph was modified according to what was suggested by the review

• Line 134 -  Its main characteristic is its  specificity for the Na/K-ATPase pump receptor [41], on the cytosolic surface of cell membranes through the action of its lipid component on the cell membrane (oleic acid) and the poor adsorption of the albumin toward these fatty acids [42–44]

- The paragraph was modified according to what was suggested by the review

Line 162 - Acute interstitial nephritis is the main pathological change in patients with leptospirosis even in the absence of AKI.

- The paragraph was modified according to what was suggested by the review

• Line 178 - However, the definitive diagnosis is made by detecting Leptospira in culture samples [6]. PCR tests remain important, but they are expensive and difficult to apply in our region [10].

- The paragraph was modified according to what was suggested by the review

• Line 185 -  RIFLE and AKIN stages are good markers to stratify the severity of patients with leptospirosis [64]

- The paragraph was modified according to what was suggested by the review

• Table 1-  The table is very confusing and should be redone in order to better display the data

- Was modified according to what was suggested by the review

• Ref 41 - outside the standard format of other references

- Was modified according to what was suggested by the review

Reviewer 3 Report

I think the responses and revision is acceptable. No more comment is addressed. 

Author Response

Our team thanks the comments, valuable review